Harnessing the chemical ecology of multitrophic interactions for plant health and protection
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Concerns about insecticide resistance and losses of beneficial arthropods have contributed to a growing interest in developing alternative pest management strategies that reduce insecticide use1. Augmenting or supporting existing populations of natural enemies that prey on herbivores is one strategy that offers a promising alternative for controlling insect pests, however adoption rates among growers have been limited2. Entomopathogenic nematodes (EPN) are important natural enemies that can be used for biological control of insect herbivores in soil, including cucumber beetles, which are economically important pests of cucurbit crops. Recent work has revealed that plant exposure to live EPN or their chemical cues can enhance plant systemic resistance against pests, including pathogens and herbivores3,4. However, mechanisms underlying this resistance or plant responses to EPN have not been fully characterized, and the broader ecological significance of plant response to an herbivore natural enemy remains unknown. Because EPN occur naturally in many soil environments and can be introduced to control agricultural pests, there is a critical need to determine how EPN-induced changes in plant defenses influence other members of the community, such as insect herbivores and plant- associated microbes. In the absence of such knowledge, it will remain difficult to improve implementation strategies for EPN biological control or to increase adoption rates among growers.The long-term goal of this project is to improve our understanding of the chemical ecology of belowground multitrophic interactions to reveal indirect benefits or potential disadvantages of EPN biological control for plant protection against pests. The overall objective is to characterize changes in plant defenses following exposure to EPN or associated chemical cues and to determine how these changes influence other organisms associated with plants. Our central hypothesis is that plant exposure to EPN or EPN chemical cues enhances systemic defense responses that decrease the performance of herbivores and plant-associated microbes..........