Submitted to: Environmental Entomology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/11/2000
Publication Date: 10/1/2000
Citation: MCGUIRE, M.R., BEHLE, R.W., GOEBEL, H.N., FRY, T.C. CALIBRATION OF A SUNLIGHT SIMULATOR FOR DETERMINING SOLAR STABILITY OF BACILLUS THURINGIENSIS AND ANAGRAPHA FALCIFERA NUCLEAR POLYHEDROVIRUS. ENVIRONMENTAL ENTOMOLOGY. 2000. v. 29(5). p. 1070-1074. Interpretive Summary: Control of insect pests has long been accomplished by the use of chemical pesticides. Recently, political and consumer-driven changes have necessitated a search for alternatives to chemical pesticides. Microbial pesticides, based on diseases that affect only insects, have achieved some success in the marketplace. However, sunlight can limit the effectiveness of microbial pesticides. The availability of machines that produce light close in spectrum and intensity to sunlight have allowed year round testing of materials that might be effective in protecting microbial pesticides from light. These machines must be calibrated to determine if the light they generate affect microbial pesticides in a manner similar to sunlight. A bacterium and a virus were subjected to both sunlight and simulated light. We found that the two light sources were virtually identical when total energy of exposure was used as a measuring stick for loss of insecticidal activity. These results, of use to other scientists working in similar areas and to companies manufacturing microbial pesticides, suggest that solar simulators can be an effective and accurate research tool.
Technical Abstract: The effect of light on survival of entomopathogens is well described, and efforts are underway to develop formulations that may protect an entomopathogen from damage by sunlight. The availability of solar simulators allows for year round testing of solar protectants. Bacillus thuringiensis and a baculovirus isolated from Anagrapha falcifera were exposed to various amounts of light from a solar simulator or the sun to determine the relative effect of each source on loss of insecticidal activity. Rate of pathogen degradation was essentially the same for both light sources when total energy (as measured by joules/m2) was regressed against original activity remaining. The amount of time required to reduce activity was different, however, due to a difference in total energies produced by the solar simulator and natural sunlight. Virus was approximately two times more sensitive to light than bacteria. The importance of reporting energy levels from various solar simulators is discussed.