Genetic modification of predator foraging traits enhances biological control of twospotted spider mites within experimental plantscapes

For augmentative biological control programs to be effective, natural enemies must be released in ways that suppress and maintain pests throughout the crop.  While inundative releases of predators, parasitoids or pathogens applied to the entire landscape may achieve this goal, it comes at a monetary cost to producers.  Decreasing the number and/or frequency of enemies released, and making releases at fixed points versus broadcast applications reduce costs; however, they may compromise efficacy if natural enemies do not maintain spatial coincidence with pests, thus allowing crop damage to occur. A potential solution is to genetically modify enemy foraging traits to enhance performance.  We present data suggesting that selecting the predatory mite Phytoseiulus persimilis for enhanced foraging may lead to better biological control of the twospotted spider mite Tetranychus urticae, on greenhouse crops, and that the type of foraging trait selected for is important when pests are distributed unevenly throughout the plantscape.