The role of synergists in trapping of tropical Curculionidae

Both sexes of all species of palm weevils in the genus Rhynchophorus studied to date respond weakly to male-produced pheromones when these pheromones are emitted from traps in the field. Emission of food based volatiles from pheromone-containing traps increases captures dramatically while the additional emission of low molecular weight esters such as ethyl acetate from pheromone-food containing traps increases captures still further. Attempts to mimic food generated volatiles have met with mixed success. The behavior of Rhynchophorus palm weevils toward pheromone and food volatiles is linked in this talk to interaction with the hosts. Curculionidae in the genus Metamasius exhibit a similar pheromone-food-ethyl acetate response. In the case of Metamasius hemipterus, the West Indian sugarcane weevil the relative importance of pheromone and food as an attractant changes over a generation. By way of contrast another tropical Curculionidae, Cosmopolites sordidus, the banana corm weevil, exhibits a relatively strong response to its male-produced pheromone and a relatively weak increase in response when host volatiles are added. This behavior is linked to the interaction of this insect with its host.