Insecticidal Activity of Pea Albumin 1b Homologous against Granary Weevil (Sitophilus granarius L.)

Abstract

The aim of this study was to evaluate the toxicity of pea albumin 1 subunit b (PA1b) homologous against granary weevil (Sitophilus granarius L.). Adults of less than 5 days were maintained at 27±0.2°C and 70±5% relative humidity, on bread wheat (Triticum aestivum L. subsp. Aestivum) flour dumplings (control) and on pea flour, chickpea, bean, lentil, broad bean (toxic) during 15 days. The concentrations of used pea flour were 10, 20, 40, 60 and 80%. On PA1b reference: Pea/wheat with 80% pea flour, we have observed on the 3rd day, a mortality rate over 10%. From 7 days there were no survivors. For concentrations of 40 and 60%, the mortality rate was 73 and 93%, respectively; but at 10 and 20% of pea, the rate was low not exceeding the 20% threshold. A significantly positive correlation (R 2 = 0.91) was observed between the concentration of pea flour extract and the mortality rate of Sitophilus granarius L. The linear regression of semi-logarithmic curve is highly significant (p = 0.012, <0.05) and allow to determine the LD 50 of which is 25.63±3.26% or 64.075±8.14 mg. At the maximum concentration of 80% on lentil, bean and broad bean, there was a total mortality of the insect at 7 days; others are less toxic such as pea with 30% and chickpea, whose mortality rate does not exceed the 23% threshold. Furthermore, complete mortality of the insect was observed after 14 days in all grain legumes.