Compatibility of Jatropha curcas seed extract and entomopathogenic fungus Akanthomyces lecanii against the citrus red mite Panonychus citri

Abstract

ABSTRACT The citrus red mite (CRM), Panonychus citri (McGregor) (Acari: Tetranychidae), is a pervasive pest of numerous deciduous and evergreen fruit trees. The persistent use of acaricides in controlling the mite has been known to cause unwanted negative impacts. In this study, the bio-efficacy of individual and combined application of Jatropha curcas seed extract (JcSE) (Euphorbiaceae) and entomopathogenic fungus Akanthomyces lecanii (Cordycipitaceae) on the mortality and oviposition rate of CRM was investigated. The effects of JcSE on A. lecanii were initially evaluated by incorporating JcSE into potato dextrose agar medium at various concentrations. After that, A. lecanii was inoculated on the medium, and its mycelial growth, conidia production, and conidia viability were observed. The results indicated that JcSE at all concentrations had no deleterious effects on the fungus, illustrating high compatibility and suggesting their combined application. The application of JcSE and A. lecanii increased the CRM mortality and reduced the mite oviposition rate, both when applied singly and in combinations. At 144 h after application, their combined application at the highest concentration used caused 97.5% mortality of CRM and decreased the mite oviposition rate to 0.5 eggs, while the mite mortality and oviposition rate were 2.5% and 38.7 eggs, respectively, in control. Therefore, the combined application of JcSE and A. lecanii can be considered as a promising option in integrated management programmes of CRM, particularly in organic farming.