EXPERIMENTAL INDUCTION AND TERMINATION OF NONRECIPROCAL REPRODUCTIVE INCOMPATIBILITIES IN A PARAHAPLOID MITE

Two experiments were conducted to investigate the relationship between rearing temperatures, the presence or absence of Wolbachia endosymbio nts, and non-reciprocal reproductive incompatibility in inbred lines o f the parahaploid phytoseiid mite Metaseiulus occidentalis (Nesbitt) ( Acari: Phytoseiidae). Heat-treated females crossed with infected males reared at room temperature produced few eggs and high proportions of shriveled eggs. No female progeny were produced. The reciprocal cross was normal. A second experiment showed that the incompatible cross fro m the first experiment could be made compatible if the infected line w as heat-treated and those males crossed with the original heat-treated females. Furthermore, a new incompatibility was induced in a formerly compatible cross when the newly heat-treated females were crossed wit h males from their base colony. Heat-treatment was correlated with the loss of Wolbachia in both experiments. Wolbachia may thus affect non- reciprocal reproductive incompatibility in M. occidentalis, and may pr oduce a unique incompatibility phenotype in this parahaploid species, including both reduced numbers of male progeny and a lack of female pr ogeny.