Effects of a Lectin from Polygonum Persicaria L. on Pieris Brassicae L. (Lepidoptera: Pieridae)

In the current study, the entomotoxic effects of a lectin, extracted from Polygonum persicaria, were determined on Pieris brassicae larvae. The purified molecule significantly decreased larval survival, weight, and mass protein. Different concentrations of P. persicaria agglutinin (PPA) (0.5, 1 and 2 mg/ml) significantly decreased nutritional indices including: the efficiency of conversion of ingested food (ECI), the efficiency of conversion of digested food (ECD), and approximate digestibility (AD) in a dose-dependent manner. There was a significant decrease in larval α-amylase activity after larval fed on PPA. The decreased activity was found in both the biochemical assessment and gel electrophoresis; sharpness of one isozyme decreased and another completely disappeared. Meanwhile, PPA significantly decreased activities of glucosidases mainly β-glucosidase. Fed of P. brassicae larvae on different concentrations of PPA, significantly decreased activity of TAG-lipase in both the biochemical assessment and gel electrophoresis. It was found that alkaline phosphatase (ALP) and acid phosphatase (ACP) were also affected by PPA but concentrations of 1 and 2 mg/ml showed statistical differences compared to the control. General and specific proteolytic activities statistically decreased after larvae fed on different concentrations of PPA. Results of our study could bring attention to this molecule, showing it to be a safe and efficient control of the pest worldwide.