|GROOT, ASTRID - North Carolina State University|
Submitted to: Southwestern Entomologist
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/29/2007
Publication Date: 12/1/2008
Citation: Blanco, C.A., Perera, O.P., Groot, A., Hernandez, G., Teran-Vargas, A.P. 2008. Paternity Allocation in a Mutant Heliothis virescens Colony. Southwestern Entomologist. 33:253-263.
Interpretive Summary: Tobacco budworm moths (one of the most important cotton pests) mate multiple times over their relatively short life period (<16 days). Field-captured females have been found to mate up to seven times, while under laboratory conditions this mating frequency has a record of twelve times over a 14 day period. Plans to mitigate the potential resistance development to Bt cotton rely on the premise that Bt-resistant moths emerging from Bt-cotton fields will randomly mate with Bt-susceptible moths that emerge from non Bt-cotton fields and other crops and plants. Because Bt-resistance is known (so far) to be a recessive condition, this mating(s) of Bt-resistant and Bt-susceptible moths will produce Bt-susceptible offspring. However, the mating of Bt-resistant moths among themselves should not be ruled out. In this study we further characterized the reproductive biology of tobacco budworm. We have demonstrated that a female can produce progeny of two different males at once (a phenomenon not previously described for this species) challenging some of the basic assumptions of Bt-resistance management for transgenic crops (e.g. refuges). For example, if a Bt-resistant female mates with a Bt-resistant male and a Bt-susceptible male, her progeny can be partially Bt-resistant and bt-susceptible. The information generated here can be useful to refine mathematical models that predict Bt-resistance development, insecticide resistance in general and species conservation.
Technical Abstract: Females of the economically-important pest Heliothis virescens can copulate multiple times during their reproductive life span. The presence of multiple ejaculations in their spermatheca creates the possibility for sperm competition, post-copulatory female choice and/or perhaps a random use of sperm to fertilize eggs. It is believed that H. virescens paternity comes from only one male, in general the last one that copulates with the female. In this study we utilized a colony with a recessive mutation resulting in lack of wild pigmentation on the wings (albino). Females from this colony that were mated in sequence two days apart with two 2-day old males, one albino and one wild type, produced progeny belonging to every possible combination of paternities. Almost a third of the females produced offspring from the first mate. However, a significantly higher proportion of the offspring was produced by the first mate when the wild type male was the first mate. A fourth of the females produced offspring from the second male exclusively and a significantly higher proportion of offspring was produced when the wild type male was the second mate. Nearly half of the females produced offspring form both males simultaneously or switched paternities during most of their reproductive lives. This suggests that post-copulatory cryptic female choice might be a possible explanation for the paternity allocation mechanism in this strain of tobacco budworm instead of sperm precedence or random mixing of sperm inside the spermatheca. The additional information on H. virescens multiple matings generated by this study can be directly applied to insecticide resistance and conservation programs.