HOSTS AND SEASONAL ACTIVITY OF THE BOLL-WEEVIL (COLEOPTERA, CURCULIONIDAE) IN TROPICAL AND SUBTROPICAL HABITATS OF NORTHEASTERN MEXICO

The presence and seasonal activity of the boll weevil, Anthonomus grandis Boheman, was monitored in the state of Tamaulipas, Mexico, using pheromone traps during 1985, 1986, and 1987. Weevils were captured primarily during winter months, and weevils were found in virtually all habitats in which traps were placed. Significantly more female weevils (56.1%) were captured than males, although the sex ratio approached 50% in late winter months. The percentage of reproductive females decreased from December through February, whereas reproductive status of male weevils changed little during these months. Results indicate that the presence of weevils in cotton-free areas of Tamaulipas was the result of relatively long-range dispersal of weevils from cultivated cotton in southern Tamaulipas and not due to development on local wild hosts. This evidence included: the total mean number of weevils per trap decreased exponentially with the distance north from known commercial cotton areas; peak weevil catches for all traps were synchronized with the dates of cotton harvest and destruction during the winters of 1985-1986 and 1986-1987; no alternate boll weevil host plant was found during field collections, or indicated from analysis of pollen isolated from the alimentary tract of trapped weevils; and trapped weevils were found with ingested pollen grains from plant species whose range was at a considerable distance from the trap location. The importance of these findings in understanding the dispersal behavior of the boll weevil and in pest management programs of the boll weevil in southern Texas and northern Mexico is discussed.