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Mechanisms of Boll Weevil (Coleoptera: Curculionidae) Bait Stick Activity Relative to Pheromone Traps

1999; Oxford University Press; Volume: 92; Issue: 4 Linguagem: Inglês

10.1093/jee/92.4.960

1938-291X

D. W. Spurgeon, J. R. Coppedge, J. R. Raulston, Harold G. Marshall,

Insect behavior and control techniques

Mechanisms of bait stick activity against boll weevil, Anthonomus grandis grandis Boheman, including attractiveness relative to traps, competition with traps, longevity of the pheromone lure, and behavior and mortality of responding weevils, were studied in the Lower Rio Grande and Brazos Valleys of Texas. Adhesive-coated bait sticks captured 2–4 times as many weevils as adhesive-coated trap bases, although the lateral surface area of the bait stick was only 1.5-fold that of the trap base. Overall, reductions in trap captures because of competitive interactions with bait sticks were not clearly demonstrated. However, temporal patterns of capture suggested that competition from bait sticks may have reduced trap captures initially when bait stick pheromone sources were fresh. Initial pheromone release rates by the bait stick lure were ≈8.1 times greater than for the trap lure and may have caused a temporary competitive effect. Responding weevils did not feed on or probe the bait stick surface, and when stationary assumed a departure posture with the tip of the abdomen held low and the head held high. Responding weevils contacted the bait stick for an average of 9.4 ± 1.7 min, but nearly half remained on the device for <5 min. Exposure to the bait stick in the field resulted in mortality similar to that of unexposed weevils, whereas forced-contact bioassays indicated high levels of mortality. These results indicate that forced-contact bioassays may be inappropriate for assessing the toxicity of the bait stick to boll weevils.