Biological Effectivity of Insecticides to Control the Agave Weevil,Scyphophorus acupunctatusGyllenhal (Coleoptera: Curculionidae), in Mexico

Abstract

Scyphophorus acupunctatus Gyllenhal causes economic losses to plants of the Agavaceae and Dracaenaceae families and, recently, in commercial plantations of nardo, Polianthes tuberosa L. Synthetic insecticides are the main controls, but these pesticides may not be effective, because larvae and adults are frequently found feeding in the interior of the “ball” of agave plants, far from the reach of the insecticide. The efficacy of insecticides to control this pest is unknown. In this study, we evaluated the effectiveness of synthetic insecticides of different toxicological groups to control S. acupunctatus. The experimental design was completely randomized. The number of dead adults was analyzed using a nonparametric variance of Kruskal Wallis. The percentages of biological effectiveness of insecticides in each bioassay were obtained by using the Abbott formula. Malathion, endosulfan, methomyl, and fipronil showed high biological efficacy. Conversely, cypermethrin, lambda-cyhalothrin, deltamethrin, and betacifluthrin, of constant use in Tamaulipas to control S. acupunctatus, produced a minor effect similar to the nontreated check. However, although some insecticides were effective, it is recommended they be rotated with insecticides with different modes of action or in conjunction with other controls such as food attractants, entomopathogenic fungi and nematodes, and aggregation pheromones, to obtain better control of S. acupunctatus and prevent development of resistance to insecticide.