BIOLOGY AND ECOLOGY OF COTTON PESTS EMPHASIZING MANAGEMENT OF BOLL WEEVILS
Title: REPRODUCTIVE POTENTIAL OF OVERWINTERING, F1, AND F2 FEMALE BOLL WEEVILS (COLEOPTERA: CURCULIONIDAE) IN THE LOWER RIO GRANDE VALLEY OF TEXAS.
Submitted to: Environmental Entomology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: December 15, 2006
Publication Date: April 1, 2007
Citation: Greenberg, S.M., Sappington, T.W., Setamou, M., Armstrong, J.S., Coleman, R.J., Liu, T.X. 2007. Reproductive potential of overwintering, F1, and F2 female boll weevils (Coleoptera: Curculionidae) in the Lower Rio Grande Valley of Texas. Environmental Entomology. 36(2):256-262.
Interpretive Summary: Control of boll weevil is critical to cotton production. The seasonal reproductive potential of boll weevil populations is an important consideration in determining the success of any control strategy. The feeding and oviposition activity of overwintering boll weevil, and seasonal fluctuation in oviposition, development, and in survival of progeny of overwintering, 1st and 2nd generation female boll weevil were studied in the subtropical Lower Rio Grande Valley of Texas. Basic research designed to address unanswered questions on the seasonal dynamics of boll weevils is vital to successful expansion of eradication, containment, and management programs into subtropical and tropical environments.
The feeding and oviposition activity of overwintering boll weevils, Anthonomus grandis grandis (Boheman), and seasonal fluctuations in development, survival, and reproduction of progeny of overwintering, 1st, and 2nd generation boll weevil females were determined in the laboratory at 27ºC, 65% RH, and a photoperiod of 12:12 (L:D) h. During the cotton-free period in the Lower Rio Grande Valley, female boll weevils without access to cotton resorb their unlaid eggs and enter reproductive diapause. However, when they were provided daily with greenhouse-grown cotton squares, commencement of oviposition began after 7, 15, or 20 days depending on when they were captured. Females captured later in the winter fed longer before laying eggs than those captured in the early fall, suggesting that it may take females longer to terminate diapause the longer they have been dormant. The rate of feeding by females was significantly less during the winter months, and this may have affected the rate of diet-mediated termination of dormancy. Females of the 1st and 2nd generations following the overwintering generation produced a significantly higher percentage of progeny surviving to adulthood, and a higher proportion of these progeny were females. Offspring development time from overwintering female parents was significantly longer than that from 1st and 2nd generations under the same laboratory conditions. The total number of life-time eggs produced by females of the 2nd generation during the cotton growing season were about 9.9-fold higher than for overwintering females and 1.5-fold higher than for 1st generation females. Life table calculations indicated that the population of 2nd generation boll weevils increased an average of 1.5-fold higher each generation than for females of the 1st generation, and 22.6-fold higher than for overwintering females. Our data showed variation in boll weevil survival, development, and reproductive potential among the overwintering, 1st, and 2nd generation females, suggesting inherent seasonal fluctuations in these parameters.