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Summary: POPULATION ECOLOGY
Seasonal Dynamics of Mites and Fungi and Their Interaction with
Southern Pine Beetle
RICHARD W. HOFSTETTER,1, 2
KIER D. KLEPZIG,3
JOHN C. MOSER,3
AND MATTHEW P. AYRES4
Environ. Entomol. 35(1): 22Ð30 (2006)
ABSTRACT We evaluated whether Dendroctonus frontalis Zimmermann populations were inßu-
enced by nontrophic interactions involving commensal mites, their mutualistic bluestain fungus
Ophiostoma minus (Hedgc.) H. and P. Sydow, and beetle-mutualistic mycangial fungi. We tested for
effects of delayed, nonlinear, or positive feedback from O. minus and mites on D. frontalis population
growth. We predicted that (1) high mite densities have demographic consequences for beetles by
inßuencing the prevalence of O. minus and antagonistic interactions between O. minus and mycangial
fungi,and(2)inter-relationsandabundancesofmitesandfungidifferentiallyvarythroughouttheyear
in a seasonally variable climate. Surveys of D. frontalis populations revealed that temporal and spatial
patterns in abundance of mites and their mutualistic fungus, O. minus were inversely related with
beetle population growth. Negative demographic effects of O. minus on D. frontalis were nonlinear,
only affecting beetle per capita reproduction when fungi colonized 35% of phloem habitat. Mite
abundance was strongly correlated with O. minus and was an important driving force in promoting
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