Eficiência de ácaros predadores e de Acmela oleracea (Asteraceae) no controle do ácaro-vermelho-das-palmeiras Raoiella indica (Acari: Tenuipalpidae)

Abstract

The red palm mite, Raoiella indica (Acari: Tenuipalpidae), is a serious pest that attacks and cause damages to several plants, including coconut (Cocos nucifera L.). The phytoseiid predatory mites Amblyseius tamatavensis, Iphiseiodes zuluagai, and Typhlodromus (Anthoseius) ornatus are often found in coconut palms and could help in the control of R. indica in the field. Extracts from Acmella oleracea (Asteraceae) have bioactivity against pests, however there are no studies on its toxicity to pest mites as well as its compatibility with predatory mites. We aimed at evaluating the efficiency of predatory mites and the extract from A. oleracea in controlling the red palm mite R. indica. The three predatory mites exhibited a type II functional response, indicating that they can assist in the control of R. indica, mainly in low densities of this pest. However, A. tamatavensis consumed more eggs, had a lower handling time, a larger mean variation rate in egg consumption in comparison with I. zuluagai and T. ornatus. The extract of A. oleracea was toxic to R. indica (LC50 = 0.45mg/mL; LC80 = 1.34 mg/mL), but did not kill the predatory mite A. tamatavensis. The LC50 and LC80 of the extract from A. oleracea, estimated for R. indica, were highly repellent to the pest for up to 48 hours after spraying, while repelling the predator only up to 1h in its highest concentration. Also, the LC50 and LC80 of the extract from A. oleracea drastically reduced the growth rate of R. indica while the same concentrations did not affect the growth rate of the predator. We conclude that A. tamatavensis is a potential biological control agent of R. indica and that the extract from A. oleracea could be used in the management of this pest.