Developing a Vegetable Oil Formulation as a Safe Acaricide against Tetranychus urticae

The two-spotted spider mite, Tetranychus urticae Koch, is a highly polyphagous pest that is considered a serious pest worldwide. Due to problems associated with chemical pesticides such as resistance to pesticides and environmental contamination, plant oils have been considered for use against mites’ control. However, their low solubility in water and phytotoxicity are the major constraints that limit their application. In this research, a developmental screening process was carried out on some commercial emulsifiers and stabilizers to obtain a safe acaricide from suitable vegetable oils including castor and soybean. Among eight emulsifiers, Nonylphenol Ethoxylate ۶M (NPE۶) had far more excellent emulsification ability and less phytotoxicity with some level of mite toxicity. Among vegetable oils, castor oil had greater toxicity in comparison with soybean oil. Also, Polyethylene Glycol ۴۰۰ (PEG ۴۰۰) had more thermal stability in the formulation. In the last step, the best ratios of NPE۶, castor oil, and PEG ۴۰۰ were evaluated for their toxicity, stability, and phytotoxicity. Finally, the ratios of ۱:۸:۱ or ۲:۶:۲ (NPE۶: Castor oil: PEG ۴۰۰) were found as the best end product that could be potent for use in a large scale rose greenhouse. Also, the efficacy of emulsifier-oil-stabilizer mixtures was investigated against T. urticae by two different methods. The results indicated that the petri dish test method caused overestimating in mortality rates compared to the standing leaf test method. New methods such as polymerization can show a new insight for pest control without chemical pesticides.

کلیدواژه ها:

Emulsions ، Nonylphenol ethoxylate ۶ ، Phytotoxicity ، Polymerization ، Spider mite.