Are synthetic volatiles, typically emitted by insect-damaged peach cultivars, navigation signals for two-spotted lady beetle (Adalia bipunctata L.) and green lacewing (Chrysoperla carnea [Stephens]) larvae?

Abstract

Upon herbivore attack, plants produce and emit volatile organic compounds (VOCs). Some of these compounds may be used in defensive strategy namely the attraction of the herbivores natural enemies. To increase our knowledge of aboveground-induced VOCs on beneficial organisms, we describe laboratory study on the chemotactic behavior of two-spotted lady beetle (Adalia bipunctata L.) and green lacewing (Chrysoperla carnea [Stephens]) larvae toward synthetic VOCs (methyl salicylate, (E)-β-farnesene, (E)-β-ocimene, and E-nerolidol) typically emitted by insect-damaged peach cultivars. All tested VOCs influenced the behavior of both tested organisms. Our results are suggesting that VOCs can influence the movement of green lacewing larvae only for short period of time, while on the other hand two-spotted lady beetle larvae can follow the chemical signal for longer period of time. Results demonstrate a laboratory attraction of two-spotted lady beetle and the green lacewing larvae to a synthetic (E)-β-ocimene. Furthermore, our study showed a repellency of two-spotted lady beetle and the green lacewing larvae to a synthetic (E)-nerolidol, (E)-β-farnesene, and methyl salicylate.