Host-virus and virus-virus interactions in broad host range alphabaculoviruses: implications for the development of virus-based insecticides
This thesis examined the insecticidal potential of the broad host range baculovirus Mamestra brassicae multiple nucleopolyhedrovirus (MbMNPV), and this interaction with Helicoverpa armigera multiple nucleopolyhedrovirus (HaMNPV) during the coinfection of a shared host. The results provide greater understanding of host-virus and virus-virus interactions in broad host range alphabaculoviruses that should help define effective strategies for pest control in field and greenhouse crops. First, the insecticidal activity and stability of the two closely related alphabaculovirus isolates, HearMNPV and MbMNPV derived from the commercial bioinsecticide Mamestrin®, were evaluated in a permissive (Spodoptera exigua) and a semi-permissive host (Spodoptera littoralis). The genetic structure of MbMNPV derived from the biological insecticideMamestrin® was then studied with the aim of assessing the insecticide properties of the genotypic variants comprised this wild-type isolate. Finally, interactions between two phylogenetically closely related viruses during coinfection of a shared host were analysed. In conclusion, the results obtained in this thesis contribute to a better understanding of the interactions between viruses and their hosts, which can contribute to the development of baculovirus-based insecticides and to design of effective strategies for the control of lepidopteran pest complexes.