Abstract:

OBJECTIVE: To detect the acute oral toxicity/pathogenicity of trichoderma wettable powder (WP)，and to explore the application of PCR method in the pathogenicity of microbial pesticides.  METHODS：56 Wistar rats were randomly divided into a control group and exposed groups with 28 rats in each group and half male and half female. Trichoderma WP was selected as the test sample. The rats of exposure group were treated with 108 spores by gavage. Animals of control group were gavaged with normal saline. At the 1st，7th，14th and 21st day after exposure，stools were collected，then rats were sacrificed and the kidneys，liver，heart，and other organs were eviscerated. DNA of the tissue samples were extracted，then amplified with PCR. The symptoms of poisoning including mortality and body weight of animals were recorded. Dead animals were dissected and histopathological examination were performed. RESULTS： Only the amplification products of stools on the 1st day appeared positive but not on the 7th，14th and 21st days.  The amplification products of the remaining organs did not appear positive. No mortality was observed after exposure . In the histopathological examination no pathological changes were found. CONCLUSION： The trichoderma was found to exist only in the gastrointestinal tract，and was gradually excreted，It did not infect the animal’s tissues and organs，suggesting the test sample had no pathogenicity in rats.  PCR method could effectively detect the excretion of the test substance，with a good specificity which could be used as a detection method for oral toxicity/pathogenicity of microbial pesticide.

Key words: microbial pesticides, acute oral toxicity, pathogenicity, trichoderma