Synergistic Effects of Insecticides and Wetting Agents on Mango Mealybug (Drosicha mangiferae Green) Management

Abstract

The experiment was conducted at the Entomology Laboratory of Sher-e-Bangla Agricultural University to understand the efficacy of different insecticidal combinations with wetting agents against the nymphs and the adults of devastating mango mealybug. The treatments consisted of T1 = Nitro 505 EC + Petroleum oil, T2 = Nitro 505 EC + Ethyl alcohol, T3 = Nitro 505 EC + Detergent, T4 = Capture 75 WG + Petroleum oil, T5 = Capture 75 WG + Ethyl alcohol, T6 = Capture 75 WG + Detergent, T7 = Imitaf 20 SL + Petroleum oil, T8 = Imitaf 20 SL + Ethyl alcohol, T9 = Imitaf 20 SL + Detergent. The study examined the mortality rate of mealybugs by treating these combinations. Treatment T8 consistently showed the highest nymphal mortality rates across different application times, significantly outperforming other treatments. Conversely, T6 exhibited the lowest control of first instar nymphs, with notably fewer nymphs controlled after 48 hours compared to other treatments. T3 and T9 also showed significant results in nymphal mortality, gradually increasing over time. While T2 initially showed high nymphal mortality, it revealed statistically similar results to T1, T5, T4, T7, and T8. T9 performed the poorest, with the lowest control of second instar nymphs after 48 hours, while T3 and T6 also demonstrated lower efficacy. Regarding adult mealybugs, mortality rates were lower compared to nymphs, attributed to the development of a protective waxy layer. Treatment T5 showed the highest control of adult mealybugs, followed by T2, with statistically significant differences observed. T6 exhibited the lowest control, significantly different from T5. Despite slight increases over time, all treatments resulted in significantly lower numbers of adult mealybugs compared to the initial 12-hour application period. Overall, the study highlights the differential efficacy of treatments in controlling mealybug nymphs and adults, with T8 (Imitaf 20 SL + Ethyl alcohol) showing consistent effectiveness against nymphs and T5 being most effective against adult mealybugs.