Sweetpotato weevil pheromones and their precursors: Dose-response and structure activity relationship in Cylas formicarius Fabr., Cylas brunneus Olivier and Cylas puncticollis Boheman

Abstract

Structure-activity and species specificity of the three synthetic sweetpotato weevil pheromones, (Z)-3-dodecenyl-(E)-2-butenoate of C. formicarius, dodecyl-(E)-2butenoate of C. brunneus and decyl-(E)-2-butenoate C. puncticollis and their corresponding precursor free alcohols and trans-crotonic acid were assayed on virgin males of the three weevil species in the laboratory using one-arm olfactometer with bidirectional airflow. Each of the sex pheromones was specific to its conspecific males, however, a pheromone of a particular species may become active to another species only at higher amount to elicit the same degree of response. The free alcohol precursor of the pheromone of C. formicarius, 3-Z- dodecen-1-ol, showed sexual stimulation on C. brunneus and C. puncticollis while dodecan-1-ol functioned as an aggregation compound. The decan-1-ol, precursor of C. puncticollis pheromone, had the lowest attraction index regardless of weevil species tested. Males of C. formicarius and C. brunneus exposed to trans-crotonic acid performed a complete series of mating behavior