Formulação emulsionável de sementes de Annona muricata L. (annonaceae) sobre Aleurocanthus woglumi (ASHBY, 1915) (hemiptera: aleyrodidae)

Abstract

The citrus blackfly, Aleurocanthus woglumi Ashby, 1915 (Hemiptera: Aleyrodidae) is an insect native to Southeast Asia and widespread in several regions around the world. It is highly polyphagous and cosmopolitan, with a high rate of reproduction and dissemination, whose injuries can compromise up to 80% of the viability of citrus plantations, especially the orange tree, Citrus sinensis (L) Osbeck (Rutaceae). The pest causes direct and indirect damage to the host plant by sucking the sap from the leaves, excreting significant amounts of sugary substances (known as honeydew) that cover the surfaces of leaves and fruits, causing physiological disorders in the plant and contributing to the emergence of the etiological agent ofsooty mold, Capnodium citri Berk. & Desm. This opportunistic fungus proliferates, reducing the photosynthetic capacity of the attacked crop and the nitrogen level of the leaves, making the fruit unviable for sale. Since Brazil is the world's largest orange producer and the third largest citrus producer in the world, the control of citrus blackfly is vehemently necessary, as the reduction in orchard production can, consequently, reduce the supply of jobs and income generated by the citrus sector in the country. Chemical, cultural, biological control and alternative control are the most used tactics to control insect pests, among which biological control is considered the most efficient. In addition to these, the use of botanical extracts from plants with insecticidal potential has been widely used, with emphasis on the botanical family Annonaceae, for its deleterious effects on several orders of insect pests of agricultural importance. Considering the urgency of controlling the citrus blackfly, the harmful effects that chemical insecticides can cause to the environment, and considering the growing demand for alternative pest control methods, the objective of this study was to evaluate the emulsifiable formulation of the ethanolic extract of the soursop seed, Annona muricata L. (Annonaceae), on the immature stages of the citrus blackfly, A. woglumi, under laboratory conditions. The experiments were conducted at the Entomology Laboratory: Alternative Pest Control (LECAP), with insects obtained from lime orange leaves with an average age of 15 years, infested by the pest. The emulsifiable formulation based on ethanolic extract of A. muricata seeds was applied to the immature stages of the insect (embryonic and 2nd and 3rd instar nymphs). The treatments were evaluated 72 hours after application of the emulsifiable formulation. According to the results, the emulsifiable formulation showed an ovicidal effect, with hatch reduction of up to 100%; and moderate nymphid effect, with 50% mortality of nymphs subjected to treatments, both at the highest concentration tested. Due to the scarcity of studies on annonaceous extracts on A. woglumi, more studies are necessary.

Keywords: Citriculture; Citrus blackfly; Soursop; Ovicide; Nymphid.