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Incidence Pattern of Egg Parasitoid of Brown Planthopper (bph)

Nadira Afsana
Scientific Officer
Entomology Division, BRRI, Gazipur-1701

Dr. Mainul Haq
CSO and Head
Entomology Division, BRRI, Gazipur-1701

Abstract/ Executive Summary:

Brown planthopper (BPH) is a major pests of rice in Bangladesh. Most of the farmers of Bangladesh used insecticides to control this pest. Sometimes the pest made resistance against different insecticides. Therefore, it is urgently needed to now the role of natural enemies to control this pest. The study was conducted with a view to know the incidence pattern of egg parasitoid of BPH and their role in parasitism during different times of the year. Freshly laid eggs on potted plants were placed in the field for natural parasitism. The pots were retrieved back from the field after 24 hrs of exposure. The rice stem were cut and kept in the test tubes. Test tubes were checked regularly and emergence of parasitoid was recorded.The experiment was laid out in CRD with 5 replications. Higher egg parasitism of BPH was found with Anagrus sp. Among the four parasitoids Paracentrobia sp. showed least parasitism. Parasitism was observed throughout the year with a wide variation in rate and two peaks in the month of May and November. About 100% of Gonatocerus sp. was found female.

Keywords: Incidence, BPH, Egg parasitoid, Parasitism

Location: BRRI, Gazipur

Start Date: 01-07-2005

End Date: 30-06-2006

Program Area: Pest Management

Commodity: Rice

Objectives:

To know the incidence pattern of egg parasitoid of BPH and their role in parasitism during different times of the year

Methodology:

The experiment was laid out in CRD with 5 replications. Fifteen gravid BPH adults were caged on a potted rice plant (two tillers/pot) in the greenhouse and allowed to lay eggs for 24 hours twice in a month. Freshly laid eggs on potted plants were placed in the field for natural parasitism. The pots were retrieved back from the field after 24 hrs of exposure.The rice stem were cut and kept in the test tubes. Test tubes were checked regularly and emergence of parasitoid was recorded.

Source of Information: Proceedings of BRRI Annual Internal Review for 2005-2006

Article Link (Online Journal):

Funding Source:

1. Government

Budget:

Total Budget (Tk.) :

Achievement/Findings:

Ten egg parasitoid species belonging to 4 genera, Anagrus, Oligosita, Gonatocerus and Paracentrobia were found . Among them, Paracentrobia sp. was found in very few number. The parasitism rate ranged from 1.21-75.0 % during the study period with an average of 25.81%. The parasitoids were observed in the field during all the months of the year but the rate of parasitism was higher in the month of May (55.91%) and November (57.33%). Lower parasitism occurred in the month of June-July (8.81-12.14%), September (10.30%) and January- February (4.74-8.59%). Such a lower parasitism might be due to heavy rainfall and low temperature prevailing during those months. Among the parasitoid species, highest parasitism occurred by Anagrus spp. followed by Oligosita spp. and Gonatocerus spp. The parasitoids peaked once in April to May and another in October to November. The sex ratio of the three genera were female biased. Female sex ratio of the genus Anagrus, Oligosita and Gonatocerus were 86%, 89% and 100% respectively.

Knowledge Management: Report/Proceedings