Sorghum Stink Bug: Symptoms And Solutions

Sorghum stink bug is an important insect pest of sorghum and is commonly known as the green vegetable bug or green shield bug. The Sorghum stink bug is a polyphagous pest, which means it feeds on a wide range of plants other than sorghum, such as pulses, pearl millet, sunflower etc. They feed on all parts of the plants, but mainly cause damage to the developing grains. In this article, we will explore the impact of stink bugs on sorghum crops and management strategies for controlling their populations. 

The adult sorghum stink bug is a greenish brown insect with a shield-shaped body and has a characteristic triangular pattern on their body. Sorghum stink bugs are known for their unpleasant odor, which is emitted as a defense mechanism when they are disturbed or crushed. 

Type of Infestation

Sorghum stink bug infestation can be categorized into two types, viz. primary and secondary. Primary infestation occurs when the insect feeds on the plant during the vegetative stage, leading to stunted growth. Secondary infestation occurs when the insect feeds on the developing grains, causing the grains to shrink and deform.  

Scientific Name: Nezara viridula 

Most Affected States

Sorghum stink bug is a major pest of sorghum in many parts of India. Some of the states most affected by this pest include Maharashtra, Karnataka, Andhra Pradesh, Tamil Nadu, Gujarat and Rajasthan.  

Symptoms of Sorghum Stink Bug

Sorghum stink bug infestation can cause significant damage to the sorghum crop. Some of the symptoms of sorghum stink bug infestation are as follows:  

• They feed on the leaves of sorghum plants, making rows of holes on leaves.
• Using their sucking type of mouthparts, they feed on the developing grain.
• As a result of sucking, shrinkage and black color discoloration of grains can be seen.
• Infested grains become ill filled or chaffy.

Control Measures

The following are the various cultural, physical, mechanical, biological and chemical measures that can be employed to effectively manage sorghum stink bug infestations. 

Cultural Control

• Following crop rotation with non-host crops reduces the sorghum stink bugs population.
• Early planting decreases the likelihood of the flowering period coinciding with the peak activity of stink bugs.
• Proper nutrition management, including balanced fertilization and irrigation can also help to reduce the susceptibility of sorghum plants to stink bug attacks.

Physical Measures

• Installing Solar Light Traps in sorghum fields helps in trapping the stink bugs. For effective trapping install one light trap per acre.

Mechanical Measures

• Collect and destroy the heavily infested plants.
• Barrix Magic Sticker Trap Yellow Sheet attracts adult stink bugs and kills them. For an acre, use 10 sheets of sticky trap and place them above the plant foliage for effective trapping.

Biological Measures

• Release natural enemies such as spiders and birds to prey on the sorghum stink bugs.
• Parasitic tachinid flies and wasps lay eggs into the eggs of stink bugs and their larvae feed on the hatching maggots, thereby reducing stink bug population.
• Ecotin Insecticide is a neem based biological insecticide containing Azadirachtin, which can be used effectively to control sorghum stink bugs. The recommended dosage is 0.4 – 0.7ml per liter of water.

Chemical Control

Commercial chemicals that can be used to control sorghum stink bug includes, 

Product Name	Technical Content	Dosage
Karate Insecticide	Lambdacyhalothrin 5% EC	1.5 ml/lit of water
Ekalux Insecticide	Quinalphos 25% EC	2 ml / lit of water
Alika Insecticide	Thiamethoxam 12.6% + Lambda-cyhalothrin 9.5% ZC	0.5 ml/lit of water
Profex Super Insecticide	Profenophos 40% + Cypermethrin 4% EC	2 ml/lit of water
Asataf Insecticide	Acephate 75% SP	1.5 gm/lit of water
Koranda Insecticide	Chlorpyrifos 50% + Cypermethrin 5% EC	2 ml/lit of water