Relationships of different cotton square sizes to boll weevil (Coleoptera: Curculionidae) feeding and oviposition in field conditions

Authors: Showler, Allan

Submitted to: Journal of Economic Entomology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/12/2005
Publication Date: 10/14/2005
Citation: Showler, A. 2005. Relationships of different cotton square sizes to boll weevil (Coleoptera: Curculionidae) feeding and oviposition in field conditions. Journal of Economic Entomology. 98(5):1572-1579.

Interpretive Summary: Boll weevil reproduction is known to be enhanced by feeding on cotton fruit (squares) of a particular size, but their preference for different cotton fruiting sizes and stages is poorly understood. For two growing seasons, cotton planted at different dates was studied for boll weevil feeding and egg laying on various sizes and stages of cotton fruiting bodies. Large, and sometimes medium, sized squares were found to be preferred for boll weevil oviposition and feeding under field conditions which assists in identifying the stage of the cotton crop at which protection from boll weevils is most important.

Technical Abstract: Feeding and oviposition preferences of the boll weevil for four different cotton square size classes in field conditions of the Lower Rio Grande Valley of Texas were studied during 2002 and 2003. Large squares were fed upon more by adult boll weevils than pinhead or match-head squares at least in part because larger squares are known to enhance boll weevil fecundity. The preference for large squares as food and the associated accelerated fecundity explain the substantial boll weevil population build-ups that occur after large squares form. Large (5.5 to 8-mm-diameter) squares were most commonly used for oviposition, and medium (3 to 5.5-mm-diameter) squares were also used, but to a lesser extent. Feeding and oviposition on pinhead (1 to 2-mm-diameter) and match-head (2 to 3-mm-diameter) squares were negligible. Boll weevil damage was greater in middle- or late-planted plots than in early-planted cotton during at least one year. Large squares had probably reached a critical size capable of supporting immatures to adulthood, and might also be superior, and therefore more attractive, for nutritional reasons.