Submitted to: Journal of Cotton Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/5/2004
Publication Date: 4/1/2004
Citation: Esquivel, J.F., Spurgeon, D.W., Suh, C.P.C. 2004. Longevity of overwintered boll weevils (Coleoptera: Curculionidae) on pre-fruiting cotton. Journal of Cotton Science. 8(1):13-16.
Interpretive Summary: Previous field studies established the misconception that adult boll weevils exhibited limited survival when feeding on pre-fruiting cotton plants, and this misconception has been a critical component of cultural control methods such as uniform delayed planting of cotton. However, environmental conditions were not controlled in previous field studies. We examined the influence of pre-fruiting cotton on potential survival of overwintered boll weevils under controlled environmental conditions. Our findings indicate overwintered weevils can live considerably longer than previously reported on pre-fruiting cotton, and suggest sufficient nutritional resources are available to extend boll weevil survival. These findings suggest that consideration of factors other than limited survival on pre-fruiting cotton will lead to more effective implementation of cultural control methods such as uniform delayed planting of cotton. Other factors affecting weevil survival are likely specific to production regions, and identification of these factors will require additional study.
Technical Abstract: Field-cage studies have suggested that pre-fruiting cotton (Gossypium hirsutum L.) is nutritionally inadequate to support extended longevity of overwintered boll weevils, Anthonomus grandis Boheman. However, these earlier studies did not separate the respective effects of environment and nutrition on survival. We examined the longevity of trap-captured overwintered weevils fed pre-fruiting cotton under controlled conditions. Weevils held at 24±1°C under a 12:12 [L:D] h photoperiod were supplied water, water plus cotyledon stage plants, or water plus four-leaf stage plants. Longevities of both sexes were similar, and averaged 81.7, 61.8, and 6.8 d for cotyledon stage plants, four-leaf stage plants, and water alone, respectively. Temporal patterns of mortality also differed among the feeding treatments. Observed longevities were substantially greater than those previously reported, suggesting pre-fruiting cotton is of greater nutritional value than is generally recognized. Our findings suggest that factors other than the nutritional inadequacy of cotton seedlings likely play important roles in the effectiveness of cultural practices such as uniform delayed planting. Continued study of the ecology of overwintered weevils should provide additional insights that will permit more effective implementation of early-season cultural practices.