THE INFLUENCE OF DIET QUALITY AND PHYSIOLOGY ON BOLL WEEVIL (ANTHONOMUS GRANDIS) PHEROMONE PRODUCTION

Authors: Young, Hugh; Spurgeon, Dale

Submitted to: National Cotton Council Beltwide Cotton Conference
Publication Type: Proceedings
Publication Acceptance Date: 1/11/2002
Publication Date: N/A
Citation: N/A

Interpretive Summary: Current control practices used against the cotton boll weevil depend on information from traps using male boll weevil pheromones -- chemicals that weevils release to attract other weevils. Patterns of pheromone production based on the developmental stage of both the weevils and the fruiting parts (squares and bolls) of the cotton plant that they feed on also impact the boll weevil eradication program. Our research with individual male boll weevils found higher rates of pheromone production than once believed. Pheromone production was not affected by square size but did increase with age. Weevils switched from squares (their preferred food) to bolls made more pheromone (76.2 micrograms/weevil/day) than weevils kept on squares (50.2 micrograms/weevil/day). Weevils switched to bolls increased pheromone production more than weevils kept on squares through the ninth day of adulthood. All males with well-developed reproductive organs made high levels of pheromone. These results provide a basis for additional studies of the dynamics of boll weevil pheromone production.

Technical Abstract: Recent research examining individual male boll weevils has indicated higher rates of pheromone production than were previously reported. However, influences on pheromone production of food type and size have not been examined using these techniques. We examined the influences of square size (5-6 mm versus 8-9 mm diameter) and diet switching (maintained on 6-7 mm diameter squares versus switched from squares to 15-mm diameter bolls) on pheromone production by individual weevils. Weevils were fed squares of the assigned size class for 4 d (square size) or 5 d (switching) before daily pheromone collections were initiated on days 5-7 (square size) or 6- 9 (switching). No influence of square size on pheromone production was demonstrated (5-6 mm squares, 52.9 +/- 6.6 micrograms/weevil/day; 8-9 mm squares, 85.5 +/- 14.7 micrograms/weevil/day). However, pheromone production did increase from the fifth day (60.3 +/- 10.3 micrograms/ weevil/day) to the seventh day (83.4 +/- 8.7 micrograms/weevil/day). Weevils switched from squares to bolls produced more pheromone (76.2 +/- 9.7 micrograms/weevil/day) than weevils remaining on squares (50.2 +/- 4.9 micrograms/weevil/day) Also, the increase in pheromone production from the sixth to ninth day of adulthood was greater for weevils switched to bolls than for weevils remaining on squares. In both studies, pheromone production was positively associated with the presence of well-developed accessory glands. These results provide a basis for additional studies of the dynamics of boll weevil pheromone production.