Acute, subacute and dermal toxicology of the bioinsecticide from Stemona curtisii Hook. F.

Abstract

A formulation of bioinsecticide from Stemona curtisii Hook. F. (Family Stemonaceae) marketed in Thailand as Biopes, is used in agriculture by the farmers in the northern area of Thailand. Consequently, insecticide used for insect control is common and may lead to pesticide toxicity to the consumers as well as to the farmers. The aim of the present study is to evaluate the safety of Biopes (containing 20% W/W of Stemona crude extract) to mammals. Safety assessments included an acute oral toxicity test [1] and a repeated dose 90-days oral toxicity test [2] in Wistar rats, and acute dermal irritation test [3] in guinea pigs. In acute oral toxicity test, the marketed Biopes product showed lethal effect with the LD50 of 1,078.95 and 630.96mg/kg body weight in male and female rats, respectively. In the 90-days oral toxicity test at the dose of 80 and 140mg/kg body weight (50 and 100 folds to the concentration used in agriculture), there were minimal but significant differences in body weight gain, some values of hematology, blood biochemical indices, and organ weights between control and treated groups. The histopathology findings indicate small toxic effects of Biopes to gastrointestinal tract, lung and liver of the treated rats. In dermal irritation test, the direct exposure to non-diluted Biopes caused irritation on the skin, and might be harmful to the users. However, although the diluted solution of Biopes at the concentration used in agriculture can cause the dermal irritation, but it was slight and improved within the short period. All the above results demonstrated that Biopes has low toxicity and low dermal irritation to laboratory mammals and therefore could be regarded as safe for use as an insecticide.