Toward the Identification of the Sex Pheromone of Diatraea indigenella Dyar & Heinrich (Lepidoptera: Crambidae): Calling Behavior and Chemical Structure of a Major Component.

Abstract

Behavioral patterns and pheromone titer in females of the steam borer Diatraea indigenella Dyar & Heinrich were assessed for 7days during scotophase under a 13:11 L:D photoperiod. Calling was observed from the first scotophase for most of the females. The highest percentage of calling females was recorded 6h after the onset of scotophase. Calling bouts and length of calling were affected by age, decreasing dramatically after the sixth scotophase. By coupling chemical and electrophysiological techniques (GC-EAD, GC-MS) and olfactometer bioassays (Z,E)-9,11-hexadecadienal was identified as the main sex pheromonal component in the extracts of female glands. The concentration varied from 2.53 to 13.7nggland(-1) with a peak at the 6th hour of scotophase. In addition, two unidentified secondary active components were detected at very low concentrations. Behavioral assays showed that 86% of the male moths were more attracted to the gland extracts than to hexane (control), and 77% of the male moths were more attracted to the gland extract than to the synthetic major component (Z,E)-9,11-hexadecadienal. However, 68% of males preferred the synthetic major component over hexane. The identification of the major sex pheromonal component represents an important step toward the complete elucidation of the composition of the sex pheromone of D. indigenella in order to develop monitoring tools.