Potencial bioinseticida de sementes de Ziziphus joazeiro MART. contra a praga de armazenamento Callosobruchus maculatus

Abstract

The Callosobruchus maculatus (Coleoptera: Bruchidae) is the most destructive pest of the cowpea beans (Vigna unguiculata). The conventional pest control is based on the use of insecticides and pesticides, however, the exposure of rural workers to pesticides are reported to cause various diseases and are also not environmentally friendly. Due to this, is important studies for the detection and characterization of new bioactive molecules safer for human and environmental health. Bioactive molecules from plants, including bioactive proteins, can be considered possible alternatives to the use of pesticides to control insect pests. Ziziphus joazeiro (Rhamnaceae) is a tropical tree, usually found in the caatinga northeastern part of Brazil, resistant to dry conditions and widely used as a medicinal plant. This study aimed to evaluate the bioactive compounds properties of meal, protein extract and fractions obtained by sequential precipitation of proteins with ammonium sulfate from the seeds of Z.joazeiro on the development of the bruchid. We performed bioassays in a system of artificial seeds incorporating the flour, total extract and the protein fractions of the seeds of Z. joazeiro for monitoring development parameters such as: oviposition, weight, larval survival and adult emergence of insect C. maculatus. Incorporation of the seed extracts into the insect diet showed Z. Joazeiro seed meal promoted a decrease in oviposition of females from the 2% concentration, where no oviposition occurred in 5% and 10%, the seeds containing the F2 and F3 fractions showed no significant decrease in oviposition. As for the weight parameter of the larva, a reduction of 50% was observed at the concentration of 0.1% in the seeds with the flour, EB and F3 and in the concentration 0.4% of the F2 fraction. A reduce in larval survival was considerably higher from 1.6% in all samples tested, with no live larvae being detected in the following concentrations of flour, in addition to increasing the development time of adult insects. We evaluated the presence of inhibitors of digestive proteases in EB and fractions and found inhibition for serine and cysteine proteases that may be related to alterations in the development of bruquídeo. These results demonstrate that Z. Joazeiro is a promising source of bioactive proteins with potential for biotechnology in the control of insect pests.