Also known as cotton stainer, this insect and its nymphs mainly attack partially-opened cotton bolls, causing stained lint, boll discoloration, rot and occasionally, also shedding (partly due to the bacteria transmitted while feeding on the cotton sap). Further symptoms are underdeveloped, light seeds that fail to ripen properly. High infestations can cause a severe loss in quality of the harvest due to the stained lint, hence the common name cotton stainer. When feeding on other host plants like okra, common symptoms are a pungent smell and greasy secretions.
Damage is caused by the dusty cotton stainer, Oxycarenus hyalinipennis, a polyphagous insect that may be a severe pest of cotton. Adults reach a length of 4-5 mm and are dusky brown with transparent wings. Males are slightly smaller than females. Whitish-yellow eggs are laid in groups of up to 4 on the lint of open bolls, close to the seeds. Nymphs are up to 2.5 mm long and change their color from pink to brown during the different stages of their life cycle, which lasts about 40-50 days in total. The infestation occurs in the end of the season, when most bolls are already open. Further host plants are okra and other plants of the malvaceae family.
In Africa, some species of parasitic mites are found on the bugs, which become sluggish and soon die. Some spiders also attack this pest. Foliar sprays with diluted neem oil (5%), entomopathogenic fungi, like Beauveria bassiana and Metarhizium anisopliae have also shown some effect on the control of populations.
Always consider an integrated approach with preventive measures and biological treatments if available. The foliar application of insecticide formulations containing chlorpyrifos, esfenvalerate, bifenthrin, deltamethrin, lambda-cyhalothrin or indoxacarb works against the pink bollworm and has shown to reduce dusky cotton stainer population as well. However, because this insect usually infests fields late in the season, chemical control is often not feasible due to the residues on the harvest. Resistance to insecticides has also been described.
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