|FAAL, HAJAR - State University Of New York (SUNY)|
|HAJEK, ANN - Cornell University|
|TEALE, STEPHEN - State University Of New York (SUNY)|
Submitted to: Fungal Ecology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/12/2021
Publication Date: 8/25/2021
Citation: Faal, H., Cha, D.H., Hajek, A.E., Teale, S.A. 2021. A double-edged sword: Amylostereum areolatum odors attract both Sirex noctilio (Hymenoptera: Siricidae) and its parasitoid, Ibalia leucospoides. Fungal Ecology. 54. Article 101108. https://doi.org/10.1016/j.funeco.2021.101108.
Interpretive Summary: The Eurasian woodwasp, Sirex noctilio, is a serious pest in pine plantations in US and the Southern Hemisphere. This woodwasp maintains an obligatory mutualistic relationship with a fungus, Amylostereum areolatum. It has been known that this fungus attracts both S. noctilio and a specialist parasitoid of the woodwasp, Ibalia leucospoides. Researchers at USDA-ARS in Hilo, Hawaii, State University of New York, and Cornell University isolated and identified fungal volatiles that are detected by S. noctilio and I. leucospoides. S. noctilio antennae detected 4 compounds (6-methyl-5-hepten-2-one, trans-3-hexenyl acetate, linalool, and geraniol) and I. leucospoides detected one additional compound, '-anisaldehyde. In olfactometer bioassays, the 4- and 5-compoent blends were necessary to attract S. noctilio and I. leucospoides, respectively. In field trapping experiments, the 5-component blend could capture both S. noctilio and I. leucospoides, suggesting that these fungal volatiles can serve as a basis for the development of improved lures for both species.
Technical Abstract: Volatiles emitted from the symbiotic fungus are reliable cues for both pests and their parasitoids to optimize their foraging behavior (host location and host habitat finding) in a chemically complex environment. The headspace volatiles of the fungal symbiont of Sirex noctilio, Amylostereum areolatum, were analyzed using coupled gas chromatography (GC) electroantennographic detection and GC-mass spectrometry for both S. noctilio and its parasitoid Ibalia leucospoides females. Analysis revealed that both species could detect several fungal volatiles. In olfactometer bioassays, S. noctilio females were attracted to a 4-component blend of 6-methyl-5-hepten-2-one, trans-3-hexenyl acetate, linalool, and geraniol, while the addition of '-anisaldehyde to the blend was necessary for attraction of I. leucospoides females. The results of trap catches in field experiments confirmed that these fungal volatiles are attractive for both species, although the release rate of the fungal volatiles is important. These volatiles can serve as a basis for the development of improved lures for both species.