Behavioral responses of Callosobruchus maculatus to volatile organic compounds found in the headspace of dried green pea seeds

There is growing evidence that insects rely on chemical cues to locate food, hosts, predators, and potential mates. The pulse beetle Callosobruchus maculatus has been recognized for decades as the major post-harvest insect pest of legume seeds. In a previous study, we identified five volatile organic compounds in the headspace of dried green pea seeds as electroantennographically active in C. maculatus antennae: 1-pentanol, 1-octen-3-ol, (E)-2-octenal, nonanal, and 3-carene. Some of these compounds used individually elicited attraction toward C. maculatus adults. However, since volatile compounds are generally perceived by insects as blends, we hypothesized that C. maculatus might particularly show attraction to different mixtures of the aforementioned compounds. To test this, we examined the behavioral response of C. maculatus toward a quinary, a quaternary, two ternary, and three binary mixtures in a dual choice Y-tube olfactometer. The results seem to indicate that in a dual choice situation, the first choice made by the beetles is an indication of the attractive or repellent properties of the mixture tested. In most cases, a positive response of C. maculatus to the mixtures of volatiles was observed. Females were attracted to five mixtures, while males were attracted only to two binary mixtures consisting exclusively of aldehydes. The other mixtures caused C. maculatus to respond negatively, suggesting they were repellent. Further investigations with the attractive mixtures should be done in real storage conditions with the aim of developing a trap for the pulse beetle, C. maculatus.