Pedro Sánchez

OLFACTORY BEHAVIOR AND ELECTROANTENNOGRAPHIC RESPONSES OF THE COCOA BEETLE, STEIRASTOMA BREVE (COLEOPTERA: CERAMBYCIDAE)

Abstract With the aim of studying the olfactory behavior of one of the main pests in neotropical cocoa plantations, the cocoa beetle Steirastoma breve (Sulzer) (Coleoptera: Cerambycidae), we studied behavioral and antennal responses towards different odor sources in a two-choice olfactometer and an electroantennographic system, respectively. Odor sources tested as stimuli in olfactometric experiments were chopped pieces of cocoa branches, adult males, adult females of S. breve, and combinations of these. Extracts of female and male body parts in n-hexane were tested in electroantennnographic experiments. Statistically significant attraction responses in the olfactometer were observed only when S. breve individuals were stimulated with odors from pieces of cocoa branches. Both sexes showed active EAG responses to odors of cocoa branches, and females showed active EAG responses to adult male odors. These results suggest that olfactory behavior of S. breve is mediated by volatiles derived from cocoa trees and from adult male insects.

Rhyncophorus palmarum L. (Linnaeus, 1758): A morphological and histological study of the female reproductive system

Rhyncophorus palmarum (Coleoptera) is a pest of great economic importance because of the damage caused in the plants of the Palmae family. This study showed that the female reproductive system of this beetle is composed of two ovaries of the telotrophic meroistic type invariably containing two ovarioles per ovary. Each ovariole is home to about 50 oocytes at different stages of maturation. The proximal region of the ovary is rather peculiar because it houses inside it a large quantity of bacilliform structures immersed in a glycolipoprotein substance, which has never before been described in the literature. The function of these structures is still unknown. However, it is suggested that they can function as a method of neutralizing the resistance of the plant because these insects are responsible for the transmission of the red ring disease to the palm plants. Microsc. Res. Tech., 2011.