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Parasitism Pattern, Egg Laying Frequency and Development Duration of Trichogramma Zahiri

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

Mohammad Fazle Rabbi
PSO
Entomology Division, BRRI, Gazipur-1701

Abstract/ Executive Summary:

Rice hispa eggs suffered 16-55% parasitism by an egg parasitoid, Trichogramma zahari. Highest egg parasitism was observed in August (55%) and lowest in the month of May (16%). Very often, multiple parasitism was observed and up to four parasitoids wee emerged from a single parasitized egg. Male and female T. zahiri had almost same pre-imaginal development duration, which varies from 7-10 days. Their sex was always female biased (69% female).

Keywords: Parasitism, Egg laying, Development duration and T. zahiri

Location: BRRI, Gazipur

Start Date: 01-07-2003

End Date: 30-06-2004

Program Area: Pest Management

Commodity: Insects

Objectives:

To know the parasitism pattern, egg laying frequency and development duration of T. zahiri

Methodology:

Rice hispa egg parasitism was estimated by placing potted rice plant with hispa egg in the rice fields and retrieving after 24 hrs round the year at 15 days interval and reared the eggs in test tubes. For egg laying frequency study a total of 1300 eggs laid by rice hispa on potted rice (var. BR-3) plants in the net-house were exposed to T. zahiri in a rice field at BRRI farm Gazipur during July 2003 - June 2004. Eggs were retrieved after 24 hours of exposure and reared individually in small vials. Egg to adult developmental period of T. zahiri was studied on rice hispa egg. Hispa eggs laid on potted BR 3 plants were exposed to T. zahiri in a rice field for one night. The leaves with the parasitized hispa eggs were reared individually in small vials.

Source of Information: Proceedings of the BRRI Annual Internal Review for 2003-2004

Article Link (Online Journal):

Funding Source:

1. Government

Budget:

Total Budget (Tk.) :

Achievement/Findings:

Rice hispa eggs suffered 16-55% parasitism by T. zahiri. Parasitism rates showed two peaks; one in June–August (40-55% parasitism) and another in September–November (29-48% parasitism). Parasitism rate was highest in the month of August (55%) and lowest in the month of May (16%). No parasitism occurred from December to March. Average egg parasitism throughout the year was 26.58%. A total of 367 eggs were parasitized out of 1300 eggs. One T. zahiri emerged from each of 128 parasitized eggs. Two, 3 and 4 individuals of the parasitoids were emerged from each of 149, 68 and 22 parasitized eggs respectively. Most of the cases (65%) more than one parasitoid emerged from a hispa egg during the period. The findings also supports results of the previous year and confirms that T. zahiri is a gregarious parasitoid. It was found that T. zahiri needs 07 to 10 days for the emergence when reared on rice hispa eggs. Developmental period for male and female were more or less similar i.e., 8.64 days in male and 8.85 days in female. On an average 9.68 days were required for the development of T. zahiri. The secondary sex ratio was female biased with 69% female found during the reporting period.

Knowledge Management: Report/Proceedings