Ontogeny, life history and sex ratio evolution in Ensliniella kostylevi (Acari: Winterschmidtiidae)



The nest-inhabiting ontogenetic stages of the mite Ensliniella kostylevi Zakhvatkin, 1941, an associate of the eumenine vespid Allodynerus rossii (Lepeletier, 1841), are described, with a redescription of the phoretic deutonymph. Observations on the life history of E. kostylevi show the presence of male dimorphism and a very high degree of correlation in developmental timing of the mites and their hosts. This life history is compared to that of related species, with an emphasis on the variously biased sex ratios observed among the oviparously produced adults. The extent of this bias is hypothesized to be directly related to the number of founders in each wasp cell, a number which, in turn, is largely determined by morphological and behavioural characteristics of the hosts.