Alterações fisiológicas em plantas de coqueiro provocadas por Raoiella indica Hirst e a endoterapia como alternativa para seu controle

Abstract

Raoiella indica is an exotic and invasive mite species in the Americas. Knowledge about the basic (ecological) and applied (management) aspects of this species is still scarce. This is the first study to investigate not only the use of endotherapy to control R. indica in coconut plants, but also the potential physiological changes in the host plant due to R. indica attack. Coconut plants were subjected to three distinct treatments: control (no phytosanitary treatment), endotherapy (abamectin injection into the plant stem), and spraying (abamectin spraying directed at the leaflets). Plant leaflets were evaluated for R. indica infestation (number of motile forms/leaflet) monthly and until the infestation level was reestablished during the endotherapy treatment. Additionally, physiological parameters were measured on the leaflets collected in each treatment at two different time points (one in the rainy season and the other in the dry season). The results of this study demonstrated that: (i) endotherapy with the acaricide abamectin was effective in reducing R. indica populations; (ii) the interval between abamectin acaricide applications via endotherapy can reach 10 months (300 days); (iii) abamectin applications every 2 months via spraying of the plant canopy can contribute to reducing R. indica populations; (iv) the main physiological changes in coconut plants mediated by R. indica attack are observed in the net photosynthetic rate, stomatal conductance, and transpiration; and (v) physiological changes vary according to environmental conditions (rainy and dry seasons).