Abstract

The use of botanical acaricides extracted from plants as an alternative to replace the chemical acaricides is an interesting and efficient option to control pests and ameliorate their toxic effects to humans and the environment. The aim of this work was to evaluate the effect of seed extracts of Annona muricata (Annonaceae) to control the mite Tetranychus urticae (Acari: Tetranychidae) using disks of 5.0 cm in diameter jack bean leaves, Canavalia ensiformis (Fabaceae) as a substrate. The ethanolic extract of the seeds showed the highest toxicity to the mite, with LC₅₀ around 1.77 mg/ml, followed by hexanic and aqueous extracts, with LC₅₀ estimated at 3.29 and 151.74 mg/ml, respectively. Abamectin caused mortality of 40% to T. urticae in a commercial dosage of 100 ml/100 L. The repellent effect of the ethanolic extract, the toxicity on eggs and the residual effect on mites were also evaluated. The concentrations of 0.61, 0.88 and 1.77 mg/ml, as well as Abamectin had neutral effects on T. urticae and the concentrations of 3.10, 5.11 and 12.07 mg/ml were repellent. The viability of the eggs when sprayed with the ethanolic extract (LC₉₉), Abamectin and the control was 9.5, 76.5 and 91.5%, respectively. The residual effect of ethanolic extract was 120 h after application (HAA), with mortality rates above 80%; Abamectin presented residual effect of 48 HAA with 33.3% mortality. In this way, the ethanolic extract of A. muricata proved to be a promising product to the control of T. urticae.

Key words: Botanical acaricide, spotted spider mite, soursop.