Early-Season Colonization Patterns of the Boll Weevil (Coleoptera: Curculionidae) in Central Texas Cotton

Abstract

It is commonly believed that colonization of early-season cotton, Gossypium hirsutum L., by overwintered boll weevils, Anthonomus grandis grandis Boheman, is concentrated on field margins. However, supporting experimental evidence is not available. In 1999 and 2000, we examined colonization patterns of overwintered boll weevils in Central Texas cotton on the bases of adult collections by a pneumatic sampler and hand collections of abscised infested squares. Samples were taken from sites arranged in a grid that extended inward >70 m from the field margin. Adults were collected from shortly after seedling emergence until the flowering stage, and infested squares were collected during the one-third grown square stage. Despite numerical trends, the numbers of adult weevils collected were not significantly different between years or sexes, or among plant phenological stages. Field-to-field variation among collections was considerable and likely prevented detection of differences among these factors. Spatial patterns represented by adult weevil and infested square collections were examined by logistic regressions fitted to the respective probabilities of weevil detection at each designated sample site. Although we observed trends for slightly decreased probability of weevil detection with increased distance from the field margin, these trends were too weak to be demonstrated statistically. Our results indicate the boll weevil does not consistently exhibit a strong edge-oriented colonization pattern, and that management tactics that are predicated on these patterns, such as border sprays, should be used with caution.

Colonization and Spatial Distribution of Boll Weevil in Commercial Cotton Fields

“…Irrespective of the bordering vegetation, weevils were captured early and across the whole field, despite the boll weevil low density near the center of these large surveyed fields. This outcome agrees with Reardon & Spurgeon (2003) for the weak border-oriented cotton field colonization by overwintered boll weevil in Central Texas cotton. Our results could be due to two possible reasons.…”

“…Thus, the boll weevil distribution maps built for surveyed fields confirm our suspicions that the boll weevil can be present across large fields (ca., 150 ha) and not only restricted to the borders of refuge areas at the beginning of the season. The maintenance of weevils in the field also justifies the lack of a strong colonization pattern as a function of the bordering vegetation (Reardon & Spurgeon 2003). The early presence of the weevils in the field will depend on the control adopted at the end of the previous cotton season.…”

Influence of Row Spacing, Herbicide Technology, and Tillage on Fiber Quality and Economic Returns

“…More specifically, mixed logit models, a type of logistic regression, allows for both fixed and random effects. Logit models have been applied to agronomic and livestock data (Kyveryga et al, 2010;Landschoot et al, 2013;Osterstock et al, 2010;Reardon and Spurgeon, 2003;Wu et al, 2005); however, with one exception (Zhao et al, 2010) it is not evident that cotton fiber quality attributes have been analyzed in categories using logit analysis.…”