Risk assessment, fitness and field release of a transgenic entomopathogenic nematode

Entomopathogenic nematodes can be used as biological control agents that are particularly suited for controlling soil pests. One problem with current commercial formulations is a lack of tolerance to brief exposures to high temperatures that often occur during product distribution. This can result in death of the nematodes and a loss of product efficacy. To counter this, a strain of Heterorhabditis bacteriophora was genetically engineered by the addition of the heat shock protein gene (hsp70A) from the free-living nematode Caenorhabditis elegans. Prior to field release of the nematode we performed laboratory experiments to compare the physiological fitness of the transformed nematode with the wild-type. The transformed nematode was not different from the wild-type in terms of infectivity, reproductive capacity and survival at 16, 25, 30 or 37degreesC, nor were there any detectable differences in the virulence to a range of invertebrates or to mice. Three enclosed field releases were to monitor the persistence of wild-type and transformed nematodes in the environment. There were no significant differences in persistence between the two nematode types.