IDENTIFICATION AND SYNTHESIS OF THE AGGREGATION PHEROMONES OF THE VANILLA WEEVIL, Montella sp. (COLEOPTERA: CURCULIONIDAE)

Abstract

Beetles of the genus Montella (Coleoptera: Curculionidae) are found in the literature as important orchid pollinators and contribute to the reproductive success of these plants. In Bahia State, Brazil, Montella sp. is a pest which attacks Vanilla culture (Vanilla Planifolia). Due to the periodicity and intensity of the attack, Montella sp. has caused reduction of productivity and large economic losses. So far, there are no registered insecticides or efficient control techniques for this weevil. Thus, this work aims to extract, identify and synthesize the pheromone produced by Montella sp., in order to provide a method for monitoring and/or controlling this pest. For this, the insects were collected, separated by sex, reared in plastic cages under ambient conditions of temperature, humidity and photoperiod. The volatile compounds released by males and females were collected by the aeration process and extracted with hexane. The extracts were then analyzed by GC-FID, and the comparison of the chromatograms showed two male specific compounds. GC-MS and FTIR analysis suggested the structures are two long chain unsaturated acetates. The positions of the double bounds were assigned by performing derivatization of the extract with MTAD. The proposed structures were confirmed after obtaining the synthetic pheromone components through a seven steps and an eight steps routes. Laboratory and field experiments are being performed with the synthetic compounds. The structures of the pheromone components of Montella sp. are unusual to Curculionidae species and resemble pheromones identified for Lepidoptera.