A standardized method for rearing Rhizoglyphus robini (Astigmata: Acaridae)

Abstract

Rhizoglyphus robini Claparede (Acari: Astigmata: Acaridae) is a mite infesting crop such as saffron corms, onions, garlic, leeks and lilies. Bulb mites were observed associated with diseased saffron corms in Vermont research sites, confirming their pest status in New England. To assess the efficacy of different IPM and biological controls a standard method to rear bulb mites in the laboratory was essential. This study focused on developing an efficient laboratory medium to rear R. robini. Bulb mites were extracted from infected saffron corms in Vermont (USDA plant-hardiness zone 5a [− 20° to − 15 °F]). A bulb mite culture was first established on potato dextrose agar (PDA) medium with an average moisture content of 67% at the Entomology Research Laboratory, University of Vermont. Bulb mite species identification and R. robini separation were done, and bulb mites were incubated in a dark chamber at 25 °C. While establishing the R. robini laboratory culture, contamination of microbial disease restricted populations. Experiments were conducted to determine the most suitable growth medium that supported bulb mite population and minimized microbial disease. Three treatments were tested: 1. antibiotics (chloramphenicol) + fungicide (dodine) + PDA, 2. antibiotics + PDA and 3. PDA only. The results showed significantly (P ≤ 0.05) larger populations of R. robini in Petri dishes containing PDA with antibiotics compared to other treatments. The greatest number of bulb mites was observed 14 to 20 days after introduction on the growth media.