Elicitors aboveground: an alternative for control of a belowground pest

Authors: FILGUEIRAS, CAMILA - Universidade Federal De Lavras; Willett, Denis; PEREIRA, RAMOM - Universidade Federal De Lavras; MOINO JR, ALCIDES - Universidade Federal De Lavras; PAREJA, MARTIN - Instituto De Biologia; DUNCAN, LARRY - University Of Florida

Submitted to: Scientific Reports
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/10/2016
Publication Date: N/A
Citation: N/A

Interpretive Summary: Scientists at the chemistry group, ARS CMAVE, Gainesville Florida in collaboration with a scientist at Federal University of Lavras in Brazil, and Institute of Biology in Mexico, and the University of Florida, plants interact with insect pests and natural enemies both aboveground and belowground. Defense pathways within the plant mediate these interactions by regulating productions of signals used to defend the plant or to attract natural enemies of insect herbivores. This mediation has frequently been studied in isolation; either interactions aboveground are studied or interactions belowground are studied. Here, we explore the effects of aboveground stimulation of plant defense pathways through herbivory and application of chemical elicitors on behavior of aboveground herbivores and belowground herbivores and natural enemies. To do so, we use a corn model system involving the beetle Diabrotica speciosa as the aboveground herbivore, larvae of D. speciosa as the belowground herbivore, and the entomopathogenic nematode Heterorhabditis amazonensis as the belowground natural enemy. We find that adult D. speciosa are attracted to damaged plants, a result that corresponds with field observations. Larvae seem to be relatively unresponsive to changes in plant defense status. Entomopathogenic nematodes respond strongly to corn plants in which defense pathways have been stimulated, recruiting preferentially to plants upon which adult D. speciosa have been feeding. These results suggest that entomopathogenic nematodes belowground are be highly attuned to changes in the aboveground parts of plants and that biological control could be enhanced with induced plant defense in this and similar systems.

Technical Abstract: Plant defense pathways mediate multitrophic interactions above and belowground. Understanding the effects of these pathways on pests and natural enemies above and belowground holds great potential for designing effective control strategies. Here we investigate the effects of aboveground stimulation of plant defense pathways on the interactions between corn, the aboveground herbivore adult Diabrotica speciosa, the belowground herbivore larval D. speciosa, and the subterranean entomopathogenic nematode natural enemy Heterorhabditis amazonensis. We show that adult D. speciosa recruit to aboveground herbivory and methyl salicylate treatment, that larval D. speciosa are relatively indiscriminate, and that H. amazonensis entomopathogenic nematodes recruit to corn fed upon by adult D. speciosa. These results suggest that entomopathogenic nematodes belowground can be highly attuned to changes in the aboveground parts of plants and that biological control can be enhanced with induced plant defense in this and similar systems.