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Efficacy of Insect Growth Regulator Buprofezin Against Papaya Mealybug

Mohammed Abul Monjur Khan
Department of Entomology, Faculty of Agriculture, Bangladesh Agricultural University, Mymensingh-2202, Bangladesh.

Abstract/ Executive Summary:

The papaya mealybug, Paracoccus marginatus Williams and Granara de Willink (Hemiptera: Pseudococcidae) is a serious insect pest causing severe damage to papaya plants. To find out suitable biorational insecticides for this insect, several experiments were conducted in the laboratory with different groups of insecticides such as carbamates- Carbaryl, growth regulators- Buprofezin, microbial derivatives- Spinosad, and Neem oil. Efficacy trial revealed that Carbaryl and Buprofezin caused significant mortality of papaya mealybug, while the mortality was 100% and 96%, respectively. Treatment with Neem oil (2%) provided moderate control of papaya mealybug, while 60% mortality was achieved. The Spinosad was found less effective against papaya mealybug which caused 40% mortality. Due to complete death of mealybug in Carbaryl treated plants, no progeny was found. The number of mealybug progeny was significantly low in Buprofezin and neem oil treated plants, while the nymph number per plant was 22 and 39, respectively. In contrast, mealybug progeny in the Spinosad treated plants was similar to that of control plants. The potentiality of buprofezin to integrate in the IPM program against papaya mealybug is discussed.

Keywords: Biorational insecticide, Neem oil, Spinosad, Mortality, Progeny reduction

Location: Department of Entomology, Bangladesh Agricultural University, Mymensingh

Start Date:

End Date:

Program Area: Pest Management

Commodity: Papaya, Insects

Objectives:

The present research work was planned to evaluate the efficacy of three biorational insecticides such as buprofezin, spinosad, and neem oil on the mortality and progeny production of papaya mealybug under laboratory conditions. The efficacy of these selected biorational insecticides are compared to the broad spectrum Carbaryl which is an effective insecticide against papaya mealybug.

Methodology:

The research work was carried out in the laboratory of the Department of Entomology, Bangladesh Agricultural University, Mymensingh and all experiments were repeated twice to fulfill the research objectives. 2.1 Host Plant The Papaya plant (Carica papaya) variety Sinta (Lal Teer Seed Limited, Bangladesh) was used as host plant and grown in pots (12 x 10 cm size) filled with prepared soil media. The soil media was prepared with the mixture of loam soil and well decomposed cow dung in equal proportion. Two seeds were sown per pot and after ten days of seedling germination, only one plant/pot was allowed to grow. The seedlings were grown at 28±2⁰C temperature with the photoperiod 14L:10D. Thirty five days old seedlings were used in this research work to study the effectiveness of different insecticides for the management of papaya mealybug. 2.2 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. The reared mealybug was used in the experiments to perform different treatments and population of the papaya mealybug was maintained until completion of the research work. 2.3 Insecticides and botanical oil tested Three insecticides such as carbamates (Carbaryl), buprofezin and spinosad, and a botanical oil such as Neem oil (Azadirachta indica) were evaluated to compare their efficacy against papaya mealybug. The doses of insecticides were according to the manufacturer recommendations. In case of neem oil, 2% solution was prepared by adding 20 ml oil in 1 L of water, while 2.5 ml liquid detergent was added as emulsifier. To prepare the solution, firstly liquid detergent was added to water and agitated well until the detergent gets completely dissolved in water. Later on, neem oil was added to this solution and agitated well until a pale yellowish white emulsion is formed. 2.4 Experimental procedure To test the efficacy of selected insecticides and botanical oil, ten mealybugs per plant were released on papaya plant from the cultured populations with the help of a fine camelhair 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 placed 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 2 days, different treatments were employed. Five plants per treatment were used and plants were sprayed twice at 15 days interval 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 on the number of mealybug in each plant was collected one hour before application of insecticides and botanical oil. For recoding the data, all plants parts along with pot and soil media were observed carefully. The number of mealybug and its progeny were counted using magnifying glass. The data on the number of adult survived per plant under different treatments were recorded after one, seven and fourteen days of the first and second spraying. Finally, the mortality of papaya mealybug was calculated. 2.5 Statistics The statistical difference in mortality of mealybug and population establishment between treatments were determined using one-way-analysis of variance (ANOVA), followed by the post hoc test Tukey’s HSD at a significance level of P<0.05 in the statistical program SPSS, version 20.0. The figures and graphs were prepared by Microsoft Office 2007 (Power Point and Excel).

Source of Information: Journal of Entomology and Zoology Studies 2016; 4(4): 1000-1003

Article Link (Online Journal):

Funding Source:

Budget:

Total Budget (Tk.) :

Achievement/Findings:

The mealybug population in the field is associated with many species of parasitoids and predators. From the findings of the present research it can be suggested that rotation of Buprofezin and neem oil treatments in the IPM program may help to control papaya mealybug as well as conserve natural regulators of mealybug population. At last, chemical control measures with carbaryl can be the last option for mealybug control when above biorational insecticides do not work properly.

Knowledge Management: Journal