Mites Phoretic on Ips pini (Coleoptera: Curculionidae: Scolytinae) in Wisconsin Red Pine Stands

We sampled the bark beetle Ips pini (Say) in Wisconsin red pine stands to describe its phoretic mite community. Nearly 78% of adult beetles carried phoretic mites, with an average of 12.78 +/- 0.76 individuals and 1.69 +/- 0.05 species per beetle. Phoretic mites from flying beetles represented over 13 families. Five species of mites showed relatively close associations, being present on at least 10% of adult beetles. The most common mite species included one from each of the major guilds on bark beetles, the scavenger/fungivore Histiostoma spp. (41.5% of beetles), the egg predator Iponemus confusus (Lindquist)(41.1% of beetles) and the nematode predator Dendrolaelaps quadrisetus (Berlese) (32.8% of beetles). Beetles in northern Wisconsin had more diverse phoretic mite communities than those in central or southern Wisconsin. Beetles collected late in the season (July-August) carried more individuals and species of mites than those collected early in the season (May-June). The method we used to collect live bark beetles may be useful for other studies requiring fine-scale quantification of symbionts, such as bacteria, fungi, and nematodes.