Potencial de ácaros predadores no controle biológico aplicado de Raoiella indica (Acari: Tenuipalpidae) em coqueiro

Abstract

Predatory mites of the Phytoseiidae family are the main natural enemies of the red palm mite, Raoiella indica Hirst 1924 (Acari: Tenuipalpidae), in coconut crops. Amblyseius largoensis Muma 1955 (Acari: Phytoseiidae) is frequently found in association with R. indica in several countries and has potential to control this pest according to research conducted in laboratory and greenhouse. Amblyseius tamatavensis Blommers 1974 (Acari: Phytoseiidae), in turn, is also found in association with R. indica in Brazil, however, little is known about its ability to control R. indica under laboratory and field conditions, in addition to interactions species such as cannibalism. The objective of the present work was to evaluate A. tamatavensis on eggs of R. indica, as well as to verify the presence of cannibalism and its implications. Additionally, the efficiency of A. largoensis and A. tamatavensis releases in the control of and the influence of climatic variables on the density of this pest in the field was evaluated. The predatory mite A. tamatavensis presented a type II functional response and great reproductive potential when fed with eggs of R. indica. Therefore, A. tamatavensis was efficient in controlling R. indica under laboratory conditions, especially in low or moderate prey densities. In addition, immatures and females of A. tamatavensis cannibalized conspecifics and females laid few eggs in the absence of R. indica eggs. However, cannibalism decreased and oviposition increased in the presence of R. indica eggs as heterospecific prey. A. tamatavensis releases showed superior efficiency in reducing R. indica densities when compared to A. largoensis. Furthermore, the interaction between the mass releases of A. tamatavensis and the evaluation months influenced the reduction of the densities of active and immobile phases of R. indica in the field. Additionally, low relative humidity and low rainfall explained the population increase of R. indica, mainly in the transition period from the dry to the rainy season.. Further studies should investigate the efficiency of A. tamatavensis at different mass release densities (eg medium, high) in commercial coconut crops, especially in periods of higher pest population density.