Behavioral responses of Steirastoma breve (Sulzer) (Coleoptera: Cerambycidae) to host plant Theobroma cacao L., brushwood piles, under field conditions

Abstract

Steirastoma breve is one of the most important pests in cocoa plantations in the Neotropics. Preliminary studies suggest that the chemical communication system in S. breve may be modulated by kairomones produced by cocoa plants and pheromones released by males. We examined the role of Theobroma cacao brushwood in the communication system of S. breve under field conditions. Sixty kilograms of T. cacao and Bauhinia sp. branches were cut, grouped into separate piles, and placed in an experimental cocoa plantation as an odor source. The sex and number of S. breve adults landing on each pile were registered during 23 days from 9:00 to 15:00 h. Each individual arriving at a pile was marked with a coded color and then released onto the same pile. All behavioral activities undertaken by S. breve were evaluated and flight behavior towards the T. cacao piles was described. S. breve adults were attracted to T. cacao piles placed under both sunny and shaded conditions, but were not attracted to Bauhinia sp. S. breve males dispersed more in shaded piles than in those placed in the sun, and the proportion of encounters between sexes was higher in the piles at which they had first arrived. Analysis of the data confirmed the presence and importance of T. cacao kairomones in the chemical communication system of this important cocoa pest.