Searching for oviposition sites in the woodwasp Sirex noctilio: the relevance of volatile emissions from the fungal symbiont and the host tree

MASAGUE, SANTIAGO; FERNANDEZ, PATRICIA; DEVESCOVI, FRANCISCO; SEGURA, DIEGO F.; DE LA VEGA, GERARDO; CORLEY, JUAN C.; VILLACIDE, JOSÉ M.; MARTINEZ, ANDRÉS

Buenos Aires

Congreso; VII Congress of the latin american association of chemical ecology; 2023

ALAEQ

Sirex noctilio (Hymenoptera:Siricidae) is an invasive forest wasp that affects pines and can result in severe economic losses. Semiochemicals offer an opportunity to develop sensitive and specific capturing systems to mitigate negative impacts. Previous research showed that female S. noctilio would use volatiles emitted by its fungal symbiont, Amylostereum areolatum. Still, little is known about how these modulate behavior when combined with pine-wood emissions. Because background odors can modify an insect's response towards resource-indicating semiochemicals, we propose that the behavior towards the symbiont (resource) will be modulated by host pine emissions (background odors). In this context, our aim was to understand the relevance of fungal volatiles grown on artificial media and wood from two host trees, Pinus contorta, and Pinus ponderosa, on behavioral and electroantennographic responses of wasp females. Olfactometric assays showed that both host species with fungus were attractive when contrasted against air and suggest a clear hierarchy in terms of female preferences towards the tested stimuli, with the response highest towards the fungus grown on P. contorta, while electrophysiological analyses indicate that females detect 62 volatile compounds from the tested sources. Results indicate a strong synergy between symbiont and host semiochemicals, suggesting that pine volatiles could play a fundamental role in the interaction. Further understanding of the chemical basis of this, could guide the development of specific and attractive lures, in order to maximize the attraction of wasps in surveillance programs.