Overwinter Survival of Boll Weevil (Coleoptera: Curculionidae) in Southern Texas: Entrapment in Desiccated Bolls

Research conducted in the Lower Rio Grande Valley of Texas demonstrated the significance of cotton residue as potential overwintering habitat for boll weevils, Anthonomus grandis Boheman. Observations of boll weevil cohorts under laboratory conditions demonstrated the ability of immature stages to complete development within desiccating bolls, and following eclosion, the ability of adults to survive considerable periods of entrapment (up to 3 mol within desiccated bolls with little or no adverse effects on the reproductive system. Field surveys conducted during 1985 revealed: (1) significant densities of boll weevils overwintering in freeze-killed cotton regrowth between 25 January (54,000 per ha, 94.6% immature stages) and 5 April (200 per ha, 100% adults), and (2)a significant emergence of adult boll weevils (≈ 1,600 adults per ha during a 30-d period) from buried residue of cotton plants “destroyed” by conventional tillage operations ≈3 mo earlier. Both habitats allowed boll weevils (both adults and immature stages) to overwinter in numbers greatly in excess of established economic thresholds.