Sorghum stem borer, Chilo partellus, Family Crambidae, and Order Lepidoptera, is an important pest of sorghum crops widely distributed in tropical and subtropical parts of the world. It is a major pest of millet, sorghum, and other cereals, legumes, and fodder crops in Africa and other parts of the world.
In addition to grain yield losses, the pest can also cause significant damage to the crop by introducing diseases, such as smut and rust, which can significantly reduce the quality of the crop. To effectively manage this pest, it is important to understand its life cycle, preferred habitats, and the best methods for controlling it. The sorghum stem borer will be described in detail in this blog, along with its symptoms, locations, and control methods.
Stem Borer Management in Sorghum
Life Cycle of Sorghum Stem Borer
The pest has a complex life cycle involving multiple stages and plant and insect hosts. The adult stem borer is a moth that lays its eggs on the leaves and stem of the sorghum plant. These eggs hatch into larvae within an incubation period of 2-5 days, which feed on the plant for two to three weeks. The larval phase includes seven instars. During this time, the larvae create tunnels in the stem of the plant, causing it to become weak and prone to breakage.
Once the larvae have finished feeding, they move to the ground, where they pupate in the soil within 7 to 10 days. After two to three weeks, the adult moths emerge from the soil and begin the cycle again. The life cycle is completed in 30 to 40 days. The damage caused by the stem borer can be devastating. The tunnels weaken the plant and reduce the amount of grain produced. In addition, the tunnels can be a source of infection for other plant diseases.
Occurrence of Sorghum Stem Borer
- Location of Sorghum Shootfly: The pest globally occurs in India, Pakistan, Sri Lanka, Indonesia, Iraq, Japan, Uganda, Taiwan, Sudan, Nepal, Bangladesh, and Thailand.
- Host Range: The pest can cause an infestation in Maize, Sorghum, Sugarcane, Bajra, Rice, and Finger millet.
Factors Favoring Population Increase in Sorghum Stem Borer in Field
- Climate Change –Warmer temperatures and increased rainfall favor the survival of the SSB larvae and other life cycle stages.
- Poor Pest Management Practices – These include the lack of appropriate chemical applications, inadequate use of cultural practices to reduce the population of SSB, and the lack of proper monitoring and scouting to detect the presence of SSB in the field.
- Cropping Practices – Continuous cropping of sorghum without crop rotation or intercropping can also increase the SSB population. The same crop allows the SSB to build up its population and attack the crop more severely.
- Host Plants – SSB also finds suitable host plants other than sorghum, such as maize, wheat, and millet. These host plants provide an alternate food source for the pest and can contribute to the increase in its population in sorghum crops.
- Natural Enemies – The poor management of natural enemies, such as parasitic wasps and entomopathogenic fungi, can increase the SSB population.
Identification of Sorghum Stem Borer in Sorghum Field
- Egg: Yellowish, scale-like flat oval eggs laid up to 50 in groups on the lower side of leaves closer to the midribs and on the stems.
- Larva: Yellowish brown colored, brown head and prothoracic shield.
- Adult: The moth is medium size, straw-colored. The adult male moth has a white tuft of hair near its head.
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