Tea shot-hole borer, Euwallacea perbrevis Schedl (Coleoptera: Curculionidae), is an ambrosia beetle that has become a destructive alien pest in Florida. Like all ambrosia beetles, E. perbrevis is a wood-boring insect that cultivates symbiotic fungi as a nutritional source for larvae and adults. However, the symbionts of Euwallacea spp. are pathogenic to host trees, inducing Fusarium dieback. This destructive vascular disease affects avocado, woody ornamentals, and native trees. Despite growing knowledge about ambrosia beetle symbiosis, no studies to date have investigated which symbionts of E. perbrevis produce volatile attractants (food-based kairomones). In this study, headspace solid-phase microextraction (HS-SPME) coupled with gas chromatography–mass spectroscopy (GC–MS) were used to analyze the volatile emissions from six E. perbrevis fungal symbionts: Fusarium sp. AF-6, Fusarium sp. AF-8, Fusarium sp. nov., Graphium sp., Acremonium sp., and Acremonium murorum. A total of 15 compounds were detected, with monoterpene hydrocarbons and oxygenated monoterpenoids predominating. Based on principal component analysis (PCA) and hierarchical cluster analysis (HCA), cis- and trans-p-menth-2-en-1-ol were the key components for discriminating effect of symbionts. In addition, Super-Q collections followed by GC analyses were performed to quantify cis- and trans-p-menth-2-en-1-ol emissions for three months. Laboratory bioassays showed that Fusarium sp. nov. was the most attractive symbiont, which produced only two volatiles, trans-p-menth-2-en-1-ol and limonene. Further research is needed to determine which enantiomers confer attraction. These results provide insight into the chemical communication between E. perbrevis and its symbiotic fungi, and may facilitate development of improved lures for early detection and management of this invasive pest.

Volatile emissions from exotic fungi vectored by Euwallacea perbrevis Schedl (Coleoptera: Curculionidae)

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