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Responses of Different Brown Planthopper (bph) Populations to Differential Rice Varieties. O

Dr. Mohibul Hasan
Principal Scientific Officer
Entomology Division, BRRI, Gazipur-1701

Mahfuj Ara Begum
SSO
Entomology Division, BRRI, Gazipur-1701

Abstract/ Executive Summary:

The preliminary screening for the determination of biotype of brown planthopper (BPH) showed some difference in the reactions of the plants of differential materials against the different BPH populations. However, it needs confirmation by retest and other supporting experiments.

Keywords: Screening, Resistance, BPH, Rice

Location: BRRI, Gazipur

Start Date: 01-07-2009

End Date: 30-06-2010

Program Area: Pest Management

Commodity: Rice

Objectives:

To differentiate among the BPH populations on the basis of their reactions to differential varieties

Methodology:

A total of 21 BPH populations were screened against differential varieties during 2009-10 seasons. The BPH populations were collected from different locations (15 districts) of Bangladesh. Gravid adult and nymphs were collected from the infested rice fields. The collected insects were brought to the greenhouse of Entomology Division and were allowed to grow separately to provide populations of specific locations. The collected BPH populations were screened against a set of differential varieties by seedling bulk test method. For this, eleven rice varieties (9 differentials having different genes for resistance to different biotypes and 2 checks, one resistant and one susceptible to all the biotypes) were sown in seeding trays measuring 65x 45x15 cm in size and containing soil 8 cm in depth. The varieties were sown in 10 cm long rows providing a space measuring 4 cm in between the rows. Each row represented a variety. Thus, there were 44 rows in 3 blocks of a tray. The design was CRD with 4 replications. Each of the trays had the same varieties sown in the same design and was used for each of the BPH populations. Every day, the trays were sprinkled with water and kept covered with nets to avoid any damage by other insects or rats. After 5 days of sowing, the seedlings were thinned, leaving 25 plants per row and the trays were placed in larger iron trays having water in it to provide required moisture for the plants. On the 7th day of sowing, the water level of the iron tray was increased a little, just to flood the soil surfaces of the seeding trays. BR3 rice plants harbouring BPH nymphs of same age (second/third instar BPH nymphs) were gently tapped on the test seedlings. Each tray was used for a single BPH population. The plants having BPH nymphs were tapped in such a way that each test seedling of the seed boxes had the opportunity of receiving approximately 5-7 nymphs. After five to seven days of infestation when 90% of the seedlings of the susceptible check TN1 were found dead, plant damage for each variety was recorded based on a visual damage rating of 0-9 scale given in SES developed by IRRI (1996, 4th edi.).

Source of Information: Proceedings of the BRRI Annual Internal Review, 2009-10

Article Link (Online Journal):

Funding Source:

1. Government

Budget:

Total Budget (Tk.) :

Achievement/Findings:

The reaction of the seedlings of 9 differentials varieties, one resistant T27A and one susceptible TN1 against each of the collected BPH population were evaluated. Resistant and the susceptible varieties were easily identified on the basis of the developed damage symptoms on them. After 5 to7 days of infestation, the seedlings of the susceptible varieties showed retarded growth and yellowing of the leaves at the beginning, and finally died. In some of the varieties, such as, Mudgo, ASD7, ARC 10550, T12 and Chinsaba, the whole process was so rapid that the reactions of the plants could hardly be recognized before the death of the plants. In some replications, Mudgo, ASD7, ARC 10550, T12 and Chinsaba were found dead even before the susceptible check TN1. The other varieties, Swarnalata and Pokkali; showed similar susceptibility (score 5-9) for all the populations. The BPH reaction scores for the susceptible varieties, namely, Mudgo, ASD7, ARC 10550, Chinsaba and the susceptible check TN l ranged from 7 to 9, and those of the resistant varieties, T27A (resistant check), Rathuheenatii and Sinnasivappo varied between 1 and 9. The scores of Rathuheenatii, Sinnasivappo and T27A varied greatly among the different BPH populations and also from replication to replication. This variation was also observed for other three varieties, namely Swarnalata, T12 and Pokkali. The damage reaction of T27A ranged from 0-9. The reaction of T27A might have happened due to heavy infestation during the screening.

Knowledge Management: Report/Proceedings