SEASONAL ABUNDANCE, INFESTATION INTENSITY OF PAPAYA MEALYBUG IN DHAKA AND ITS CHEMICAL CONTROL

Abstract

The survey was conducted in five locations (Agargaon, Sher-e-Bangla Agricultural University, Mirpur- 1, Mirpur-2 and Kallyanpur) of Dhaka, Bangladesh and the experiment was conducted at the laboratory and field of SAU during the period from February, 2019 to December, 2019 to study the seasonal abundance, infestation intensity of papaya mealybug and its chemical control. Highest leaf infestation (48.10 %) and highest branch infestation (61.29 %) were found in SAU. Highest stem infestation (83.33 %) was found in Mirpur-2 and Mirpur-1 had moderate twig infestation (63.33 %) but highest inflorescence infestation was 84.85 %. Highest fruit infestation (75.00 %) was found in Kallyanpur. It was observed that the infestation was highest during March in all the locations. The infestation decreased during the month of November in all the locations. Regarding chemical control the experiment consisted of seven chemical insecticides treatments tested against papaya mealybug both in laboratory and field viz. T 1 = Abamectin 1.8 EC, T 2 = Chlorpyrifos (Dursban Pro), T = Dimethoate 30 EC, T 4 = Imidacloprid 200 SL, T 5 = Fipronil (Regent), T 6 = Spinosad 2.5 SC and T = Bioneem Plus (Azadiractin). Among all the applied chemical insecticides Fipronil showed the best performance on control of the mealybug of papaya in laboratory and Bioneem Plus showed the best performance in both laboratory and field. In laboratory after 72 hr of spray, highest mortality was found in spraying of Fipronil (99.50 %) which was statistically similar to Bioneem Plus (99.50 %), Imidacloprid (98.50 %) and Spinosad (97.50 %). Lowest mortality was found in spraying of Abamectin (95.50 %) which was similar to spraying of Chlorpyrifos (95.50%). In field at seedling stage of papaya plant after 72 hr of spray, highest mortality was found in spraying of Bioneem Plus (94.92 %) which was statistically similar to Fipronil (94.83 %) and Imidacloprid (93.68 %). Lowest mortality was found in spraying of Abamectin (86.67 %). In field at mature stage of papaya plant after 72 hr of spray, highest mortality was found in spraying of Bioneem Plus (90.91 %) which was statistically similar to Abamectin (88.77 %), Spinosad (88.33 %) and Imidacloprid (87.60 %). Lowest mortality was found in spraying of Fipronil (84.18 %). Similar trend was observed after 24 hr of spray at mature stage of papaya plant but after 72 hr of spray Bioneem Plus gave the best result. No relation was observed in the infestation of leaf, branch, stem, twig, inflorescence and fruit at different locations.