Submitted to: Annals of the Entomological Society of America
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/27/2013
Publication Date: 1/1/2014
Citation: Gautam, S., Opit, G., Margosan, D.A., Tebbets, J.S., Walse, S.S. 2014. Egg morphology of key stored-product insect pests of U.S.A. Annals of the Entomological Society of America. 107(1):1-10. Interpretive Summary: Postharvest chamber fumigation provides a biological safeguard against pests and, in many scenarios, is the only available tool for government and industry to guarantee pest-free security and food safety. In general, the eggs of insects are the most difficult life stage to control with fumigants. This research explored species-specific differences in morphology of the egg surface and initiated an attempt to relate theses differences to the relative ovicidal efficacies of fumigants. Results suggest that fumigant efficacy is related, at least in part, to the number of respiratory structures on an eggs surface, as these structures serve as passageways for all gases, including fumigants.
Technical Abstract: Eggs of Carpophilus hemipterus (L.) (Coleoptera: Nitidulidae), Lasioderma serricorne (F.) (Coleoptera: Anobiidae), Ephestia elutella (Hübner) (Lepidoptera: Pyralidae), and Amyelois transitella (Walker) (Lepidoptera: Pyralidae) were imaged with scanning electron microscopy to explore how respiratory openings on the chorion surface may affect the relative efficacy of fumigation. Each C. hemipterus egg had two aeropyles and no micropyles, A. transitella and L. serricorne eggs had many aeropyles and several micropyles, and each E. elutella egg had many aeropyles and a single micropyle. Our data suggest that gas, including fumigants, differentially diffuse into the eggs of these species, with penetration through aeropyles and micropyles likely occurring to a greater extent in L. serricorne, E. elutella, and A. transitella than in C. hemipterus. Although confirmatory measurements of fumigant diffusion into eggs are needed, findings suggest that species-specific ovicidal efficacies are related, at least in part, to the surface morphology of eggs and that chorionic respiratory structures may differentially affect fumigant penetration and/or uptake.