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Parasitism Pattern of Trichogramma Zahiri in Two Crop Stages of Different Rice Seasons

Md. Nazmul Bari
Senior Scientific Officer
Entomology Division, BRRI, Gazipur-1701

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

Abstract/ Executive Summary:

The potentiality of the parasitoid Trichogramma zahiri was evaluated as biocontrol agent of Dicladispa armigera through studying a number of its biological parameters. Parasitism rate of rice hispa egg by T. zahiri varied with seasons and crop stages of rice. The parasitism range from 14.42 to 85.92% and 30.91 to 77.0% in the vegetative and reproductive stage respectively in different rice seasons of the year 2009-2010. Similar high range from 14.71 to 75.95% and 43.06 to 67.78% were observed in the year of 2010-2011.

Keywords: Trichogramma zahiri, Parasitism, Rice crop stage and season

Location: BRRI, Gazipur

Start Date: 01-07-2010

End Date: 30-06-.2011

Program Area: Pest Management

Commodity: Rice

Objectives:

To determine the parasitism rate and pattern of T. zahiri in field.

Methodology:

Egg parasitism of rice hispa was determined using the retrieval method. Freshly laid rice hispa eggs on 2-3 potted BR3 plants and each pot contained at least 100 rice hispa eggs were made exposed to field population of parasitoids for about 48 hours. All the potted BR3 plants were brought back to laboratory after the stipulated time. The leaves of the BR3 plants having the exposed hispa eggs were cut in to pieces to facilitate placing of individual hispa egg in individual glass vials (5 mm capacity). Few drops of distilled water was added in each vials by wash bottle to maintain the turgidity of the leaf pieces. The eggs were reared until the emergence of the parasitoids. The unhatched eggs were checked and dissected under microscope. Any dead parasitoid found from dissection was taken in to consideration and counted with the number of emerged parasitoids. Percent egg parasitism was determined by the following formula: Total no of egg parasitized divided by Total no of egg rearedX100. The whole procedure was repeated at vegetative and reproductive stages of rice crop in each rice seasons. The study was conducted in two consecutive years. First year was Aus 2009 to Boro 2010 and 2nd year was Aus 2010 to Boro 2011.

Source of Information: Internal review workshop, 2010-11

Article Link (Online Journal):

Funding Source:

1.	Budget:
2. Bangladesh Agricultural Research Council	Budget:

Total Budget (Tk.) :

Achievement/Findings:

Pooled data of two years showed a similar parasitism rate in vegetative stage to reproductive stage both in Aus and T. Aman seasons but it was different in Boro season. In Aus and T. Aman seasons the parasitism of T. zahiri did not differed significantly between the crop stages. The sex ratio of T. zahiri developed from different seaon was female biased. A total of 4797 parasitoid examined under microscope during the experimental period and average female sex found 71.48%. Peak parasitism was found in the month of August, October and May. On an average 1.33 to 2.81 parasitoids emerged per parasitized eggs in the first year and 1.21 to 2.45 in the second year. No parasitism was found in the month of December to February in the first year and December to January in the second year.

Knowledge Management: Report/Proceedings