Effect of insecticide application on the dispersal patterns of the agave weevil ( Scyphophorus acupunctatus ; Coleoptera: Dryophthoridae) in Agave tequilana (Asparagaceae) plantations

The agave weevil ( Scyphophorus acupunctatus Gyllenhal; Coleoptera: Dryophthoridae) is the most important pest of cultivated and wild agaves in Mexico. The objective of this study was to analyze the effects of insecticide use on the dispersal patterns of S. acupunctatus in Agave tequilana Weber (Asparagaceae) plantations. Capture-mark-recapture techniques were used to estimate the abundance and distribution of the pest to understand its aggregation in the crop, considering abiotic factors that influence its dispersal. The study was carried out in four A. tequilana fields: one 2-year field and one 4-year field in the municipality of Tequila, and one 2-year field and one 4-year field in the municipality of Magdalena, in the state of Jalisco, Mexico. Modified traps with aggregation pheromones and agave bait were used to capture live agave weevils, while traps baited with insecticide-treated agave were used for recapture. The captured individuals were marked on their elytra with nail polish and released before and after insecticide application performed by the grower. A total of 264 and 249 weevils were captured, marked, and released in the pre- and post-application samplings, with recaptures of 68 and 36 individuals, respectively. No significant differences were found in the abundance of live weevils between sites or trap types. However, recaptured individuals showed a unidirectional dispersal pattern before insecticide application, while after application, the pattern became more uniform, suggesting a sublethal effect of the insecticide on pest dispersal. The direction of dispersal was influenced by wind and pheromone traps prior to the insecticide application, highlighting the need to adjust integrated pest management when traps and pesticide applications are used together.