Shamiran Biswas

English name of brown plant hopper: Brown Plant hopper (BPH) Delphacidae family name: Nilaparvata lugens (Stal) Common name of the species. Brown grasshopper is one of the enemies of green rice. It is also known as currant bug. They breed very quickly, resulting in the number of these insects increasing so much that the infested fields are like hoppers.

Size Shape: Their skin color is brown or dark brown. Adults are long and short. Their bodies are very soft and the abdomen of the female insect is much larger than that of the male. Adults are 3.5-5.0 mm. long Female insects are larger than males.

Life cycle: There are three stages in the life cycle of the brown treehopper. These stages are egg, juvenile and adult. The adult female grasshopper lays 8-16 eggs in clusters inside the shell leaves. The eggs hatch in 4-9 days. In the first stage the young change their shell 5 times. Juveniles are white in color and later turn brown. Juveniles can be both short- and long-winged to full-grown grasshoppers. Generally, full-grown grasshoppers with long wings are seen when the paddy is ripe. The color of the adult insect is brown. About 4 millimeters long in size.

It takes 14-26 days depending on the weather to turn from a baby to an adult grasshopper. Full grown brown tree grasshoppers can live for about 3 weeks. Brown tree grasshoppers take 21-33 days to complete a life cycle depending on the weather and can breed 10-11 times a year in favorable weather. A pair (male and female) of insect produces thousands of insects within a month or two.

Favorable Environment for Breeding:

Moist and shaded areas are essential for their survival and reproduction. The attack of this insect is more in all the lands which are always wet or some water accumulates. Dense planting and use of excess nitrogen fertilizers can lead to more infestations. If the land is not cleared of weeds regularly and if the seedlings are not planted in rows, the attack of this insect can be high. At temperature of 12-31 C, the propagation of this insect is more. They do not like sunlight. They live near wet areas. Both the young and the adult stage of this insect sit at the base of the rice plant and suck the sap of the plant. As a result, the paddy plant becomes dull. If the insect population is high, the affected crop may develop a condition like hopper bun.

Symptoms of an attack:

Brown planthopper is currently a very harmful pest to rice crops in Bangladesh. High yielding rice varieties Boro, Aush and Ropa Aman are most affected by this pest. Both juveniles and adults feed on sap from stems and leaf sheaths at the base of the rice plant. A large number of insects suck the sap at once, causing them to first turn yellow and then dry up and appear burnt from a distance. Such damage is called "hopper-burn" in English. No yield is obtained if the hopper is burnt before or during the earing of the paddy. However, 20-40% loss is caused by hopper-burn after the grain has hardened. Generally, rice borers can attack from the growing stage to the ripening stage. But most of the attacks are carried out from the milk stage to the milk stage. And sits at the base of the rice plant and eats the sap. As a result, the tree has a burnt color and is called hopper burn.
Organic Management:
1. Cultivation of brown plant hopper tolerant varieties.
2. Leave 10-12 inches between rows of rice seedlings and plant them 8-10 inches apart.
3. After 10 rows, skip 1 row and follow lag method. By doing this, a lot of light and air will enter the paddy field. As a result, brown tree locust attacks will be reduced. But there will be no reduction in yield.
4. At least once a week observe and survey the paddy field to check for insect presence.
5. To detect the presence of brown treehopper, light traps should be placed near the paddy fields for 3 hours after dusk.
6. Use balanced amounts of fertilizers. If urea fertilizer is used in excess, the seedlings become more green and juicy, resulting in an increase in insect attack. So use LCC in moderate amount of urea fertilizer 2 to 3 times.
7. Provide more light and air circulation in the field by cleaning the weeds, dead leaves, shells etc. from the affected field.
8. Do not keep water in the paddy field all the time and dry the land occasionally. This will reduce insect infestation and breeding.
9. The alternate host of this insect should be destroyed.
10. If the presence of brown grasshopper is observed in the paddy field, spread light and air in the paddy field by spreading 2 hands in succession.
11. Short life-span varieties of rice should be cultivated.
12. In case of attack of brown tree locust, everyone in the village should take emergency measures to control this pest.
13. When the rice is 80 percent ripe for eating, the rice should be cut without delay.
Chemical Management:
If the above methods fail to control the brown plant hopper (BPH), then only as a last resort, spray Pymetrazine + Dintifurni (Ibu), or Nitenpyrum (Sega) like insecticides (eg Ibu or Sega etc.) at the base of the infested plant. Take advice from the nearest agriculture office.

The writer is a, Agriculture and Environment Specialist, Dhaka.