Submitted to: National Cotton Council Beltwide Cotton Conference
Publication Type: Proceedings
Publication Acceptance Date: 1/8/2002
Publication Date: 7/1/2002
Interpretive Summary: Boll weevils are important insect pests of cotton in much of the southern U.S. Trapping is used to detect boll weevil populations and to schedule insecticide applications. However, new information is needed for improved detection of boll weevil populations during the growing season when weevils are more attracted to cotton that is producing new fruit than to adjacent traps. In field studies, fewer weevils were captured by traps more than 1000 meters (a meter is about three feet) from cotton than by traps closer to cotton. Captures were highest during the cotton harvest period at all trap distances, but seasonal patterns during earlier crop growth stages varied among trap distances. The typical reduction of captures when cotton was producing new fruit was less evident for traps location between 100 and 1000 meters from cotton than for traps located within 100 meters of cotton. These results provide additional insight into trapping patterns that may result in improved monitoring systems for boll weevil eradication programs.
Technical Abstract: Boll weevil eradication programs in the U.S. rely heavily on trap captures of boll weevils to determine the need for insecticide applications. However, currently available information regarding the interpretation of trap captures and parameters influencing the optimal design of trapping systems is incomplete. A field study was initiated in the Brazos Valley of Texas during the spring of 2000 to examine several dynamic facets of boll weevil trap captures. An objective of this study addressed herein was to examine the influence of trap distance from cotton on the seasonal distribution of boll weevil captures. Overall, weevil captures by traps more than 1000 m from cotton were less than by traps closer to cotton. Trap captures were highest during the cotton harvest period at all trap distances, but seasonal patterns corresponding to other agronomic periods varied among trap distance classes. Seasonal patterns in captures also differed between years of the study, primarily because of depressed trap captures during the harvest period of 2001, which likely resulted from ULV malathion applications by the Texas Boll Weevil Eradication Foundation during the first-year diapause phase in this region. Of particular interest, the characteristic depression of trap captures associated with the squaring and early-bloom period in cotton was less evident for traps located between 100 and 1000 m from cotton than for traps located within 100 m of cotton. These results provide additional insight into the spatial dynamics of boll weevil trapping that may result in improved monitoring systems for eradication efforts.