Fly Pupae Research Articles

Factors Affecting Species Identifications of Blow Fly Pupae Based upon Chemical Profiles and Multivariate Statistics.

Alternative methods for the identification of species of blow fly pupae have been developed over the years that consist of the analyses of chemical profiles. However, the effect of biotic and abiotic factors that could influence the predictive manner for the tests have not been evaluated. The lipids of blowfly pupae (Cochliomyia macellaria, Lucilia cuprina, Lucilia sericata, and Phormia regina) were extracted in pentane, derivatized, and analyzed by total-vaporization solid phase microextraction gas chromatography-mass spectrometry (TV-SPME GC-MS). Peak areas for 26 compounds were analyzed. Here we evaluated one biotic factor (colonization) on four species of blow flies to determine how well a model produced from lipid profiles of colonized flies predicted the species of flies of offspring of wild-caught flies and found very good species identification following 10 generations of inbreeding. When we evaluated four abiotic factors in our fly rearing protocols (temperature, humidity, pupation substrate, and diet), we found that the ability to assign the chemical profile to the correct species was greatly reduced.

Efficacy of entomopathogenic nematodes (Rhabditida: Steinernematidae and Heterorhabditidae) on developmental stages of house fly, Musca domestica.

The housefly, Musca domestica is a major domestic, medical and veterinary pest. The management of these flies reliance on insecticide, causes environmental constraints, insecticide resistance and residues in the meat, skin. Therefore one of the eco-friendly alternate methods is by using biological agents such as entomopathogenic nematodes (EPN). In the present study evaluated the survival of EPN species Steinernema feltiae, Heterorhabditis indica, S. carpocapsae, S. glaseri and S. abbasi in poultry manure and also their efficacy against different developmental stages of house fly. After exposing to poultry manure, S. feltiae showed more survival as followed by H. indica, S. carpocapsae, S. glaseri and S. abbasi in all exposition period. When the exposition period extended to 96h, all nematode species survivability was drastically reduced. After exposing these nematodes to poultry manure at 24h their virulence capacity against wax moth, Galleria mellonella showed all the nematode species were able cause 100% mortality. However their progeny production was significantly reduced. Fly eggs and pupae were refractory to these nematode infection. Petri dish without artificial diet assay showed that, second and 3rd-instar larvae were highly susceptible to EPNs as compared to larvae provided with artificial diet. H. indica showed high virulence capacity compared to other nematodes tested. Poultry manure assay revealed that, H. indica and S. carpocapsae caused minimal mortality where as S. feltiae, S. glaseri and S. abbasi did not cause any mortality. This may be because of poor survival and limited movement of nematodes in poultry manure which may be due to ammonia, other toxic substances in poultry manure. The decrease in larval mortality in manure suggests that biocontrol of housefly by using EPNs is unlikely.

Organic management of olive orchards increases the predation rate of overwintering pupae of Bactrocera oleae (Diptera: Tephritidae)

The olive fruit fly is the key pest of the olive tree and to date alternative and effective solutions to pesticide applications, such as conservation biological control techniques are scarce. Olive fruit fly overwintering pupae spend the season below the top soil, where they can be exposed to ground dwelling predators. In this study, we estimated the effect of predators on overwintering pupae sentinels considering both local and landscape variables in 18 olive orchards. We selected the experimental olive orchards in a Mediterranean-type environment, which had, as adjacent land use type olive, wood or Mediterranean garigue. In addition, we considered as local variables the distance of each pupae experimental unit from the edge with the semi-natural habitat, and the management of the fields while landscape scale variable considered the composition in semi-natural habitat type of the surrounding environment in buffer of 250 and 500m radius. In organic orchards, exposed pupae were numerically more consumed than pupae in conventional orchards. No landscape effect was detected but we found a different effect of adjacent land use type, with enhanced predation rate of olive fly pupae in olive orchards adjacent to Mediterranean garigue patches. Further experiments could clarify the role of semi-natural habitats in supporting ground pest control and suggest close-to-nature solutions to pesticide strategy.

Seasonal changes in food selection and nutrition of captive platypuses (Ornithorhynchus anatinus)

Anecdotal observations of captive platypuses (Ornithorhynchus anatinus) suggest that they show a seasonal preference for particular foods, but this has never been rigorously measured. This study aimed to determine seasonal food preferences and energy consumption of captive platypuses so that better protocols for maintaining platypuses in captivity can be developed. Seven platypuses were fed an ad libitum diet with all food items weighed in and out of tanks. Food items were analysed for energy, fats, carbohydrates, proteins, vitamins and minerals. Platypuses preferred less mobile prey (mealworms, earthworms and fly pupae) over highly mobile prey (crayfish). There was no significant seasonal change in preference for different dietary items, which is more likely to be driven by prey behaviour. Crayfish contributed the largest percentage (mass) consumed and was highly nutritious. While the relative percentage of items in the diet did not change seasonally, the quantity eaten did. The mean energy intake of platypuses was 921 kJ kg–1 day–1 and varied seasonally, being lowest during the breeding season (810 kJ kg–1 day–1) and highest in the postbreeding season (1007 kJ kg–1 day–1). These changes were associated with preparation and recovery from the breeding season. We conclude that the platypus diet is influenced by nutrition and seasonal factors as well as by prey behaviour. This knowledge will contribute to improving the husbandry and management of platypuses, which are widely recognised as difficult to maintain in captivity.

Zastosowanie entomotoksykologii w szacowaniu czasu i ustaleniu przyczyny zgonu

Entomotoxicology allows the estimation of the post-mortem interval and the determination of the cause of death in cases in which the corpse has decomposed and the tissues necessary for toxicological analysis are no longer available. Obtaining information about toxic substances potentially present in the body is possible by isolation of larvae and pupae of true flies (Diptera) and/or adult forms of, e.g., beetles (Coleoptera) present on or near the corpse. This article was intended to summarize the current knowledge in the field of entomotoxicology, including examples from the literature, and to present the impact of selected toxic substances and medicines on the development of necrophagous larvae of insects.

Scuttle Flies (Diptera: Phoridae) Inhabiting Rabbit Carcasses Confined to Plastic Waste Bins in Malaysia Include New Records and an Undescribed Species.

Scuttle flies (Diptera: Phoridae) are small-sized insects of forensic importance. They are well known for diversified species and habitats, but in the context of forensic entomology, scuttle flies' inhabitance of corpses remains inadequately explored. With recent reports indicating the existence of more scuttle fly species possibly inhabiting these environments, a decomposition study using animal carcasses in enclosed environments was conducted. The aim was to record the occurrence of scuttle flies on rabbit carcasses placed in sealed plastic waste bins for a 40-day period. The study was conducted as two replicates in Bangi, Selangor. Sampling was carried out at different time intervals inside a modified mosquito net as a trap. Inside the trap, adult scuttle flies were aspirated and preserved in 70% ethanol. The fly larvae and pupae were reared until their adult stage to facilitate identification. From this study, six scuttle fly species were collected, i.e., Dahliphora sigmoides (Schmitz) ♂, Gymnoptera simplex (Brues) ♀, Megaselia scalaris (Loew) ♂♀, Puliciphora borinquenensis (Wheeler) ♂, Puliciphora obtecta Meijere ♀ and Spiniphora sp. ♀. Both D. sigmoides and P. obtecta were newly recorded in Malaysia, whilst the Spiniphora sp. was considered an unknown species until it was linked to its male counterpart. The sealed waste bins were found to be accessible for the scuttle flies with delayed arrival (day 4-5). Megaselia scalaris was the primary scuttle fly species attracted to the carcass, and its occurrence could be observed between days 4-7 (replicate 1) and days 5-33 (replicate 2). This study also revealed Sarcophaga spp. (Diptera: Sarcophagidae) as the earliest species to colonize the remains and the longest to inhabit them (days 2-40). The larvae of Hermetia illucens (Linneaus) (Diptera: Stratiomyidae) and Fannia sp. (Diptera: Fanniidae) were found on the carcasses during the mid-advanced decay period. These findings expand the knowledge on the diversity of forensically important scuttle flies and coexisting dipterans in enclosed environments in Malaysia.

Sublethal effects of imidacloprid exposure on Spalangia endius, a pupal parasitoid of filth flies

Parasitoids and neonicotinoids can both suppress economically harmful filth fly populations. However, sublethal effects of neonicotinoids have not previously been studied for commonly used species of filth fly parasitoids. Exposure to an LC50 of imidacloprid decreased the ability of surviving individuals of the parasitoid wasp Spalangia endius Walker (Hymenoptera: Pteromalidae) to kill house fly pupae under some conditions. In an unburied-hosts experiment, significantly more flies and fewer parasitoids emerged in the LC50 imidacloprid treatment versus the LC10 or controls. Parasitoid sex ratio and longevity were not affected. However, in a buried-hosts experiment, parasitoid and fly emergence were independent of treatment. ELISA (enzyme-linked immunosorbent assay) showed lower imidacloprid residues in or on parasitoids exposed to the media in which hosts were buried. Our findings suggest that substrate may reduce pesticides on biological control agents that burrow, making them more effective.

First description of larval stages of Aleochara pseudochrysorroa Caron, Mise & Klimaszewski, 2008.

Aleochara pseudochryssoroa is an abundant species near Centro Politécnico UFPR (Federal University of Paraná), Curitiba, Paraná, Brazil. This species can easily be collected in animal carcasses being an important fly regulator in this area. The adults of Aleochara prey on fly larvae, while the immature stages of Aleochara are parasitoids of fly pupae. The larvae studied here, were reared from adults of A. pseudochrysorroa collected in Curitiba, Paraná state, Brazil in animal carcasses. The immature specimens obtained were cleared and studied in glycerin in order to describe all immature stages. In this work, we describe and illustrate for the first time all larval instars of Aleochara pseudochryssoroa.

Temporal Diversity and Abundance Patterns of Parasitoids of Fruit-Infesting Tephritidae (Diptera) in the Argentinean Yungas: Implications for Biological Control.

A 4-yr study was done to analyze seasonal patterns underlying host plant-fruit fly-parasitoid interactions in a secondary forest in the Argentinean Yunga and its importance for the implementation of conservation and augmentative biological control. Larval-pupal hymenopteran parasitoids associated with all host plants and fruit fly species were identified and the seasonal occurrence of fruit, infestation levels, parasitism percentage, and relative parasitoid abundance were determined. Three fruit fly species in two genera were found in association with surveyed plants, two of which (Ceratitis capitata (Wiedemann) and Anastrepha fraterculus (Wiedemann)) are of major economic importance. Infestation levels were strongly influenced by environmental factors and peak fruit availability. Five fruit fly parasitoid species were recovered from fly pupae, four braconid species, and one figitid. Time windows for fruit fly population growth were pinpointed. Based on results, the present analysis proposes an effective fruit fly biological control strategy tailored for the northwestern Argentinean citrus-producing area.

Temperature- and Age-Dependent Survival, Development, and Oviposition Rates of the Pupal ParasitoidSpalangia cameroni(Hymenoptera: Pteromalidae)

The combined effect of temperature and age on development, survival, attack rate, and oviposition of the parasitoid Spalangia cameroni (Perkins) (Hymenoptera: Pteromalidae) exploiting house fly pupae was investigated by conducting life-table experiments at 15, 20, 25, 30 and 35°C. Temperature had a pronounced effect on survival and development of the immature stages. Survival was highest at 25°C, where 88.5% of the parasitized host pupae resulted in adult parasitoids, and lowest at 35°C when only 3.78% emerged. Females constituted between 50% (at 20°C) and 100% (at 35°C) of the surviving immatures. Males developed faster than females, with the shortest developmental times at 30°C (18.18 d for males and 19.41 d for females). Longevity of adult females decreased with temperature from 80 d at 15°C to 18 d at 35°C. Total attack rate of female parasitoids was highest at 20°C (106 hosts per female), and life-time reproduction highest at 20°C and 25°C (about 60 offspring per female). Sex ratio was female biased (65% females). A generic model was used to estimate and predict the temperature effect on the intrinsic rate of increase (rm), the net reproduction rate (R0), and the generation time (G). The model predicted that rm peaks at 33.5°C (rm = 0.182 d(-1)), that maximum R0 is reached at 27.2°C (R0 = 50.2), and that the shortest generation time occurs at 34.5°C (G = 21.1 d). Doubling time was 4.19 d at 33°C. In the temperature range between 20°C and 30°C, S. cameroni has the potential to be an efficient control agent against nuisance flies.

Численность имаго мух и их личинок в условиях свинокомплекса в осенний период

Objective of research: To study the abundance of adult of flies and their larvae in a pig farm in the fall two weeks before the end of the production cycle. Materials and methods: The abundance of adult flies and their larvae was investigated in September - October 2015 at the pig farm “Kuznetsovsky” of Moscow region in two sow houses and one pigsty for weaned piglets two weeks before the end of the production cycle. To calculate the number of adult flies, we have placed in each selected pigsty the flytraps (sticky tapes) “Mukholov-Proshka” produced in St. Petersburg. The trap has an adhesive base containing rosin, rubber and mineral oil. Traps were placed at 1 and 2 m from the floor, six traps in each room. The number of adhered insects was calculated at the laboratory of the All-Russian Research Institute of Fundamental and Applied Parasitology of animals and plants named after K.I. Skryabin, 24 hours after placement of traps. To calculate the number of fly larvae and pupae, in cooperation with the pig farm veterinary service the scrapings were taken from the floor with dimensions of 10 × 10 cm (six scrapings from each pigsty). Scrapings with the mass of 3-5 g were placed into individual plastic minicontainers with a particular number and delivered to the laboratory of the Institute for examination. Results and discussion: The study on initial number of adult flies and their larvae conducted two weeks before the end of the previous technological cycle showed a significant insect number at different heights from the floor. In the first pigsty, the number of flies in a flytrap (at a height of 1 and 2 m from the floor) ranged from 199 to 286 ind. Calculated 24 hours after the placement of flytraps; the average number was 257 individuals. In the second pigsty, the number of flies ranged from 108 to 198 individuals; the average number was 147individuals. In the pigsty for weaning piglets, one day after the placement of traps, the number of adult flies in one flytrap ranged from 162 to 286 individuals, and the average number was 249 individuals. The average number of fly larvae in one tested sample taken from the floor of a pigsty was 267 and 118 individuals, and in a pigsty for weaning piglets - 29 individuals.

Influence of natal host on parasitism by Spalangia cameroni (Hymenoptera: Pteromalidae)

Spalangia cameroni Perkins (Hymenoptera: Pteromalidae) is sold commercially as a biocontrol agent of filth flies, including the house fly, Musca domestica L. (Diptera: Muscidae). For this reason, S. cameroni is mass-reared for inundative releases to control harmful flies. However, the mass-rearing protocols include very little information on the influence of natal host on subsequent host selection by parasitoids with more than one potential host as in the genus Spalangia. Here, we report on the use of S. cameroni against M. domestica. The S. cameroni were reared using Ceratitis capitata Wiedemann (Diptera: Tephritidae) (natal host) pupae for several generations. Freeze-killed fly pupae were used in assays to determine the fecundity, number of adult progeny and sex-ratio of this parasitoid. Realized fecundity and number of adult progeny were greater when provided with house fly pupae than Mediterranean fruit fly pupae. Thus S. cameroni parasitized more house fly pupae than C. capitata pupae, even though the parasitoid was reared on Mediterranean fruit fly for many generations. These results indicate that S. cameroni reared on C. capitata can be successfully used in inundative releases against both fruit flies (agriculture) and house flies (livestock farming).

Searching Ability of Pupal Parasitoid, Dirhinus giffardii (Silvestri) on Bactrocera zonata (Saunders) at Various Depths of Plant Debris

The present study was carried out to determine the searching ability of pupal parasitoid, Dirhinus giffardii of Bactrocera zonata in the Bio Control Research Laboratory, | department of Entomology, SAU, Tandojam, at temperature 27 ± 1ºC and 60 ± 5% relative humidity. Adults of fruit fly were fed with water, sugar and needo milk powder, whereas, Dirhinus giffardii were fed with honey and water solution. Ten days old D. giffardies were used against 20 pupae of Bactrocera zonata in the experiment and data recorded on parasitized pupae and un-parasitized pupae after 24, 48, 72 and 96 hours. The results in all treatments indicates that highest parasitized pupae were at peak level of (16.66) after 72 hours age of pupae on the depth of 0 cm in plant debris followed by 4 cm depth (16.33), whereas lowest parasitized pupae were recorded at 5cm depth (13.66) after 72 hours of age inside plant debris. Likewise, the highest un-parasitized pupae were at peak level of (14.00) after 24 hours of age of pupae on the depth of 3cm in plant debris followed by 1cm depth (13.00), whereas lowest un parasitized pupae were recorded at 4cm depth (11.66) after 24 hours of age inside plant debris. The analysis of variance indicated that there wasno significant difference among the parasitized and unparasitized pupae of flies in the different depths of plant debris and age intervals (P

A Houdini's trick in a fly: Leg unfolding with the aid of transient hinges in an extricating Calliphora vicina (Diptera: Calliphoridae)

Legs in a fly pupa are tightly folded in Z-configuration: the femur points forward. The fly emerges from the pupa with all legs stretched backwards. How does the fly turn long femora inside the tight puparium? Flies were captured during emergence at various moments of progress out of the puparium and at once fixed in ethanol, postfixed in Bouin's solution. Specimens were ranged by the grade of progressive extrication and maturation. Legs were excised, their configurations photographed. Legs are anchored to the VIII. abdominal segment of the puparium with the pupal sheath. Some podomers were arched or buckled yet in pharate adults. At the initial moment of extrication, new buckles appeared in femora, they split femora into 2–3 subpodomers. Instead of turning the whole femur, the fly dragged through the puparium a chain of short subpodomers linked together with transient hinges. Hinges emerged in unsclerotized areas of the tubular podomer, close to sclerotized areas (juvenile sclerites). During extrication, legs were stretched passively. This process lasted for 1–3 min, initial phase – few seconds. Residual distortions were left in hind legs of free juvenile adults. Mechanics of buckling and straightening is discussed from the viewpoint of strength of materials.

Bacterial Associations Across House Fly Life History: Evidence for Transstadial Carriage From Managed Manure.

House flies (Diptera: Muscidae; Musca domestica L.) associate with microbe-rich substrates throughout life history. Because larvae utilize bacteria as a food source, most taxa present in the larval substrate, e.g., manure, are digested or degraded. However, some species survive and are present as third-instar larvae begin pupation. During metamorphosis, many bacteria are again lost during histolysis of the larval gut and subsequent remodeling to produce the gut of the imago. It has been previously demonstrated that some bacterial species survive metamorphosis, being left behind in the puparium, present on the body surface, or in the gut of the emerged adult. We used a combined culture-molecular approach to identify viable microbes from managed manure residue and a wild population of house fly larvae, pupae, puparia, and adults to assess transstadial carriage. All larval (10/10), pupal (10/10), and puparial (10/10) cultures were positive for bacteria. Several bacterial species that were present in larvae also were present either in pupae or puparia. Four viable bacterial species were detectable in 6 of 10 imagoes reared from manure. Of note is the apparent transstadial carriage of Bacillus sonorensis, which has been associated with milk spoilage at dairies, and Alcaligenes faecalis, which can harbor numerous antibiotic resistance genes on farms. The potential of newly emerged flies to harbor and disseminate bacteria from managed manure on farms is an understudied risk that deserves further evaluation.

Near Infrared Imaging As a Method of Studying Tsetse Fly (Diptera: Glossinidae) Pupal Development.

Near infrared (NIR) photography and video was investigated as a method for observing and recording intrapuparial development in the tsetse fly Glossina palpalis gambiensis and other Muscomorpha (Cyclorrhapha) Diptera. We showed that NIR light passes through the puparium, permitting images of the true pupae and pharate adult to be captured. Various wavelengths of NIR light from 880 to 1060 nm were compared to study the development of tsetse fly pupae from larviposition to emergence, using time-lapse videos and photographs. This study was carried out to advance our understanding of tsetse pupal development, specifically with the goal of improving a sorting technique which could separate male from female tsetse flies several days before emergence. Separation of the sexes at this stage is highly desirable for operational tsetse sterile insect technique control programmes, as it would permit the easy retention of females for the colony while allowing the males to be handled, irradiated and shipped in the pupal stage when they are less sensitive to vibration. In addition, it presents a new methodology for studying the pupal stage of many coarctate insects for many applications. NIR imaging permits observation of living pupae, allowing the entire development process to be observed without disruption.

Influence ofOecophylla longinodaLatreille, 1802 (Hymenoptera: Formicidae) on Mango Infestation byBactrocera dorsalis(Hendel) (Diptera: Tephritidae) in Relation to Senegalese Orchard Design and Management Practices

Damage caused by the fruit fly Bactrocera dorsalis (Hendel) (syn. B. invadens Drew, Tsuruta & White) (Diptera: Tephritidae) on mangoes in Senegal leads to production losses. A potential biological control agent against this pest is the weaver ant Oecophylla longinoda Latreille (Hymenoptera: Formicidae). Senegalese mango-based orchards present a diversity in design and management practices that can influence the abundance of these two species in orchards. In this study we evaluated i) the ability of the O. longinoda ant to limit B. dorsalis damage in Senegalese orchards, and ii) variations in population abundance for these two species depending on orchard design and management practices. The study was conducted in Senegal in the Niayes area and the Thies plateau. Fifteen orchards were sampled among three out of four kinds of orchards identified in this area: (1) ‘No-input mango diversified orchards’, (3) ‘Medium-input citrus-predominant orchards’ and (4) ‘Medium-input large mango- or citrus-predominant orchards’. In one of the orchards we measured infestation rates and numbers of fly pupae that developed from mangoes collected from trees (cv. Kent) ‘with’ and ‘without’ O. longinoda colonies over three harvesting periods (May, July and August) in 2013. The abundance of O. longinoda and B. dorsalis was measured for two months in the dry season and two others in the rainy season in the 15 orchards in 2012. The presence of O. longinoda on trees reduced the proportion of mangoes attacked by B. dorsalis as well as the number of pupae that developed from infested mangoes. The abundance of O. longinoda and B. dorsalis was negatively correlated. The abundance varied depending on the orchard design and management practices. O. longinoda abundance was greater in orchard types 1 and 3 than in type 4. Conversely, B. dorsalis abundance in the rainy season tended to be greater in orchard type 4 than in types 1 and 3. This study showed that O. longinoda is effective in limiting mango infestations by B. dorsalis. It also showed that the abundance of these two species was influenced by the orchard design and management practices. Therefore, using O. longinoda to control fruit flies is possible in Senegalese mango-based orchards by promoting weaver ant preservation.

Chilling and Host Plant/Site-Associated Eclosion Times of Western Cherry Fruit Fly (Diptera: Tephritidae) and a Host-Specific Parasitoid.

The western cherry fruit fly, Rhagoletis indifferens Curran (Diptera: Tephritidae), is an endemic herbivore of bitter cherry, Prunus emarginata (Douglas ex Hooker) Eaton, but ∼100 years ago established on earlier-fruiting domesticated sweet cherry, Prunus avium (L.) L. Here, we determined if eclosion times of adult R. indifferens from sweet and bitter cherry differ according to the phenology of their respective host plants and if eclosion times of the host-specific parasitoid Diachasma muliebre (Muesebeck) (Hymenoptera: Braconidae) attacking bitter and sweet cherry flies differ according to the eclosion phenology of their fly hosts. Fly pupae from sweet and bitter cherry fruit were collected from sympatric and allopatric sites in Washington state, and chilled at 5°C. Because timing of eclosion in R. indifferens depends on chill duration, eclosion time in wasps could also vary with chill duration. To account for this, fly pupae were chilled for 1, 2, 2.5, 3, 4, 6, or 8 mo. Both flies and wasps eclosed earlier with longer chill durations. Eclosion times of sweet and bitter cherry flies from a sympatric site in central Washington did not differ. However, at allopatric sites in northwestern and central Washington, bitter cherry flies eclosed later than sweet and bitter cherry flies at the sympatric site. Correspondingly, D. muliebre parasitizing a more isolated bitter cherry fly population eclosed later than D. muliebre parasitizing earlier-emerging sweet and bitter cherry fly populations. These results provide evidence for D. muliebre rapidly responding to changes in host plant shifts by R. indifferens.

Effect of Mutual Interference on the Ability of Spalangia cameroni (Hymenoptera: Pteromalidae) to Attack and Parasitize Pupae of Stomoxys calcitrans (Diptera: Muscidae).

We investigated the effect of mutual interference on the attack efficiency and the rate of successful parasitism on the parasitoid Spalangia cameroni (Perkins) attacking pupae of the stable fly Stomoxys calcitrans (L.). Female parasitoids (2, 4, 8, 16, or 32) were exposed to 100 fly pupae during 24 h. The number of pupae that were attacked and the number successfully parasitized increased with the parasitoid density and reached a maximum of ∼70 and 50, respectively. Parasitoid-induced mortality (PIM) was about 20 pupae, irrespective of parasitoid density. The per capita rates of attack, successful parasitism and parasitoid-induced mortality declined monotonously with parasitoid density. Progeny sex ratio was female biased for all parasitoid densities, but declined significantly with increasing parasitoid density from ∼70% females at the lowest density to ∼60% at the highest. Mutual interference was incorporated into a functional response model to predict the attack rate and the rate of successful parasitism at different temperatures, host densities and parasitoid densities. The model explained 93.5% of the variation in the observed number of attacked pupae and 91.5% of the variation in the number of successfully parasitized pupae. The model predicts that increasing parasitoid densities will increase the percentage of killed hosts, but only up to a certain density. Above this density, a further increase in parasitoid abundance will actually lead to a decline in the percentage parasitism. These findings may have some implications for using S. cameroni in biological control against flies using inundative releases.

Drilling-in and Chewing-out of Hosts by the Parasitoid Wasp Spalangia endius (Hymenoptera: Pteromalidae) When Parasitizing Musca domestica (Diptera: Muscidae).

Many organisms are protected from natural enemies by a tough exterior. Such protection is particularly important for immobile stages, such as pupae. The pupa of some insects is protected by a puparium, which is a shell formed from the exoskeleton of the last larval instar. However, the puparium of certain fly species is drilled through by adult females of the wasp Spalangia endius Walker. The female wasp then deposits an egg on the fly pupa within the puparium. After the wasp offspring finishes feeding on the fly pupa, it chews through the puparium to complete emergence. Despite the apparent toughness of the puparium, there was no detectable wear on the ovipositor of S. endius females even when females had been encountering fly pupae (Musca domestica L.) for weeks, and regardless of whether the pupae were large or old or both. Energy dispersive spectroscopy did not reveal any metal ions in the ovipositor's cuticle to account for this resistance against wear. Offspring of S. endius that chewed their way out of pupae also showed no detectable wear on their mandibles. Tests with a penetrometer showed that the force required to penetrate the center of a puparium was greater for larger and for older pupae; and an index of overall thickness was greater for large old pupae than for small old pupae. The lack of an effect of pupal size or age on wear may result from wasps choosing locations on the puparium that are easier to get through.