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.

摘要

柑橘红螨 (CRM)、柑橘全爪螨(McGregor) (Acari: Tetranychidae) 是一种普遍存在于许多落叶和常绿果树的害虫。众所周知，在控制螨虫中持续使用杀螨剂会造成不必要的负面影响。在这项研究中，研究了麻疯树种子提取物（Jc SE）（大戟科）和昆虫病原真菌蜡梅（ Cordycipitaceae）单独和联合应用对CRM死亡率和产卵率的生物效应。Jc SE 对A. lecanii的影响最初是通过将Jc SE 加入到不同浓度的马铃薯葡萄糖琼脂培养基中来评估的。在那之后，将A. lecanii接种在培养基上，观察其菌丝生长、分生孢子产生和分生孢子活力。结果表明，所有浓度的Jc SE 对真菌没有有害影响，说明了高度的相容性并建议将它们组合应用。Jc SE 和A. lecanii的应用增加了 CRM 死亡率并降低了螨产卵率，无论是单独应用还是联合应用。在施用后144小时，它们以最高浓度联合施用导致CRM死亡率为97.5%，螨产卵率降至0.5个卵，而对照的螨死亡率和产卵率分别为2.5%和38.7个卵。因此，结合应用Jc SE 和A. lecanii可以被认为是 CRM 综合管理计划中的一个有前途的选择，特别是在有机农业中。