Ecology and Behavior Herbivore Damage and Prior Egg Deposition on Host Plants Influence the Oviposition of the Generalist Moth Trichoplusia ni (Lepidoptera: Noctuidae) Guadalupe G. Coapio, 1,2 Leopoldo Cruz-L opez, 1 Pablo Guerenstein, 3 Edi A. Malo, 1 and Julio C. Rojas 1 1 Grupo de Ecolog  ıa de Artr opodos y Manejo de Plagas, Departamento de Agricultura, Sociedad y Ambiente, El Colegio de la Frontera Sur, Carretera Antiguo Aeropuerto Km 2.5, Tapachula, Chiapas, Mexico (ggarcia@ecosur.edu.mx; lcruz@ecosur.mx; emr@ecosur.mx; jrojas@ecosur.mx), 2 Corresponding author, e-mail: ggarcia@ecosur.edu.mx, and 3 CICyTTP, CONICET Matteri 49 (y Espa~ na) 3105 Diamante, Entre R  ıos, Argentina (pguerenstein@yahoo.com) Received 29 June 2016; Accepted 10 August 2016 Abstract Female insects have the difficult task of locating host plants that maximize the survival and success of their off- spring. In this study, the oviposition preferences of the cabbage looper moth, Trichoplusia ni (Hu ¨ bner), for soy- bean plants, Glycine max (L.), under various treatments—undamaged, mechanically damaged, damaged by T. ni or Spodoptera frugiperda (Smith) larvae or by Bemisia tabaci (Gennadius) adults, egg-free plants, and plants previously oviposited by conspecific or heterospecific females (S. frugiperda)—were investigated using two-choice tests. Additionally, the volatile compounds emitted by the plants under the different treatments were identified by gas chromatography–mass spectrometry. Our results showed that females showed no pref- erences for undamaged or mechanically damaged plants. However, they oviposited more often on undamaged plants than on those previously damaged by T. ni, S. frugiperda, or B. tabaci. In contrast, females preferred to oviposit on plants previously oviposited by conspecific and heterospecific females than on egg-free plants. Plants damaged by conspecific or heterospecific larvae emitted methyl salicylate, indole, and octyl butyrate, compounds not released by undamaged or mechanically damaged plants. Whitefly damage induced the re- lease of higher quantities of Z(3)-hexenyl acetate, (R)-(þ)-limonene, and (E)-b-ocimene compared to plants dam- aged by larvae and suppressed the emission of linalool. Egg deposition by conspecific and heterospecific moths induced the emission of (R)-(þ)-limonene, octyl butyrate, and geranyl acetone but suppressed the release of lin- alool. This study showed that a generalist moth species can discriminate between plants of different quality, and suggests that females use volatile compounds as cues during this process. Key words: Glycine max, Spodoptera frugiperda, Bemisia tabaci, host-finding behavior, volatile compound Female holometabolous insects have the difficult task of locating host plants that ensure the survival and success of their offspring (Renwick 1989, Landolt and Phillips 1997, Thompson 1998, Bernays 2001, Gripenberg et al. 2010). During this search process, females are stimulated by external and internal factors that influence their choice and acceptance of host plants (Visser 1986, Bell 1990, Schoonhoven et al. 2005). Moreover, the degree of diet specializa- tion of insects may affect the host-finding behavior of ovipositing fe- males (Sch€ apers et al. 2015). A number of studies have shown that females with a broad diet breadth (generalists) have relatively more difficulty in discriminating between good and bad host plants (Levins and Macarthur 1969, Janz and Nylin 1997). This may occur because generalist insects have a limited neuronal capacity for pro- cessing sensorial information, making them less efficient in discrimi- nating between host plants (Bernays 2001, Cunningham 2012). During the host-finding process, females may use chemical cues (e.g., volatile and nonvolatile compounds) as well as physical cues (e.g., color, size) originating from both the habitat and from the plants to determine acceptable host plants (Renwick 1989, Schoonhoven et al. 2005). The cabbage looper moth, Trichoplusia ni (Hu ¨ bner), is consid- ered a generalist species. Although it prefers cruciferous plants (Janmaat and Myers 2003), it can attack >160 species distributed across 36 plant families (Sutherland and Greene 1984). Relatively little is known concerning the host-finding behavior of this moth species (Khan et al. 1987; Landolt 1989, 1993, 2001; Landolt and Molina 1996). For instance, Khan et al. (1987) reported that females were attracted to extracts from a susceptible soybean variety, whereas extracts from a resistant variety repelled them. Landolt (1989) found that mated females were attracted to intact potted V C The Authors 2016. Published by Oxford University Press on behalf of Entomological Society of America. All rights reserved. For Permissions, please email: journals.permissions@oup.com 2364 Journal of Economic Entomology, 109(6), 2016, 2364–2372 doi: 10.1093/jee/tow198 Advance Access Publication Date: 2 September 2016 Research article Downloaded from https://academic.oup.com/jee/article/109/6/2364/2631631 by guest on 10 January 2023