Changed host plant volatile emissions induced by chemical interaction between unattacked plants reduce aphid plant acceptance with intermorph variation

Abstract

Olfactory orientation by aphids is guided by specific volatile blends released from their hosts. Host plants that co-exist with other plants may be less attractive for aphids due to volatile interactions between neighboring plants which can lead to changes in their volatile emissions. These changes in host plant volatile profiles induced by interactions between undamaged plants could be used to manage aphid populations in crops. When potato plants are exposed to volatiles from onion plants, the volatile profile of potato changes in relation to that of unexposed plants with consistently greater quantities of two terpenoids released. We examined the host plant searching behavior of aphids and showed that induced changes in plant volatile emissions affect aphid behavior. We assessed olfactory responses of winged and wingless aphids, Myzus persicae Sulzer (Hemiptera: Aphididae) to the changed volatile emissions. Both morphs were significantly less attracted to odors of potato plants that had been exposed to volatiles from onion than to odors of unexposed potato plants. Further, both morphs were significantly less attracted to synthetic blends mimicking volatiles emitted by onion-exposed potato plants than to blends mimicking non-exposed controls, and to single compounds emitted in greater quantities by exposed potato. Aphid morphs were repelled differently depending on the concentration of odor sources; winged aphids responded to higher doses than did wingless aphids. The aphid responses to changes in plant volatile profiles induced by neighboring plants may facilitate refinement of habitat manipulation strategies (e.g., intercropping) for integrated pest management to reduce aphid occurrence in crops.