Summary: OIKOS 102: 243252, 2003
Strong indirect interactions of Tarsonemus mites (Acarina:
Tarsonemidae) and Dendroctonus frontalis (Coleoptera:
MariŽa J. Lombardero, Matthew P. Ayres, Richard W. Hofstetter, John C. Moser and Kier D. Lepzig
Lombardero, M. J., Ayres, M. P., Hofstetter, R. W., Moser, J. C. and Lepzig, K. D.
2003. Strong indirect interactions of Tarsonemus mites (Acarina: Tarsonemidae) and
Dendroctonus frontalis (Coleoptera: Scolytidae). Oikos 102: 243252.
Phoretic mites of bark beetles are classic examples of commensal ectosymbionts.
However, many such mites appear to have mutualisms with fungi that could
themselves interact with beetles. We tested for indirect effects of phoretic mites on
Dendroctonus frontalis, which attacks and kills pine trees in North America. Tarson-
emus mites are known to carry ascospores of Ophiostoma minus, which tends to
outcompete the mutualistic fungi carried by D. frontalis. Experimental additions and
removals of mites from beetles demonstrated that Tarsonemus propagate O. minus in
beetle oviposition galleries. Furthermore, the abundance of Tarsonemus and O. minus
tended to covary in nature. These results verified a strong mutualism between
Tarsonemus and O. minus. Results also indicated that O. minus is an antagonist of D.
frontalis: beetle larvae seldom survived in the presence of O. minus (compared to 83%
survival elsewhere). Apparently, this is an indirect result of O. minus outcompeting