Volatile Compounds Attract the Pepper (Capsicum spp.) Weevil (Anthonomus eugenii Cano) and Synergize its Aggregation Pheromone
The pepper (Capsicum spp.) weevil (Anthonomus eugenii Cano) is the principal pepper pest in America, and its management requires efficient monitoring techniques. The host volatile compounds could be used for this purpose. In this research the attraction of A. eugenii adults towards an individual compound and 12 mixtures of synthetic volatile compounds (identified previously in Capsicum spp.) was evaluated, the effect of three isomers [(Z)-β-ocimene, (E)-β-ocimene, and D-limonene] was determined in the weevil response, and the best mixture of host volatiles was evaluated, as well as their combination with the A. eugenii aggregation pheromone and the pheromone alone. The insect’s response was evaluated through pairwise choice experiments, carried out in a Y-type olfactometer, with two treatments. The proportions of insects responding to each treatment were compared with the binomial test. Results showed that the mixture of (Z)-β-ocimene, D-limonene and 2-isobutyl-3- methoxypyrazine attracted (p≤0.01) A. eugenii adults of both sexes. The (Z)-3-hexenyl acetate and the terpinolene, added individually to the prior combination, increased the response of females (p≤0.05) and males (p≤0.01), respectively. The inclusion of (E)-β-ocimene as principal compound, in the same mixture, increased the response by males (p≤0.05) and the exclusion of D-limonene did not decrease the effectiveness of the remaining combination. In the final experiments, males had a greater response to the mixture of host volatile compounds (p≤0.05) and to its combination with the A. eugenii aggregation pheromone (p≤0.001), than to the pheromone by itself; in contrast, females did not show a differentiation in their choice. The research allowed selecting pepper volatile compounds with potential to attract A. eugenii adults.