|Armstrong, John - Scott|
Submitted to: Journal of Insect Science
Publication Type: Peer reviewed journal
Publication Acceptance Date: 6/10/2005
Publication Date: 12/1/2005
Citation: Greenberg, S.M., Setamou, M., Sappington, T.W., Coleman, R.J., Armstrong, J.S., Liu, T. 2005. Temperature-dependent development and reproduction of the boll weevil (Coleoptera: Curculionidae). Journal of Insect Science. 12:231-240. Interpretive Summary: The boll weevil is an important cotton pest that damages cotton by puncturing and laying eggs in flower buds and small fruit. Current management strategies and suppression programs for boll weevils depend on substantial insecticide input. Improvements in pest management require new information about weevil growth rate, reproductive rate, and mortality rate relative to temperature. We found that immature weevils developed 3.6 times faster and adult weevils began laying eggs 3.3 times earlier at a temperature of 30 C than at 15 C. Lower temperature thresholds for development and egg laying were determined, and cumulative heat units were calculated to model the growth rate and reproductive rate of weevils. These findings will be useful in developing sampling protocols, timing insecticide applications, and implementing management strategies that strategically target susceptible pest life stages and reduce associated environmental problems.
Technical Abstract: Effects of temperatures on development, viability, and fecundity of boll weevil, Anthonomus grandis Boheman, were assessed at 10, 15, 20, 25, 30, 35, 45°C, 65% humidity, and a photoperiod 13:11 (L:D) h. The mortality of boll weevil immature stages was 100% at 12°C and decreased to 36.4% as the temperature increased to 25°C. When the temperature increased from 30°C to 45°C, the mortality of weevils also increased from 50.1 to 100%. From 15°C to 35°C, the boll weevil preimaginal development rate was linearly related to temperature. The average development time of total boll weevil immature lifestages decreased 3.6-fold and the preovipositional period decreased 3.3-fold when the temperature was increased from 15°C to 30°C. The lower threshold for development was estimated at 10.9, 6.6, 7.0, and 9.0°C for eggs, larval, pupal, and total immature stages, respectively, with total thermal time requirement to complete immature stages of 281.8 DD (15°C) and 247.8 DD (35°C). At 11°C and 46°C, weevil females did not oviposit. Longevity of adult females decreased 4.6-fold with increasing temperatures from 15°C to 35°C. Fecundity increased with increasing temperatures up to 30°C and significantly decreased thereafter. These findings will be useful in creating a temperature-based degree-day model for predicting the occurrence of key life stages in the field.