DESENVOLVIMENTO DE BIOINSUMOS PARA O CONTROLE DE INSETOS EM CULTIVOS DE ARROZ (O. sativa L.)

Abstract

The development of bioinputs represents a strategic and sustainable alternative for controlling insect pests in agricultural crops. Thus, the objective of this work was to develop natural formulations, including extracts of Azadirachta indica (neem), free lausone (from Lawsonia inermis) and complexed with magnesium ions, for the control of insect pests of stored grains. The methodology was structured in stages: diagnosis of the main rice pests; preparation of natural and treated plant extracts; synthesis and characterization of a magnesium-lausone coordination compound (Mg-bisla); preliminary toxicity testing on Artemia salina; and bioassays of insecticidal and repellent activity against Tribolium castaneum and Sitophilus zeamais. Analytical and spectroscopic characterization data indicate the formation of the Mg-bisla compound, which exhibits superior thermal stability to free lausone. Biological assays revealed that, although no significant mortality due to ingestion was observed in T. castaneum, fresh neem leaf powder showed a repellent effect, while treated neem and Mg-bisla exhibited attractive behavior. Free lausone showed significant repellency against T. castaneum. In contact tests, both lausone and Mg-bisla showed low efficacy in the mortality of S. zeamais (10%), being lower than commercial neem oil (30%). The reduced toxicity of Mg-bisla in A. salina suggests potential for safe application. In conclusion, the results demonstrate the selective potential of bioinputs in grain protection, reinforcing the importance of coordination chemistry as a tool for modulating biological properties.