|SANT' ANA, JOSUE|
|DA SILVA, ROGERIO|
Submitted to: Journal of Chemical Ecology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/12/1999
Publication Date: N/A
Interpretive Summary: Insect predators may be used to manage insect pests. Chemical signals used by immature and adult stages of predators could coordinate their activities with those of their prey; thus increasing their effectiveness. Until now little was known about chemical signals important to behavior of the immature stages of insect predators or how these signals were detected by them. We investigated olfactory sensitivity of immature stages of the spined soldier bug, a predator of the Colorado potato beetle. Immature stages were sensitive to both the adult aggregation pheromone and chemicals released by plants (both at the wound site and systemically over several hours) in response to insect feeding (i.e. potential prey). Different immature stages responded distinctly to pheromone and plant odors suggesting differing behavioral roles for specific chemicals. Receptors for these chemicals were localized to the terminal antennal segment. This new knowledge of chemical communication in immature stages of predaceous bugs will be used by entomologists interested in biological control to formulate improved control strategies, and chemical ecologists as a guide to discovery of new chemical signals.
Technical Abstract: Olfactory reception of 23 odorants, including plant volatiles and male-produced aggregation pheromone, by third and fifth instars of the spined soldier bug (SSB) Podisus maculiventris (Say) was investigated using electroantennograms (EAGs). Both nymphal stages were sensitive to male-produced aggregation pheromone components (E)-2-hexenal, benzyl alcohol and à-terpineol. The plant volatile, (E)-2-hexen-1-ol (a chemical known to be released by plants in response to prey feeding over the short-term), elicited the largest EAGs of all volatiles tested. While third instars were sensitive to nonanal, only fifth instars responded to both nonanal and (ñ)-linalool, both compounds released systemically by plants in response to feeding by potential prey. Antennal extirpation experiments showed that sensilla responsive to hexan-1-ol, (E)-2-hexenal and alpha-terpineol are situated mainly on the terminal antennal segment. The results support the hypothesis that P. maculiventris nymphs use both plant volatiles and pheromone components in locating potential prey and other behaviors.