Understanding how insects interact with their pathogens not only contributes to fundamental knowledge about how communities function but also allow us to design more effective biological control programmes using insect pathogens and to make more accurate predictions about the risk of releasing genetically modified biopesticides. Particular emphasis is being placed on how host plants may influence virus population dynamics. Virus yields are always highest on insects infected on oak. This was confirmed by transmission experiments in the field which demonstrated that there were strong differences in the resulting mortality of larvae reared on different host plants. Studies of this kind are beginning to demonstrate the complexity of the interaction between pathogens and insects and are helping us to unravel the role that pathogens play in insect population dynamics and the development of community structure.
Ticks are blood-feeding ectoparasites that transmit a wide range of pathogens.
Such tick-borne pathogens include viruses that cause disease in humans and other animals. Scientists at CEH Oxford showed that these partially fed ticks present an increased threat as they transmit virus infections more efficiently. Initial experiments demonstrated that when infected ticks fed on susceptible hosts, the animals died from the tick transmitted infection before the ticks had completed feeding. When these partially fed infected ticks infested new hosts, they transmitted the virus infection more rapidly than unfed infected ticks. One infected tick was able to transmit the virus to three different hosts before it completed engorgement.