Alternative technologies for insect pest control are becoming increasingly important as a result of increasing insecticide resistance in the cotton pest Helicoverpa armigera the move towards ecologically sustainable agriculture. Two biotechnological approaches under investigation are insect resistant transgenic crops and insect viruses engineered for increased speed of kin. An important limiting factor for both approaches is the availability of efficacious insecticidal insert genes that can be inserted into the crop or virus. Juvenile hormone esterase (JHE) is an attractive candidate, especially for transgenic insect viruses. JHE acts to control juvenile hormone and hence is a key controller of metamorphosis and maturation of reproductive tissues in a range of invertebrates. A form of JHE specific for Iepidopterans has already been isolated and engineered into an insect virus, demonstrating insecticidal properties against Helicoverpa species. Infection of Iepidopteran larvae with a baculovirus engineered to produce a large increase in JHE causes a reduction in juvenile hormone level, leading to aberrant moults and the end of feeding behaviour. Here we describe a project that aims to isolate a more versatile JHE, which should be effective against a range of chewing and sucking pests.