Dutch elm disease (DED) is a destructive vascular wilt disease of elm (Ulmus) trees caused by the introduced Ascomycete fungus Ophiostoma novo-ulmi. In Europe, this DED pathogen is transmitted by elm bark beetles in the genus Scolytus. These insects carry phoretic mites to new, suitable habitats. The aim of this study was to record and quantify conidia and ascospores of O. novo-ulmi on phoretic mites on the three elm bark beetle species Scolytus multistriatus, Scolytus pygmaeus, and Scolytus scolytus. Spores of O. novo-ulmi were found on four of the ten mite species phoretic on Scolytus spp. These included Elattoma fraxini, Proctolaelaps scolyti, Pseudotarsonemoides eccoptogasteri, and Tarsonemus crassus. All four species had spores attached externally to their body surfaces. However, T. crassus carried most spores within its sporothecae, two paired pocket-like structures adapted for fungal transmission. Individuals of Pr. scolyti also had O. novo-ulmi conidia and ascospores frequently in their digestive system, where they may remain viable. While E. fraxini and P. eccoptogasteri rarely had spores attached to their bodies, large portions of Pr. scolyti and T. crassus carried significant numbers of conidia and/or ascospores of O. novo-ulmi. P. scolyti and T. crassus, which likely are fungivores, may thus contribute to the transmission of O. novo-ulmi, by increasing the spore loads of individual Scolytus beetles during their maturation feeding on twigs of healthy elm trees, enhancing the chance for successful infection with the pathogen. Only S. scolytus, which is the most efficient vector of O. novo-ulmi in Europe, carried high numbers of Pr. scolyti and T. crassus, in contrast to S. multistriatus and S. pygmaeus, which are known as less efficient vectors. The high efficiency of S. scolytus in spreading Dutch elm disease may be partly due to its association with these two mites and the hyperphoretic spores of O. novo-ulmi they carry.

The species composition and abundance of phoretic mites of the bark beetle Pityokteines curvidens caught in pheromone traps were investigated in Croatia. The P. curvidens trapping programs have been in an experimental phase in Croatia since 2004 as a possible monitoring and control system. The trapping program also permits the opportunity to sample phoretic mites found associated with the beetles. Beetles were caught using Curviwit pheromones in Theysohn traps placed in the Litorić region of Croatia. A total of 12 mite species were recovered, including Schizostethus simulatrix, Dendrolaelaps quadrisetus, Histiostoma piceae, H. cf. varia, Paraleius leontonychus, Pleuronectocelaeno barbara, Tarsonemus minimax, Trichouropoda lamellosa, Uroobovella ipidis, Schwiebea sp., Phauloppia lucorum and Dolicheremaeus dorni. Five species, Pl. barbara, Schwiebea sp., H. cf. varia, Ph. lucorum and Do. dorni, are identified for the first time in association with P. curvidens. These findings increase the number of mite species known to be phoretic on P. curvidens from 11 to 16. The present study also increases the number of known mite associates of Pityokteines spp. from 14 to 18.

More than 4,665 phoretic arthropods comprising 29 species were collected from alates of the red imported fire ant, Solenopsis invicta Buren, preparing to fly from nests in Pineville, LA. A wide variety of taxonomic groups were represented, including two insect and 17 mite families. Most arthropods fell into two classes: 1) those that may be truly phoretic with more than four specimens collected (13 species) and 2) those seeming to be accidentally phoretic with one to three specimens collected (16 species). The latter group may be the result of gathering “accidental” mites from adjacent sources, such as grass, soil, tree bark; thus, practically any very small arthropod may use phoresy as a dispersal mechanism. The arthropod with perhaps the highest total numbers was Cyphoderus similis Folsom, a wingless insect, and the only known Collembola phoretic species. Eight new species of mites found in this study were recently described, with several other species future candidates for descriptions. Results indicate the more common species may actively persist in nests for the entire year. At least 11 species from six families may feed on fungi within nests. These and common associates from other families carry hyperphoretic spores of fungi that live inside fire ant nests. All three of the laelapid associates may be important predators or parasitoids of individuals within the nests. The collembolan is possibly a general feeder, and Histiostoma spp. are filter feeders that consume microorganisms. S. invicta is native to Argentina, and we speculate that some of the common mites associated with this ant species also may have originated in Argentina.

Samples of bark and logs damaged by bark beetles were collected from 16 states of Mexico from 2007 to 2012. Fifteen bark beetle species were found within the bark and log samples and were examined for phoretic mites and arthropod associates. Thirty-three species of mesostigmatid mites were discovered within the samples. They were identified in several trophic guilds based on the mites' feeding habits if known. Over half of the 33 mite species were found to be predators feeding on arthropods or nematodes, with the most voracious mites in this study being Dendrolaelaps quadrisetus, Hypoaspis (Cosmolaelaps) vacua, Macrocheles boudreauxi, Proctolaelaps dendroctoni, and Schiztothetus lyriformis.