Effects of chlorpyriphos on the alpha amylase activity in the in vivo and in vitro conditions: Case study: Sitophilus oryzea

Abstract

Many species of insects case losses to the grains in the postharvest stage in the different crops. Chemical controls as practical approaches were used for several decades in the stored grain pest management. Certain risks were reported after using broad-spectrum insecticides on the environment and non-target organisms. Hence, new opportunities were open in the modern toxicology to improve selection and application process of insecticides in the economic agriculture. One of the significant challenges in the molecular toxicology is determining indirect targets of pesticides in the insect bodies. In this study, the effects of chlorpyriphos on the amylase enzyme activity were monitored in both in vitro and in vivo conditions. The first step, contact toxicity was tested, and LC50 was determined. There was a positive correlation between inhibitory effects with increasing concentrations. Results showed that Vmax and Km in the in vivo and in vitro experiment were 18.75; 38.65 and 68.03 109.3, respectively. There was a significant difference among toxicant concentration and the control, except in the lowest toxicant concentration. Inhibitory effects in the in vitro condition were more robust in comparison to in vivo. These data suggest that chlorpyriphos could affect alpha-amylase activity in the gut of rice weevil. It was proved that many targets in the insect body might be changed after treatment with this insecticide.