Herbivore-Induced Volatiles from Maize Plants Attract Chelonus insularis, an Egg-Larval Parasitoid of the Fall Armyworm
Chelonus insularis (Hymenoptera: Braconidae) is an egg-larval endoparasitoid that attacks several lepidopteran species, including the fall armyworm (FAW), Spodoptera frugiperda, as one of its main hosts. In this study, we identified the volatiles emitted by maize plants undamaged and damaged by S. frugiperda larvae that were attractive to virgin C. insularis females. In a Y-glass tube olfactometer, parasitoid females were more attracted to activated charcoal extracts than Porapak Q maize extracts. Chemical analysis of activated charcoal extracts from maize plants damaged by S. frugiperda larvae by gas chromatography coupled with electroantennography (GC-EAD) showed that the antennae of virgin female wasps consistently responded to three compounds, identified by gas chromatography-mass spectrometry (GC-MS) as α-pinene, α-longipinene and α-copaene. These compounds are constitutively released by maize plants but induction via herbivory affects their emissions. α-Longipinene and α-copaene were more abundant in damaged maize plants than in healthy ones, whereas α-pinene was produced in higher amounts in healthy maize plants than in damaged ones. Female parasitoids were not attracted to EAD-active compounds when evaluated singly; however, they were attracted to the binary blend α-pinene + α-copaene, which was the most attractive blend, even more attractive than the tertiary blend (α-pinene + α-longipinene + α-copaene) and the damaged maize plant extracts. We conclude that C. insularis is attracted to a blend of herbivore-induced volatiles emitted by maize plants.
KeywordsChemical cues Plant volatiles Tritrophic interaction Olfaction Parasitoids
We thank Antonio Santiesteban and Armando Virgen for technical assistance. The English text was corrected by Trevor Williams (INECOL). The Consejo Nacional de Ciencia y Tecnología (CONACYT) provided a scholarship to Fabian Ruben Ortiz Carreon (grant number: 705220/594873).
- Blanco CA, Portilla M, Jurat-Fuentes JL, Sanchez JF, Viteri D, Vega-Aquino P, Teran-Vargas AP, Azuara-Dominguez A, Lopez JD, Arias RS (2010) Susceptibility of isofamilies of Spodoptera frugiperda (Lepidoptera: Noctuidae) to Cry1Ac and Cry1Fa proteins of Bacillus thuringiensis. Southwest Entomol 35:409–415CrossRefGoogle Scholar
- Christensen SA, Nemchenko A, Borrego E, Murray J, Sobhy IS, Bosak L, DeBlasio S, Erb M, Robert CAM, Vaughn KA, Herrfurth C, Tumlinson J, Feussner I, Jackson D, Turlings TCJ, Engelberth J, Nansen C, Meeley R, Kolomiets MV (2013) The maize lipoxygenase, ZmLOX10, mediates green leaf volatile, jasmonate and herbivore-induced plant volatile production for defense against insect attack. Plant J 74:59–73CrossRefGoogle Scholar
- Fatouros NE, Lucas-Barbosa D, Weldegergis BT, Pashalido FG, van Loon JJA, Dicke M, Harvey JA, Gols R, Huigens ME (2012) Plant volatiles induced by herbivore egg deposition affect insects of different trophic levels. PLoS ONE 7:e43607. https://doi.org/10.1371/journal.pone.0043607 CrossRefGoogle Scholar
- Huddleston T, Walker AK (1994) A revision of the Chelonus scrobiculatus species-group of Cheloninae (Insecta: Hymenoptera: Braconidae). Ann Naturhist Mus Wien 96:153–168Google Scholar
- Ngi-Song AJ, Njagi PGN, Torto B, Overholt WA (2000) Identification of behaviourally active components from maize volatiles for the stemborer parasitoid Cotesia flavipes Cameron (Hymenoptera: Braconidae). Insect Sci Appl 20:181–189Google Scholar
- Ortiz-Carreón FR (2015) Respuestas de Chelonus insularis Cresson (Hymenoptera: Braconidae) a volátiles de plantas de maíz (Zea mays L.). Tesis de Licenciatura. Instituto Tecnológico de Tapachula, Chiapas. México. 40 pGoogle Scholar
- Roque-Romero L (2018) Atracción de Chelonus insularis a volátiles del huésped y del hábitat, durante la búsqueda de huevos de Spodoptera frugiperda. Tesis de Maestría. El Colegio de la Frontera Sur, Chiapas. Mexico. 42 pGoogle Scholar
- Steidle JLM, van Loon JJA (2002) Chemoecology of parasitoid and predator oviposition behaviour. In: Hilker M, Meiners T (eds) Chemoecology of insect eggs and egg deposition. Blackwell Publishing, Berlin, pp 291–317Google Scholar