Inseticida de extrato de sementes de Annona squamosa sobre Chrysodeixis includens

Abstract

The constant and excessive use of pesticides has been causing a major environmental aggravating factor. The use of pesticides is often essential in certain situations in plant production and crop management. However, the effects of these substances on the environment have been negatively interfering with human health, the environment and the entire natural cycle of ecosystems. Based on this problem, the search for alternative control methods to prevent agricultural pests’ development becomes an essential issue for reconciling agricultural efficiency and sustainable development. Promising reports on the use of plant extracts to control agricultural pests have been reported. The custard apple (Annona squamosa) is a promising plant for acting as an insecticide. The objective of this work was to carry out the plant extract of custard apple seed for the investigation of the insecticide effect on one of the main agricultural pests, the false-medideira caterpillar (Chrysodeixis includens), and the analysis of toxicological effects on a non-target aquatic organism. For the investigation and comparison of the insecticidal and toxicological effects, both experiments will be carried out with the vegetal extract of the seeds of custard apple and the biological bioinsecticide Dipel®. Ingestion bioassays were carried out to verify the insecticidal action of the extract on the false-medideira caterpillar. The insects were exposed to dosages of 0.25, 0.5, 1.0, 1.5, 2.0, 2.5, 3.0, 3.5, 4.0, 4.5, 5.0, 7.5 and 10.0 g/L for the extract, and 0.5 g/L for the Dipel®. To quantify the dosages, a spray volume of 100 L/ha was considered. The evaluation of toxicological effects in a nontarget organism was carried out using the zebrafish (Danio rerio) as an experimental model. The fish was exposed to different dosages of extract (0.84, 1.68, 2.52, 3.36 and 16.80 μg/L) and to the bioinsecticide Dipel® (16.80 μg/L). At the end of 120 h of exposure, the fish was anesthetized and euthanized for the collection of biological tissues of interest and subsequent biochemical analysis, namely: acetylcholinesterase (AchE), glutathione-S-transferase (GST), lipid peroxidation (PLO), and protein carbonyl (PC). The change in the levels of these analyses allowed the verification of oxidative damage in fish. The results of this work indicate the insecticidal action of the seed extract of custard apple against the false-medideira caterpillar, and the analysis of the different treatments showed that the extract at a dosage of 1 g/L does not differ statistically from the higher concentrations and also the Dipel® treatment. Based on the biomarkers of exposure to contaminants (PLO, PC, GST, and AchE), the occurrence of toxicological effects and consequent oxidative damage to fish was evidenced. Considering the same concentration of product (16.8 μg/L), treatment with the bioinsecticide Dipel® showed higher changes in biomarkers, indicating the occurrence of higher oxidative damage when compared to the extract of custard apple seeds.