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Title: BOLL WEEVIL (COLEOPTERA:CURCULIONIDAE) FEEDING AND REPRODUCTION AS FUNCTIONS OF COTTON SQUARE AVAILABILITY

Author
item Greenberg, Shoil
item Sappington, Thomas
item Spurgeon, Dale
item SETAMOU, M - TX AGRIC EXP STN-WESLACO

Submitted to: Environmental Entomology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/24/2003
Publication Date: 6/1/2003
Citation: Greenberg, S.M., Sappington, T.W., Spurgeon, D.W., Setamou, M. 2003. Boll weevil (Coleoptera: Curculionidae) feeding and reproduction as functions of cotton square availability. Environmental Entomology. 32(3):698-704.

Interpretive Summary: The boll weevil is an increasingly destructive primary insect pest on cotton. The National Cotton Council estimates that the boll weevil costs the U.S. cotton industry $300 million annually. Control of this insect is key to successful cotton production. Chemical control programs that rely on broad-spectrum insecticides have associated environmental problems and can lead to insect resistance. Development of efficient strategies for controlling the boll weevil that are relatively safe for the environment will require better knowledge of the biological relationships between the host plant and the insect. Understanding the effects of food quantity on oviposition behavior is of particular importance in evaluating the potential magnitude of injury that can be inflicted by an individual boll weevil. We evaluated the feeding and reproductive potential of boll weevils as affected by the availability of cotton squares. These findings provide important life table data that will improve our capacity to develo methods to predict fruit loss and changes in boll weevil populations in the field, given a starting density of suitable fruit for oviposition and a corresponding starting population density of weevils.

Technical Abstract: The dependence on food item availability of boll weevil, Anthonomus grandis grandis Boheman, feeding and reproductive potential was determined by providing different numbers of cotton squares to different weevils. Squares were replaced daily. The total numbers of egg and feeding punctures were highest in the 10:1 (squares:females) treatment and lowest in the 1:1 treatment. Lifetime fecundity was significantly higher in the 10:1, 15:1, and 20:1 treatments than in the 1:1 and 5:1 treatments. The relationship between eggs laid per day and the square to female ratio changed significantly over the life of the female, with the largest differences among treatments occurring in the first three weeks after eclosion. Survival of weevil progeny to adulthood was about 2 times higher in the 10:1, 15:1, and 20:1 treatments than in the 1:1 and 5:1 treatments. The total number of punctures (feeding and oviposition) caused dby boll weevil females was 2.8-fold higher than that caused by males (feeding only). When each boll weevil female was provided 10, 15, or 20 cotton squares per day, estimates of a growth index (percent immature survival divided by immature development time) and the exponential rate of increase (rm=0.446) were significantly higher than for those provided only 1 or 5 squares per day. Females, which were provided only one square per day, limited the number of feeding and oviposition punctures they made. Data from boll weevils maintained on 10 cotton squares per day indicate that the population would increase by 102.3 times each generation (Ro), a rate significantly higher than that exhibited under higher or lower square:female ratios.