DEVELOPMENT OF A NATURAL FORMULATION OF ESSENTIAL OIL AND Annona muricata EXTRACT ON MAIZE WEEVIL Sitophilus zeamais Mots., 1855 (COLEOPTERA: CURCULIONIDAE)

Abstract

In the maize crop, it is estimated that around 20% of the total produced annually in Brazil is wasted in the harvesting processes, transport and storage and approximately 10% of these losses are caused by pests in grain storage (BRAZIL, 1993). Being considered species of the genus Sitophilus (Coleoptera: Curculionidae) the main stored grain pests. The Sitophilus zeamais Motschulsky, known as maize weevil is a plague of great economic importance, being one of the most important of the maize stored, due to its high destructive capacity both in adulthood and in the larval phase, the adult insect causes damage to healthy and intact grains, while the larvae feed on their inside, so it is considered an internal primary plague. Researches with natural products derived from plants, such as plant extracts, essential oils, have shown promising for the management of primary and secondary pests of stored grains, since they have secondary metabolites with fumigant and repellent property. Thus, the objective of this study was to evaluate whether the ethanolic extract of soursop has repellent, fumigant and contact action. In the repellency test, concentrations of 20, 40, 50 and 60μL. The repelence index (CI) was observed in 1.13 and 1.33, referring to the concentrations of 50 and 60 μL, respectively. In other words, at concentrations equal to or greater than 50 μL, the ethanolic extract of soursop caused a repellent effect in S. Zeamais. Concentrations of 20 and 40 μL were neutral, with no effect on insect pests. In the contact test, the ethanolic extract of soursop presented LC95 of 246.214 μL/40g of grains and the LC50 corresponding to 91.637 μL/40g of grains. For fumigation test, the ethanolic extract of soursop was not efficient because very high concentrations were tested and did not cause mortality of the insects.