Research
INDEX
RECENT RESEARCH
(FFRL investigators within a mixed group are underlined)
Production of better flies to be used in the Fruit Fly Production Facility.
S Gilchrist and A Meats.
Funding: HAL industry grant and ARC Linkage with Riverina Citrus and Central Darling Shire and the DPIs of South Australia, Victoria and NSW.
Synopsis: Up until now, the strain used in the Factory has been quite inbred. This inbreeding has been a problem even when new flies from the wild are bought into the Factory, as our DNA microsatellite studies have shown.
We are using traditional animal breeding techniques to show that it is simple to construct 4-way hybrids that perform better than the Factory flies. The hybrids are as productive as the Factory flies but more hardy. At the moment, we are doing mass-release trials to see how dispersal of the two types of fly compare. With equivalent survival rates, dispersal becomes the next most important parameter for successful SIT. At the same time, we are developing new genetic markers for future Factory strains that will speed up DNA identification of sterile and wild flies at least 10 times.
Creation of non-GMO genetically marked strains of B. tryoni
S Gilchrist
Funding: HAL industry grant and ARC Linkage with DPIs of South Australia, Victoria and NSW, Riverina Citrus and Central Darling Shire.
Synopsis: We have developed genetic marker for B. tryoni by transferring B. jarvisi mitochondrial DNA into B. tryoni. This is possible because, although B. tryoni and B. jarvisi are distinct species by morphological and DNA sequence criteria, they will mate in the lab to produce fertile offspring and the F1 hybrids will mate successfully with both parent species. Through single pair matings of B. tryoni males with B. jarvisi females and subsequent backcrossing to B. tryoni males for six generations, we have developed two lines of B. tryoni marked with B. jarvisi mitochondrial DNA. We are currently testing the longer-term stability of the jarvisi mitotype and developing a simple molecular test for the identification of the jarvisi mitotype in the tryoni background. These two strains were developed by conventional breeding and are therefore considered to be non-GMO strains. This approach will provide a more robust genetic marker than the microsatellite markers described in our original grant application since the jarvisi mitotype will be unique to the SIT release strain. There is always a possibility that a rare microsatellite marker will be present in trapped wild flies tested alongside released and recaptured sterile flies. The role of PIRSA and Victorian Dept. Ag is to test a simple molecular protocol for the detection of the jarvisi mitotype. Carry out field release, recapture and PCR tests of sterile flies.
Development of genetic transformation protocols for Qfly
Kathie Raphael, Debora Shearman and Marianne Frommer.
Funding ; ARC Linkage with DPIs of South Australia and Victoria., Griffith Council.
Synopsis: We have achieved genetic transformation of B. tryoni by microinjection of two piggyBac vectors, one marked with the fluorescent protein EGFP the other with DsRed. Transformation frequency is good - a minimum of 5.6% with the EGFP vector and 8.6% with the DsRed vector. Expression of the fluorescent proteins is strong, meaning that it is easy to detect with fluorescence microscopy. We obtained 6 fertile lines with the DsRed vector and 9 fertile lines with the EGFP vector. We are in the process of establishing homozygous (pure breeding) lines for each of these and we are developing a DNA test that will characterise the insertion sites. Recently, technology that enables site-specific integration of transgenes has been developed for D. melanogaster, and we plan to use this for B. tryoni. It has the potential to substantially increase transformation frequency and enable the comparison of different transgenes at the same insertion site.
Developing the technology for the construction of a male-only strain of Qfly. Kathie Raphael, Debora Shearman and Marianne Frommer.
Funding ; ARC Linkage with DPIs of South Australia and Victoria., Griffith Council.
Synopsis: Isolation of sex-determination genes tra and tra2 cDNA and genomic sequences is nearing completion. Experiments are underway to characterise embryonic expression patterns. This will contribute to our understanding of gene expression during the critical period when sex is being established in the embryo and enable us to design strategies for manipulating the sex-determination pathway for generating male-only strains. It will also provide information as to the timing of expression of M, the dominant male determiner on the Y chromosome, which is at the top of the sex determination pathway in Tephritid fruit flies.
Push-pull behavioural control of tephritid fruit flies in domestic gardens and PNG village agriculture.
Farman Ullah, A. Meats and G.A.C. Beattie
Funding ; ACIAR and Baxter Charitable Trust
Synopsis: We have tested various attractants and repellants on Qfly in the laboratory using still and moving air olfactometry and EAG technology. Field trials have started using push-pull designs in all possible combinations on small tomato crops and we have established that some designs are remarkably effective. Further field trials are now under way and trials with other fruit crops will follow.
Conservation of natural enemy fauna in citrus canopies by horticultural mineral oil: comparison with effects of carbaryl and methidathion treatments for armoured scale insects
W. G. Liang,1 A. Meats,2* G.A.C. Beattie,1 R. Spooner-Hart1 and L. Jiang1
Abstract: The disruptive effects of an nC24 horticultural mineral oil (HMO) and two other insecticides (carbaryl and methidathion) on two armoured scale insects and natural enemy fauna were evaluated in two citrus orchards. In the first orchard, all three spray treatments and non-sprayed controls were distributed separately among individual trees in one block whereas in the second orchard the control, HMO and methidathion treatments were applied at the level of whole blocks. The results in both orchards were similar. All three of the spray treatments had a lethal effect on the red scale insects and the effects of the two tested at the second site lasted for at least one year. HMO did not have a significant effect on the abundance and species diversity of parasitoids, coccinellids and predatory mites whereas both carbaryl and methidathion significantly reduced abundance and diversity. In most cases, there appeared to be no advantage in using high volume rather than low volume sprays or in spraying twice rather than once, indicating that water savings of up to 16,000 L/ha can be made. No treatment resulted in the resurgence of the scale insects or the outbreak of phytophagous mites even where whole blocks were sprayed.
Multiple mating by females of two Bactrocera species (Diptera: Tephritidae: Dacinae)
A. Chinajariyawong, R.A.I. Drew, A. Meats, S. Balagawiand S. Vijaysegaran
Abstract: Under laboratory conditions, wild females of Bactrocera cacuminata (Hering) reared from field collected fruits of Solanum mauritianum Scopoli lived for up to 134 days and mated up to three times with refractory periods between matings averaging 27-39 days. Laboratory reared females of Bactrocera cucumis (French) lived up to 274 days and refractory periods averaged 59-63 days. However, the distribution of matings among B. cucumis females was not significantly different to that expected by chance. The distribution of the number of matings among females of B. cacuminata was non-random because of the high proportion of non-maters (50%) but when only females mating more the once were considered, there was no significant departure from random expectation. Most B. cucumis females began oviposition after the first mating and mated females produced significantly more eggs than unmated ones.
Bacteria as food had no effect on fecundity during domestication of the fruit fly, Bactrocera tryoni.
Meats A, Streamer K, Gilchrist AS (2009) Journal of Applied Entomology 133: 633-639.
Abstract: Adult Bactrocera tryoni from different generations of domestication were given various diets to determine whether either or both the bacteria Klebsiella oxytoca and Klebsiella pneumoniae could provide a source of proteinaceous material sufficient to allow the female flies to produce mature oocytes and eggs or alternatively, whether the bacteria could act as a beneficial supplementary food when given in addition to the usual laboratory proteinaceous food that consisted of a paste of sucrose and yeast autolysate. Overall, there was no evidence from any generation studied that female flies could produce eggs or mature oocytes on a bacterial diet above the levels attained with access to culture medium without bacteria. Similarly, there was no evidence that bacterial supplementation to a diet that included a paste of sucrose and yeast autolysate was more beneficial than when the paste was the sole source of proteinaceous food. There was an increase in mature oocytes per female with the number of generations of culture but the extent of increase was greater when sugar/yeast paste was included in the diet. There was no evidence that mixtures of either bacterium species in nutrient broth or the broth itself was attractive to female B. tryoni over a distance of a few centimetres when the tested flies were caged at low density but flies of later generations did feed when offered either type of food at very close range.
Correlation measures for linkage disequilibrium within and between populations.
Sved JA (2009) Genetics Research 91, 183-192.
Abstract: Correlation statistics call be used to measure the amount of linkage disequilibrium (LD) between two loci in subdivided Populations. Within Populations, the square of the correlation of gene frequencies, r(2), is a convenient measure of LD. Between populations, the statistic r(i)r(j), for Populations i and j, measures the relatedness of LD. Recurrence relationships for these two parameters are derived for the island model of population subdivision, under the assumptions of the linked identity-by-descent (LIBD) model in which correlation measures are equated to probability measures. The recurrence relationships closely predict the build-up of r(2) and r(i)r(j) following Population Subdivision in computer simulations. The LIBD model predicts that a steady state will be reached with r(2) equal to 1/[1 +4N(e)c(1 + (k - 1)rho)], where k is the number of island Populations, N-e is the effective local Population (island) size, and rho measures the ratio of migration (m) to recombination (c) and is equal to m/[c(k- 1) + m]. For low values of m/c, rho =0, and E(r(2)) is equal to 1/(1 +4N(e)c). For high values of m/c, rho = 1, and E(r(2)) is equal to 1/(1 +4k N(e)c). The value of r(i)r(j) following separation eventually settles down to a steady state whose expectation, E(r(i)r(j)), is equal to E(r(2)) Multiplied by p. Equations predicting the change in r(i)r(j) Values are applied to the separation of African (Yoruba - YR1) and non-African (European - CEU) populations, using data from Hapmap. The primary data lead to an estimate of separation time of less than 1000 generations if there has been no migration, which is around one-third Of minimum current estimates. Ancient rather than recent migration call explain the form of the data.
Relative toxicity of nC24 agricultural mineral oil to Tetranychus urticae Koch (Acari: Tetranychidae) and Phytoseiulus persimilis Athias-Henriot (Acari: Phytoseiidae) and its relationship to egg ultrastructure.
Yingen Xue, G Andrew C Beattie, Alan Meats, Robert Spooner-Hart and Grant A Herron (2009). Aust J. Entomol. 48: 251-257.
Abstract: Two-spotted mite (TSM) Tetranychus urticae Koch is a major pest of agriculture and its predator Phytoseiulus persimilis Athias-Henriot is used in farming systems for its control. However, effective predator / prey ratios often require adjustment with sprays and mineral oils are ideal for such use in sustainable integrated pest management (IPM) programs. Although mineral oils are used in IPM, the relative selectivity of mineral oils between TSM and P. persimilis is not well understood. Here, we evaluated the relative toxicity (LC50 values based on μg oil/cm2) of aqueous nC24 agricultural mineral oil (AMO) emulsions to the egg, six-legged nymph (larva), eight-legged protonymph and adult stages of TSM and P. persimilis in situ, on French bean Phaseolus vulgaris L. cv. Redlands Pioneer leaf discs, using a Potter spray tower to apply of the oil. The egg of P. persimilis was the least susceptible stage (LC50 444.84) and its LC50 was significantly higher than all other stages tested of either P. persimilis or TSM. The LC50 for adult female TSM (LC50 63.89) was significantly lower than the larva (LC50 93.86), however, there was no significant difference in response between the protonymph (LC50 70.44) and the larva, which were both higher than TSM eggs (LC50 17.55). LC50s for P. persimilis larva (LC50 43.87), protonymph (LC50 41.55) and adult female (LC50 53.34) were similar. Photomicrographs taken by an environmental scanning electron microscope showed that the egg surface of TSM is usually well covered with fine silk that may trap more oil and increase AMO efficacy. Other possible differences in AMO efficacy between TSM and P. persimilis may be due to differences in egg size, egg incubation period, egg surface structure and the presence of vulnerable respiratory cones in TSM eggs. We consider the most appropriate doses for nC24 AMOs for use against TSM in combination with P. persimilis in IPM programs would be 0.2-0.3% (w/w).
Impact of nC24 agricultural mineral oil deposits on the searching efficiency and predation rate of the predatory mite Phytoseiulus persimilis Athias-Henriot (Acari: Phytoseiidae) Aust J. Entomol. 48: 258-264.
Yingen Xue, G Andrew C Beattie, Alan Meats, Robert Spooner-Hart and Grant A Herron (2009).
Abstract: Walking activity, straightness, speed, and searching efficiency of the predatory mite Phytoseiulus persimilis Athias-Henriot were measured on French bean leaf discs that were sprayed with either distilled water, or one of 0.25%, 0.50% and 1.00% w/w aqueous emulsions of an nC24 agricultural mineral oil (AMO). There was no significant difference in percentage of time that mites spent walking in the control (water sprayed) conditions and in any of the oil treatments. Walking straightness on control discs was significantly less than in the oil treatments, but differences among the oil treatments did not differ significantly. Walking speeds in the oil treatments were significantly slower in the oil treatments than in the control and decreased with increasing oil concentration. Deposits of oil at all concentrations significantly suppressed searching efficiency in comparison with control, and searching efficiency in the 1.00% oil treatment was significantly lower than in the 0.25% oil treatment. First predation of P. persimilis on AMO-contaminated eggs of two-spotted mite (Tetranychus urticae Koch) (TSM) on unsprayed leaf discs, was significantly delayed in all oil treatments in comparison with the control. However there was no significant effect on the overall predation rate. In the tests of P. persimilis predation on AMO-contaminated TSM eggs on sprayed leaf discs, the number of first predation occurrences in the first hour was significantly lower in 0.50% and 1.00% oil treatments than in the control. Overall predation rates were significantly reduced by oil but they did not differ significantly among the oil treatments.
The influence of sublethal deposits of agricultural mineral oil on the functional and numerical responses of Phytoseiulus persimilis Athias-Henriot (Acari: Phytoseiidae) to its prey, Tetranychus urticae Koch (Acari: Tetranychidae),
Yingen Xue, Alan Meats G Andrew C Beattie, Robert Spooner-Hart and Grant A Herron (2009) Experimental and Applied Acarology 48, 291-302.
Abstract: The phytoseiid predatory mite Phytoseiulus persimilis Athias-Henriot exhibited Type II functional responses to adult two-spotted spider mite (TSM) Tetranychus urticae Koch adult TSM in both control conditions and in a treatment with a sub lethal dose of agricultural mineral oil (AMO) on excised leaf discs. The asymptote of the functional response was significantly higher in the AMO conditions but this was due to the fact that prey grew slower and reached a smaller size in this treatment. In terms of prey volume eaten, the satiation level of the predator was unchanged by the AMO deposits. The numbers of eggs produced by adult P. persimilis females at densities of 4, 8 and 16 TSM adult females/disc in the control were significantly more than those in the AMO treatment, but were similar for the higher density levels, 32 and 64 prey per disc.
Properties of re-arranged P elements in Drosophila melanogaster.
Liang X, Sved JA (2009). Heredity 102, 342-348
Abstract: P elements, both complete and incomplete, contain a left and right end, normally depicted as pointing away from each other. Here, we examine the properties of P elements that may be described as 're-arranged elements' or 'inside-out elements', containing inverted ends. Two such structures exist, having either ends pointing towards each other, 'head-to-head or H-H', or ends pointing in the same direction 'head-to-tail or H-T'. We show that both structures are unstable in the presence of P element transposase. For the H-H element there is a high frequency of deletion of the intervening material and almost exact rejoining of element ends with the 4 bp CATG palindromic end sequence shared by the two element ends. This result is predicted by the Beall and Rio model of P element excision. For the H-T element there is a high frequency of exact excision of the entire inverted right-end, a result again predicted by the Beall and Rio model. Both structures lead to recombination in the way expected from a normal element. The rates of recombination are, however, much lower than might be expected from the organization of ends, a result that can be explained in terms of the low likelihood of insertion into a chromosomal region lacking another P element end. We also investigate the properties of combinations of re-arranged and normal elements, and show that there is a directionality property when left and right ends are combined in trans that can be explained in terms of strand repair.
Linkage Disequilibrium and Its Expectation in Human Populations.
Sved JA (2009). Twin Research and Human Genetics. 12 : 35-43.
Abstract: Linkage disequilibrium (LD), the association in populations between genes at linked loci, has achieved a high degree of prominence in recent years, primarily because of its use in identifying and cloning genes of medical importance. The field has recently been reviewed by Slatkin (2008). The present article is largely devoted to a review of the theory of LD in populations, including historical aspects.
Repair of P element ends following hybrid element excision leads to recombination in Drosophila melanogaster.
Liang X, Sved JA (2009) Heredity 102: 127-132
Abstract: P elements are thought to replicate themselves starting with the association of the left and right ends, followed by a cut-copy-paste process. An abnormal form of this process has been shown to occur when the associated left and right ends come from sister elements rather than from the same element, leading to formation of a 'hybrid element.' These ends can insert nearby in the genome to produce recombination, with associated structural changes. We have previously increased the frequency of such 'hybrid element insertion' by combining end-deleted elements in trans in a genotype with a left-end on one chromosome and a right-end on the homologous chromosome. Although many recombinants produced by this genotype have structural changes expected with insertion, nearly 50% of the predicted insertional recombinants contain no structural change. We present evidence using RFLP markers closely linked to the end-deleted elements that in these cases the P element ends dissociate before insertion, and are subsequently ligated together following a process analogous to synthesis-dependent strand annealing. The results suggest that broken ends containing P elements are resolved by the same repair process as ends not containing P elements, and that such repair from hybrid element events may occur in the majority of cases.
Relation of constant, daily fluctuating, and ambient feeding temperature to daily and accumulated consumption of yeast autolysate and sucrose by female Queensland fruit fly.
Meats, A; Kelly, GL (2008) Entomologia Experimentalis et Applicata. 129, 87-95.
Abstract: Intake rates by the Queensland fruit fly, Bactrocera tryoni (Froggatt) (Diptera: Tephritidae), of yeast autolysate and sucrose were clearly related to temperature in constant thermal regimes, but consumption occurred only in light. In regimes of fluctuating temperature, rates of consumption were not necessarily related to the temperatures that prevailed during the photophase, but were more consistently related to daily mean temperature and best related to day degrees per day above the gonadotrophic threshold of 13.5 degrees C. Day degrees per day could be related to age-specific changes in the daily rate of yeast autolysate and sucrose consumption, the rate of accumulated consumption of these foods, and thus the time taken to consume the amount of yeast autolysate known to be required for the attainment of sexual maturity. Consumption rate changed within 1 or 2 days of a change between a gonadotrophic regime and a non-gonadotrophic one (or vice versa), which is consistent with the known rapid effects of temperature change on ovarian maturation.
Short- and long-range dispersal of the Queensland fruit fly, Bactrocera tryoni and its relevance to invasive potential, sterile insect technique and surveillance trapping.
Meats A, Edgerton JE (2008). Australian Journal of Experimental Agriculture 48, 1237-1245.
Abstract: Dispersal of immature and sexually mature Queensland fruit fly, Bactrocera tryoni (Froggatt) from releases made at a single point was assessed from recapture rates obtained by using arrays of traps. The recapture data (pertaining to distances up to 480 m) fitted both logarithmic and Cauchy models although the fits for the releases of immature flies were inferior because of high variability in catches at certain distances. When combined with data previously published for longer distances, a Cauchy model fitted data for releases of immature flies well and indicated that the median distance dispersed after emerging from the puparium was similar to 120 m and that 90% of flies would displace less than 800 m despite the fact that a consistent trend in declining catch rates can be obtained up to at least 85 km. This is consistent with the tail of the Cauchy distribution having a slope congruent with a negative power curve and thus being scale invariant for longer distances. The distribution of recaptured flies that were released as adults also fitted a Cauchy model with a tail of the same slope, suggesting that the spatial distribution of long-distance dispersers is not only scale invariant but also age invariant. This has significance to the ability of surveillance trapping arrays to detect infestations and also to methods of distributing insects for the sterile insect technique. Whereas the spread of invading propagules in the first generation is likely to be limited by a decline to non-viable density within 1 km or less of the incursion point, the influence of larger infestations on nearby uninfested regions would be limited by the longevity of the dispersers.
Seasonal dynamics, dispersion, sequential sampling plans and treatment thresholds for the citrus leafminer, Phyllocnistis citrella Stainton (Lepidoptera : Gracillariidae), in a mature lemon block in coastal New South Wales, Australia.
Liu, ZM; Meats, A; Beattie, GAC (2008). Australian Journal of Entomology 47, 243-250.
Abstract: Studies of citrus leafminer in a coastal orchard in NSW, Australia indicated that an increase in abundance to about one mine per flush was followed during the midseason flush by a rapid increase in population that was related to an increase in the percentage of leaves infested within flushes and the number of mines per leaf. The fits of frequency distributions and Iwao's patchiness regression indicated that populations were highly contagious initially, and as the exponent k of the negative binomial distribution increased with increasing population density, the distribution approached random. Concurrently, the coefficient of variation of mines per flush (which was strongly related to the proportion of un-infested flushes) decreased to about unity as the proportion of un-infested flushes reached zero and fell further as the number of mines per flush increased. Both numerative and binomial sequential sampling plans were developed using a decision threshold based on 1.2 mines per flush. The binomial sampling plan was based on a closely fitting model of the functional relationship between mean density and proportion of infested flushes. Functional relationships using the parameters determined from Iwao's patchiness regression and Taylor's power law were equally satisfactory, and one based on the negative binomial model also fitted well, but the Poisson model did not. The three best fitting models indicated that a decision threshold of 1.2 mines per flush was equivalent to 50% of flushes infested. From a practical point of view, the transition from 25% infestation of flushes through 50% is so rapid that it may be prudent to take action when the 25% level is reached; otherwise, the 50% may be passed before the crop is checked again. For valuable nursery stock should infestation be detected in spring, it may be advisable to apply prophylactic treatment as the midseason flush starts.
Foot mucus is a good source for non-destructive genetic sampling in Polyplacophora
Palmer ANS, Styan CA, Shearman DCA (2008) Conservation Genetics 9, 229-231.
Abstract: A non-destructive method for collecting samples for DNA analysis from the mucus of molluscs was successfully adapted for use with the genus Ischnochiton. DNA was extracted using a Chelex-based method and the COI subunit of the mtDNA was amplified and sequenced. Sequences from the mucus were crosschecked against sequences from the foot tissue of the same animal and were found to be identical. This method provides a non-destructive way of carrying out larger studies of the genetics of rare organisms and may be of general use for genetic-based field studies of molluscs.
Distribution and eradication of an exotic tephritid fruit fly in Australia: relevance of invasion theory.
Meats, A; Fay, HAC; Drew, RAI (2008) Journal of Applied Entomology. 132, 406-411.
Abstract: Data from the eradication of the incursion of Bactrocera papayae Drew and Hancock (Dipt.: Tephritidae) in Australia (1995-1998) are used to assess the significance of various aspects of invasion theory, including the influence of towns on establishment, influence of propagule pressure on the pattern of establishment, and the existence of source-sink dynamics. Because there were no sentinel traps in place, considerable spread had occurred before the eradication campaign started. The distribution of fly density around the epicentre in the town of Cairns and a transect along the main traffic routes to the north and south fitted a Cauchy model with a tail having the same slope as a power model with an exponent of -2.4 extending to 160 km. The Cauchy model indicated that 50% of the flies on the transect would have occurred within 3.2 km of the epicentre, 90% within 13.2 km, and 99% within 60 km. The two major satellites at Mareeba (35 km from the epicentre in Cairns) and Mossman (65 km) were not used for the transect data and had respectively 15 and 30 times the density predicted by the model. The proportion of traps that caught flies (a measure of site occupancy) fell with distance from the epicentre. B. papayae was trapped consistently on only three of the 16 rainforest transects that were surveyed and these were relatively close to urban areas where eradication efforts were intense. Despite there being no eradication effort in the rainforest, the trends to extinction were similar to those in adjacent areas. The strategy of initially concentrating eradication efforts on the core and major satellites while maintaining a quarantine barrier at the airport and the boundaries of the infested area appears to be the key to the containment and rapid eradication of the incursion.
Divergence between Human Populations Estimated from Linkage Disequilibrium.
Sved JA, McRae AF, ,Visscher PM (2008 American Journal Of Human Genetics. 83: 737-743.
Abstract: Observed linkage disequilibrium (LD) between genetic markers in different Populations descended independently from a common ancestral population can be used to estimate their absolute time of divergence, because the correlation of LD between populations will be reduced each generation by an amount that, approximately, depends only on the recombination rate between markers. Although drift leads to divergence in allele frequencies, it has less effect on divergence in LD values. We derived the relationship between LD and time of divergence and verified it with coalescent simulations. We then used HapMap Phase II data to estimate time of divergence between human populations. Summed over large numbers of pairs of loci, we find a positive correlation of LD between African and non-African populations at levels of up to similar to 0.3 cM. We estimate that the observed correlation of LD is consistent with an effective separation time of approximately 1,000 generations or similar to 25,000 years before present. The most likely explanation for such relatively low separation times is the existence of substantial levels of migration between populations after the initial separation. Theory and results from coalescent simulations confirm that low levels of migration can lead to a downward bias in the estimate of separation time.
2007 PAPERS PUBLISHED
Short-range dispersal of recently emerged males and females of Bactrocera tryoni (Froggatt) (Diptera : Tephritidae) monitored by sticky sphere traps baited with protein and Lynfield traps baited with cue-lure.
Weldon, C; Meats, A (2007) Australian Journal of Entomology 46: 160-166.
Abstract: Dispersal of immature male and female Queensland fruit fly, Bactrocera tryoni (Froggatt) (Diptera: Tephritidae), was assessed over a period of 1 week from a single release point on three separate occasions using an array of Lynfield traps baited with cue-lure and odouriferous yellow or black sticky spheres baited with food lure (protein autolysate). Lynfield traps recaptured males; yellow or black spheres recaptured both sexes in approximately equal proportions, although at a much lower rate. As a percentage of the recapture rate for males by Lynfield traps, the mean recapture rate for yellow spheres ranged from 1.0% to 7.5% for males and 0.7% to 4.0% for females, whereas the recapture rates for black spheres ranged from 0.4% to 3.6% and 0.6% to 1.8%, respectively. The rate of recapture of sterile male flies was greater than that of unsterilised flies; this may have been due to a faster maturation rate in sterile males or because a greater proportion of them remained within the trap array rather than dispersing. There was no significant trend in recapture rate with distance from the release point to the edge of the array (88 m), except in the case of females on sticky traps where no trend was detected between 19 and 88 m. These results lend support to assumptions made about the distribution of males and females with respect to the minimum breeding density of fruit fly propagules invading a fly-free zone, and the method chosen to distribute sterile B. tryoni for the sterile insect technique.
Impact on soil-dwelling arthropods in citrus orchards of spraying horticultural mineral oil, carbaryl or methidathion
Liang, WG; Beattie, GAC; Meats, A, et al (2007). . Australian Journal of Entomology 46: 79-85.
Abstract: Impacts of an nC24 horticultural mineral oil (HMO) and two synthetic insecticides (carbaryl and methidathion) on the abundance and species diversity of soil-dwelling arthropods were evaluated in two citrus orchards in the coastal region of New South Wales, Australia. In the first orchard, mature Valencia orange trees were sprayed in summer with one of HMO, carbaryl or methidathion delivered at low (2000 L/ha) or high (10 000 L/ha) volumes; the sprays were applied either once (February) or twice (December and February). HMO had no significant impact but the synthetic insecticides, irrespective of spray frequency or spray volume, significantly reduced the abundance and species diversity of the arthropods including springtails and generalist predators, such as spiders, staphylinid beetles and mesostigmatid mites. In the second orchard, blocks of Washington navel and Valencia orange trees were sprayed with either HMO or methidathion; sprays were applied twice, 2 weeks apart, in late summer (February), first at a rate of 6500 L/ha and second at 5500 L/ha. Results were similar to those in the first orchard, except that the effect of methidathion on carabid beetles and ants was not significant.
Short- and long-range dispersal of medfly, Ceratitis capitata (Dipt., Tephritidae), and its invasive potential.
Meats, A; Smallridge, CJ (2007) Journal Of Applied Entomology 131: 518-523.
Abstract: Data were obtained from mark recapture trials pertaining to the dispersal of medfly, Ceratitis capitata (Dipt., Tephritidae), over both short (10-160 m) and very long distances (0.5-9.5 km) within the surveillance trapping array in Adelaide, Australia. They could be related to previously reported data sets by expressing the capture rates of each set in common terms that corrected for differences in recapture rate resulting from type of trap, season or climate. The mean capture rate at each distance from the point of release in each data set was expressed as a percentage of the real or inferred rate of that set at a distance of 100 m. The resulting distribution of dispersal distances conformed to both an inverse power model and a modified Cauchy model regardless of whether the present and previous data were combined or not. The modified Cauchy model inferred that the median distance flown was extremely short and 90% of flies displaced only 400-700 m despite the fact that a consistent trend in declining catch rates was obtained up to 9.5 km. The spread of invading propagules in quarantined zones in the first generation is likely to be limited by a decline to non-viable density within 1 km or less of the incursion point and the spread of larger infestations could be limited by the longevity of the dispersers. The results also have significance to the ability of surveillance trapping arrays to detect infestations and also to methods of distributing insects for the 'sterile insect technique'.
Behavioural responses of female Queensland fruit fly, Bactrocera tryoni, to mineral oil deposits.
Nguyen, VL; Meats, A; Beattie, GAC, et al. (2007) Entomologia Experimentalis et Applicata. 122: 215-221.
Abstract: Behavioural responses of Queensland fruit fly, Bactrocera tryoni (Froggatt) (Diptera: Tephritidae), females to fruit dipped in water and fruit dipped in 0.5% (vol/vol) aqueous emulsions of a mineral oil were determined and analysed. The mineral oil was an nC20-22 distillation fraction of the base oil used to produce an nC23 horticultural mineral oil. Females caged with oil-treated fruit had significantly longer prelanding intervals than females caged with water-dipped fruit. The latter was attacked immediately or shortly after being caged with flies whereas some oil-dipped fruit was not attacked within 180 min. The percentage of landings that led to oviposition on water- and oil-treated fruit were 58 and 13%, respectively, and the percentages ovipositing after probing were 74 and 25%, respectively. Likewise, average times spent probing were 7 vs. 31 s whereas average times spent ovipositing were 321 vs. 223 s. Females spent less than half as much time on oil-treated fruit than on water-treated fruit. Transition probabilities of rejection, when applied to the behaviour sequence indicated that oil-treated fruits are about nine times less likely to be infested with B. tryoni.
Dispersion of fruit flies (Diptera : Tephritidae) at high and low densities and consequences of mismatching dispersions of wild and sterile flies.
Meats, A (2007) Florida Entomologist 90: 136-146.
Abstract: Both wild and released (sterile) Bactrocera tryoni (Froggatt) (Diptera: Tephritidae) and wild Bactrocera papayae (Drew and Hancock) in Australia had patchy distributions and comparisons with predictions of the negative binomial model indicated that the degree of clumping was sometimes very high, particularly at low densities during eradication. An increase of mean recapture rate of sterile B. tryoni on either of 2 trap arrays was not accompanied by a reduction in its coefficient of variation and when recapture rates were high, the percentage of traps catching zero decreased only slightly with increase in recapture rate, indicating that it is not practicable to decrease the heterogeneity of dispersion of sterile flies by increasing the number released. There was often a mismatch between the dispersion patterns of the wild and sterile flies, and the implications of this for the efficiency of the sterile insect technique (SIT) were investigated with a simulation study with the observed degrees of mismatch obtained from the monitoring data and assuming the overall ratio of sterile to wild flies to be 100:1. The simulation indicated that mismatches could result in the imposed rate of increase of wild flies being up to 3.5 times higher than that intended (i.e., 0.35 instead of 0.1). The effect of a mismatch always reduces the efficiency of SIT. The reason for this asymmetry is discussed and a comparison made with host-parasitoid and other systems. A release strategy to counter this effect is suggested.
2006 PAPERS PUBLISHED
Microsatellite markers for the pest fruit fly, Bactrocera papayae (Diptera : Tephritidae) and other Bactrocera species.
Shearman DCA, Gilchrist AS, Crisafulli D, Graham G, Lange C, Frommer M (2006). Molecular Ecology Notes 6: 4-7.
Abstract: The dorsalis complex contains some of the most economically important fruit fly pests of the Asia-Pacific regions, including Bactrocera dorsalis, Bactrocera papayae and Bactrocera carambolae. These species are morphologically indistinct and genetically very similar. We describe the development of 12 microsatellite markers isolated from a representative of the dorsalis complex, B. papayae. We show the potential utility of the B. papayae microsatellites and a set of microsatellites isolated from Bactrocera tryoni as population and species markers for the dorsalis complex.
Attributes pertinent to overwintering potential do not explain why Bactrocera neohumeralis (Hardy) (Diptera : Tephritidae) does not spread further south within the geographical range of B-tryoni (Froggatt).
Meats A (2006) Australian Journal of Entomology 45, 20-25.
Abstract: The geographical range of Bactrocera neohumeralis does not extend as far south as that of its sibling species, B. tryoni. However, there was no evidence of any difference between the two species in terms of physiological limitation to southerly spread when comparisons were made of low temperature torpor thresholds of adults, survival time of adults at -4 degrees C and development rates of all stages in either warm or cool regimes. The survival schedule of the two species was similar in the laboratory and also in the moderately cold conditions experienced by caged cohorts that were exposed to winter field temperatures between late April and early November at Richmond, New South Wales (500 km south of the usual southerly limit of B. neohumeralis). Overwintered cohorts of both species laid similar numbers of eggs in September in terms of eggs per emerged female (an indicator of the reproductive potential). However, because the proportion of B. tryoni surviving to the period of 1-15 September was less than half that for B. neohumeralis, the production per surviving female was more than double in B. tryoni. The possibility of the southerly spread of B. neohumeralis being limited by an Allee effect is discussed.
The contrasting genetic architecture of wing size, viability, and development time in a rainforest species and its more widely distributed relative
Schiffer M, Gilchrist AS, Hoffmann AA (2006)Evolution 60: 106-114.
Abstract: Divergence among populations can occur via additive genetic effects and/or because of epistatic interactions among genes. Here we use line-cross analysis to compare the importance of epistasis in divergence among two sympatric Drosophila species from eastern Australia, one (D. serrata) distributed continuously and the other (D. birchii) confined to rainforest habitats that are often disjunct. For D. serrata, crosses indicated that development time and wing size differences were due to additive genetic effects, while for viability there were digenic epistatic effects. Crosses comparing geographically close populations as well as those involving the most geographically distant populations (including the southern species border) revealed epistatic interactions, whereas crosses at an intermediate distance showed no epistasis. In D. birchii, there was no evidence of epistasis for viability, although for development time and wing size there was epistasis in the cross between the most geographically diverged populations. Strong epistasis has not developed among the D. birchii populations, and this habitat specialist does not show stronger epistasis than D. serrata. Given that epistasis has been detected in crosses with other species from eastern Australia, including the recently introduced D. melanogaster, the results point to epistasis not being directly linked to divergence times among populations.
Variation in population structure across the ecological range of the Queensland fruit fly, Bactrocera tryoni
Gilchrist AS, Dominiak B, Gillespie PS, Sved JA Australian Journal of Zoology 54: 87-95.
Abstract: We sampled a pest fruit fly species, the Queensland fruit fly, Bactrocera tryoni, across its entire ecological range in eastern Australia, from ancestral high-density populations in tropical regions through to isolated outbreak populations in marginal arid areas. Using DNA microsatellite markers, we found that in ancestral areas, population differentiation was low and populations were genetically homogeneous over large distances. In more temperate areas, populations were far more genetically differentiated but there was no pattern of isolation-by-distance (no drift/migration equilibrium). Genetic drift appeared to be the major influence on population differentiation. The transition between these extremes was abrupt and unexpectedly far from the species border. Limited geographic structuring among the non-equilibrium populations was apparent from patterns of genetic differentiation, patterns of allelic richness and an ordination analysis. Our results also suggested that there might be recurring migration of flies into a neighbouring quarantine area.
Modification of host finding and oviposition behaviour of the citrus leafminer, Phyllocnistis citrella, by horticultural mineral oil.
Liu ZM, Meats A, Beattie GAC (2006) Entomologia Experimentalis et Applicata 121: 243-251.
Abstract: Horticultural mineral oil (HMO) deposits affect postlanding searching behaviour and contact evaluation of oviposition substrates by females of the citrus leafminer, Phyllocnistis citrella Stainton (Lepidoptera: Gracillariidae). Both unsprayed and sprayed lemon trees were equally capable of arresting randomly moving female moths by eliciting kinetic responses. The presence of HMO deposits did not affect the approach of female moths to flushes (shoots with immature leaves suitable as oviposition sites), and female moths were equally likely to land on sprayed and unsprayed immature flushes provided mature leaves were not sprayed. The presence of HMO on both the mature leaves and the flushes caused shorter residence and search times within trees and also resulted in fewer immature leaves visited. The HMO-sprayed flushes were also more likely to be rejected for oviposition after contact. Nevertheless, eggs were sometimes deposited on sprayed flushes between residues of the oil droplets.
Dispersion theory and the sterile insect technique: application to two species of fruit fly.
Meats A, Smallridge CJ, Dominiak BC (2006) Entomologia Experimentalis et Applicata 119: 247-254.
Abstract: Dispersion theory is applied to the distribution of two kinds of sterile insect, Mediterranean fruit fly (Medfly), Ceratitis capitata (Wiedemann), and Queensland fruit fly (Qfly), Bactrocera tryoni (Froggatt) (Diptera: Tephritidae). Dispersion theories are an essential basis of sampling theory and sampling plans, but this paper looks at them from another direction and uses data from arrays of sterile insect technique (SIT) monitoring traps to compare the utility of different measures such as coefficient of variation (CV), the exponent b of Taylor's power law, and exponent k of the negative binomial distribution and also derives predictions pertaining to the density (and hence release rate) of sterile insects that would be required to achieve effective coverage of the target area. This is far more useful than reliance on just the mean values of trap catches because such reliance takes no account of the fact that sterile flies distribute themselves unevenly with many patches inadequately covered despite the impression given by the mean. Data were used from recapture rates following either 'roving releases' of Medfly or releases from fixed points of Qfly. The relation of recapture rate to CV indicated that a doubling of release rate in order to double average recapture rate from 150 per trap per week to a value of 300 would have very little effect in terms of reducing CV and that there appears to be no practical prospect of reducing CV to below unity with the current methods of release without incurring a manifold increase in cost. Similarly, models derived from the negative binomial equation indicated that a law of diminishing returns applies in terms of the increase in the amount of adequate coverage (such as the percentage of traps catching > 50 flies per week) that can be obtained by increasing release rates.
Optimum sample size and spatial dispersion of red scale, Aonidiella aurantii on an orange orchard in Australia.
Song, J. H. Meats, A.; Riu, K. Z.; Beattie, G. A. C. (2006) Journal of Asia-Pacific Entomology. 9: 49-54.
Abstract: Two-stage sampling and geostatistical techniques for cost-effective and precise sampling were examined using red scale data that were collected from a commercial orange orchard in Kulnura, Australia in mid-summer, 2004 and 2005. The distribution pattern of red scale on a twig and a fruit well followed the negative binomial, and the degree of aggregation was higher on a fruit than a twig. The analysis of variance and two-stage sampling were used to obtain the suitable sample unit (a leaf, a twig including 2 leaves and 15 cm branch and a fruit in this study) and optimum sample size. A fruit was the most suitable than any other sample units, and a twig was better than a leaf. The optimum sample size for twigs and fruits per tree was 4 twigs (2 leaves and 15 cm branch) and 4 fruits (2 directions), respectively. The variance of primary sample unit for fruits was higher than that of secondary sample unit, but that was reversed for twigs. There was a non-linear relationship between 2 years for the density on 40 fruits of the same tree, because the Spearman rank correlation coefficient (0.84) was much higher than the Pearson's (0.29). The spatial continuity for directions of 0 degrees, 45 degrees, 90 degrees, 135 degrees, and omni-direction was similar except 90 degrees in which trees were touched with together. The autocorrelation analysis showed that omnidirectional 10m apart from each sampled tree was needed to obtain the independent data.
Using variation in wing shape to distinguish between wild and mass-reared individuals of Queensland fruit fly, Bactrocera tryoni. A.S. Gilchrist. Crisafulli D.C.A (2006) Entomologia Experimentalis et Applicata119: 175-178.
Abstract: In SIT programs, sterile flies appearing in monitoring traps after release are identified by the presence of fluorescent dust in the ptilinum, a sac on the top of the head that is temporarily everted to crack open the puparium. The ptilinum remains everted for a time after emergence during which time the fluorescent dust adheres to its surface. After the ptilinum retracts into the head, some fluorescent particles are, in effect, embedded in the head, resulting in relatively permanent marking. However, among the millions of mass-reared flies, this method of marking fails to mark a small proportion of the sterile flies. The wing shape test is much cheaper and faster than using DNA microsatellite markers and a major advantage is the ease and speed of collecting test material. As the insect wing is mainly composed of non-living tissue, it can be easily collected from both live individuals and long-dead specimens. Data collection for wing shape analysis is both relatively cheap (requiring only microscope mounted video-camera) and fast: several hundred wings can be digitised and analysed on the same day
DNA microsatellite analysis of naturally occurring colour intermediates between Bactrocera tryoni (Froggatt) and Bactrocera neohumeralis (Hardy) (Diptera : Tephritidae).
Gilchrist AS, Ling AE (2006) Australian Journal of Entomology 45: 157-162.
Abstract: The sympatric tephritid fruit flies Bactrocera tryoni (Froggatt) (Queensland fruit fly) and B. neohumeralis (Hardy) differ in time of mating and for the colour of the humeral callus ('shoulder pad'), which is typically entirely yellow in B. tryoni and typically entirely brown in B. neohumeralis. Field collections in sympatric regions usually include at least 1% of individuals whose humeral calli show mixed patches of yellow and brown ('intermediates'). Over 40 years, a number of studies have debated the possibility that these intermediates are interspecific hybrids. In the present study, we have used microsatellites to show that few if any of these intermediates are hybrids. Instead, most variation humeral callus appears to be confined to one species, B. tryoni. We discuss these results in the context of geneflow between the two species and suggest directions for future research.
DNA methylation: Bisulphite modification and analysis.
Clark SJ, Statham A, Stirzaker C, Molloy PL, Frommer M. (2006). Nature Protocols. 1, 2353-2364
Abstract: DNA methylation is an important epigenetic modification of DNA in mammalian genomes. DNA methylation patterns are established early in development, modulated during tissue-specific differentiation and disrupted in many disease states, including cancer. To understand further the biological functions of these changes, accurate and reproducible methods are required to fully analyze the DNA methylation sequence. Here, we describe the 'gold-standard' bisulphite conversion protocol that can be used to re-sequence DNA from mammalian cells in order to determine and quantify the methylation state of a gene or genomic region at single-nucleotide resolution. The process of bisulphite treatment exploits the different sensitivities of cytosine and 5-methylcytosine (5-MeC) to deamination by bisulphite under acidic conditions - in which cytosine undergoes conversion to uracil, whereas 5-MeC remains unreactive. Bisulphite conversion of DNA, in either single tubes or in a 96-well format, can be performed in a minimum of 8 h and a maximum of 18 h, depending on the amount and quality of starting DNA.
2005 PAPERS PUBLISHED
Zero catch criteria for declaring eradication of tephritid fruit flies: the probabilities
Meats A, Clift AD (2005) Australian Journal of Experimental Agriculture 45: 1335-1340.
Abstract: We examine procedures for declaring an area free of pest fruit flies following an eradication campaign. To date, the acceptable period of trapping zero flies has been calculated without an estimate of the probability of being wrong. The zero trapping periods are usually shorter when declaring local 'area freedom' from an endemic fly, than when claiming eradication of an exotic species. We use a model to calculate the probability of zero trap captures and therefore the probability of trapping further flies. The latter probability is always finite. A zero trapping result does not indicate the absence of flies. There must also be evidence of what constitutes a non-viable density, as indicated by the trapping rate. The non-viable densities of certain pest fruit fly species are known from decades of managing small incursions in fly-free zones. There is no need for implementation of eradication procedures if the trapping rate is sufficiently low, in these areas. For a given density of flies (defined in terms of expected mean catch per trap per week), the probability of zero trap captures reduces with time and the number of traps employed. If the model calculations use a non-sustainable density (inferred from trapping rate) then we may declare the actual density of flies to be less if the trapping result is zero for a given number of weeks with a given number of traps when the model predicts the probability of such a result to be sufficiently low, according to a criterion that is selected at a level suited to the purpose of the declaration.
Use of a Bayesian Belief Network to identify situations that favour Fruit Fly incursions in inland SE Australia.
Clift A. & Meats A. (2005) In: Zerger, A. and Argent, R.M. (eds) MODSIM 2005, pp. 170-176. International Congress on Modelling and Simulation; Modelling and Simulation Society of Australia and New Zealand.
Procedures for declaring pest free status.
Barclay, H. J, Hargrove, J. W., Clift, A., Meats, A (2005). In:Sterile Insect Technique: Principles and Practice in Area-Wide Integrated Pest Editor(s): Dyck, VA; Hendrichs, J; Robinson, AS, Management: 363-386
2004 PAPERS PUBLISHED
Comparison of wild-type and mutant white eye alleles in melon fly (Diptera : Tephritidae)
Peabody NC, Shearman DCA, McCombs SD (2004) Annals of The Entomological Society of America Volume: 97 Issue: 5 Pages: 1018-1025
Abstract: The DNA sequence of the coding region of the wild-type and mutant alleles of the white eye gene from the melon fly, Bactrocera cucurbitae Coquillett, was obtained. The mutant white eye allele had a single base pair mutation at the 5' end of intron 4b in the RNA splice recognition site. Due to the disrupted splice recognition site, intron 4b was not removed from the mutant RNA transcript. The resulting mRNA transcript was 68 bp longer than that of the wild type, containing a frameshift and premature stop codon. Transport of pigment precursors would be blocked, resulting in a lack of pigmentation deposition consistent with the known mutant phenotype.
Genetic relations between outbreaks of the Queensland fruit fly, Bactrocera tryoni (Froggatt) (Diptera : Tephritidae), in Adelaide in 2000 and 2002
Gilchrist AS, Sved JA, Meats A (2004) Australian Journal of Entomology Volume: 43 Pages: 157-163.
Abstract: The Queensland fruit fly (Q-fly), Bactrocera tryoni, is a serious horticultural pest throughout eastern Australia, and apart from isolated outbreaks, is absent from Adelaide and South Australia. Considerable resources are put into preventing the entry of Q-fly into South Australia and the eradication of any outbreaks. Nevertheless, some flies are still trapped in Adelaide and, because known permanent populations are too distant for unaided dispersal, these flies must arrive as larvae in infested fruit. To provide authorities with more information on the nature of and the extent of outbreaks, the authors used 26 microsatellite markers to test the relationships between outbreak flies caught in Adelaide in 2000 and 2002. Groupings between individuals were tested using both a model-based clustering method (implemented in the Structure program) and relatedness testing, using both simple exclusion tests and relatedness coefficients. While many flies appeared unrelated, one group of at least six full sibs was detected, all of which were trapped in the same month. Unexpectedly, these six flies were trapped at sites separated by distances greater than the unaided dispersal distance of Q-fly, implicating human-aided dispersal of infested fruit within Adelaide. Thus simultaneous trappings of flies separated by kilometres are not necessarily separate outbreaks as has been assumed. The implications for current outbreak control strategies are discussed.
The cryptochrome (cry) gene and a mating isolation mechanism in tephritid fruit flies
An X, Tebo M, Song S, Frommer M, Raphael KA (2004) Genetics 168: 2025-2036.
Abstract: Two sibling species of tephritid fruit fly, Bactrocera, tryoni and Bactrocera neohumeralis, are differentiated by their time of mating. which is genetical v determined and requires interactions between the endogenous, circadian clock and light intensity. The cryptochrome (cry) gene, a light-sensitive component of the circadian clock, was isolated in the two Bactrocera species. The putative amino acid sequence is identical in the two species. In the brain, in situ hybridization showed that cry is expressed in the lateral and dorsal regions of the central brain where PER immunostaining was also observed and in a peripheral cell cluster of the antennal lobes. Levels of cry mRNA were analyzed in whole head, brain, and antennae. In whole head, cry is abundantly and constantly expressed. However, in brain and antennae the transcript cycles in abundance, with higher levels during the day than at night and cry transcripts, are. more abundant in the brain and antennae of B. neohumeralis than in that of B. tryoni, Strikingly, these results are duplicated in hybrid lines, generated by rare mating between B. tryoni and B. neohumeralis and then selected on the basis of mating time, suggesting a role for the cry gene in the mating isolation mechanism that differentiates the species.
Bactrocera tryoni and closely related pest tephritids-molecular analysis and prospects for transgenic control strategies
Raphael KA, Whyard S, Shearman D, An X, Frommer M (2004) Insect Biochemistry and Molecular Biology 34: 167-176.
Abstract: Bactrocera tryoni is a serious pest of horticulture in eastern Australia. Here we review molecular data relevant to pest status and development of a transformation system for this species. The development of transformation vectors for non-drosophilid insects has opened the door to the possibility of improving the sterile insect technique (SIT), by genetically engineering factory strains of pest insects to produce male-only broods. Transposition assays indicate that all five of the vectors currently used for transformation in non-drosophilid species have the potential to be useful as transformation vectors in B. tryoni. Evidence of cross mobilization of hobo by an endogenous Homer element emphasises the necessity to understand the endogenous transposons within a species. The sex-specific doublesex and yolk protein genes have been characterized with a view to engineering a female-specific lethal gene or modifying gene expression through RNA interference (RNAi). Data are presented which indicate the potential of RNAi to modify the sex ratio of resultant broods. An understanding of how pest status is determined and maintained is being addressed through the characterization of genes of the circadian clock that enable the fly to adapt to environmental cues. Such an understanding will be useful in the future to the effective delivery of sophisticated pest control measures. (C) 2003 Elsevier Ltd. All rights reserved.
Laboratory adaptation of Bactrocera tryoni (Diptera : Tephritidae) decreases mating age and increases protein consumption and number of eggs produced per milligram of protein
Meats A, Holmes HM, Kelly GL (2004) Bulletin of Entomological Research 94 : 517-524.
Abstract: A significant reduction in age of mating occurred during the first four generations (G1-G4) of laboratory adaptation of wild Bactrocera tryoni (Froggatt) and this was associated with the earlier attainment of peak egg load although no significant differences were detected in the peak egg load itself. A long term laboratory (LTL) strain had a significantly earlier mating age and higher peak egg load than flies of wild origin or those from the first four laboratory generations. The amount of protein consumed by females in the first week of adult life was significantly higher in the LTL strain than in flies of wild origin or G1-G4 but there were no significant changes (or only slight changes) with laboratory adaptation in the amounts of protein consumed up to the ages of mating and peak egg load. Laboratory adaptation resulted in no significant changes in egg size, egg dry weight, puparial fresh weight and the dry weight of newly emerged females. The large increase in fecundity with laboratory adaptation is associated with a 4- to 5-fold increase in the rate of conversion of dietary protein to eggs (i.e. eggs produced per mg of protein consumed).
When does zero catch in a male lure trap mean no tephritid flies in the area?
Clift, A.; Meats, A. (2004) Proceedings of the 6th International Symposium on fruit flies of economic importance, Stellenbosch, South Africa, 6-10 May 2002: Page(s) 183-188 Published: 2004 Editor(s): Barnes, B. N.
Abstract: Outbreaks of economically important fruit flies frequently occur in Australia. These outbreaks are eradicated as quickly as possible and a code of practice has been established to manage eradication programmes. The code presently specifies that eradication can be claimed three generations plus 28 days after the last fly has been trapped. To determine how closely this requirement fits real fruit fly outbreak trapping records, the complete trapping record from a large outbreak of the exotic fruit fly Bactrocera papayae Drew & Hancock was examined. Trapping in this case was carried out using methyl-eugenol baited traps. The observed record was compared to the output from a simulation model and discussed in relation to the code of practice.
Protein consumption by mated, unmated, sterile and fertile adults of the Queensland fruit fly, Bactrocera tryoni and its relation to egg production
Meats A, Leighton SM (2004) Physiological Entomology 29: 176-182
Abstract: Female adults of Bactrocera tryoni (Froggatt) (Diptera: Tephritidae) at 25 degreesC require more than 0.1 mg of yeast autolysate per day to mature their oocytes to the vitellogenic stage and mate. Those given 0.2 mg per day from day 2 of adult life mated (when given the opportunity between 11 and 13 days) and each laid approximately 100 eggs (just over one egg per ovariole) by day 56. Females allowed to feed ad libitum from day 2, then 0 or 0.2 mg per day from day 14, laid approximately 75 and 100 eggs, respectively (after mating), whereas those fed ad libitum from day 2 to day 56 laid approximately 540 eggs after mating (averaging just over six eggs per ovariole). The developmental pattern of intake of normal females when on an ad libitum diet showed a rise to a peak at 5-7 days, followed by a decline to sustained low levels if not mated, but rising to a lower peak if mated between days 11-13 followed by a steady decline. Female flies that had been sterilized by 80 Gy gamma irradiation at the puparial stage had a pattern of food consumption similar to that of normal females mated at 7 days but they produced no yolky oocytes and had a darkened fat body. Normal and irradiated males had a feeding pattern similar to that of unmated nonirradiated females but at a lower level. The results are discussed in terms of the control of protein intake and the rate of its conversion to yolk.
2003 PAPERS PUBLISHED
Trials on variants of the Sterile Insect Technique (SIT) for suppression of populations of the Queensland fruit fly in small towns neighbouring a quarantine (exclusion) zone
Meats A, Duthie R, Clift AD, Dominiak BC (2003) Australian Journal of Experimental Agriculture 43: 389-395:
Abstract: Seven small unquarantined towns in the central western district of New South Wales were used to compare variants of the sterile insect technique with respect to their suitability for suppression of populations of the Queensland fruit fly, Bactrocera tryoni (Froggatt). Two towns were treated with weekly releases of immature sterile flies at rates varying from 48000 to 115000 sterile males per km(2). Evidence for suppression was poor (from comparison with 2 untreated towns) and the ratio of sterile to wild flies caught in monitoring traps never exceeded 80: 1 in the last 4 weeks of any season or 40: 1 during other parts of any season. However, the recapture rates of the sterile flies and estimates of their survival rates were often as good as the best that have been reported previously. Two other towns were treated with weekly releases of mature flies at rates of 5000-12000 sterile males per km(2). The recapture rates and estimates of survival rates of flies released when mature were unexpectedly low and the ratios of sterile to wild flies were often less than 1: 1 and never exceeded 12:1. The results are discussed in terms of the relatively harsh climate of these towns (located in a region of average annual rainfall of 450-600 mm) and lack of quarantine.
Incipient founder populations of Mediterranean and Queensland fruit flies in Australia: the relation of trap catch to infestation radius and models for quarantine radius
Meats A, Clift AD, Robson MK (2003) Australian Journal of Experimental Agriculture 43: 397-406.
Abstract: We examined data from 75 infestations of the Mediterranean fruit fly (Medfly) and 286 of the Queensland fruit fly (Qfly) that have occurred in quarantined and normally fly-free zones in Australia from 1974 to 2000. The radius of occurrence of both adult male flies and infested fruit was almost always less than 1 km. The rare cases where there was an isolated occurrence beyond 1 km of an epicentre were most likely due to (and can be treated as) separate introductions. Our analysis shows that effective quarantine radii for suspension of fly-free status should be related to the number of flies trapped around the epicentre and the density of the trap array ( if the appropriate code of practice is applied). Most detections of fruit flies involve the trapping of very few flies and 18% of Medfly infestations and 71% of Qfly infestations that are detected are not classified as outbreaks and are left to die out without any treatment. For each species, we have used 3 alternative methods to calculate confidence limits for infestation radii. The upper limits could also serve as quarantine radii. These limits increase with the rate of trapping of male flies and have a theoretical probability of 3/100000 (i.e. probit 9) of being exceeded. The quarantine radii for most declared outbreaks, when calculated with any of our methods, would be small because the number of flies detected is usually only just above the threshold for such a declaration. If our methods were used for beneficial species or for re-introductions of endangered species, the lower confidence limits could be used to calculate the size of inoculum required for a high probability of initial establishment.
The effects of selection for early (day) and late (dusk) mating lines of hybrids of Bactrocera tryoni and Bactrocera neohumeralis
Meats A, Pike N, An X, Raphael K, Wang WYS (2003)Genetica 119:283-293.
Abstract: Bactrocera neohumeralis and Bactrocera tryoni are closely related tephritid fruit fly species. B. neohumeralis mates throughout the day ( in bright light) and B. tryoni mates at dusk. The two species can also be distinguished by the colour of their calli ( prothoracic sclerites) which are brown and yellow, respectively. The F-1 hybrids can mate both in bright light just before dusk and during dusk and have calli that are partly brown and partly yellow. The F-2 hybrids have a wider range of callus patterns and mating occurs more widely in the day as well as at dusk. We directly selected hybrid stocks for mating time, creating 'early' (day-mating) and 'late' (dusk-mating) lines. As an apparently inadvertent consequence, the two types of line respectively had predominantly brown and predominantly yellow calli and thus came to closely resemble the original two species in both behaviour and appearance. Lines that were evenly selected (half for day and half for dusk) essentially retained the mating pattern of F-2 hybrids. Selection for callus colour alone also affected the distribution of mating times in a predictable way. We propose a genetical model to account for the results and discuss them in the light of the apparent maintenance of species integrity in nature.
The likely fate of hybrids of Bactrocera tryoni and Bactrocera neohumeralis
Pike N, Wang WYS, Meats A (2003) Heredity 90:365-370 :
Abstract: Bactrocera tryoni (Froggatt) and B. neohumeralis (Hardy) (Diptera: Tephritidae) are sympatric species which hybridise readily in the laboratory yet remain distinct in the field. B. tryoni mates only at dusk and B. neohumeralis mates only during the day, but hybrids can mate at both times. We investigated the inheritance of mating time in successively backcrossed hybrid stocks to establish whether mating with either species is more likely. The progeny of all backcrosses to B. tryoni mated only at dusk. The majority of the progeny of the first and a minority of the progeny of the second backcross to B. neohumeralis also mated at dusk, but the third successive B. neohumeralis backcross produced flies that mated only during the day. This trend towards dominance of the B. tryoni trait was also reflected in a diagnostic morphological character. We discuss the possible genetic background for these phenomena and propose that unidirectional gene flow might explain how the two species remain distinct in the face of natural hybridisation.
Tendency for upwind movement in the sibling fruit fly species, Bactrocera tryoni and B-neohumeralis and their hybrids (Diptera : Tephritidae): influence of time of day, sex and airborne pheromone
Pike N, Meats A (2003) Bulletin of Entomological Research 93: 173-178:
Genetic delineation of sibling species of the pest fruit fly Bactocera (Diptera: Tephritidae) using microsatellites.
Gilchrist, A S; Wang, Y; Yu, H; Raphael, K; (2003) Bulletin of Entomological Research 93: 351-60:
Abstract: Using a large set of microsatellites, the genetic relationships between three closely related Australian fruit fly species, Bactrocera tryoni (Froggatt), B. neohumeralis (Hardy) and B. aquilonis(May) were investigated. Bactrocera tryoni and B. neohumeralis are sympatric, while B. aquilonisis allopatric to both. The sympatric species, B. tryoni and B. neohumeralis, were found to be genetically distinct. It is likely that despite differences in mating time between these two species, some gene flow still occurs. In contrast, the sibling species B. tryoni and B. aquilonis were found to be closely related, despite allopatry. The level of genetic divergence was similar to that found within eastern Australian populations of B. tryoni. Consideration of all available genetic data suggests that this similarity is not due to recent (i.e. within the last 30 years) displacement of B. aquilonis by B. tryoni from the B. aquilonis region (north-western Australia). Instead the data suggests that, at least in the areas sampled, asymmetrical hybridization may have occurred over a longer timescale.
Inferring modes of colonization for pest species using heterozygosity comparisons and a shared-allele test
Sved JA, Yu H, Dominiak B, Gilchrist AS (2003) Genetics 163: 823-831.
Abstract: Long-range dispersal of a species may involve either a single long-distance movement from a core population or spreading via unobserved intermediate populations. Where the new populations originate as small propagules, genetic drift may be extreme and gene frequency or assignment methods may not prove useful in determining the relation between the core population and outbreak samples. We describe computationally simple resampling methods for use in this situation to distinguish between the different modes of dispersal. First, estimates of heterozygosity can be used to test for direct sampling from the core population and to estimate the effective size of intermediate populations. Second, a test of sharing of alleles, particularly rare alleles, can show whether outbreaks are related to each other rather than arriving as independent samples from the core population. The shared-allele statistic also serves as a genetic distance measure that is appropriate for small samples. These methods were applied to data on a fruit fly pest species, Bactrocera tryoni, which is quarantined from some horticultural areas in Australia. We concluded that the outbreaks in the quarantine zone came from a heterogeneous set of genetically differentiated populations, possibly ones that overwinter in the vicinity of the quarantine zone.
The scarlet eye colour gene of the tephritid fruit fly: Bactrocera tryoni and the nature of two eye colour mutations
Zhao JT, Bennett CL, Stewart GJ, Frommer M, Raphael KA (2003) Insect Molecular Biology 12: 263-269:
Abstract: A homologue of the Drosophila melanogaster eye-colour gene, scarlet (st), has been isolated from the genome of the tephritid fruit fly, Bactrocera tryoni . The comparison of the B. tryoni and D. melanogaster scarlet gene shows 71.2% and 79.3% sequence identity at the DNA and the derived amino acid level, respectively. Two allelic eye-colour mutations of B. tryoni, orange-eyes and lemon-eyes , have been recovered and found to be colocalized with the st gene. The st gene sequence in the two mutant strains has been examined for DNA sequence changes and expression levels.
EARLIER PUBLICATIONS
AN, X., WILKES, K., BASTIAN, Y., MORROW, J.L., FROMMER, M. and RAPHAEL, K.A. (2002) The period gene in two species of tephritid fruit fly differentiated by mating behaviour Insect Molecular Biology 11: 419-430.
SHEARMAN, D.C.A. (2002) The evolution of sex determination mechanisms in dipteran insects other than Drosophila. Genetica 116: 25-43
MEATS, A., MAHESWARAN, P., FROMMER, M., and SVED, J. (2002) Towards a male-only release system for SIT with the Queensland fruit fly, Bactrocera tryoni, using a genetic sexing strain with a temperature-sensitive lethal mutation.. Genetica 116: 97-106.
DALBY-BALL, G. and MEATS, A. (2002) The role of foliage in differential landing of the Queensland fruit fly,Bactrocera tryoni (Froggatt) (Diptera: Tephritidae) on odoriferous and odourless fruit models. General and Applied Entomology 32: 29-34.
MEATS, A., CLIFT, A. D., & PEREPELICIA, N. (2002) Performance of permanent and supplementary traps for Mediterranean and Queensland fruit flies in South Australia 1975-2001: comparison of male lure and food lure traps. General and Applied Entomology 32: 53-57.
PIKE, N., and MEATS, A. (2002) The potential for mating between Bactrocera tryoni (Froggatt) and B. neohumeralis (Hardy) (Diptera: Tephritidae). Australian Journal of Entomology 41 : 70-74.
YU, H., FROMMER, M., ROBSON, M.K., MEATS, A.W., SHEARMAN, D.C.A. and SVED, J.A. (2001) Microsatellite analysis of the Queensland fruit fly indicates spatial structuring: implications for population control. Bulletin of Entomological Research 91, 139-147.
GREEN, C.L. and FROMMER M. (2001) The genome of the Queensland fruit fly Bactrocera tryoni contains multiple representatives of the mariner family of transposable elements. Insect Molecular Biology. 10: 371-386.
CLIFT, A.D. and MEATS, A. (2001) Why model tephritid fruit fly incursions in agricultural production areas? Modsim 2001: Proceedings of the International Congress on Modelling and Simulation. 14: 1835-840.
MORROW, J., SCOTT, L., CONGDON, B., YEATES, D., FROMMER, M. and SVED, J.A. (2000). Close genetic similarity between two sympatric species of tephritid fruit fly reproductively isolated by mating time. Evolution, 54: 899-910.
YU, H., FROMMER, M., ROBSON, M.K. and SVED, J.A. (2000). A population analysis of the Queensland fruit fly Bactrocera tryoni using microsatellite markers. In "Area-Wide Control of Fruit Flies and Other Insect Pests”. K.H. Tan (ed.) USM Press, Penang, Malaysia, pp 497-508..
DALBY-BALL, G. and MEATS, A (2000) Effects of fruit abundance within a tree canopy on the behaviour of wild and cultured Queensland fruit flies, Bactrocera tryoni (Diptera: Tephritidae). Australian Journal of Entomology. 39, 201-207.
DALBY-BALL, G. and MEATS, A (2000) Influence of the odour of fruit, yeast and cue-lure on flight activity of the Queensland fruit fly, Bactrocera tryoni (Diptera: Tephritidae). Australian Journal of Entomology 39: 195-200.
THOMAS, B.J., and MEATS, A. (2000) The relation of dose rate and light intensity to the effect of bait spray formulations with the photo-insecticide Phloxine B on the Queensland fruit fly, Bactrocera tryoni (Diptera: Tephritidae ) General & Applied Entomology 29: 1-4.
MEATS, A, and OSBORNE, A. (2000) Dose-related upwind anemotaxis and movement up odour gradients in still air by the wild tobacco fly, Bactrocera cacuminata . Physiological Entomology 25: 41-47.
MEATS, A, and FAY, H.A.C. (2000) Distribution of mating frequency among males of the Queensland fruit fly, Bactrocera tryoni, in relation to temperature, acclimation and chance. General & Applied Entomology. 29: 27-30.
CLIFT, A.D., GLEESON, P.J. and MEATS, A. (1999) Risk analysis studies on banana fruit fly, Bactrocera musae , recolonising an area near Cairns, North Queensland, after area-wide insecticide treatments had ceased. Modsim 99, Proc.Int.Congress on Modelling and Simulation. 13: 649-653.
THOMAS, B.J., and MEATS, A. (1999) The effect of simulated ‘wash off ’ from spot-sprays containing either Malathion or Phloxine B on ground-dwelling arthropods in an orchard. Agricultural & Forest Entomology.1: 55-60.
MEATS, A, and HARTLAND, C.L. (1999) Upwind anemotaxis in response to cue-lure by the Queensland fruit fly, Bactrocera tryoni. Physiological Entomology 24: 90-97.
SHEARMAN, D. C .A. and FROMMER, M. (1998) The Bactrocera tryoni homologue of the Drosophila melanogaster sex-determination gene doublesex. Insect Molecular Biology. 7, 355-366.
ZHAO, J.T., FROMMER, M., SVED, J.A and ZACHAROPOULOU, A (1998) Mitotic and polytene chromosome analyses in the Queensland fruit fly, Bactrocera tryoni. Genome 41: 510-526.
MEATS, A. (1998). Predicting or interpreting trap catches resulting from natural propagules or releases of sterile fruit flies. An actuarial and dispersal model tested with data on Bactrocera tryoni. General and Applied Entomology 28: 29 – 38.
MEATS, A. (1998). A quality assurance measure for field survival rates of released sterile flies based on recapture rates. General and Applied Entomology 28: 39 –46.
MEATS, A. (1998) The power of trapping grids for detecting and estimating the size of invading propagules of the Queensland fruit fly and risks of subsequent infestation. General and Applied Entomology 28: 47 –55.
MEATS, A, (1998). Cartesian methods of locating spot infestations of the Papaya fruit fly Bactrocera papayae Drew and Hancock within the trapping grid at Mareeba, Queensland, Australia. General and Applied Entomology 28: 57 –60.
KINNEAR, M.W., BARIANA, H.S., SVED, J.A. and FROMMER, M. (1998) Polymorphic microsatellite markers for population analysis of a tephritid pest species, Bactrocera tryoni. Journal of Molecular Ecology 7: 1489-1495
CLIFT, A.D., MEATS, A. and GLEESON, P.J. (1998) A dispersal model for papaya fruit fly, Bactrocera papayae Drew and Hancock and its application to treatment priorities in an eradication protocol. In: Zalucki, M.P., Drew, R.A.I. & White, G.G. (eds) Pest Management - Future Challenges, pp. 27-31.Sixth Australasian Applied Entomology Research Conference, Brisbane, 1998.
CLIFT, A.D.and MEATS, A. (1998) The relation of 'percentage positive traps' to the negative binomial distribution and to progress in the eradication of Bactrocera papayae Drew and Hancock (Diptera:Tephritidae) in northern Queensland. General and Applied Entomology 28: 61-64.
COATES, C.J., TURNEY, C.L., FROMMER, M., O’BROCHTA, D.A. and ATKINSON, P.W. (1997). Interplasmid transposition of the mariner transposable element in non-drosophilid insects. Molecular and General Genetics 253: 728-733.
CLIFT, A.D. and MEATS, A. (1997). Using the negative binomial distribution and risk analysis software to simulate Bactrocera papayae Drew and Hancock (Diptera: Tephritidae) metapopulations in an eradication context. Modsim 98: Proc. Int. Congress on Modelling and Simulation. 12: 792–795.
BENNETT, C.L. and FROMMER, M. (1997). The white gene of the tephritid fruit fly Bactrocera tryoni is characterised by a ling untranslated 5” leader and a 12 kb first intron. Insect Molecular Biology 6: 343-356.
OSBORNE, R., MEATS, A.FROMMER, M., SVED, J.A., DREW, R.A.I. and ROBSON, M.K. (1997). Australian distribution of 17 species of fruit flies (Diptera: Tephritidae) caught in cue lure traps in February 1994. Australia Journal of Entomology 36,45-50.
MEATS, A. (1996). Demographic analysis of sterile insect trials with the Queensland fruit fly Bactrocera tryoni (Froggatt) (Diptera: Tephritidae). General and Applied Entomology 27: 2-12.
FROMMER, M., MEATS, A., SHARKEY, D., SHEARMAN, D., SVED, J. AND TURNEY, C. (1996). Sequences from eye colour genes, chorion gene and mariner-like transposable elements in the Queensland fruit fly, Bactrocera tryoni. In "Fruit Fly Pests: A World Assessment of Their Biology and Management", B. A. McPheron and G. J. Steck (eds.). St. Lucie Press, Florida, pp. 209-220.
COATES, C. J., TURNEY C. L., FROMMER, M., O'BROCHTA D. A. , WARREN, W. D. & ATKINSON P. W. (1995) The transposable element mariner can excise in non-drosophilid insects. Molecular & General Genetics. 249,. 246-252.
