Pupal Parasitoid Research Articles

Selectivity of Insecticides to a Pupal Parasitoid, Trichospilus diatraeae (Hymenoptera: Eulophidae), of Soybean Caterpillars

Selectivity is an important aspect of modern insecticides to be able to target pests whilst maintaining beneficial entomofauna in the crop. The present objective was to assess the selectivity of different insecticides for the pupal parasitoid of soybean caterpillars, i.e., Trichospilus diatraeae Cherian & Margabandhu, 1942 (Hymenoptera: Eulophidae). Acephate, azadirachtin, Bacillus thuringiensis (Bt), deltamethrin, lufenuron, teflubenzuron and thiamethoxam + lambda-cyhalothrin at the highest recommended concentrations for the soybean looper Chrysodeixis includens (Walker, [1858]) (Lepidoptera: Noctuidae), as well as water in the control, were used against the pupal parasitoid T. diatraeae. The insecticides and the control were sprayed on the soybean leaves, which were left to dry naturally and placed in cages with T. diatraeae females in each one. Survival data were submitted to analysis of variance (ANOVA) and the means were compared using Tukey's HSD test (α = 0.05). Survival curves were plotted according to the Kaplan-Meier method, and the pairs of curves were compared using the log-rank test at 5% probability. The insecticides azadirachtin, Bt, lufenuron and teflubenzuron did not affect T. diatraeae survival, while deltamethrin and thiamethoxam + lambda-cyhalothrin presented low toxicity and acephate was highly toxic, causing 100% mortality in the parasitoid. Azadirachtin, Bt, lufenuron and teflubenzuron are selective for T. diatraeae and could be used in IPM programs.

First report on classical biological control releases of the larval parasitoid Ganaspis brasiliensis against Drosophila suzukii in northern Italy

Current management strategy of the invasive fruit fly Drosophila suzukii (Matsumura) (Diptera: Drosophilidae) exploits different tools but relies mainly on chemical control. In the invaded areas, the local natural enemy community mostly consists of generalist pupal parasitoids unable to control the pest efficiently. Conversely, in the pest native area, there are more specialized sympatric larval parasitoids attacking D. suzukii. Following foreign explorations and quarantine risk assessments, the larval endoparasitoid Ganaspis brasiliensis (Ihering) (Hymenoptera: Figitidae) was selected as the best candidate for classical biological control programs. In 2021, the first ever propagative biocontrol program using a Japanese G1 lineage of G. brasiliensis started in Italy. Here we report the results of the first year of releases in the province of Trento (Northeast Italy), wherein G. brasiliensis was released in 12 locations. Pre- and post-release samplings on fresh and fallen fruits were performed around the release points to assess the recapture rate, the impact of the exotic parasitoid on D. suzukii and its potential interactions with local non-target species. After releases, G. brasiliensis was recovered at 50% of the locations. The exotic parasitoid only emerged from D. suzukii, mostly from fresh fruit still on the plant. Post-overwintering monitoring revealed the presence of a four G. brasiliensis individuals at two release locations.

Comparative toxicity of spinetoram to Trialeurodes vaporariorum Westwood and its parasitoid Eencarsia formosa Gahan

The role of selective new generation bioisecticides, beside their effectiveness against key pests, relies on their safety to beneficial arthropods. Spinetoram, a semi-synthetic analogue of the microbial-derived bioinsecticide spinosad is registered worldwide for application in numerous crops, but assessment of its ecotoxicological risk to beneficial arthropods has scarcely been documented. Moreover, this is the first report on toxic effects of spinetoram on a pest, the greenhouse whitefly Trialeurodes vaporariorum Westwood (Hemiptera: Aleyrodidae), and/or its successful biocontrol agent, the parasitoid Encarsia formosa Gahan (Hymenoptera: Aphelinidae). Under laboratory conditions, we assessed the acute toxicity of spinetoram insecticide (25% a.i.) to adults, nymphs and eggs of the greenhouse whitefly, as well as to parasitoid adults and pupae. In all concentration-response bioassays, the spinetoram insecticide was applied to tobacco leaves settled onto 1% agar layer in ventilated Petri dishes using a Potter spray tower. The parameters of spinetoram acute toxicity to adults of both the pest and the parasitoid were evaluated in residual contact bioassays, while whitefly eggs and nymphs, and parasitoid pupae were topically treated with a series of spinetoram concentrations, covering a range of 10-90% mortality. Lethal spinetoram effects on the parasitoid E. formosa were assessed through selectivity ratio (SR) estimations, showing the ratios beetween median lethal concentrations (LC50s) estimated for the parasitoid, and LC50s estimated for the pest. The following LC50 values were obtained: 4.593, 15.027 and 11.73 mg a.i./l for whitefly adults, nymphs and eggs, respectively, and 0.686 and 1.715 mg a.i./l for parasitoid adults and pupae, respectively. The calculated SR estimations were below 1, indicating that spinetoram insecticide is non-selective to both tested stages of the parasitoid E. formosa. A more detailed understanding of spinetoram impact on E. formosa in whitefly integrated management requires further evaluation of sublethal effects and greenhouse trials, with an emphasis on population-level responses.

Biology of Brachymeria kamijoi Habu (Hymenoptera: Chalcididae), a pupal parasitoid of the coconut black-headed caterpillar, Opisina arenosella Walker (Lepidoptera: Xyloryctidae)

The coconut black-headed caterpillar, Opisina arenosella Walker (Lepidoptera: Xyloryctidae) has been one of the most serious defoliators of coconut plants in Vietnam. Brachymeria kamijoi Habu (Hymenoptera: Chalcididae) is a pupal parasitoid of O. arenosella with high percent parasitism and abundance in the coconut fields and appears to be a good biological control agent against the coconut black-headed caterpillar in Vietnam. This study was carried out at Entomology Laboratory, Faculty of Agronomy, Nong Lam University, Vietnam during 2020 – 2021 to determine some biological characteristics of B. kamijoi on O. arenosella at a constant temperature of 28 oC and a photoperiod of 12L: 8D. Total developmental time from egg to adult emergence was 13.8 days. The females laid a mean of 98.1 eggs during an average lifespan of 30.7 days. Fecundity peaked at a large range of age 7 -29 days. The results would contribute to the knowledge of the biology of B. kamijoi to optimize a mass-rearing system for a biological control programme against O. arenosella.

Nonnutritive Sugars for Spotted-Wing Drosophila (Diptera: Drosophilidae) Control Have Minimal Nontarget Effects on Honey Bee Larvae, a Pupal Parasitoid, and Yellow Jackets.

Drosophila suzukii Matsumura, spotted-wing drosophila, is a major pest of small fruits and cherries and often managed with conventional insecticides. Our previous work found that erythritol, a nonnutritive polyol, has insecticidal properties to D. suzukii. Two formulations of erythritol (1.5M), with 0.5M sucrose or 0.1M sucralose, are most effective at killing D. suzukii. In this study, we investigated the nontarget effects of these erythritol formulations on honey bee Apis mellifera Linnaeus larvae, a pupal parasitoid of D. suzukii, Pachycrepoideus vindemiae Rondani, and western yellow jacket, Vespula pensylvanica Saussure. We directly exposed honey bee larvae by adding a high dose (2 µl) to larval cells and found no significant mortality from either formulation compared to the water control. Pachycrepoideus vindemiae may encounter erythritol in field settings when host plants of D. suzukii are sprayed. The erythritol+sucralose formulation was more detrimental than erythritol+sucrose to P. vindemiae, however, this effect was greatly reduced within a 21-d period when a floral source was present. Since yellow jackets are a nuisance pest and were attracted to the erythritol formulations in recent field trials, we tested adult V. pensylvanica survival with continuous consumption of these formulations in the laboratory. We found no detectable detriment from either formulation, compared to the sucrose control. Overall, both erythritol formulations caused minimal nontarget effects on honey bee larvae, P. vindemiae parasitoids, and western yellow jackets.

Limited gains in native parasitoid performance on an invasive host beyond three generations of selection.

Co-evolved natural enemies provide sustainable and long-term control of numerous invasive insect pests, but the introduction of such enemies has declined sharply due to increasing regulations. In the absence of co-evolved natural enemies, native species may attack exotic invasive pests; however, they usually lack adaptations to control novel hosts effectively. We investigated the potential of two native pupal parasitoids, Pachycrepoideus vindemmiae and Trichopria drosophilae, to increase their developmental success on the invasive Drosophila suzukii. Replicated populations of the two parasitoids were subjected to 10 generations of laboratory selection on D.suzukii with Drosophila melanogaster serving as the co-evolved host. We assessed developmental success of selected and control lines in generations 0, 3, and 10. Changes in host preference, sex ratio, development time, and body size were measured to evaluate correlated responses with adaptation. Both parasitoid species responded rapidly to selection by significantly increasing their developmental success on the novel host within three generations, which remained constant for seven additional generations without further improvement. The generalist parasitoid species P.vindemmiae was able to reach similar developmental success as the control populations, while the performance of the more specialized parasitoid T.drosophilae remained lower on the novel than on the co-evolved host. There was no increase in preference towards the novel host over 10 generations of selection nor were there changes in development time or body size associated with adaptation in either parasitoid species. The sex ratio became less female-biased for both parasitoids after three generations of selection but rebounded in P.vindemmiae by generation 10. These results suggest that a few generations of selection may be sufficient to improve the performance of native parasitoids on invasive hosts, but with limits to the degree of improvement for managing invasive pests when exotic co-evolved natural enemies are not available.

Discrimination Abilities and Parasitism Success of Pupal Parasitoids Towards Spotted-Wing Drosophila Pupae Previously Parasitized by the Larval Parasitoid Ganaspis brasiliensis (Hymenoptera: Figitidae).

Pachycrepoideus vindemiae (Rondani) (Hymenoptera: Pteromalidae) and Trichopria drosophilae (Perkins) (Hymenoptera: Diapriidae) are two cosmopolitan and generalist pupal parasitoids that are among a few of the resident parasitoids in North America capable of attacking Drosophila suzukii (Matsumura) (Diptera: Drosophilidae), an invasive pest of small and soft fruit crops worldwide. Ganaspis brasiliensis (Ihering) is a specialist larval parasitoid of D. suzukii that was recently approved for biological control introduction against D. suzukii in the USA. As a solitary koinobiont species, G. brasiliensis oviposits in the host larva but emerges as an adult from the host puparium. This study investigated the discrimination ability and parasitism success by the pupal parasitoids towards D. suzukii pupae previously parasitized by G. brasiliensis, to examine whether interactions with resident parasitoids will affect G. brasiliensis after it is released in the USA. We found preliminary evidence that neither pupal parasitoid could discriminate towards D. suzukii pupae parasitized by early instars of G. brasiliensis. Pachycrepoideus vindemiae was able to successfully develop on D. suzukii pupae containing all preimaginal stages of G. brasiliensis, although parasitism success was significantly higher on those bearing later rather than early stages of G. brasiliensis. Trichopria drosophilae was only able to successfully develop on D. suzukii puparia containing early instars of G. brasiliensis. These results suggest that D. suzukii parasitized by the larval parasitoid could be subsequently attacked by the pupal parasitoids, possibly affecting the success of G. brasiliensis releases.

Laboratory Evaluation of Pupal Parasitoids for Control of the Cornsilk Fly Species, Chaetopsis massyla and Euxesta eluta.

Cornsilk flies are serious pests of sweet corn through damage to cobs and secondary fungal establishment. As pupae are generally outside the infested cob on the ground, there can be potential for use of pupal parasitoids for control. Two species of gregarious parasitoids, Muscidifurax raptorellus and Nasonia vitripennis, and three species of solitary parasitoids, Spalangia endius, Spalangia cameroni and Muscidifurax raptor, were evaluated against pupae of the two cornsilk fly species, Euxesta eluta and Chaetopsis massyla. House fly pupae, the most common host for most of the parasitoids, were included for comparison. All of the parasitoids killed and successfully parasitized pupae of the two cornsilk fly species at rates that were similar to house fly pupae. Adult parasitoids that emerged from cornsilk fly hosts were somewhat smaller than parasitoids reared from house flies and had proportionally fewer females. These parasitoids, which are widely and commercially available for filth fly control, warrant further consideration for their potential against cornsilk flies in the field.

Natural Parasitism Influences Biological Control Strategies Against Both Global Invasive Pests Ceratitis capitata (Diptera: Tephritidae) and Drosophila suzukii (Diptera: Drosophilidae), and the Neotropical-Native Pest Anastrepha fraterculus (Diptera: Tephritidae).

Ceratitis capitata (Wiedemann) and Drosophila suzukii (Matsumura) are two severe invasive pests widespread in all Argentinean fruit-producing regions. Both coexist with the Neotropical pest Anastrepha fraterculus (Wiedemann) in northern Argentina. The northwestern region shelters major soft fruit and Citrus producing and exporting industries, which are heavily affected by these dipterans. Eco-friendly strategies are under assessment in Argentina. This study mainly assessed D. suzukii, C. capitata, and A. fraterculus temporal abundance variations and their natural parasitism levels on a 1.5-ha-patch of feral peach trees within a disturbed secondary subtropical rainforest of northwestern Argentina. Fly puparia were mainly collected from the soil under fallen peach. Sampling was performed over three peach fruiting seasons. The most abundant pest species was C. capitata. Drosophila suzukii was only found in the last collecting period, but outnumbered A. fraterculus. Natural parasitism distinctly affected the temporal abundance of these dipterans: it significantly depressed C. capitata abundance in last sampling weeks, it did not substantially affect D. suzukii abundance, but it increased synchronously with the increase in the A. fraterculus abundance. Parasitism on C. capitata was mostly exerted by a combination of both a cosmopolitan pupal and a native larval parasitoid, while A. fraterculus was mainly parasitized by two indigenous larval parasitoids. Only three resident pupal parasitoids were associated with D. suzukii, of which the cosmopolitan Pachycrepoideus vindemiae Rondani (Hymenoptera: Pteromalidae) was the most significant. Data on the resident parasitoid impact are relevant for designing biocontrol strategies in noncrop habitats.

Effects of Host Ages and Release Strategies on the Performance of the Pupal Parasitoid Spalangia endius on the Melon Fly Bactrocera cucurbitae

The melon fly, Bactrocera cucurbitae Coquillett (Diptera: Tephritidae), is a quarantine pest that causes considerable economic losses to growers of vegetables and fruits worldwide. Spalangia endius (Walker) (Hymenoptera: Pteromalidae) is a solitary pupal parasitoid of various dipteran hosts. We assessed the impact of the host pupal age (2, 4, and 6 days old), host density (5, 10, 15, 20, 25, and 30), and parasitoid density (1, 2, 3, 4, 5, and 6) on the parasitizing potential of S. endius on B. cucurbitae pupae under laboratory conditions. The effects of different soil depths on the parasitism rate of S. endius and the dispersal behavior of S. endius at distances of 0, 5, and 10 m were also evaluated under field conditions. The results showed that the parasitism rate of S. endius significantly increased with the increase in host density and parasitoid density. The host pupal age did not influence the number of pupae parasitized by S. endius and the progeny sex ratio of S. endius under different host densities. In the fields, different puparium burial depths of B. dorsalis pupae significantly influenced the parasitism and eclosion rates of S. endius but did not influence the eclosion rate of B. cucurbitae. Spalangia endius females could travel up to 10 m to parasitize at a similar rate on B. cucurbitae pupae compared to S. endius placed at 0 m.

Searching of Underground Host Patches by a Pupal Parasitoid.

When hosts are distributed in discrete patches, ways in which parasitoids search and move between patches affect variability in parasitism risk among hosts and host-parasitoid population dynamics. This study examined the patch searching behavior of the solitary pupal parasitoid Dirhinus giffardii (Silvestri) (Hymenoptera: Chalcididae) on its host Bactrocera dorsalis (Hendel) (Diptera: Tephritidae) which pupates underground. In a series of two laboratory experiments, host patches were created by burying pupae in peat moss, and the foraging behavior of the parasitoid was recorded. If D. giffardii can detect underground patches, the parasitoid would preferentially exploit high quality patches where the quality of a patch is represented by the number of unparasitized hosts in the patch. The first experiment investigated the effect of patch size (i.e., number of hosts) and host status (whether hosts are parasitized or unparasitized) on patch searching behavior. Results showed parasitoids were more likely to exploit a large patch than a small patch regardless of host status. The second experiment examined the effect of relative locations of patches by establishing three patches (one large patch and two small patches with unequal inter-patch distances from the large patch). The probability of parasitism was lower for the small patch close to the large patch than the small patch far from the large patch. The parasitism patterns described in the experiments have important implications on the distribution of parasitism risk among hosts and population dynamics.

Native generalist natural enemies and an introduced specialist parasitoid together control an invasive forest insect.

Specialized natural enemies have long been used to implement the biological control of invasive insects. Although research tracking populations following biological control introductions has traditionally focused on the impact of the introduced agent, recent studies and reviews have reflected an appreciation of the complex interactions of the introduced specialist agents with native generalist natural enemies. These interactions can be neutral, antagonistic, or complementary. Here we studied the invasive defoliator winter moth (Operophtera brumata) in the Northeast USA to investigate the role of native, generalist pupal predators along with the introduced, host-specific parasitoid Cyzenis albicans. Prior research in Canada has shown that predation of winter moth pupae from native generalists increased after C. albicans was established as a biological control agent. To explain this phenomenon, the following hypotheses were suggested: (H1 ) parasitoids suppress the winter moth population to a density that can be maintained by generalist predators, (H2 ) unparasitized pupae are preferred by predators and therefore experience higher mortality rates, or (H3 ) C. albicans sustains higher predator populations throughout the year more effectively than winter moth alone. We tested these hypotheses by deploying winter moth pupae over 6 years spanning 2005 to 2017 and by modeling pupal predation rates as a function of winter moth density and C. albicans establishment. We also compared predation rates of unparasitized and parasitized pupae and considered additional mortality by a native pupal parasitoid. We found support for the first hypothesis; we detected both temporal and spatial density dependence, but only in the latter years of the study when winter moth densities were low. We found no evidence for the latter two hypotheses. Our findings suggest that pupal predators have a regulatory effect on winter moth populations only after populations have been reduced, presumably by the introduction of the host-specific parasitoid C. albicans.

Natural Enemies of Rice White Stem Borer <i>Scirpophaga fusciflua</i> (Hampson) in Himachal Pradesh

Fortnightly surveys were made to study natural enemies of white stem borer (WSB) Scirpophaga fusciflua (Hampson) in rice. The surveys revealed that the predators of S. fusciflua first appeared in the second fortnight of July, with the peak during second fortnight of September during 2016 and 2017; and their relative proportion was- spiders (49.4% and 51.2%), dragonflies (22.2% and 22.6%) and damselflies (28.4% and 26.2%). Four species of parasitoids viz., egg- Telenomus sp. and Tetrastichus sp., larval- Stenobracon sp. and pupal parasitoids- Xanthopimpla punctata were observed from egg mass, larvae and pupae collected from Kangra valley of Himachal Pradesh. During 2016 and 2017, the % parasitization was observed to be maximum in the first fortnight of October (53.5 and 62.0%) followed by second fortnight of September (36.4 and 49.1%), respectively.

Specificity within bird–parasite–parasitoid food webs: A novel approach for evaluating potential biological control agents of the avian vampire fly

Abstract Quantitative food web analyses can provide insights into the specificity of consumers such as herbivores, parasites and parasitoids. Understanding such patterns can be useful in forecasting the potential benefits and risks of biological control agents being considered for introduction against invasive species. The avian vampire fly, Philornis downsi (Diptera: Muscidae), is a neotropical bird parasite that is invasive in the Galapagos Islands, where it is causing substantial mortality of endemic bird species. We used a novel in‐field experimental food web approach within the native range of P. downsi in Ecuador to test the hypotheses that pupal parasitoids known to attack P. downsi specialize on members of the genus Philornis, which occur only in bird nests. We deployed pupae of non‐Philornis fly species adjacent to bird nests to assess specificity of the parasitoids and used two indices to assess specificity: Resource Range (RR), which evaluates the breadth of host use, and Pair Difference Index (PDI), which evaluates interaction strength. The results revealed very strong compartmentalization within the guild of pupal fly parasitoids, with four species attacking only Philornis spp. Both specificity indices indicated significant levels of specificity towards the genus Philornis for two of these species: Conura annulifera and Trichopria sp. novus. We also assessed the specificity of the two dominant Philornis species attacking 11 bird species and preference of the two dominant parasitoid species for bird species. Although there was some significant preference for particular bird species by the Philornis spp., there was no indication that this drove specificity patterns by the parasitoids. Policy implications. Our results confirm previous laboratory studies indicating specificity by C. annulifera and support the hypothesis that this species would produce few, if any, nontarget impacts if released into Galapagos to suppress populations of the P. downsi. These results can inform an environmental risk assessment framework to guide governmental agencies in deliberation on potential field releases of parasitoids in the Galapagos Islands.

Safety Evaluation of Chemical Insecticides to Tetrastichus howardi (Hymenoptera: Eulophidae), a Pupal Parasitoid of Spodoptera frugiperda (Lepidoptera: Noctuidae) Using Three Exposure Routes.

Simple SummarySpodoptera frugiperda is an important pest in many crops worldwide, causing substantial economic losses. The main control strategies are biological control and chemical control. However, pesticides also have varying degrees of toxicity to parasitic wasps in the field. In this study, we evaluate the safety of insecticides for Tetrastichus howardi, an important pupal parasitoid of S. frugiperda. We tested the toxicity of six major control insecticides against the parasitic wasps. Indoxacarb was the less toxic pesticide to T. howardi due to its toxicity’s low-risk quotient (7.43). Furthermore, we used three methods to simulate the side effects of different concentrations of indoxacarb on T. howardi. The exposure of adults to pesticide residues on the glass tube was the most significant in inhibiting development and fecundity. Moreover, T. howardi had a lower parasitism rate and emergence rate with the higher pesticide concentrations. Overall, our study showed that different exposure patterns and concentrations of pesticides have varying degrees of side effects on T. howardi. Even if the pesticide residues are low, such exposures can affect the life cycle of parasitic wasps, affect their population establishment, and thus affect pest control. This study guides a more scientific and comprehensive pesticide application and releases natural enemies.Spodoptera frugiperda has become a major pest in many crops worldwide. The main control strategies are biological and chemical controls. However, pesticides have varying degrees of toxicity to parasitic wasps in the field. To integrate chemical and biological controls, we evaluated the safety of insecticides to Tetrastichus howardi, an important pupal parasitoid of S. frugiperda. This study assessed the toxicity of six major control insecticides (emamectin benzoate, chlorfenapyr, indoxacarb, chlorantraniliprole, bisultap, and lufenuron) to T. howardi based on risk quotient. The results showed that indoxacarb had the lowest risk quotient (RQ = 7.43). Then the side effects of three sublethal concentrations (LC20, LC30, LC40) of indoxacarb were tested using three methods (1. Adult exposure to pesticide residues on the glass tube; 2. Adult exposure to pesticide residues on the host; 3. Larval exposure to pesticides through host exposure). Overall, T. howardi had a lower parasitism rate and emergence rate with the higher pesticide concentrations. Furthermore, among three methods, the adult exposure to pesticide residues on the glass tube was the most efficient in inhibiting the parasitism rate, and impairing the emergence rate and the offspring female/male ratio. This study guides a more scientific and comprehensive application of pesticides and releases natural enemies in the field.

Overwintering of two pupal parasitoids of Drosophila under natural conditions

The overwintering capacity of biocontrol agents is of fundamental relevance for biological control of pests in temperate regions. In this study we tested the cold tolerance of the indigenous Drosophila pupal parasitoids Pachycrepoideus vindemmiae and Trichopria drosophilae at constant low temperature in the laboratory and exposed different preimaginal parasitoid stages in the field during winter. We evaluated whether semi-natural habitats promote overwintering via more favorable microclimatic conditions as well as higher host availability compared to orchards. Further, we studied the parasitoids’ phenology in a semi-field experiment during autumn. We found that P. vindemmiae larvae and pupae were most cold tolerant under laboratory and field conditions, while all preimaginal stages of T. drosophilae displayed similar cold tolerance. Semi-natural habitats buffered temperature extremes, yet overwintering survival was not enhanced compared to orchards. Suitable overwintering hosts were present in all habitats at times when parasitoids were still active parasitizing. These results demonstrate that P. vindemmiae overwinters most likely as larva or pupa and that T. drosophilae can overwinter in a preimaginal life stage. Further, we provide evidence that both parasitoids can overwinter in a wide range of habitats and that the availability of hosts for overwintering is unlikely a limiting factor for the parasitoids during fall.

Releases of the parasitoid Pachycrepoideus vindemmiae for augmentative biological control of spotted wing drosophila, Drosophila suzukii

Spotted wing drosophila, Drosophila suzukii, is native to East Asia but has become a major pest of soft-skinned fruit crops in its invaded range in the Americas, Europe and North Africa. Control efforts are complicated by the seasonal movement of D. suzukii into crops from non-crop or untreated-crop habitats. Biological control may help to suppress D. suzukii populations. However, surveys have found that few parasitoid species attack D. suzukii in North America and Europe, with low levels of parasitism by the pupal parasitoids Trichopria drosophilae and Pachycrepoideus vindemmiae and little or no parasitism by larval parasitoids. Augmentation of these resident pupal parasitoids may be a sustainable tool for D. suzukii management. Most augmentation efforts to date have focused on T. drosophilae, although P. vindemmiae is the more abundant and widespread species in North America. In this study, we tested whether augmentative releases of P. vindemmiae could help control D. suzukii in caneberry hoop houses in Minnesota, Oregon and California. Results were inconsistent. Most trials showed no detectable post-release effects on parasitism or D. suzukii levels, although one trial in Oregon did show elevated parasitism levels in release plots. Larger releases of P. vindemmiae may be needed when D. suzukii numbers are high, or to overcome the effects of suboptimal conditions and/or dispersal.

Parasitoids of Dasiops (Diptera: Lonchaeidae) in sweet granadilla orchards in an Andean forest of Peru

ABSTRACT We report hymenopteran larval and pupal parasitoids of the Dasiops species in sweet granadilla (Passiflora ligularis J.) orchards in a Peruvian Andean forest. Flower bud and fruit samples infested by Dasiops were collected in three orchards from Oxapampa (Pasco, Peru). In addition, we exposed non-parasitized Dasiops pupae at ground level to verify the presence of pupal parasitoids. We identified Utetes anastrephae (Viereck) and Opius sp. (Hymenoptera: Braconidae) on flower buds infested b.y Dasiops inedulis Steyskal. However, Aganaspis pelleranoi (Brèthes) (Hymenoptera: Figitidae) emerged from D. frieseni pupae reared from unripe fruits. Also, the pupal parasitoids Pachycrepoideus vindemmiae (Rondani) (Hymenoptera: Pteromalidae) and Coptera sp. (Hymenoptera: Diapriidae) emerged from pupae of both D. inedulis and D. frieseni exposed to parasitism at ground level. Our findings shed new light into new interactions for species in the genus Dasiops and their larval and pupal parasitoids in sweet granadilla agroecosystems from the Neotropical region.

Parasitism preference of Chalcid hymenopteran Dirhinus giffardii (Silvestri) confirms higher parasitism against housefly (Musca domestica) (Diptera: Muscidae) pupae.

The housefly, Musca domestica (Diptera: Muscidae), is capable of transmitting many pathogens that cause severe diseases in humans and animals. Mostly the management tactics rely on synthetic chemicals, but these chemicals creates lethal effects on biological ecosystem. For natural and safe options, bio-control strategy is one of the choice. The present study was a part of such effort to use this strategy and validate the biological performance of the potential pupal parasitoid Dirhinus giffardii (Silvestri) against house fly and provide alternative and safe control of filthy flies. This is the first report on parasitism potential and preference of D. giffardii against house fly. The D. giffardii, early reported as an effective pupal parasitoid of tephritid flies, here in the case presented, showed overall 70% reduction in the house fly population by parasitizing pupae. The parasitism efficiency and longevity of hymenopteran parasitoid was remarkably noted two-fold higher and one-fold more female production on house fly pupae as compared to primary hosts (Tephritids). Furthermore, sex ratio of the resultant progeny was also confirmed the dominancy of female by 74% as compared to males. Based on the novel findings we therefore conclude that D. giffardii is the best bio-control agent for controlling house flies.

Seasonal activity of oil palm leaf webworm, Acria meyricki Shashank and Ramamurthy and its natural enemies in oil palm-cocoa intercropping system and their management in oil palm

The pest was active during October to March. The population density ranged from 0.31 to 2.31 larvae/frond and 0.05 to 9.35 larvae/frond during first and second study periods respectively. The larval parasitoid, Dolichogenidea hyposidrae Wilkinson (Hymenoptera: Braconidae) was recorded to the tune of 7.14 to 98.21% and 2.66 to 95.0% during the first and second study periods respectively. Level of parasitism by pupal parasitoid, Brachymeria albotibialis (Ashmead) (Hymenoptera: Chalcididae) was 8.62 to 64.0%. In oil palm-cocoa intercropping system, lower pest density, lower pest damage and high level of parasitism by natural enemies were recorded. Insecticides viz., deltamethrin, lambda cyhalothrin, chlorantraniliprole, thiodicarb and fipronil were found effective in managing this pest under severe conditions in oil palm gardens.