Reduction of pre-harvest infestations of African sweetpotato weevils Cylasbrunneus and C. puncticollis (Coleoptera : Apionidae) using a pheromone mating-disruption technique

A trial was carried out in Uganda for the control of sweetpotato weevils, C ylas puncticollis and C. brunneus, by mating-disruption using the synthetic sex pheromone of C. brunneus formulated in PVC resin dispensers. Almost no C. brunneus males were caught in pheromone traps in the treatment plot, wh ereas catches in the control plot ranged up to 30 weevils per trap over eac h two-night monitoring period. Suppression of C. puncticollis catches was w eaker. Mating of C. puncticollis was significantly suppressed on one sample date, 18 weeks after planting, but not on two subsequent occasions, at 19 and 33 weeks. Yields of roots in the two plots were similar, but root infes tation was lower in the plot treated with pheromone on four out of five sam ple harvest dales, from 17 to 36 weeks after planting. (C) 2001 Elsevier Sc ience Ltd. All rights reserved.