Efeito do extrato aquoso de plantas arbóreas em lagartas desfolhadoras

Abstract

Defoliating caterpillars are among the most concerning pests, as they affect various crops in Brazil, causing a loss of leaf area, which results in a decrease in photosynthetic activity and subsequently reduces the growth and development quality of the affected individual. In this context, plant extracts have emerged as a potential natural insecticidal agent, providing fewer residues to the environment and representing an efficient alternative, gaining even greater strength when integrated with Integrated Pest Management (MIP). In the present study, the insecticidal potential of tree plant extracts at a 30% concentration was evaluated. The extracts originated from the fruits of Magonia pubescens A. St.-Hil. (Sapindaceae) and Sapindus saponaria L. (Sapindaceae) and were tested on the fall armyworm, Spodoptera frugiperda Smith, 1797 (Lepidoptera: Noctuidae) at the third instar stage, maintained on an artificial diet in the laboratory and observed until they reached the juvenile phase. Four treatments were used, consisting of two plant extracts, one positive control (insecticide), and one negative control (water). Each treatment had four replicates with 20 individuals each, totaling 320 individuals observed. According to the evaluated parameters, the extract from M. pubescens influenced the larvae’s weight gain at 7 days and consequently affected the pupal weight. The duration of the developmental stages was not influenced by the extracts. The M. pubescens extract was the most effective, showing activity by affecting food consumption, resulting in lower weight at 7 days and, consequently, lower pupal weight. It also caused 32.5% mortality. The results may also have been influenced by the storage time of the extracts.