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Control Strategies of Papaya Mealybug, Paracoccus Marginatus Williams and Willink in the Laboratory Condition

M. J. H. Biswas
Department of Entomology, Bangladesh Agricultural University, Mymensingh-2202, Bangladesh

M. A. M. Khan
Department of Entomology, Bangladesh Agricultural University, Mymensingh-2202, Bangladesh

K. S. Ahmed
Department of Entomology, Bangladesh Agricultural University, Mymensingh-2202, Bangladesh

Abstract/ Executive Summary:

The laboratory experiment was conducted at the laboratory of the Department of Entomology, Bangladesh Agricultural University to determine the effectiveness of polythene band, predatory ladybird beetles (available species found in Bangladesh viz. Coccinella transversalis (F.), Micraspis discolor (F.), Menochilus sexmaculatus (F.), Cyclonida sanguinea, Adalia bipunctata, Coccinella novemnotata and Illeis koebelei), four chemical insecticides and three botanical oils in controlling papaya mealybu g, Paracoccus marginatus Williams and Granara de Willink. The chemical insecticides were Sevin 85 SP, Dimethoate 40 EC, Fipronil 50 EC, Deltamethrin 2.5 EC, and the botanical oils were Neem oil, Mahogany oil and Karanja oil. In the laboratory experiment, polythene banding failed to prevent the plant from the infestation of papaya mealybug. Seven commonly available species of ladybird beetles in Bangladesh did not provide any control to papaya mealybug. Among the chemical insecticides, Sevin 85 SP and Dimethoate 40 EC showed significant mortality of papaya mealybug. Deltamethrin 2.5 EC and Neem oil (2%) provided moderate control of the pest. The remaining insecticides and botanical oils were less effective to control papaya mealybug.

Keywords: Papaya mealybug; Sevin 85 SP; Neem oil; Ladybird beetle

Location: Laboratory of the Department of Entomology, Bangladesh Agricultural University, Mymensingh-2202

Start Date: 26-01-2014

End Date: 16-08-2014

Program Area: Crop-Soil-Water Management

Commodity: Papaya

Objectives:

Objective of the study was to find out appropriate management strategies to control this insect in Bangladesh

Methodology:

Laboratory Experiments for Controlling Papaya Mealybug: Host plant; The Sinta papaya seed variety of Lal Teer Company was used for raising seedlings in polythene bags (12 x 8 cm size with 3-4 holes at the bottom) filled with prepared soil media. The soil media was prepared with the mixture of loam soil and well decomposed cowdung in equal proportion. Two seeds were sown per bag at 1 cm depth in the soil media and watered regularly to keep the media moist for higher germination. The seedlings were grown at 28±2⁰C temperature with the photoperiod 12L: 12D in the IPM lab. Thirty five (35) days old seedlings were used in this experiment to study the effectiveness of different control approaches. Rearing of papaya mealybug: Papaya mealybugs were collected from the papaya field and reared on papaya plant in the insect rearing room of the department of Entomology, Bangladesh Agricultural University. New plants were added roughly every 4 weeks, and old plants were removed after the mealybug had settled on the new plants. Population of the papaya mealybug was maintained until completion of the research work. The reared mealybugs were used in this experiment to perform different treatments. Treatments: Use of polythene band; In this experiment three types of plants were used such as mealybug infested plants as source of mealybug, uninfested plants with polythene band as treatment, and uninfested plants without polythene banding as control plants. In polythene banding, the trunk of papaya plants were covered with 3 inch polythene band at the base, 1 inch apart from the soil surface. Total five plants were banded with polythene sheet. Later on, plants were arranged in three rows, where mealybug infested plants were placed in left row, the ploythene banded plants were kept in middle row, and the uninfested control plants were kept in right row.The distances between plant rows were 35 cm. All plants were carefully observed for the next 60 days to observe the movement of mealybug and their possible infestation. Use of predatory ladybird beetles to control papaya mealybug: Free choice test; In the free choice test experiment for the selected ladybird beetles, both papaya mealybug and cowpea aphids were provided together to feed on. In a 15 cm petridishes, ten papaya mealybugs were kept at one side and ten cowpea aphids were kept on another side along with their host plant parts, where one ladybird beetle was released in the middle. Continuous observation on feeding behavior of ladybird beetle was made for the next 6 hours and data were recorded. Forced feeding experiment: In force feeding experiment, a pair of adult beetle was released in a petridesh and ten mealybugs/petridesh were supplied as food for the predator. The supplied mealybugs were tiny immature stages to adult. Predation behavior of the selected ladybird beetle was observed hourly for the first 12 hours, and after wards observation was made at every 24 hours. Methodology for testing botanicals and chemical insecticides: Four synthetic insecticides such as Sevin 85 SP, Dimethoate 40 EC, Fipronil 50 EC, Deltamethrin 2.5 EC and three botanical oils viz. Neem oil, Mahogany oil and Karanja oil (2 times at the rate of 3.44gm/liter of water) were evaluated to compare their efficacy against papaya mealybug. The doses of insecticides were according to the manufacturer recommendations and presented in table 1. In case of botanical oils, 2% solution was prepared by adding 2 ml oils in 100 ml water with detergent powder at the rate of 1 gram/L. The efficacy of insecticides and botanical oils was tested against papaya mealybug on standing papaya plant organized according to a Randomized Complete Block Design in the laboratory. Ten mealybugs per plant were released on papaya plant from the cultured populations with the help of a fine camel hair brush and special care was taken during transferring mealybugs to avoid injury. After the release of mealybugs, each plant was placed individually on a special plastic tray with an inner and outer ring. The plant was place on inner ring and the outer ring was filled with detergent water to prevent mealybugs escaping. When all mealybugs were properly settled on experimental plants within 3 days, different treatments were employed. Five plants per treatment were used and plants were sprayed 2 times at 15 days interval. The first and the second spraying were made on 26 January 2014 and 10 February 2014, respectively with the help of a hand-operated sprayer. Care was taken to avoid spray drift on adjacent plants. The spraying was done in such a way that the whole plant was thoroughly covered by spray material. The control plants were sprayed only with water. Pre-treatment data were collected one hour before application of insecticides and botanical oils. For recording the data all plants parts along with polythene bag and soil media were observed. The number of mealybugs and its progeny were counted using magnifying glass. The data on the number of adults survived per plant under different treatments were recorded after one, seven and fifteen days of the first and second spraying. The number of offspring per plant for each treatment was recorded on the last date of data collection (after fifteen days of the second spraying). Statistical analysis: Results were subjected to a one-way analysis of variance. Differences between mean values were tested using Tukey’s-HSD-test at p = 0.05.

Source of Information: Int. J. Appl. Sci. Biotechnol., Vol 3(4): 687-691, 2015

Article Link (Online Journal):

Funding Source:

1. Government

Budget:

Total Budget (Tk.) :

Achievement/Findings:

Polythene band alone cannot prevent the movement of tiny crawlers. However, any sticky substances on the polythene band may prevent the infestation. Azadirachtin affects the formation of spermatozoa. Although Neem had less effect on mortality, it can be used to suppress the population increase when the number of papaya mealybug remains below economic injury level. In severe attack, Sevin 85 SP or Dimethoate 40EC can be used for immediate control of this insect pest.

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