New pesticide bioassay method for Thrips palmi Karny (Thysanoptera : Thripidae) using cucumber seedlings.

A new bioassay method for Thrips palmi, called the CST (Cucumber Seedling T reatment) method, was established. The CST method is characterized by easy chemical application, easy observation, long observation period, high survi val rate and high reproducibility. The Ist-instar larvae attached to a cucu mber seedling grow healthily, and the rate of pupation and emergence is ver y high (90%-100%). These merits enable evaluation of slow-acting compounds, such as chitin synthesis inhibitors and hormone analogues. In the CST meth od, the feeding damage appears as dead spots on the leaves, and visual eval uation of control efficacy is easy. The CST method can be used to determine susceptibility of Thrips palmi to insecticides with different modes of act ion.