Sexual Maturation and Temporal Variation of Neural Responses in Adult Colorado Potato Beetles to Volatiles Emitted by Potato Plants

Abstract

Neural responses of the Colorado potato beetle (CPB), Leptinotarsa decemlineata to volatiles emitted by potato plants, Solanum tuberosum L were investigated. Amplitudes of electroantennograms to measured amounts of a standard odorant, (Z)-3-hexenyl acetate, increased from day of emergence through at least six to eight days of adulthood. Among 20 potato volatiles examined, several constitutive compounds, e.g., the green leaf volatiles (Z)-3-hexen-1-ol, (E)-2-hexen-1-ol, and (Z)-3-hexenyl butyrate, and systemic volatiles released primarily in response to insect feeding, e.g., (±)-linalool, nonanal, methyl salicylate, and indole, were the most effective stimuli. A statistic called linear age-skew (linear orthogonal polynomial) was used to examine differences in responses to potato volatiles between young and mature CPB. Based on plots of linear age-skew and overall neural responsiveness, 10 volatiles could be identified for which responses increased at a rate similar to or greater than the standard. The results are discussed with regard to the relationship of the CPB to its host plant and developmental studies of insect sensory responses to chemical signals.