Dietary history modifies the innate responses of lady beetles (Coleoptera: Coccinellidae) to odors of their prey-infested host plants

• Published in: Biological control 2022-11, Vol.175, p.105050, Article 105050
• Main Authors: Ranjbar, Fateme, Michaud, J.P., Jalali, M. Amin, Ziaaddini, Mahdi
• Format: Article
• Language: English
• Subjects: Agonoscena pistaciae; Curcurbita pepo; Menochilus sexmaculatus; Oenopia conglobata; Pistacia vera; Prey preference
• ISSN: 1049-9644; 1090-2112
• DOI: 10.1016/j.biocontrol.2022.105050

•O. conglobata and M. sexmaculatus prey on pistachio psyllids and use cotton aphids as alternative prey.•After rearing for 5 generations on Ephestia eggs, both beetles responded to odors of pistachio, but not cucumber.•After 5 generations on psyllids, O. conglobata prefered aphid-infested cucumber to psyllid-infested pistachio.•After 5 generations on aphids, M. sexmaculatus prefered psyllid-infested pistachio to aphid-infested cucumber.•Thus, dietary history modified innate responses, sometimes in favor of a novel plant/prey combination. Oenopia conglobata (L.) and Menochilus sexmaculatus F. are two important predators of pistachio psyllid, a key pest of pistachio in Iran, the former indigenous, and the latter recently adventive. Aphis gossypii Glover infests understory plants in pistachio orchards and is used by both species as an alternative prey when psyllids are scarce. We 'conditioned' beetles by rearing them for five generations on these prey and their respective host plants (Pistacia vera L. and Curcurbita pepo L.), or on eggs of Ephestia kuehniella (Zeller) as a control, and measured the preferences of female beetles for plant and plant/prey odors in an olfactometer. When conditioned on Ephestia eggs, both species found P. vera odors attractive, but not C. pepo odors, and although both plants became more attractive when infested with prey, O. conglobata preferred pistachio/psyllid odors over cucumber/aphid odors, whereas M. sexmaculata showed no preference. Whereas conditioning on pistachio/psyllid caused O. conglobata to prefer (unfamiliar) cucumber/aphid odors, its innate preference for the former disappeared when conditioned on cucumber/aphid. In contrast, conditioning on pistachio/psyllid did not alter the innate responses of M. sexmaculata to cucumber/aphid odors, whereas conditioning on pistachio/psyllid caused odors of this complex to be preferred to those of aphid/cucumber. Thus both species exhibited asymmetric, species-specific responses to conditioning treatments that reflected both innate recognition of plant/prey odors, and some plasticity as a function of recent dietary history, which in some cases led beetles to prefer the novel (unconditioned) plant/prey complex. The observed plasticity of innate olfactory responses as a function of conditioning might be advantageous for generalist predators that must frequently switch among different prey types associated with different plants.