What are the latest control methods for the rice water weevil?
The rice water weevil is one of the more damaging invasive alien species in China, but it has not been included in China's first list of invasive alien species. Also known as the rice water weevil and rice root weevil, it is a national class II quarantine pest. It originated in North America and was first discovered in 1988 in Tanghai County, Tangshan City, China. It has now successively occurred in 11 provinces and cities across the country. Let's take a look below at how to control the rice water weevil!
Morphological characteristics of the rice water weevil
The adult rice water weevil is 2.6-3.8 mm long, with a snout nearly equal in length to the pronotum, slightly curved, and flatly cylindrical. The pronotum is wide. The lateral margins of the elytra are parallel and wider than the pronotum, the shoulders are slanted, and there are tubercles on the intervals of the apical half of the elytra. Females have a sharp anterior process and a sharp process on the hind tibia, the sharp process being long and pointed, while males have only a short, stout forked sharp process. The pupa is about 3 mm long and white. The larva is white with a yellowish-brown head. The egg is cylindrical with rounded ends.
Damage characteristics of the rice water weevil
The rice water weevil is a semi-aquatic insect. Adults overwinter on dead grass on the ground, mate and lay eggs in late March, and the eggs are mostly laid inside submerged leaf sheaths. Newly hatched larvae feed only inside the leaf sheaths, then enter the roots to feed. Newly emerged adults crawl out from the pupal chambers attached above the roots and feed on the leaves of rice or weeds. The average adult lifespan is 76 days, and females live longer, up to 156 days. When causing damage, the insect population density can reach more than 200 per sq m.
Control methods for the rice water weevil
Spray with 4.5% beta-cypermethrin emulsifiable concentrate at 3000 times dilution per mu, or spray with 48% chlorpyrifos emulsifiable concentrate at 1000 times dilution; per mu, use 150 ml of 48% chlorpyrifos mixed with 15 kg of poisoned soil and broadcast it, keeping water in the field and letting it dry naturally. When spraying, add rice high-yield king or other foliar fertilizers and regulators to supplement nutrients and reduce losses. In hot seasons, pay attention to safe pesticide use, ensure personal protection for applicators, and spraying in the afternoon after 5 o'clock is preferable.
Control methods for the rice water weevil
1. Autumn plowing of rice fields to destroy stubble can greatly reduce the survival rate of overwintering adults in the field. Combined with manure accumulation and field management, clear weeds to eliminate overwintering adults.
2. After rice harvest, plow the land in time, which can reduce its overwintering survival rate, and protect natural enemies such as frogs, toads, spiders, ants, and fish.
3. The application of Beauveria bassiana and nematodes is effective for controlling adults. For pesticide varieties, it is preferable to choose pyrethroid pesticides.
4. It is strictly prohibited to transfer items that can carry and spread this insect from epidemic areas. Vehicles and packaging filler materials coming from epidemic areas should be strictly inspected, and insect-killing treatment should be carried out when necessary.