Abstract
The research was carried out to know the abundance and damage severity of mealybug on sarupkathi variety of guava and to evaluate the efficacy of jet powder and Fighter 2.5EC for suppressing populations of mealybug during January to October 2014. Results revealed that the highest number of guava mealybug was observed on middle leaf (42/leaf) while the lowest number was on lower leaf (13/leaf). The highest percent leaf area covered by mealybug was found on middle leaf (78%) while the lowest was on fruit (18%). Maximum temperature and relative humidity had a positive correlation on the mealybug population while the rainfall showed a negative correlation. The highest percent mortality was observed in T2 treatment (Jet powder applied @ 5.0 g L-1 of water) at 24 HAT (hours after treatment) (86.05%) and 48 HAT (93.83%), respectively. At 72 HAT, the highest percent mortality was observed T3 treatment (Jet powder applied @ 7.5 g L-1 of water). In case of insecticidal control, the highest percent mortality was observed in T2 (100%) and T3 (100%) treatments, respectively followed by T1 (98.03%) at 24 HAT. Similar trends were also observed among all treatments at 48 HAT and 72 HAT, respectively. No significant differences were found among three doses of Fighter 2.5EC. The lowest percent mortality of mealybug population was found in T4 (Water spray forcibly) at 24 HAT, 48 HAT and 72 HAT, respectively. No mortality was recorded in untreated control at different HAT in both application of soap solution and insecticides.
 SAARC J. Agri., 16(2): 73-82 (2018)
Highlights
Guava (Psidium guajava: Myrtaceae) known as the apple of the tropics and is one of the most common and popular delicious fruits in Bangladesh
The highest number of mealybug per plant was recorded on middle leaf (42) followed by upper leaf (26) while the lowest number was on fruit (6) followed by twig (9) and lower leaf (13)
The highest percent leaf area covered by mealybug was found on middle leaf (78%) followed by upper leaf (63%) while the lowest was in fruit (18%) followed by twig (25%) and lower leaf (33%)
Summary
Guava (Psidium guajava: Myrtaceae) known as the apple of the tropics and is one of the most common and popular delicious fruits in Bangladesh. Mealybugs damage plants by inserting their threadlike mouthparts into any part of the plant and sucking out sap (Frank, 2011) Both nymphs and adult females of these mealybugs suck cell sap from different parts of the plant like the leaves, twigs, tender shoots, branches and fruits thereby reducing the vigour of plant as well as the drying up the tender shoots. They excrete honeydew, a sweet sticky liquid on which sooty moulds often grow causing infested plants to turn black. Considering above facts, the present research work was undertaken to know the abundance and damage severity of mealybug on guava and to evaluate the efficacy of detergents and insecticides for suppressing population of mealybug
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