Submitted to: Journal of Chemical Ecology
Publication Type: Peer reviewed journal
Publication Acceptance Date: 3/26/2013
Publication Date: 8/25/2013
Publication URL: http://handle.nal.usda.gov/10113/58294
Citation: Davis, T.S., Landolt, P.J. 2013. A survey of insect assemblages responding to volatiles from a ubiquitous fungus in an agricultural landscape. Journal of Chemical Ecology. 39:860-868. Interpretive Summary: Reduction of the use of pesticides on agricultural crops is a primary directive of basic biological research within the Agricultural Research Service. One way this can be achieved is through integrated pest management approaches that utilize odor sources to trap pest insects and attract beneficial insects. Recent studies have shown that microorganisms represent a novel source of odors for attracting insects. Researchers at the USDA-ARS in Wapato tested cultures of an environmentally common fungus and volatiles identified from fungal headspace for attractiveness to insects. They found that odors from a common yeast-like fungus attract beneficial pollinators and predatory insects, as well as plant pests. Synthetic chemicals attracted significantly more predators and herbivores, but pollinators responded similarly to fungal cultures and synthetic test chemicals. Our results suggest that odors from an abundant microbe may be useful for developing lures with broad-spectrum bioactivity in agricultural landscapes.
Technical Abstract: We report here a first survey of insect orientation to fungal cultures and and fungal volatiles from a community ecology perspective. We tested whether volatiles from a ubiquitous yeast-like fungus (Aureobasidium pullulans) are broadly attractive to insects in an agricultural landscape. We evaluated insect attraction to fungal cultures and synthetic compounds identified in fungal headspace (2-methyl-1-butanol, 3-methyl-1-butanol, 2-phenylethanol) in a spearmint (Mentha spicata L.) plantation. Three important findings emerged: (1) 1,315 insects representing seven orders and 39 species oriented to traps, but 65% of trapped insects were Dipterans, of which 80% were hoverflies (Diptera: Syrphidae); (2) traps baited with A. pullulans caught 481% more insects than unbaited control traps on average, and contained more diverse (Shannon’s H index) and species rich assemblages than control traps, traps baited with Penicillium expansum, or uninoculated media; and (3) insects oriented in greatest abundance to a 1:1:1 blend of A. pullulans volatiles, but mean diversity scores were highest for traps baited with only 2-phenylethanol or 2-methyl-1-butanol. Our results show that individual components of fungal headspace are not equivalent in terms of the abundance and diversity of insects orienting to them. The low abundance of insects captured with P. expansum suggests that insect assemblages do not haphazardly orient to fungal volatiles. We conclude that volatiles from a common fungal species (A. pullulans) are attractive to a variety of insect taxa in an agricultural system, and that insect orientation to fungal volatiles may be a common ecological phenomenon.