Use of artificial diet system to assess the potential bio-insecticide effect of a fungal lectin from Xerocomus chrysenteron (XCL) on Myzus persicae.

Lectins are carbohydrate binding proteins which are widely distributed in nature: they have been isolated from microorganisms, fungi, plants and animals. Many of these proteins were tested for their potential biocide effect on lot of pests. Indeed, lectins can cause dramatic changes in the cellular morphology and metabolism, particularly on the digestive system of insect having ingested them, by lectin binding to membrane glycosyl groups of the digestive tract cells. A fungal lectin, namely Xerocomus Chrysenteron lectin (XCL) was previously purified and was shown to be toxic to several pests including aphids. At the cell level, an increase in the endocytosis, the induction of morphological changes such as the actin cytoskeleton shape was determined. In this work, the recombinant XCL was produced and was tested for its potential aphicide effect on Myzus persicae, a polyphagous aphid found on more than 400 host plant species and transmitting more than 100 viral diseases. We developed bioassays using different artificial diets incorporating a broad range of XCL concentrations (from 10 microgx ml(-1) to lmg.ml(-1)) to assess the potential negative effects of XCL on the development and reproduction of the M. persicae aphid. Significant mortality rates, changes of developmental durations and nymph production were observed depending on the XCL concentration in the artificial diet. Concanavalin A lectin was also used in a new range of experiments to compare the effects of the two lectins on the aphid biological parameters. According to the observed dose responses toward the XCL and Con-A lectins included in the artificial diet and the action mode of this kind of proteins, the perspectives of lectin use in pest control will be discussed.