Venom gland of the ichneumonid Diadromus collaris： morphology, ultrastructure and age-related changes

Females of the solitary parasitoid Diadromus collaris （Insecta： Hymenoptera： Ichneumonidae） lay eggs in the pupae of Plutella xylostella （Lepidoptera： Plutellidae）, and the venom is synchronously injected into hosts. The venom apparatus consists of two glandular tubules terminating in a common reservoir, A ductule connects the reservoir with the sting apparatus, by which the reservoir content enters the latter. Secretory units line the two glandular tubules. All secretory cells belong to dermal gland type Ⅲ. Dermal gland cells in glandular tubules are more abundant and developed than those in the reservoir. There are extensive rough endoplasmic reticulum and electrondense vesicles, and the microvilli are well developed. By the cuticle-lined central funnel secretion products of secretory units reach the reservoir. Moreover, the secretory apparatus undergoes age-related changes. The secretory units in the venom gland are better developed and more vigorous 7 days after eclosion than those 1 day after eclosion; autolytic processes occur 15 days after eclosion, and the tissue of the reservoir is more prostrate 15 day after eclosion than those 1 day after eclosion. The ovipostion peak of this parasitoid, about 3-7 days after eclosion, corresponds with the period when the venom gland is highly developed in the life span of the wasp.

Vertical stratification of ichneumonid wasp communities： the effects of forest structure and life-history traits

Parasitoid wasp communities of the canopy of temperate forests are still largely unexplored. Very little is known about the community composition ofparasitoids between canopy and understory and how much of this difference is related to forest structure or parasitoid biological strategies. In this study we investigated upon the difference in the community composition of the parasitic wasps Ichneumonidae between canopy and understory in a lowland temperate forest in northern Italy. We used general linear models to test whether parasitic strategy modifies species vertical stratification and the effect of forest structure. We also tested differences in β-diversity between canopy and understory traps and over time within single forest layers. We found that stand basal area was positively related to species richness, suggesting that the presence of mature trees can influence local wasp diversity, providing a higher number of microhabitats and hosts. The ichneumonid community of the canopy was different from that of the understory, and theβ-diversity analysis showed higher values for the canopy, due to a higher degree of species turnover between traps. In our analyses, the vertical stratification was different between groups of ichneumonids sharing different parasitic strategies. Idiobiont parasitoids of weakly or deeply concealed hosts were more diverse in the understory than in the canopy while parasitoids of spiders were equally distributed between the two layers. Even though the ichneumonid community was not particularly species-rich in the canopy of the temperate forests, the extension of sampling to that habitat significantly increased the number of species recorded.

Wing-fanning frequency as a releaser boosting male mating success— High-speed video analysis of courtship behavior in Campoplex capitator, a parasitoid of Lobesia botrana

Campoplex capitator is an ichneumonid parasitoid with a narrow host range,comprising grapevine moth pests.Despite being considered one of the possible candidates for biocontrol of Lobesia botrana,knowledge about its biology is limited and massrearing for commercial purposes is still lacking.This research provides a quantitative analysis of the C.capitator courtship and mating behavior.C.capitator mating sequence was analyzed by high-speed video recordings.Main behavioral parameters,with special reference to male wing fanning and antennal tapping,were quantified and linked with mating success.Furthermore,we analyzed the occurrence of population-level behavioral asymmetries during C capitator sexual interactions and their impact on male success.Results showed that male wing fanning was crucial to successfully approach the female.Males achieving higher mating success performed wing-fanning at higher frequencies over unsuccessful ones.After wing fanning,most of males palpated the females body with their antennae,before attempting copulation.The overall mating success was>70%,with a rather long copula duration(254.76±14.21 s).Male wing-fanning was lateralized on the left at population level,while antennal tapping displays were right-biased.Sidebiased male displays do not differ in terms of frequency and duration of their main features.This research adds basic knowledge to the C.capitator behavioral ecology.Since rearing protocols for C.capitator are being developed male wing fanning frequency may represent a useful benchmark for monitoring mate quality over time,tackling mating success reductions due to prolonged mass-rearing.