Bioefficacy of extracts, fractions and tannins obtained from Magonia pubescens St. Hill. (Sapindaceae) in the control of Sitophilus zeamais (Coleoptera: Curculionidae)

Abstract

Introduction: The knowledge of natural substances as an ecological alternative for pest control is necessary, as long as bioinsecticides are effective, minimally toxic or even non-toxic to humans, and also biodegradable. Objectives: To evaluate the insecticidal potential of extracts, fractions, and tannins obtained from the bark and seeds of Magonia pubescens St. Hil. on Sitophilus zeamais. Methodology: The fruits of M. pubescens were collected, dried in a greenhouse, and subsequently crushed and separately macerated in ethanol for 10 days, with part of the material used to obtain tannins. After obtaining the ethanolic solution from the bark and seeds of the fruits, it was concentrated in a rotary evaporator, yielding the ethanolic extract, which was subjected to partitioning, providing aqueous and organic fractions. The extracts, fractions, and tannins were used in ingestion and contact bioassays. Results: The data do not indicate the bioinsecticidal potential of extracts and fractions from the bark and seeds of M. pubescens on S. zeamais, considering the concentrations used. However, the ingestion bioassay with tannins obtained from the seeds showed 67.5% and 70.0% mortality at concentrations of 0.5% and 1.0%, respectively. Conclusion: The study highlights the need for further research on the insecticidal potential of M. pubescens on S. zeamais and other plant parts, aiming to establish formulations and application methods.