Location: Southern Insect Management Research Unit
Title: Mating behavior of wild Helicoverpa zea (Lepidoptera: noctuidae) males with laboratory females Authors
|Lopez, Juan DE Dios|
|Hernandez, Gerardo - CINVESTAV, MEXICO|
Submitted to: Journal of Cotton Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: October 1, 2010
Publication Date: December 6, 2010
Citation: Blanco, C.A., Sumerford, D.V., Lopez, J., Hernandez, G., Abel, C.A. 2010. Mating behavior of wild Helicoverpa zea (Lepidoptera: noctuidae) males with laboratory females. Journal of Cotton Science. 14(4):191-198. Interpretive Summary: The bollworm corn earworm is perhaps the most important lepidopterous pest of cotton and corn in North America. It is also one of the less sensitive insects to Bacillus thuringiensis-expressing crops (Bt cotton/Bt corn) making it a potential pest to develop resistance to this important insecticide. To measure the susceptibility of this insect to B. thuringiensis, laboratory tests with bollworms obtained from the field are usually conducted. Bollworms males can be abundant and easily collected in pheromone-baited traps, but it is known that this insect does not reproduce well under laboratory conditions. Results of tests involving bollworms might be misleading due to the fact that a large proportion of bollworm females produce unfertile eggs, therefore their tested offspring might have a very reduced genetic diversity. In this report we studied the optimum conditions to obtain the greatest genetic diversity and largest sample size of the offspring of pheromone trap-captures males and laboratory-reared females. Results indicate that leaving females and males together for only two days maximizes offspring diversity and abundance and reduces female mortality.
Technical Abstract: Studies conducted with the offspring of field-captured moths offer reliable indicators of their natural behavior. One of the factors that can limit the best use of these field-collected insects under laboratory conditions is their offspring production with a limited genetic diversity. In this report we studied how to maximize the offspring genetic diversity of pheromone trap-captured Helicoverpa zea males (wild) enclosed with laboratory-reared females for one to five days, compared with the enclosure of laboratory-reared females and males. Females mated with wild males obtained their highest number of copulations, produced the largest proportion of fertile eggs and lived longer when males were removed from their enclosure after two days. From the third day on these parameters significantly diminished. Higher female mortality was also observed after this time, further decreasing the potential genetic diversity of the offspring. Experiments conducted with two same-sex moth crowding ratios indicate that copulations carry important negative longevity consequences for both sexes. The reproductive parameters mentioned above and moth longevity was significantly less adversely affected when these experiments were conducted with the enclosure of laboratory females and males. Studies that can be conducted with the offspring of 2-day moth enclosure may offer their greatest genetic diversity while reducing parental moth mortality.