RESISTANCE MANAGEMENT AND INJURY POTENTIAL OF LEPIDOPTEROUS PESTS TO TRANSGENIC COTTONS
Location: Southern Insect Management Research Unit
Title: Size and Chemical Composition of Heliothis virescens (Lepidoptera: Noctuidae) Spermatophores
Submitted to: Annals of the Entomological Society of America
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: October 1, 2008
Publication Date: July 1, 2009
Citation: Blanco, C. A., Rojas, M. G., Groot, A., Morales Ramos, J. A., Abel, C. A. 2009. Size and Chemical Composition of Heliothis virescens (Lepidoptera: Noctuidae) Spermatophores. Ann. Entomol. Soc. Am. 102(4): 629-637.
Interpretive Summary: The preservation of the effectiveness of cottons that express Bacillus thuringiensis proteins (Bt cottons) is based on part on the assumption that B. thuringiensis–resistant Lepidoptera will mate with moths that are B. thuringiensis-susceptible that are produced on Bt cotton refuges and/or other crops and weeds. Since there are several crops and weeds growing simultaneously with cotton, when both types of moths (Bt susceptible and resistant) are available for copulation in space and time, moth feeding can have a direct influence on mating frequency. For example, a Bt-susceptible male moth that fed on a good plant host (for example cotton), might produce a larger progeny, therefore reducing the proportion of Bt-resistant larvae that a Bt-resistant female might produce. On this study we demonstrate that male feeding causes a greater mating potential and the influence of the ingested substances has also a direct correlation with the spermatophore chemical composition. The knowledge that male feeding can enhance mating behavior on tobacco budworm, not previously reported, can help on designing/refining the role of refuges with the goal of preserving the effectiveness of Bt cotton.
Heliothis virescens is a polyandrous species of economic importance in the American Continent. This sexual behavior allows for the presence of multiple spermatophores inside a female and the possibility of different males fertilizing the female’s offspring, a conduct that can make insecticide resistance management or sterile insect release programs particularly challenging. The presence of spermatophores in a female can greatly influence her behavior, physiology and offspring production, and the role that these reproductive structures have are directly influenced by their size and the amount and type of substances that they contain and are passed into the female during copulation. In this study we investigated the role that male feeding has on mating potential, the basic chemical composition and the coloration of three sequentially-produced spermatophores by male moths that were fed nothing, water, sucrose solution or nectar. Male moth feeding had a direct influence on spermatophore weight, used as an indicator of polyandrous behavior. Nectar-fed moths produced heavier spermatophores and copulated in greater proportion than moths exposed to the other treatments. The total sugar and protein content of spermatophores was not influenced by the type of male feeding. Red or pink spermatophores were more prevalent on the first-produced spermatophores, diminishing this proportion on the second and increasing again on the third-produced spermatophore, but this coloration proportion was influenced by male feeding. These results indicate that polyandrous behavior on H. virescens can be influenced by the type of male feeding.