BIOLOGY AND DAMAGE ASSESSMENT OF PAPAYA MEALYBUG, PARACOCCUS MARGINATUS

Abstract

Two experiments were conducted to study the biology and damage assessment of papaya mealybug. Biology of papaya mealybug studied in the laboratory of the department of Entomology and damage assessment was conducted in the farm, Sher-e- Bangla Agricultural University, Dhaka-1207 during June, 2017 to August, 2018. In damage assessment study, T is covered with fine net and sprayed with imidacloprid, at 15 days interval to avoid mealybug infestation and T was infested by mealybug. The adult female laid 97-150 eggs with an average 122.8. The ovipositional period and incubation period was 6.0 ± 1.22 days and 5.8 ±1.09 days respectively. The female has three instars and male has four instars nymphs. At 1 2

instar male and female could not be distinguished. The average duration, length and breadth of 1 st instar nymph were 4.8± 0.83 days, 0.41± 0.08 mm, and 0.25 ± 0.03 mm. The average duration of 2 nd , 3 rd instar female nymph and adult female was 4.2±0.83 mm, 3.4±0.54 mm and 10± 2 days respectively. The average length of 2 nd , 3 rd female nymph and adult female was 0.69± 0.03 mm, 1±0.14 mm and 1.94±0.27 mm respectively. The average breadth of 2 , 3 rd female nymph and adult female was 0.44±0.02 mm, 0.72±0.05 mm and 1.38 ±0.05 mm respectively. The average duration of 2 nd , 3 rd instar, pupa and adult male was 3.6± 0.54 days, 2.8 ± 0.83 days, 3.6 ±0.54 days and 2.4 ±.54 days respectively. The average length of 2

instar, pupa and adult male was 0.70±0.06 mm, 0.85±0.02 mm, 0.94±0.04 mm and 0.98 ±0.03 mm respectively. The average breadth of 2 nd , 3 rd instar, 4 th instar and adult male was 0.38 ±0.04 mm, 0.41 ±.02 mm, 0.26 ±0.03 mm, and 0.26±0.01 mm respectively. Mealybug infestation reduced plant height (34.35%), number of leaves per plant (86.08%), petiole length (53.31%), number of flowers per plant (86.23%), number of fruits per plant (89.43%), individual fruit weight (88.01%) as well as total fruit yield per plant (98%). nd 1 st nd , 3 rd