Heteromorphic deutonymph sex of the solitary bee parasite, <italic>Chaetodactylus krombeini</italic> (Baker) (Astigmata: Chaetodactylidae)

<italic>Chaetodactylus krombeini</italic> (Acariformes: Astigmata: Chaetodactylidae) mites are kleptoparasites of solitary bees in the genus <italic>Osmia</italic> and depend on bee hosts for harbourage, nutrition, and dispersal, with infestations increasing morbidity and larval mortality. The life history traits of <italic>C. krombeini</italic> are unclear, complicating the control efforts of mites in managed bee nests. Mites in the family Chaetodactylidae have a facultative life stage, the heteromorphic deutonymph, used for either dispersal or dormancy when food resources are sparse. The heteromorphic deutonymph life stage is hypothesized to consist only of females, requiring arrhenotokous parthenogenesis to reproduce. This study examined this hypothesis by determining the sex of the adults that developed from each deutonymph morph. Phoretic deutonymphs were isolated after overwintering either with or without a bee host; inert deutonymphs were isolated from field collections from various locations. Mites were individually observed for 14 days, and development was recorded. Mites that reached adulthood were sexed. After 14 days, 32–38% of heteromorphic deutonymphs that reached adulthood were male. These results disprove the previous hypothesis that heteromorphic deutonymphs are exclusively female. The survival and reproductive strategies of <italic>C. krombeini</italic> are now in question, specifically the role of true arrhenotoky in founding new mite populations. [ABSTRACT FROM AUTHOR]