Toxicity of acaricides to Raoiella indica and their selectivity for its predator, Amblyseius largoensis (Acari: Tenuipalpidae: Phytoseiidae)

Abstract

Raoiella indica Hirst (Acari: Tenuipalpidae) is considered a pest of coconut palm in Asia and the Middle East. This mite was recently introduced in the Americas, where it spread to several countries and expanded its range of hosts, causing heavy losses to coconut and banana production. The phytoseiid mite Amblyseius largoensis (Muma) is one of the predators most often encountered in coconut palms. Because the current prospects for the control of R. indica in the New World indicate the use of acaricides and the management of their natural enemies, the objective of this study was to evaluate the toxicity of selected acaricides to R. indica and the selectivity (i.e., toxicity to the predator relative to toxicity to the prey) for A. largoensis. Assays were performed by the immersion of banana leaf discs in acaricide solutions, followed by the placing of adult females of the pest or predator on the discs. Mortality of the mites was evaluated after 24 h, and the data obtained were subjected to probit analysis. Abamectin, fenpyroximate, milbemectin and spirodiclofen were the products most toxic to R. indica adults, whereas fenpyroximate and spirodiclofen were the most selective for A. largoensis.