Acute and chronic insecticidal activity of a new mannose-binding lectin from Allium porrum against Acyrthosiphon pisum via an artificial diet

In view of the increasing use of plant proteins as valuable alternatives to chemical insecticides, the Susceptibility of pea aphids, acyrthosiphon pisitin (Harris) (Hemiptera: Aphididae), to three purified mannose-binding plant lectins was determined in an artificial-diet bioassay. The insecticidal activities of a new lectin, APA (Allium porrum L. (Liliaceae) agglutinin) from garden leek, were compared with those of GNA (Galanthus nivalis L. (Liliaceac) agglutinin) from snowdrop and ASA (Allium sativum L. agglutinin) from cultivated garlic. GNA and ASA showed acute toxicity to first-instar nymphs; LC50 values for GNA and ASA were 350 and 700 mu g/mL, respectively. With APA, mortality was scored only at high doses. In chronic experiments, however, lower closes significantly reduced survival and fecundity of adults (P < 0.05). Aphids fed a diet containing APA at 100, 500, and 750 pg/mL showed a significant delay in reaching adulthood and no aphids survived beyond 19 days of development. The data support the potential application of APA in the integrated management of insect pests