Description

The rice leafroller, is a species of moth of the family Crambidae. It is found in south-east Asia, including Hong Kong, Sri Lanka, Taiwan, Thailand and most of Australia. The wingspan is about 16 mm. The larvae are considered a pest on Zea mays, Oryza sativa and Triticum, Saccharum and Sorghum species.

The moth is very active, bright yellow or straw in colour with two distinct wavy lines in the fore wing and one wavy distinct line in the hind wing. It has a wing span of 15mm. Eggs are laid singly or in groups arranged in longitudinal rows on the undersurface of the leaves which are scaly white in color. Fecundity is about 56 eggs. Incubation period is 4–8 days. We find 5–6 larval instars, larval period is about 22–23 days. It pupates with in the infested leaf fold for a period of 6–7 days. The fully grown caterpillar is green in color and is 16.5mm long. The total life cycle completed in about 5 weeks.

Every one of the phases of the yield is assaulted by this nuisance. On incubating the recently brought forth caterpillar cut the leaf edges and overlays the leaf. At the point when youthful seedlings are assaulted it folds 3–4 contiguous plant leaves and scratches the green matter with the goal that the swarmed leaves seem white. A solitary caterpillar harms a few leaves. The assaulted plants evaporate and it decreases the force of the plant. Eventually the yield gets diminished. The yield misfortune may fluctuate up to 10–50 percent. It is more hazardous at boot leaf stage.

Rice leafroller is unsafe at the phase of hatchling. A solitary hatchling can devour roughly 25 square centimeter of leaf tissue, establishing under 40% of a typical leaf of rice. For the most part, the first instar hatchling slithered into the heart leaf or the leaf sheath close by, and the second instar hatchling started to turn silk at the leaf tip, and afterward started to transform into a little bug bud after the third instar. The food consumption at fourth and fifth instar, which representing over 90% of the absolute food admission of the hatchling. Despite the fact that, there are a few contrasts between various ages.

Methods of pest control

Cultural Control

Reform the tillage system and cultivation system, rational fertilization, avoid the early growth of rice, late ripening. Also, the damage of rice leaf roller could be reduced by avoiding early, middle and late rice mixed cropping. It is also possible to reduce the damage of pests through variety layout, setting up trapping and killing fields and reducing application area. It is also possible to harvest early rice according to the growth rate of the leaf roller, and then kill some larvae and pupae in deep water, so as to reduce the birth rate of the next generation

Physical and Mechanical Control

Rice leaf roller has phototaxis, it has a strong tendency to metal halogen lamp, and farmers can use light to lure and kill pests. Lure insect lamp has the advantage of quick, effective, and simple operation. It rarely requires medicament, and does not cause environmental pollution.

Biological Control

and re-event of the vermin, and furthermore slaughters characteristic adversary of the nuisances. In any case, regular foes can viably control the pest.It is assessed that there are in excess of 130 normal adversaries of rice leaf roller. Along these lines, the insurance and use of characteristic adversaries is vital to improve the maintainability of rice bug the executives

Chemical Control

The determination of pesticides ought to be founded on organic pesticide bacillus thuringiensis, select some high proficiency, low poisonousness pesticides. According to various ages, the utilization of pesticides ought to be sensibly masterminded and utilized on the other hand to forestall the obstruction of rice leaf roller.