Persistence and bioefficacy of insecticides in okra and sponge gourd

Beta-cyfluthrin @ 18.75 g a.i. ha⁻¹ deltamethrin @ 20 g a.i. ha⁻¹ endosulfan @ 700 g a.i. ha⁻¹ and neem Azal (azadirachtin 50,000 ppm) @ 500 ml ha⁻¹ were sprayed on the sponge gourd crop at the flowering stage and the treatments were repeated after 15 days. Deltamethrin @ 20 g a.i. ha⁻¹ was sprayed on okra crop at the fruiting stage. The residue studies were carried out only for beta-cyfluthrin and deltamethrin. Bioefficacy studies for all the insecticides were carried out only for sponge gourd against blister beetle, Mylabris pustulata. Residues of beta-cyfluthrin and deltamethrin were nondetectable after 7 days in okra and sponge gourd fruits. Washing of 0 day and 3 days contaminated okra fruits dislodged 42 and 38% residues of beta-cyfluthrin and deltamethrin and washing followed by steaming/cooking brought down the residues by 62.3 and 61.8%. Unwashed or washed samples of sponge gourd when peeled and steamed showed maximium mitigation of residues of beta-cyfluthrin and deltamethrin i.e. 72 to 73.4%. The insecticides concentrated maximum on the peel of sponge gourd fruits. Beta-cyfluthrin and deltamethrin treatments effectively controlled blister beetles in sponge gourd in comparison to endosulfan and neem Azal. The treatments did not exhibit any phytotoxicity.