Stunting is also a damage symptom caused by other insect pests like root grubs and rice root aphids. To confirm the cause of damage, check for presence of insect: hyaline to yellowish to pinkish eggs. crawlers or nymphs, unwinged pink female adults and winged pale yellow males removing plant sap.
What it does
Both adult and nymph mealybugs remove plant sap by sucking. This results in curling of leaves and wilting of plants.
Importance of the issue
Mealy worm is the most important and commonplace pest in rice fields. The insect is located in upland and rainfed environments. It happens in nice quantity all over the rainy season. The insect feeds on rice all over the tillering and stem elongation phases. The noticeable symptoms are yellowing and stunting of the crop. And when the population of mealy bug is going very top management strategy need to be followed.
Common signs and symptoms
- Hyaline to yellowish to pinkish eggs
- Crawlers or nymphs, unwinged purple female adults and winged light yellow males disposing of plant sap
- Appearance of wax overlaying the eggs, nymphs and adults that stick at the stem or leaf
- Plant stunting
- Yellowish curled leaves
- Damaged spots or chakdhora or soorai disease
- Not uniform development of wear and tear
Problems with identical signs
Stunting is also a harm symptom led to by means of different insect pests like root grubs and rice root aphids. However, presence of rice mealy worm confirms its harm at the rice plant.
Causal organism and their spread
Rice mealy bug (Brevennia rehi (Lindinger)) reasons the damage. Both grownup and nymph causes the wear by way of sucking the plant sap.
The light yellowish male adults have a unmarried pair of wings and a waxy style-like procedure on the end of the stomach. The first and heart legs of the male are approximately equivalent, while the last or 3rd legs are longer. The body is 0.7-zero.nine mm long.
Adult women folk are rectangular and wingless. They are reddish white and soft-bodied. Their body is covered with a definite waxy or powdery coating. They measure about 1.2-three.zero mm lengthy and zero.five-1.5 mm large. They resemble woodlice in shape.
The first instar nymphs or crawlers measure 0.1-zero.2 mm wide and nil.3-0.five mm lengthy. Mature crawlers are 3-4 mm long.
The elongated or oval eggs are hyaline to yellowish to pinkish. They are zero.3 by means of 0.5 mm. They are lined with wax. The eggs turn grayish red when about to hatch.
Dry spells and the presence of grassy weeds (similar to Echinochloa sp. and Cyperus sp) that harbor this insect pest want the inhabitants buildup of the rice mealy worm. Likewise, well-drained soils are also suitable for the insect pest.
The rice mealy trojan horse is located in upland and rainfed environments. It isn’t commonplace in irrigated rice. It happens in great number during the rainy season.
The insect is considerable in April to early July where two generations are finished all through this era.
Mechanism of damage Both the adults and nymphs remove plant sap the use of their sucking mouthparts.
Ideal control strategy
Apply dimethoate at 0.05%
Why and where it occurs
Dry periods and the presence of grassy weeds that harbor this insect pest favor the population buildup of the rice mealybug. Likewise, well-drained soils are also suitable for insect pest.
The rice mealybug is found in upland and rainfed environments. It is not common in irrigated rice. It occurs in great number during the rainy season.
The nymphs are active until they molt. They first stay under the body of the adult female and later crawl from plant to plant. They are also dispersed by wind. After dispersal, they stay between the leaf sheath and stem to feed and complete their entire larval development. After molting, the female attaches itself to the plant for life and grows in size.
The adult females remain stationary and feed while the winged adult male flies off.
The insect is abundant from April to early July. Two generations are completed during this period.
How to identify
- Mealybug damage causes:
- plant stunting
- yellowish curled leaves
- damaged spots or chakdhora or soorai disease
It does not have a uniform pattern of damage.
Stunting is also a damage symptom caused by other insect pests like root grubs and rice root aphids. To confirm the cause of damage, check for presence of insect:
- hyaline to yellowish to pinkish eggs
- crawlers or nymphs, unwinged pink female adults and winged pale yellow males removing plant sap
- appearance of wax covering the eggs, nymphs and adults that stick on the stem or leaf
Why is it important
When conditions are favorable to the insect, high population of the pest can cause yellowing and stunting of the crop.
Rice mealybug causes heavy losses to crops in Bangladesh, India, and Thailand. High pest density (>100 mealybugs/hill) can cause plants to wilt and die.
Encourage biological control agents: small encyrtid wasps, spiders, chloropid fly, drosophilid, and lady beetles