The Ambrosia Beetle Sueus niisimai (Scolytinae: Hyorrhynchini) is Associated with the Canker Disease Fungus Diatrypella japonica (Xylariales)

Abstract

Ambrosia beetles in the subtribe Hyorrhynchini are one example of an entire ambrosia beetle lineage whose fungi have never been studied. Here, we identify one dominant fungus associated with a widespread Asian hyorrhynchine beetle Sueus niisimai. This fungus was consistently isolated from beetle galleries from multiple collections. Phylogenetic analyses of combined ITS rDNA and β-tubulin sequences identified the primary fungal symbiont as Diatrypella japonica Higuchi, Nikaido & Hattori (Diatrypaceae, Xylariales, Sordariomycetes), which was recently described as a pathogen of sycamore (Platanus spp.) in Japan. To assess the invasion potential of this beetle-fungus interaction into the US, we have investigated the pathogenicity of two Diatrypella japonica strains on four species of healthy landscape trees native to the southeastern United States. Only Shumard oak (Quercus shumardii) responded with lesions significantly greater than the control inoculations, but there was no observable dieback or tree mortality. Although disease symptoms were not as prominent as in previous studies of the same fungus in Japan, routine re-isolation from the inoculation point suggests that this species is capable of colonizing healthy sapwood of several tree species. Our study shows that the geographical area of its distribution is broader in Asia and potentially includes many hosts of its polyphagous vector. We conclude that the Sueus-Diatrypella symbiosis has high invasion potential but low damage potential, at least on young trees during the growing season.

Ambrosia Beetles

“…In some beetles, the ambrosia farming lifestyle is evident from galleries lined with luxuriant fungal growth, yet the presence of a mycangium is yet to be confirmed [e.g. Sueus and several Platypodinae, (Li et al 2020)]. Other beetles possess small external structures that frequently hold a few fungal cells, but their function is uncertain.…”

Identification of Potentially Invasive Wood Borers From China Using Sentinel Gardens of Stressed American Trees

“…Two adult Sueus niisimai (Scolytinae: Hyorrhynchini) were recovered from a single gallery of a dead experimental oak tree ( ood treatment) during the test trial at Shuyang Village in 2018. S. niisimai mostly colonizes dead twigs (Kabe 1960); it is considered to have high invasion potential, but low damage potential (Li et al 2020).…”