Vectors

Armillaria and insects typically co-occur and exhibit strong interactions that are often difficult to interpret. Armillaria infection of spruce (Picea) can induce the production of volatile compounds that attract bark beetles, such as engraver beetles (Ips spp.). Because both, Armillaria and bark beetles tend to attack stressed trees, interactions among Armillaria and bark beetles are common, but temporal and causal relationships cannot always be definitively determined.

Another type of Armillaria-insect association includes defoliating insects, such as spongy moth (Lymantria dispar), eastern spruce budworm (Choristoneura fumiferana), maple webworm (Tetralopha asperatella), and saddled prominent caterpillar (Heterocampa guttivitta). In these interactions, insect defoliation is believed to predispose trees to Armillaria infections. Attack by root collar weevils (Hylobius spp.) has also been hypothesized to facilitate Armillaria infection by providing wounds that serve as points of entry for the pathogen. In many other cases, Armillaria and insects may simply co-occur without any direct interaction, while other Armillaria-insect interactions are yet to be examined.