Effect of host odours on trap catch composition of Glossina pallidipes in Kenya

The effect of odour attractants on the composition of samples of Glossina pallidipes Austen was investigated by comparing the age and nutritional status of flies caught in unbaited biconical traps with those caught in traps baited with cow urine and acetone. For both male and female flies, baited traps caught more flies with significantly higher fat content than did unbaited traps. Thus the samples from baited traps were more representative of the population as a whole: males showed a fuller range of the fat/haematin conditions known to occur in the field and proportionately more females were in later stages of the pregnancy cycle, than from unbaited traps.     

Lifetime changes in the nutritional characteristics of female tsetse Glossina pallidipes caught in odour-baited traps

Female Glossina pallidipes Austen were captured in odour-baited traps at Rekomitjie Research Station, Zambezi Valley, Zimbabwe during February 1994; 2890 were dissected and assigned to their ovarian age category and day of pregnancy using the lengths of the oocytes and uterine content. For 1838 of these flies, the nutritional state of the mother and her uterine content were estimated separately. It was thereby possible to see how, during pregnancy, the females acquired fat and residual dry weight (RDW) and transfered them to the larva. Newly emerged flies contained 1 mg fat and 6 mg RDW, of which 4 mg was in the thorax (TRDW). Fat hardly increased by the first ovulation; RDW increased by 2.5 mg and 1.5 mg of this increase was in TRDW. Mean haematin levels increased from 2 to 8 microg during each pregnancy. Fat increased from 1.2 mg to 4.5-5 mg by day 7 and was then rapidly transferred to the larva. RDW increased by only 1.8 mg by day 7, but larval RDW increased thereafter by > 6 mg. Amino acids from late-pregnancy bloodmeals are incorporated directly, in the uterine gland, into 'milk' that is taken up rapidly by the larva. Capture probability was highest on day 1 of pregnancy, when nutritional levels were lowest, with lesser peaks on days 5 and 8 when the fly was nourishing a rapidly developing larva. On day 1, the peak of the logarithm of the haematin distribution corresponded to flies estimated to have fed approximately 75 h previously; by day 8 it had shifted to approximately 60 h post-feeding. A model in which feeding rates and capture probabilities increased exponentially with time since feeding accounted for 97% of the variance in log haematin frequencies. On 4/9 days of pregnancy there was no significant decline in fat with haematin content during the lipolytic phase. The rate of decline is not a satisfactory estimate of the rate of fat usage. Flies in this study had longer wings and higher TRDW than those from refuges in an earlier study, but had lower levels of fat and haematin.     

The use of discriminant analysis for the estimation of sampling biases for female tsetse

ABSTRACT.

• 1 In this paper we investigate whether the technique of discriminant analysis can be used to estimate sampling biases for female tsetse.
• 2 Discriminant analysis was first applied to laboratory samples of female tsetse, Glossina morshans morsitans Westwood, to test whether flies of known history could be assigned to the correct day of the pregnancy cycle on the basis of their fat, haematin and corrected residual dry weight.
• 3 Following the satisfactory results from the laboratory samples, the same technique was applied to field samples of G.m. centralis Machado captured by electric traps and hand nets in Zambia and of G.palpalis palpalis (Robineau-Desvoidy) captured in biconical traps at five sites in Ivory Coast. The results show that flies on day 1 of the pregnancy cycle were most likely to be caught, with a second peak of day-6 and day-7 flies, while very few day-8 or day-9 flies were caught.
• 4 These major peaks in fly trappability coincide with the known feeding habits of female tsetse, and indicate synchrony of feeding by many members of the population immediately after larviposition and again as the larva in utero moults from the second to third instar. G.palpalis is relatively more available at this later stage of its pregnancy cycle to the capture methods used than is G.morsitans. A third feed may be taken at a more variable point in the pregnancy cycle.
• 5 This method of estimating the sampling biases of female tsetse could allow an estimate of total population size, as long as the absolute sampling efficiency of flies on any one day of the pregnancy cycle could be established by, for example, mark-release-recapture experiments.

     

Trap efficiency for Glossina pallidipes (Diptera: Glossinidae) at Nguruman, south-west Kenya

An incomplete ring of electric nets was evaluated as a means of estimating trap efficiency for Glossina spp. This methodology assumes flies approach the trap directly, and then enter, or leave directly in random directions. These results showed that the ratio of the number of flies intercepted on the outside of the electric nets to the number on the inside was lower than predicted by this single-approach behavioural model. Moreover, an incomplete ring of nets around a trap reduced trap catch more than the model predicted. These inconsistencies were greater early in the day, and greater for females than for males. It is suggested that flies may make several approaches to a trap before entering or departing. This mixes arriving and departing flies on each side of the electric nets. Use of a complete ring of nets around a trap to estimate trap efficiency entails fewer behavioural assumptions. Catches at a complete ring around a trap were compared to catches in a trap without nets, replicated in a cross-over design. The efficiency of an odour baited NG2G trap was estimated to be 58% for males and 37% for females. Biconical traps were much less efficient. Both trap types were less efficient in the early morning, suggesting entry response is temperature dependent. The NG2G trap was more efficient for non-teneral nulliparous females than for other ages. For both trap types there was little difference between mean fat content of approaching and trapped males, but the mean fat content of trapped females was lower than that of approaching females.     

Nutritional levels of pregnant and postpartum tsetse Glossina pallidipes Austen captured in artificial warthog burrows in the Zambezi Valley of Zimbabwe

In Zimbabwe, female tsetse Glossina pallidipes Austen, collected from artificial warthog burrows and subjected to ovarian dissection and nutritional analysis, provide the first field estimates of resource allocation from mother to offspring across all of pregnancy. Approximately 45% of 1833 females captured are full‐term pregnant on entering the burrow. The remainder presumably use burrows as refuges at temperatures >32 °C. Maternal residual dry weight (RDW) increases by 1.5 mg after the first feed post‐larviposition but, thereafter, only by 1.4 mg by 90% of pregnancy completion. Uterine RDW changes little by 60% of pregnancy completion but increases by >6 mg by parturition. Between the times of 5% and 90% pregnancy completion, maternal RDW is approximately constant: it then declines 2.8 mg by parturition, balancing larval gains of 2.6 mg. Mothers accumulate 6.3 mg of fat in the first 80% of pregnancy, while uterine fat increases by only 0.8 mg. Thereafter, by parturition, larval fat increases by 4.1 mg, whereas maternal fat declines by 3.3 mg. The larva deposited is 5% heavier than its mother and has 52% more fat. RDW and fat levels, corrected for fly size and haematin, are 1 and 2 mg, respectively, lower in females from traps than those from burrows. Burrow catches provide an improved picture of tsetse pregnancy dynamics, highlighting a reproductive strategy involving resource commitment to the larva being delayed until late pregnancy when sufficient stores guarantee viable pupal production. Larval development in tsetse starts significantly later than the analogous changes during pregnancy in two mammals and two viviparous fish.     

Reproductive under-performance of tsetse flies in the laboratory, related to feeding frequency

Abstract. The rates of development of the eggs and larvae in utero and the next two developing ovarioles were measured by ovarian dissection on each day of the pregnancy cycle in tsetse, Glossina morsitans, subject to different feeding regimes. Compared with flies fed four times per pregnancy cycle, flies fed three times per cycle showed a lower pupal production rate (70%), the same (zero) adult mortality, a slightly slower growth rate of the larva and second ovariole only from day 8 onwards, but the same growth rate of the first ovariole. Flies fed only twice per pregnancy cycle produced no pupae, suffered 18% adult mortality and showed a significantly slower growth rate of the larva and second ovariole from days 6 and 7 respectively, but still the growth rate of the first ovariole was barely affected. Flies offered food three times or twice per pregnancy cycle engorged fully at every opportunity, but 16.5% of the flies offered food four times per cycle did not feed on every occasion, while 12–22% did not engorge fully on days 3, 5 or 7. In assessing the applicability of these laboratory results to the field situation the following points must be borne in mind: in the laboratory flies take smaller mean blood meals than in the field; during protein production associated with larval growth the proportion of the blood meal lost to transformation and excretory costs is less than during normal lipid metabolism; the balance between the tsetse's known fertility rate and adult and pupal mortality rates reveals that the abortion rate in the field must be extremely low. The high abortion rates usually observed in laboratory colonies, even when flies are offered food daily_l would be quite untenable in the field and indicate that laboratory conditions impose physiological stresses on the flies that are quite different from those in the field. These facts indicate that three field-sized meals may be sufficient to meet the energy demands of normal larval development in the field.     

Physiological correlates of the availability of Glossina morsitans centralis Machado to different sampling methods

Abstract.

• 1 The feeding cycle for male tsetse flies and the pregnancy cycle for females are used as frameworks for investigating the field behaviour of Glossina morsitans centralis Machado in Zambia, and hence the sampling biases of different capture devices.
• 2 Flies were collected in the field using hand nets and an electric back pack on foot patrols, and hand nets, hand-catching and an electric screen on landrover patrols. They were analysed for wing-fray, vein-length, chloroform-extractable fat and haematin. In addition, samples of laboratory-bred females killed daily during their second pregnancy cycle were analysed for the last two parameters.
• 3 The daily flying time of males is estimated from the fat—haematin curve to be about 32 min/day, which is identical to previous estimates for G. morsitans from Tanzania.
• 4 From the varying numbers and fat content of male flies caught by the different sampling methods during the course of the feeding cycle it is concluded that both haematin levels and fat reserves influence fly behaviour.
• 5 Comparison of the frequency distribution of wild-caught and laboratory-bred females along the corrected residual dry weight axis of the pregnancy cycle suggests that the results of combined electric-trap and hand-net sampling reflect the actual frequency distribution in the wild population at least for the first 7 days of the pregnancy cycle; but females in the last 2 days of their pregnancy cycle are apparently unavailable to sampling devices, perhaps because of their reduced flight activity.
• 6 The very variable percentage female catch (10.9–43.4%) returned by the different sampling methods is discussed in the light of the detailed analysis of the differential availability of male and female flies to each capture device.

     

Trapping oestrid parasites of reindeer: the relative age, fat body content and gonotrophic conditions of Cephenemyia trompeand Hypoderma tarandifemales caught in baited traps

Abstract. Dissection of flies caught in northern Norway revealed that only mated, gravid females of H.tarandi (L.) and larviparous C.trompe (Modeer) were caught in host-mimicking C0₂-baited traps. Trapped females had the same gonotrophic and fat body (FB) conditions as females caught on and around reindeer. Most trapped females of both species were of middle to old age, having only one-half to no FB reserves left and only a few to moderate numbers of eggs or larvae remaining. Most young females trapped also had previously oviposited or larviposited at least once, and some newly eclosed, mated females were present throughout the fly season. Based on the known location of reindeer herds, it was evident that trapped flies that had recently oviposited or larviposited had dispersed into the trapping area from 25–100 km away. Declining FB reserves sustained wild-caught C.trompe females (and in utero larvae) in the laboratory for 14 days and H.tarandi females for 18 days. Reserve FB also was depleted during long flights. Females of both species that flew for the longest times (5.1–11.7 h) on a laboratory flight mill had low FB reserves, but nearly maximum numbers of eggs or larvae. Conversely, most females that flew for less than 5 h on the flight mill had little or no FB remaining, and few eggs or larvae. The large FB reserves accumulated as larvae feed in the vertebrate host enable the non-feeding adults to survive and infect their hosts even after prolonged periods of flight-inhibiting climatic conditions.     

Regulation of synthesis of larval serum proteins after transplantation of larval fat body into adult Drosophila melanogaster

The larval serum proteins, LSP1 and LSP2, of Drosophila melanogaster are synthesized by the fat body during the third instar. We examined the potential for LSP synthesis by fat body implants in adult flies. Fat body from third instar donors will continue to synthesize LSPs in both males and females. Implants from late second instar larvae will start synthesizing LSP1 and LSP2 in females but only LSP1 in males, suggesting that regulation of these proteins is not the same and that the physiological milieu in the two sexes differs. The newly synthesized LSPs are secreted into the hemolymph for approximately 48 hr when secretion stops but synthesis continues. This sequence follows the pattern for LSP secretion in situ. Fat body from mid second instar larvae is variable in its ability to synthesize LSPs. LSPs are not detected in implants from first instar larvae despite there being a high level of protein synthesis in the implant and considerable growth of the fat body cells. We conclude that there is a critical stage of differentiation during the latter half of the second instar when the fat body becomes independent of the larval milieu and can synthesize LSPs in the adult.     

Ecdysone 20-hydroxylation and 3-epimerization in larvae of the gypsy moth,Lymantria dispar L.: tissue distribution and developmental changes

The potential for ecdysone metabolism was determined for various larval tissues of the gypsy moth, Lymantria dispar. Homogenates of fat body, midguts, and Malpighian tubules, taken on different days during the second half of the fifth instar, were incubated with [(3)H]ecdysone, and the products were analyzed by reversed-phase and normal-phase HPLC. All tissues showed conversion to 20-hydroxyecdysone, and midguts also produced 3-epiecdysone. Ecdysone 20-monooxygenase (E20MO) activity in the fat body increased from a low level on day 5 to a peak on day 11, coinciding with the peak in the hemolymph ecdysteroid titer on the penultimate day of the instar. Midguts and Malpighian tubules showed E20MO activity only during the last 3 or 4days of the instar, with the highest activity also occurring on the penultimate day. For the midguts, the appearance of the E20MO coincided with the transition from larval to pupal tissue. No activity was detected in larval midguts. 3-Epiecdysone formation, however, was mainly found in larval midguts, with only marginal activity detectable in pupal midguts.     

Flower nitrogen status and populations of Frankliniella occidentalis feeding on Lycopersicon esculentum

Alighting and capture of wild olive fruit flies, Bactrocera oleae (Rossi) (Diptera, Tephritidae), on spheres of seven different colours was studied on Chios island, Greece. The 70-mm-diam plastic spheres, coated with adhesive, were suspended on olive trees. Yellow and orange spheres trapped the greatest number of males while red and black spheres trapped the greatest number of females. White and blue spheres were the least effective for both sexes. Peak captures occurred in the late afternoon and especially around sunset. Since mating takes place in the last hours of the photophase, the increased captures during that period may be related to the sexual behaviour of the fly. When red spheres were assessed against glass McPhail traps baited with 2% ammonium sulphate, which consist a standard tool for monitoring the olive fruit fly in Greece, there were no significant differences in male captures. However, spheres trapped almost three times as many females as McPhail traps. The possible mechanisms underlying colour discrimination, the motivation of alighting flies and the possible use of red spheres for monitoring and controlling B. oleae are discussed.     

The nutritional state of male tsetse flies,Glossina pallidipes,at the time of feeding

Abstract. The feeding intervals of tsetse flies have been estimated from the nutritional state of flies caught in traps. However, such estimates have been disputed on the grounds that traps catch a biased, hungry sample of the flies which are seeking hosts and will feed. In this paper we present data on the nutritional state of tsetse flies caught approaching and feeding on oxen. Individual oxen were surrounded with an incomplete ring of electric nets which caught Glossina pallidipes Austen that were approaching, departing unfed and departing fed from an ox. Non-teneral males caught in this way were analysed for their fat and haematin contents. The feeding interval was estimated from a comparison of the frequency distributions of the pre- and post-feed haematin contents of the flies which fed. The former was not measured directly, and was deduced from the frequency distributions of the haematin contents of the male flies caught approaching and departing unfed from the oxen, since it is assumed that the departing unfed and fed flies together form a sample of the approaching flies. There was no difference between the frequency distributions of haematin contents of flies caught approaching and departing unfed, and therefore the pre-feed haematin contents of the males which fed should have the same frequency distribution. Comparison of this distribution with that of the post-feed haematin contents of the males which fed indicated that the majority of male G.pallidipes were returning to feed after digesting on average 1.4 log haematin units of the previous bloodmeal. From data published elsewhere, this corresponds to a mean feeding interval of 42-60h. There was a strong, linear, negative relationship between the fat contents of males and their probability of taking a bloodmeal, suggesting that fat content is important in determining the feeding behaviour of tsetse flies.     

Nutritional levels of female tsetse Glossina pallidipes from artificial refuges

Female tsetse flies, Glossina pallidipes Austen, caught in artificial refuges were subjected to ovarian dissection and analysed for levels of fat, residual dry weight (RDW) and haematin. There were rather small proportions of flies in ovarian categories 0 and 1, in part due to large losses in the immature and teneral stages at the hottest time of year. The distribution of the female catch among pregnancy days was close to uniform. The wet and dry weights (WW and DW) and RDW of eggs, larvae and pupae increased by 0.821, 0.303 and 0.204 mg respectively, with each mm3 increase in volume. Water accounted for 71.7% of the fat-free WW, and fat for 32.7% of the DW. Between birth and ovulation, fat increased from 2 to 4 mg and RDW from 7 to 11 mg; thoracic RDW increased by 2.5mg and changed little thereafter. Fat levels increased 3.5mg by day 6 of pregnancy, but only 0.5 mg thereafter. Over the same periods RDW corrected to zero haematin (CRDW) increased by 1 and 8 mg respectively. Full-term fat and CRDW levels were 8.2 and 19.4 mg respectively. Cumulative haematin frequencies formed a smooth curve with a slope that increased continuously. The raw data were well fitted by a model where feeding rates increased exponentially and capture probability was independent of haematin content. The mean feeding interval was 60 h; feeding probabilities of >0.9/day were only found in flies that had failed to feed for>72 h. In early pregnancy, fat levels declined with haematin for flies that had fed>36 h previously; by days 5-7 fat levels were maintained at a constant high level for 60 h post-feeding. Fat-haematin graphs for female tsetse cannot be used to estimate rates of fat utilization. Traps sample tsetse with below-average fat and RDW in early and late pregnancy respectively. Refuge samples are less biased than those from traps; they give a better picture of the dynamics of pregnancy in normal flies and facilitate the explanation of existing anomalies.     

Age-dependent changes of fat body stores and the regulation of fat body lipid synthesis and mobilisation by adipokinetic hormone in the last larval instar of the cricket, Gryllus bimaculatus

Data on the hormonal regulation of the formation and mobilisation of fat body stores are presented and discussed in relation to general parameters of last instar larval development such as growth, food intake, and moulting. Crickets feed voraciously during the first half of the last larval stage. With the onset of feeding, fat body lipid synthesis increases, leading to increasing lipid stores in the fat body with a maximum reached on day 5. Lipid (42% of fat body fresh mass) is the main constituent of the fat body stores, followed by protein (6%) and glycogen (2%). During the second half of the last larval stage, feeding activity dramatically decreases, the glycogen reserves are depleted but lipid and protein reserves in the fat body remain at a high level except for the last day of the last larval stage when lipid and protein in the fat body are also largely depleted. The process of moulting consumes almost three quarters of the caloric equivalents that were acquired during the last larval stage. Adipokinetic hormone (AKH) inhibits effectively the synthesis of lipids in the larval fat body. Furthermore, AKH stimulates lipid mobilisation by activating fat body triacylglycerol lipase (TGL) in last larval and adult crickets. Both effects of AKH are weaker in larvae than in adults. This is the first report on the age-dependent basal activity of TGL in larval and adult insects. In addition, for the first time, an activation of TGL by AKH in a larval insect is shown.     

家蚕五龄幼虫血淋巴内维生素的研究

本实验对家蚕Bombyx mori五龄健康的雌雄幼虫、氟中毒的雌幼虫、细胞质多角体病毒(CPV)感染的雄幼虫血淋巴内的烟酸、烟酰胺、吡哆辛(VB₆)、硫胺素(VB₁)及核黄素(VB₂)含量,采用离子对反相色谱法进行了定量测定.在五龄幼虫发育阶段,血淋巴内每种维生素含量均是雌蚕高于雄蚕,健康者高于病态者,且病蚕含维生素的量持续下降;烟酸和烟酰胺浓度一直减少,可能是部分烟酸、烟酰胺在酶作用下与某些蛋白质结合,部分烟酸、烟酰胺形成NADP酶的缘故;VB₆、VB₁和VB₂浓度增加,是幼虫大量摄食、贮存能量和营养,供日后生命循环需要的结果.     

Mark-release-recapture of sand flies fed on leishmanial dogs: the natural life-cycle of Leishmania infantum in Phlebotomus ariasi

Wild-caught Phlebotomus ariasi Tonnoir permitted to feed on dogs infected with Leishmania infantum Nicolle were marked with fluorescent powder and released into their natural habitat in an uninhabited area of the Cévennes in southern France. Over a period of 29 days after release, 253 females were recaptured with CDC miniature light traps or by active search at night with portable UV lamps. The ovaries and infections in the alimentary tract were then examined. The females oviposited 6 nights after in infecting blood meal. Second blood meals were never taken during the maturation of eggs. During the first ovarian cycle, midgut infections with promastigotes were only moderately heavy. The intensity of infection increased markedly during the second ovarian cycle and, in the third ovarian cycle, the first pharynx infected with paramastigotes was seen (on day 19). From day 19 to day 29, 76% of the flies had pharyngeal infections. Three out of 19 sand flies with pharyngeal infections recaptured during this period had metacyclic promastigotes in their mouthparts. The long time required for parasites to reach the proboscis in completely natural conditions suggests that their presence in the mouthparts is not a prerequisite for transmission by bite. It is more likely that transmission is most commonly by the regurgitation of metacyclic promastigotes from the thoracic midgut following damage to the stomodaeal valve by chitinase produced by the parasite during its development in the gut of the fly. Nevertheless, it is reasonable to assume that the bite of a fly with metacyclic promastigotes in the proboscis (or salivary glands) would also be infective.     

Methods for monitoring outdoor populations of house flies, Musca domestica L. (Diptera: Muscidae).

Relative collections of house flies were compared on two Florida dairy farms using several monitoring methods: sticky cylinders, baited jug traps (Farnam Terminator and Victor Fly Magnet), and bait strips (Wellmark QuikStrike). Bait strips were placed over collecting pans and under 61 cm square plywood roofs to protect the toxicant from sunlight ("sheltered QuikStrike traps"). Sticky cylinders collected the fewest flies (515-679 flies/trap/day) and sheltered QuikStrike traps the most (5,659-8,814 flies/trap/day). The sheltered QuikStrike traps are promising tools for disease surveillance programs. The two baited jugs collected a similar and intermediate number of flies, with collections highest during the first 2 days after placement (2,920-5,462 flies/trap/day). Jug trap collections were low after 4 days of use in the field, apparently due to deterioration in the attractiveness of the bait over time. Jug traps collected mostly females, whereas sticky cylinders and sheltered QuikStrike traps collected mostly males. Exposure of jug trap bait (Farnam) to fly cadavers for 3 days did not increase attractiveness of the bait. Combinations of the Farnam and Victor attractants were more attractive than either attractant alone and 25-43% more attractive than expected based on the sum of collections in the single-attractant jug traps. A 25% solution of farm-grade blackstrap molasses was as effective as either of the two proprietary baits tested, offering a low-cost alternative for fly population monitoring.     

Juvenile hormone-dependent vitellogenin synthesis in Locusta migratoria fat body: Inducibility related to sex and stage

Juvenile hormone (JH)-dependent vitellogenin (Vg) synthesis in the fat body of Locusta migratoria is normally limited to sexually mature adult females. As a step toward examining the basis of this limitation, we have tested female and male locusts in a series of stages after the third larval molt for inducibility of Vg synthesis by the synthetic JH analog, methoprene. We find that in the fourth and fifth larval instars fat body of both sexes can be induced to produce Vg, but in the adult stage females respond strongly while no more than trace amounts can be induced in males. Quantitative assays show relative responsiveness in the order: adult female > fifth instar female > fifth instar male ? adult male. During the fifth instar of both sexes, maximal vitellogenic response was obtained in midinstar. After the larval-adult ecdysis, female fat body was unresponsive during the first 4 days, then responsiveness increased and by Day 8 after ecdysis fat bodies were fully as competent to produce Vg as at Day 14, the usual maximum of the first vitellogenic cycle due to endogenous JH. Larval and adult female fat bodies implanted into male larvae are competent for Vg synthesis after metamorphosis, so that the differences between adult male and female cannot be imposed by the male milieu intérieur during the larval-adult molt. In male and female precocious adults, produced by treatment of fourth instars with precocene, fat body responded to methoprene as in normal adults. We conclude that factors intrinsic to the fat body cells, determined early in development, are responsible for differential gene programing in males and females, which is partially expressed by the fifth instar but fully manifest only after a molt in the absence of JH.     

Effects of decomposition on carcass attendance in a guild of carrion-breeding flies

Many forensically important calliphorids, sarcophagids and muscids (Diptera) oviposit or larviposit on corpses only during the early stages of decomposition, yet individuals may attend bodies throughout decay. A field study was conducted to investigate how patterns of carcass use and attendance by some fly species are affected by decomposition. Five fly traps were placed in the forest and baited with whole, fresh piglet carcasses. Piglets decomposed in traps throughout the experiment, and all were skeletonized within 6 days. Flies were trapped at both early and late decomposition stages, and the species and population structures of trap catches were compared. More flies attended carcasses early rather than late in decay. For all species, flies attending early were mainly gravid females, but few gravid females attended late in decay. No females ovi- or larviposited late in decay, whereas females of all fly species deposited offspring early in decay. The number of males trapped of each species correlated positively with the number of females with eggs at early development stages. Observations were made of fly predation by European wasps Vespula germanica Fabricius (Hymenoptera, Vespidae) and jumper ants Myrmecia pilosula Smith (Hymenoptera, Formicidae) throughout the experiment. There was a higher risk for smaller fly species of being killed following predator attack. Ants and wasps attacked smaller fly species, whereas only wasps attacked larger fly species.