Incidence of Caloglyphus phyllophagianus (Acari: Acaridae) on Adult Phyllophaga spp. and Other Scarabaeidae (Coleoptera) in North Central Texas

Abstract

Sixteen species of adult scarabs collected over 3 yr in ultraviolet light traps in Dallas County, Tex., had widely varying levels of infestation with a nonfeeding larval stage (heteromorphic deutonymph) of Caloglyphus phyllophagianus Oseto & Mayo. The beetles were the geotrupines Bolbocerosoma confusum Brown and B. pusillum Dawson & McCulloch; the dynastines Cyclocephala lurida Bland, Dyscinetus morator (F.), and Euetheola rugiceps (LeConte); the hybosorine Hybosorus illigeri Reiche; the ruteline Pelidnota punctata L.; the melolonthines Phyllophaga affabilis (Horn), P. congrua (LeConte), P. crassissima (Blanchard), P. crinita Burmeister, P. glabricula (LeConte), P. hirtiventris (Horn), P. rubiginosa (LeConte), and P. torta (LeConte); and the trogine Omorgus suberosus (F.). The distributions of deutonymphs were compared with eight theoretical distributions. In total, 8 of 23 data sets based on beetle species, sex, and year fit the negative binomial distribution; one set fit the positive binomial distribution; and one set fit the Neyman type A distribution. Also, 13 data sets fit none of the distributions, but variability in the entire range of data was described using Taylor's power law. Infestation rates ranged from zero ( Bolbocerosoma spp., D. morator , and E. rugiceps ) to 85.0% ( P. glabricula ). The highest mean mite density was 25.4 mites per beetle (maximum, 300 mites) on P. torta . Mite densities on some host species were influenced by host sex, year, and date. The relative ranking of beetle species as hosts tended to be consistent from year to year. Host size was only weakly correlated with mite density, and synchronously-reproducing host species that share habitats had widely varied levels of infestation. These facts suggest that some species may be inherently more preferred by the mites.