Contact Toxicity of some newer insecticides against mango mealy bug, Drosicha mangiferae (Green)

An experiment was conducted to determine the contact toxicity of some newer insecticides, viz., chlorantraniliprole, fipronil, imidacloprid, indoxacarb, and monocrotophos against second instar nymphs (mean nymphal wt. = 28 mg) of mango mealybug, Drosicha mangiferae by residue contact bioassay and nymphal dip methods. Indoxacarb and fipronil both, at 0.01% a.i., proved almost non-toxic in residue contact bioassay method on glass surface. The LC₃₀ and LC₅₀ values of monocrotophos at 24 and 48 HAE were 0.0027 and 0.0078%; and 0.0024 and 0.0073%, respectively. In nymphal dip method the LC₅₀ value of monocrotophos and imidacloprid at 48 HAE were 0.0084, 0.0022%, respectively and of indoxacarb at 72 HAE was 0.0027%. In another experiment the LD₃₀ and LD₅₀ values of indoxacarb against 4^th instar nymphs (mean nymphal wt. = 64.6 mg) of D. mangiferae by topical application method, using a micro syringe was 4.69 and 8.31; 4.57 and 7.77; and 4.302 and 6.601 μg/nymph at 24, 48, and 72 HAE, respectively. The LD₉₀ value at 72 HAE was 18.93 μg/nymph.