Ayres Abstracts

Hofstetter, R. W., K.D. Klepzig, J.C. Moser, and M.P. Ayres.  2006.  Seasonal dynamics of mites and fungi and their interaction with southern pine beetle.  Environmental Entomology 35:22-30.    pdf

We evaluated whether Dendroctonus frontalis Zimmermann populations were influenced by non-trophic interactions involving commensal mites, their mutualistic fungus Ophiostoma minus (Hedge.) H. and P. Sydow, and beetle-mutualistic mycangial fungi. We predicted that (1) high mite densities have demographic consequences for beetles by influencing the abundance of the bluestain fungus, O. minus and antagonistic interactions between O. minus and mycangial fungi, and (2) inter-relations and abundances of mites and fungi differentially vary throughout the year in a seasonally variable climate. Surveys of D. frontalis populations revealed that temporal and spatial patterns in abundance of Tarsonemus mites and their mutualistic fungus, O. minus, were inversely related with beetle population growth. Negative demographic effects of O. minus on D. frontalis were non-linear, only affecting beetle per capita reproduction when fungi colonized greater than 35% of phloem habitat. Tarsonemus abundance was strongly correlated with O. minus and an important driving force in promoting bluestain abundance within trees. Spring abundances of Tarsonemus and O. minus during D. frontalis infestation formation were strong predictors of beetle population decline later that year. The two mutualistic fungi associated with D. frontalis cycled seasonally but did not appear to influence beetle population dynamics.

Keywords: mutualism, antagonism, commensalism, bark beetle, Tarsonemus, Ophiostoma, Dendroctonus


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