Assessing the Effectiveness of Various Microalgal Species as Green Control Against Citrus Orchard Infestations of Eutetranychus orientalis (Acari: Tetranychidae)

Abstract

The citrus brown mite, known as Eutetranychus orientalis, is a frequent spider mite that poses a threat to citrus farms in Egypt. Therefore, we chose this species as most common and the most numerous among the species that were surveyed on citrus trees. The goal of this study was to evaluate the effect of five microalgae with four treatments against E. orientalis and the mortality rates were determined and measured after different periods under laboratory and field conditions. The obtained results showed that all algal treatments exhibited high toxic action against E. orientalis after 72 hours of application. The culturing broth only (T3), with algae treatment of Pseudanabaena limnetica had the highest mortality rate (100%) after 72hr, followed by Chlorella vulgaris, Chlorococcum sp., Scenedesmus obliquus, and Synechocystis aquatilis (96.7%) under field conditions. In addition, the same treatment showed high toxic effects against E. orientalis after 72 hours and a week of application under field conditions, where the greatest reduction rates are found in P. limnetica and S. aquatilis (83.29 & 85.08%) and (83.77 & 85.92%) after 72 hr and a week of application, respectively followed by Chlorococcum sp. and S. obliquus (82.19 & 85.64%) and (82.33 & 86.73%). The lowest reduction (76.30 & 85.31%) were observed in C. vulgaris after 72 hours and a week. The above mentioned results indicated the possibility of controlling the citrus brown mite, E. orientalis on citrus navel trees by using the culturing broth of microalgae as eco-friendly biopesticides instead of traditional synthetic pesticides.