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Schedule and Need Based Chemical Control of Brown Planthopper and Their Impact on the Predator Ophionea Indica (thunberg)

Mohammad Shaef Ullah
Department of Entomology, Bangladesh Agricultural University, Mymensingh-2202, Bangladesh.

Mahbuba Jahan
Department of Entomology, Bangladesh Agricultural University, Mymensingh-2202, Bangladesh.

Abstract/ Executive Summary:

Effectiveness of two chemical approaches in controlling brown planthopper, Nilaparvata lugens (Stal.) and their impact on the predator carabid beetle, Ophionea indica (Thunberg) were evaluated at Bangladesh Agricultural University during aman season. Carbofuran (Brifer 5G) was applied in Need Based Control (NBC), as judged by periodic monitoring on the level of the pest population and recommended economic thresholds. Schedule Based Control (SBC) consist of application of carbofuran (Brifer 5G) and monocrotophos (Azodrin 40 WSC) on a schedule basis. Mean number of brown planthoppers and the carabid beetles were compared in different control approaches including the natural control, where no insecticide was applied and the control was largely by the activities of naturally occurring predators. In natural control approach a high level of predatory carabid beetle was found in the field compared to the need based and schedule based protection. The population of carabid beetle fluctuated quite synchronously with the density of brown planthopper. The carabid beetle, O. Indica was found to keep the brown planthopper population down to a considerable level when chemical insecticide was not applied.

Keywords: Brown planthopper, Nilaparvata lugens, Ophionea indica, Predator, Scheduled, Need based control

Location: Bangladesh Agricultural University Farm

Start Date:

End Date:

Program Area: Pest Management

Commodity: Insects

Objectives:

1. To compare effectiveness of schedule and need based approaches of chemical control of brown planthopper

2. To study the existence of the predator in the treated rice field.

Methodology:

The study on different control approaches of brown planthopper was conducted at three different places of Bangladesh Agricultural University Farm located at 24.75°N latitude and 90.5°E longitude using the rice variety BR23 (Dishari) in Aman season. The field trial comprised of three treatments such as (1) Schedule Based Control (SBC)-consisted of application of the insecticide carbofuran (Brifer 5G) at the recommended dosages of 1.0 kg a.i/ha at 25 and 70 days after transplanting and monocrotophos (Azodrin 40 WSC) 500 g a.i/ha at 50 days after transplanting on a schedule basis involving application of insecticides based on a schedule commonly adopted by farmers. (2) Need Based Control (NBC)-application of carbofuran (Brifer 5G) at the recommended dose of 1.0 kg a.i/ ha at 50 and 80 days after transplanting as judged by periodic monitoring on the level of economic threshold of the pest and (3) Natural Control (NC) with no application of insecticide throughout the crop season. Each experimental fields comprised of the area about 250 m². So the total area covered by three plots were 750 m². The agronomic practices such as weeding, application of fertilizer, irrigation etc. were common for all the plots. Data collection started when crop was one month old. The number of brown planthopper per 25 hills of rice were recorded fortnightly. Estimation of population of the common predator, carabid beetle Ophionea indica (Thunberg) was made based on net sweeps (5 double sweep nets per plot) at same time interval. Collected data were analyzed using two way ANOVA and the means were separated using Least Significant Difference (LSD). The correlation between carabid beetle and brown planthopper was determined. All the analysis was done using the MSTAT-C statistical program.

Source of Information: Asian Journal of Plant Sciences, 3(6): 687-689, 2004, ISSN 1682-3974.

Article Link (Online Journal): DOI: 10.3923/ajps.2004.687.689, URL: http://scialert.net/abstract/?doi=ajps.2004.687.689

Funding Source:

Budget:

Total Budget (Tk.) :

Achievement/Findings:

In the present study, it could be concluded that, minimum use of insecticides in effective dose and frequencies would be helpful in the long run for the conservation of the carabid beetle, which are encouraged for the effective control of the pest, brown planthopper. There was strong correlation between brown planthopper and carabid beetle in natural control approach but little or no correlation was found between the population of brown planthopper and carabid beetle in need based protection and schedule based control. Need based control considered the economic threshold level of the pest which resulted in considerable build up of the natural enemy populations in rice ecosystems.

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