Attraction of entomopathogenic nematodes to sugarcane root volatiles under herbivory by a sap-sucking insect

Author(s)

Tonelli, Mateus ^[1] ; Gomes Villalba Penaflor, Maria Fernanda ^[2] ; Leite, Luis Garrigos ^[3] ; Silva, Weliton Dias ^[1] ; Martins, Fernanda ^[1] ; Simoes Bento, Jose Mauricio ^{[1, 4]}

Affiliation

^[1] Univ Sao Paulo, Dept Entomol & Acarol, BR-13418900 Piracicaba, SP - Brazil

^[2] Fed Univ Lavras UFLA, Dept Entomol, Campus Univ, POB 3037, BR-37200000 Lavras, MG - Brazil

^[3] Inst Biol, Biol Control Lab, BR-13092543 Campinas, SP - Brazil

^[4] Univ Sao Paulo, ESALQ, Lab Ecol Quim & Comportamento Insetos, Av Padua Dias 11, BR-13418900 Piracicaba, SP - Brazil

• Document type: Journal article
• Source: Chemoecology; v. 26, n. 2, p. 59-66, APR 2016.
• Web of Science Citations: 7

Abstract

Few systems have been described in which herbivore-induced root volatiles mediate attraction of entomopathogenic nematodes (EPNs), and they only concern root damage inflicted by chewing insects. EPNs, especially Heterorhabditis indica and Steinernema carpocapsae, are potential biological control agents of sugarcane spittlebug (Mahanarva fimbriolata) populations. Here, we investigated the response of these two species of EPNs to sugarcane root volatiles damaged by M. fimbriolata nymphs in a belowground six-arm olfactometer. We also examined changes on root volatile profile in response to herbivory of sugarcane spittlebug nymphs. Results showed that both EPN species did not discriminate between odors of undamaged sugarcane and moistened sand (blank). However, when EPNs were exposed to odors of spittlebug-damaged and undamaged sugarcane roots, both species significantly preferred odors of spittlebug-damaged roots. Headspace collection followed by GC-MS analyses showed no qualitative difference (total of 11 compounds) between volatile profiles of spittlebug-damaged and undamaged sugarcane roots. In contrast to the previous studies involving feeding by root chewing insects, our root volatile analysis did not reveal any up-regulation resulting from sugarcane spittlebug damage, but the down-regulation of the terpenes dihydromyrcenol and beta-isomethyl ionone when compared with the profile of undamaged sugarcane roots. Here, we propose alternative explanations for the EPN attraction to spittlebug-damaged roots as it is unlikely that reduced concentrations of the volatiles play a role in this interaction. Further studies are necessary to determine the key compounds of the root volatile emission to enhance biological control efficacy with EPNs against M. fimbriolata in sugarcane. (AU)

• FAPESP's process: 13/05367-0 - Sugarcane induced defenses against multiple attack and root herbivory
• Grantee: José Maurício Simões Bento
• Support type: Regular Research Grants
• FAPESP's process: 08/57701-2 - Technological bases for identification, synthesis and use of semiochemicals in agriculture
• Grantee: José Roberto Postali Parra
• Support type: Research Projects - Thematic Grants