Recombinant viral insecticides: Delivery of environmentally safe and cost-effective products

Biological control agents such as baculovirus insecticides have many attributes which make them attractive alternatives to synthetic chemical pesticides. However, there have been several economic and agronomic barriers to their widespread use. Among the obstacles to commercialization of viral insecticides have been high production costs, the lack of efficacious formulation and application technologies, and a slow speed of action. Biotechnology has contributed several advances toward overcoming these obstacles. The high cost ofin vivo production can be reduced significantly using a newly developed high-density rearing system termed HeRD. The HeRD technology can be used to rear many different species of lepidopterous larvae for production of viral insecticides, as hosts for parasitoid production, or for sterile-male release programs. Using this technology, the baculovirus production costs are equivalent to sprayable Bt toxins. The field efficacy of viral pesticides and other biological control agents requires cost effective, biologically based formulation and application technologies. Based on current field efficacy evaluations of baculovirus pesticides, formulation/application technologies must be improved for viral pesticides to compete effectively and consistently in most pesticide markets. Through recombinant DNA technology, it is now possible to insert foreign pesticidal genes into viral pesticides, resulting in faster time to death or, more importantly, time to cessation of feeding of the target pests. However, the commercial use of recombinant pesticides has raised several potential environmental issues, including possible effects on non-target organisms, ecological interactions, mitigation and genetic stability. Genetic strategies have been developed to mitigate most of the potential problems associated with recombinant baculovirus pesticides. Five field tests have been conducted in the U.S. to evaluate these strategies. The laboratory and field results illustrate that the genetic strategies employed ensure environmental safety while also reducing production costs.