Insecticide use worsens rice pests attack--PhilRice

SCIENCE CITY OF MUÑOZ, Nueva Ecija – Farmers should reduce their use of insecticide to repel rice black bugs, as it could in fact instigate more attack by the rice pests.

          This was the warning issued by experts from the Philippine Rice Research Institute (PhilRice) which stated that use of insecticides has done little to ward of rice black bugs, which had reportedly attacked some rice fields in Central Luzon. The pest attack, when not properly controlled, can reportedly cause losses of up to 35 percent involving 10 adult rice black bugs per hill.

The first reported incidence of rice black bug attack was in Bonobono, Bataraza, in Southern Palawan in 1979. A major outbreak occurred in 1982, spreading towards Central up to Northern Palawan. However, massive and intensive insecticide applications failed to control the damages that covered 4,500 ha of rice fields.

          Entomologists Gertrudo Arida and Dr. Hoai Xuan Truong of the PhilRice’s crop protection division based at its central experiment station here, observed that up to now, insecticides are ineffective against rice black bugs because they kill known enemies of the rice black bugs.

“Insecticides should be used to a minimum so as not to kill the natural enemies of rice black bugs,” they said, citing these include wasps, ground and coccinellid beetle, wolf, lynx, and long-jawed spider, red ant and damsel bug.

Arida and Truong said damage brought by rice black bug can be prevented at the start of the planting season if farmers plant rice varieties with same maturity within a month of the barangay’s regular planting season. This scheme is effective since it breaks the pests’ life cycle.

          Instead of more insecticide, the PhilRice experts recommended the use of light as traps since the bugs are strongly attracted to high intensity light.

          Light trapping, according to them, should start five days before and after the full moon. The light used should have 2,000 to 3,000 watts during outbreaks which is set up every night to obtain the most number of bugs.

Effective light trapping is from 8 to 12 pm, the experts said.

          Other schemes to prevent pest infestation is through flooding, herding of ducks in the field, and sanitation also prevent pest infestation.

          Farmers should flood the field to submerge egg masses. Eggs that are submerged for more than 24 hours will no longer hatch. Ducks also feed on the bugs. However, herd the duck in the field a month after transplanting or when the plants are established. Farmers must also clean their field by removing the weeds as these serve as alternate hosts of the rice black bugs,” the PhilRice explained. (Manny Galvez)