Octadecanal as the male-produced aggregation pheromone of the coconut weevil, Amerrhinus ynca (Coleoptera: Curculionidae)

Abstract

The beetle Amerrhinus ynca Sahlberg, 1823 (Coleoptera: Curculionidae) causes damage to several species of the Arecaceae family. The larvae of this palm weevil damage palm trees by causing perforations in the leaf rachis, obstructing the flow of nutrients to the plant. To date, are no registered insecticides for the control of A. ynca. An efficient control strategy would be the use of synthetic pheromones of this beetle for integrated pest management tactics. In this work, the aggregation pheromone of A. ynca was identified from adults collected as larvae and pupae from the rachis of coconut palm. The volatile compounds produced by A. ynca were collected via headspace aeration of adult beetles, and the identification of the pheromone was performed with gas chromatography coupled to mass spectrometry (GC-MS), GC-Fourier transform infrared spectroscopy (GC-FTIR) and GC-electroantenographic detector (GC-EAD). Dual-choice olfactometry experiments were performed to evaluate the bioactivity of the synthetic pheromone. GC analyses showed the presence of a male-specific compound that was identified as octadecanal. In GC-EAD analyses, synthetic octadecanal elicited responses of A. ynca female antennae. Behavioral bioassays showed attractiveness of synthetic compound for males and females, indicating octadecanal as the aggregation pheromone of A. ynca.