Toxicological effects of the essential oil of Premna angolensis leaves used as a rice protector against Sitotroga cerealella (Lepidoptera: Gelechiideae)

Abstract

Cereals are increasingly attacked by Sitotroga cerealella, a highly destructive and economically important insect pest. The need to control this micro Lepidoptera to reduce its pressure on rice stocks is therefore acute. Today, the use of plant extracts, particularly essential oils, is a promising natural alternative to synthetic insecticides in the fight against crop pests. The objective of this study was to evaluate the acute oral toxicity of Premna angolensis in rats in order to propose an effective means of controlling S. cerealella in rice stocks without adversely affecting human health. The toxicity of this essential oil was assessed in male Wistar rats at a single dose of 2000mg/kg. The animals' behavior was observed for 14 days. The results showed that the lethal dose 50% (LD50) is strictly higher than 2000mg/Kg bw and that this extract does not influence the normal weight growth in the treated rats. Also, the evaluation of biochemical parameters of rats proved that P. angolensis essential oil is not toxic to the liver, kidneys and did not disturb lipid metabolism in rats at 2000mg/kg bw. Haematological analyses showed no significant difference from the control (p>0.05), however, the blood platelet count was significantly increased in treated rats compared to the control at the 5% threshold. Thus, essential oil treatments that could be applied at much lower doses to rice stocks could not be harmful to humans. It could therefore be used without risk by the rice industry to control S. cerealella.