Host-free survival of boll weevils (Coleoptera: Curculionidae) from two regions of Texas.

摘要

Oviposition-punctured squares were collected in early September 1998 from commercial cotton, Gossypium hirsutum, near Lubbock, Texas, USA. Because of the mandated 1 September crop destruction deadline, weevils (Anthonomus grandis) from the Lower Rio Grande Valley were obtained from infested squares collected from caged cotton plants near Weslaco, Texas, in late-September 1998. The supply of infested squares was limited, resulting in only 38 weevils (16 females and 22 males, emerged 1-6 October and fed for 16-21 days) for determination of survival. Thus, no weevils from Weslaco were dissected. Survival data for five weevils were censored, so survival of weevils from Lubbock and Weslaco was compared using the SAS LIFETEST procedure. Totals of 148 (range of 43-55) female and 115 (range of 30-49) male weevils from Lubbock were dissected following the feeding period. Percentages of weevils classed as diapausing ranged from 91 to 98% for females and 84 to 93% for males. The experimental conditions resulted in a high incidence of diapause. Preliminary analyses comparing survival of weevil sexes within each cage did not indicate the need to control for gender. There was no statistical difference detected when survival of weevils was compared between locations. These results do not indicate fundamentally different responses to the experimental conditions by weevils from the Texas High Plains and Lower Rio Grande Valley. The absence of differences in host-free survival between the two populations under controlled conditions, suggest the need to focus instead on the overwintering environment when interpreting the apparent differences in the dynamics of boll weevil overwintering between temperate and subtropical regions.