Abstract/Summary

With the continued growth in the use of Phytoseiidae mites as Acaraine Biological Control Agents (ASAs), I have aimed to assess the cytogenetics, reproductive systems and endosymbionts of three economically important mites, namely Phytoseiulus persimilis (Athias-Henriot, 1957), Neoseiulus (= Amblyseius) cucumeris (Oudemans 1930), and Typhlodromips (= Amblyseius) swirskii (Athias-Henriot, 1962), with an aim to better understand the biology of these three mite species. Screening by means of PCR to give an indication of the endosymbiotic fauna of these mites allowed for further experiments using novel techniques, allowing us to better understand the roles and interactions of endosymbionts in these mites. However, with conflicting interpretations in the data for the presence of endosymbionts in Phytoseiidae mites -their integrity as a true endosymbiont as opposed to being simple a gut contaminant proved inconclusive. I use a novel approach in these species - Fluorescent In Situ Hybridisation (FISH) -in order to further assess the presence, as well as the location of endosymbionts (Wolbachia) in these mass reared mite species. The mites in question here also follow a genetic system whereby all offspring require fertilization, and begin embryogenesis as diploids. Whereas the females remain diploid, the males become haploid throughout this process -known as pseudoarrhenotoky or parahaploidy. This project aims to give a better understanding ofthe parahaploid nature of these mites, investigating the cytogenetics using eggs of the three species in question and also investigating the relationships between endosymbionts and haplodiploidy.