SEASONAL ACTIVITY PATTERNS OF BOLL WEEVILS IN CROPPED AND UNCROPPED AREAS OF EAST-CENTRAL TEXAS AS MEASURED WITH PHEROMONE TRAPS

Authors: Beerwinkle, Kenneth; Lopez, Juan De Dios; McKibben, Gerald

Submitted to: Southwestern Entomologist
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/10/1996
Publication Date: N/A
Citation: N/A

Interpretive Summary: Seasonal movement of adult weevils between cotton fields and between overwintering areas and cotton field contributes to their pest status. Increased knowledge of their movement behavior is important to agricultural scientists and farmers attempting to develop improved management strategies for this insect pest. Responses of weevils to pheromone-baited traps can be used to survey weevil populations in given areas and indirectly measure their movement behavior. Results of studies with pheromone traps in the Brazos River Valley of Texas in 1990 and 1991 indicated similar responses of weevils to traps located in cropped areas out to distances greater than 10 km (6.25 miles) from cotton fields during the time from April through early September. Peak responses of emerging overwintered weevils occurred in both areas during late April through May, followed by a mid-season period of minimal response from early June through mid-July. Weevil responses to traps began to increase area-wide in late July of both years, and they continued to increase through early September. During this late summer period, weevil responses to pheromone traps were uniform to relatively high levels, within-years, over the cropped area and the uncropped area out to distances of 20 km (12.4 miles) in 1990 and 13 km (8.1 miles) in 1991, indicating wide-scale migration of weevils over the whole study area. During the fall, the magnitudes of trap captures in the cropped area increased to levels of more that 5 times those in the nearest uncropped area. Knowledge gained in this study relative to the seasonal pheromone trap responses and movement of boll weevils should be useful to the development of improved management programs for this pest in the Brazos River Valley of Texas.

Technical Abstract: Boll weevil, Anthonomus grandis grandis Boheman, pheromone trapping studies were conducted in a large, relatively isolated area of contiguous row-crop farms (cropped area) and the surrounding uncropped area in the Brazos River Valley of Burleson and Brazos counties near College Station, TX, during 1990 and 991. Results indicated that variations in the timing and magnitudes of the mean weekly trap captures in the cropped and uncropped areas were similar during the early midseason periods until September when harvest began. Respohse patterns during this period were characterized by peak responses of emerging overwintered weevils during late April through May, followed by mid-season period of minimal response from early June throuhg mid-July, and then increased, uniform area-wide responses from late July through early September. During the late-summer period, weevil responses were uniform at relatively high levels, within-years, over the cropped area and the uncropped area out to distances of 20 km in 1990 and 13 km in 1991. After the beginning of harvest with the associated habitat destruction, the timing of variations in catch patterns for the traps in the cropped and uncropped areas remained similar; however, the magnitudes of mean weekly captures in the cropped area increased to levels of more than 5 times those obtained in the uncropped area. The magnitudes of mean weekly catches throughout the year in 1990 were less than half those obtained in traps at the same locations in 1991, probably because of the detrimental effects of abnormally cold temperatures in the area during December 1989.