Dalbulus maidis and Peregrinus maidis, both phloem feeding hoppers, induce different volatile profiles in maize. Consequences for a natural enemy

Abstract

We evaluated the induction of plant volatile organic compounds (VOCs) in maize after the attack of two piercing-sucking maize hoppers: the specialist Dalbulus maidis and the oligophagous Peregrinus maidis. We analyzed VOCs in plants after feeding and oviposition by females of both species. We also contrasted VOCs induced by D. maidis males with those induced by females’ infestation that comprised oviposition, to evaluate which VOC could be responsible for attracting an egg parasitoid. We quantified the damage performed by both hoppers and tested the behavioral response of the egg parasitoid Anagrus virlai to VOCs emitted by infested and healthy plants. Plants infested by D. maidis females released significantly more VOCs than the other treatments: healthy plants, plants infested by P. maidis females and plants infested by D. maidis males. β-Caryophyllene, α-bergamotene, β-farnesene and cis-3-hexenyl acetate dominated the volatile blend (46%) in plants infested by D. maidis females, while in those plants infested by P. maidis these compounds represented only 17%. Females of both hoppers inflicted a comparable amount of damage, in terms of feeding injuries and number of eggs laid. β-Caryophyllene and cis-3-hexenyl acetate were not induced in plants infested by D. maidis males, that had no oviposited eggs. Finally, females of the egg parasitoid oriented toward VOCs from plants infested by females of the specialist D. maidis, rather than those infested by the oligophagous P. maidis or those infested by D. maidis males.