Horticultural mineral oil for the management of tea mosquito bug Helopeltis antonii signoret in cashew

Abstract

An investigation entitled “Horticultural Mineral Oil for the management of tea mosquito bug Helopeltis antonii Signoret in Cashew” was conducted during 2022-2024 to evaluate the efficacy of horticultural mineral oil (HMO) for the management of tea mosquito bug in cashew. Laboratory experiments were conducted at the laboratory of Department of Entomology, College of Agriculture, Padannakkad. Phytotoxicity evaluation of different concentrations of HMO (T1: 2.0%, T2: 2.5%, T3: 3.0%, T4: 3.5%, T5:4.0%, T6:4.5%, T7:5.0%, T8: Control) in one year old cashew graft revealed that there was no phytotoxicity symptoms at the above concentrations and hence two higher concentrations viz., 5.0% and 4.5% were selected for laboratory bioassay. Evaluation of HMO against nymphs and adults of tea mosquito bug (TMB) under laboratory conditions showed that HMO at a concentration of 5.0% and 4.5% caused 64.76% and 48.57% mortality of TMB respectively, at 72 HAT. When HMO was evaluated against cashew aphids, at a concentration of 5.0% and 4.5% resulted in 85.17% and 81.64% mortality respectively, at 24 HAT in the laboratory study and 98.29% and 97.71% mortality respectively, at 8 HAT under field conditions. Since HMO at a concentration of 5.0% and 4.5% produced statistically similar results, 4.5% concentration was selected for field studies. Field evaluation of HMO was carried out at cashew estate, Cheemeni, Plantation corporation of Kerala under Randomized Block Design with nine treatments and three replications. The treatments were T1: HMO 4.5%, T2: HMO 4.5%+ λ cyhalothrin 5 EC 0.0015%, T3: λ cyhalothrin 5 EC 0.003%, T4: HMO 4.5% + Quinalphos 25 EC 0.025 %, T5: Quinalphos 25 EC 0.05 %, T6: HMO 4.5% + Mancozeb 75 WP 0.1%, T7: Mancozeb 75 WP 0.2%, T8: Quinalphos 25 EC 0.05 % + Mancozeb 75 WP 0.2% and T9: Control. Observations on mean damage score indicated that T2 was more effective in reducing the mean damage score during first and third spray application and it was on par with T3, T4, T5 and T8. The best treatment during second spray application was T4 which was on par with T2, T3, T5, T6 and T8. There was effective reduction in the mean population of TMB with T4 (1 DAT, 3 DAT, 5 DAT and 14 DAT in first spray, 3 DAT and 7 DAT in second spray) and T2 (7 DAT in first spray, 1 DAT and 7 DAT in second spray and 1DAT, 3 DAT and 5 DAT in third spray). HMO in combination with chemical insecticides resulted in effective control of TMB which ensure the application of lower doses of pesticides.