Indutores de resistência e interação silício-inseticida sistémico no controle de Schizaphis graminum (Rond.) (Hemiptera: Aphididae) em trigo

Abstract

The greenbug Schizaphis graminum (Rond.) (Hemiptera: Aphididae) is one of the main pest insects of wheat crop, its being capable of death plants by sap suction and toxin injection, in addition to transmitting viruses. A tactics recommended to the management of aphids on wheat is the use of selective insecticides, mainly in seed treatment, besides, studies with plants resistance inducers to insects, such as Acibenzolar-S-Methyl and silicon are promising. The objectives in this research were the evaluation of the feeding behavior of S. graminum on wheat plants treated with silicon, ASM and imidacloprid, in addition to the evaluation of some biological features of the insect. Two experiments were conducted, in the Entomology Department of the UFLA, Lavras, on wheat, cultivate Embrapa 22 and S. graminum. In the first experiment, the treatments were distributed in factorial scheme 2 (with silicon and without silicon) x 2 (with ASM and without ASM) and in the second 2 (with silicon and without silicon) x 2 (with imidacloprid and without imidacloprid). So, biology and honeydew excretion assays with 10 replicates each and EPG (Electrical Penetration Graphs) with 25 replicates were use in both experiments. In general, the application of resistance inducers (silicon and/or ASM) increase wheat plants resistance to greenbug, affecting its biology and feeding behavior. However, the cause of resistance associated with silicon is not related to the formation of barrier which prevents the penetration of greenbugs´ stylets into the leaf tissues. It was found also that the systemic insecticide imidacloprid acts as a deterrent on adults and it is lethal in nymphs of S. graminum till 45 days after seed treatment.