Biology and management of the banana weevil (Cosmopolites sordidus Germar) in the socioeconomic and agroecological context of the indigenous territories of Talamanca, Costa Rica.

摘要

The banana weevil is a pest on bananas and plantains throughout the tropics. No published studies exist on the banana weevil in smallholder banana and plantain systems within the Bribri-Cabecar Indigenous Territories in Talamanca, Costa Rica. These include monoculture plantain and organic banana in agroforestry systems. Concerns exist over pesticide use in plantain and conversion of agroforestry systems to monoculture plantain. Alternatives to pesticides in plantain and improved pest management in organic banana to increase profitability of agroforestry systems are needed. Such efforts must be undertaken with an understanding of the socioeconomic and agroecological context of the indigenous territories. We conducted a livelihoods analysis of cacao agroforestry systems comparing cacao to plantain and organic banana. Existing production data was integrated with data from household interviews to identify factors in the decline of cacao agroforestry systems. We also conducted a rapid rural appraisal with plantain and organic banana producers. Semi-structured interviews with 75 farmers examined current pest management practices and perceptions of pest status and biology. In plantain, 63% of farmers used combination nematicide-insecticides for banana weevil control. Most organic banana farmers (61%) did not use banana weevil management practices. We assessed banana weevil damage levels and yield in 21 organic banana agroforestry farms. Yield was correlated with damage in the banana corm cortex, and 94.7% of damage was in the cortex. To determine efficacy of pheromone traps for banana weevil management in smallholder plantain farms, we evaluated weevil damage and yield before and after 58 weeks of trapping. Traps were placed in six farms at recommended rates, and six farms without traps were controls. Weevil damage decreased by 33% in farms with traps, and did not decrease in control farms. There was no reduction in trap catches, indicating that damage reduction can occur without reduction of weevil populations. We evaluated movement patterns of banana weevils in response to host plant volatiles at 1 and 2 m distances in the field. Weevils were tagged, released, and relocated using harmonic radar. Weevils oriented to host plant volatiles at 1 m but not 2 m, and displayed positive orthokinesis at both distances.