COTTON and MEALYBUG

COTTON and MEALYBUG

Agriculture plays a pivotal role in the economy of Pakistan. It contributes about 24% to national GDP and employs 44% of the total labor force. Cotton, Gossypium hirsutum L. is the most important fiber crop of Pakistan and in the world.  It is cultivated on more than 30 million hectares in about 80 countries. The land under cotton cultivation in Pakistan has increased overtime, however, the yield per hectare is much lower compared with other cotton growing countries being fifth in the world .Cotton is cultivated over 3 million hectares, covering 15 per cent of the cultivable area in the country. It plays a significant role in the economy of Pakistan which contributes 8.5% of GDP in agriculture sector and about 60% of foreign exchange earnings and fulfills 64% of our edible oil requirements .Cotton is used to make a number of textile products. In addition to the textile industry, cotton is used in fishnets, coffee filters, tents, gunpowder, cotton paper, and in book binding. The cottonseed is used to produce cottonseed oil. Cotton linters are fine, silky fibers and these curly fibers are less than 1/8 in or 3mm long. In Pakistan two varieties of cotton are cultivated, American cotton and desi or local cotton .Cotton is the perfect host for variety of insects. There is the greatest diversity of insect pests of cotton in Pakistan; in this country more than 1300 species of insects are found attacking on cotton crop. Cotton crop is attacked by many chewing and sucking insects that cause about 20-40% loss annually. Out of the Bemisia tabaci and Oxycarenus laetus, Phenacoccus solenopsis is one of the serious pests of cotton.

Mealybug, P. solenopsis (Hemiptera: Pseudococcidae) is a polyphagous pest and multiply on different hosts like field crops, horticultural, fruits, vegetables and ornamental plants. It was described originally from the U.S in 1898 .Recently; P. solenopsis has emerged as a serious sucking pest of cotton due to decrease in the number of pesticidal applications in cotton agro-ecosystem, and caused serious damage in cotton in Pakistan during 2005. The mealy bugs feed on phloem tissue, removing plant sap and causing leaves to distort yellow and dry. They feed on all parts of a plant, particularly new growth. Yellowing of leaves or leaf drop is the symptom of its infestation. They can be observed particularly on growing tips or on leaves that join stems or along leaf veins. Like the aphids, mealy bugs also excrete the honeydew substance over plant surfaces and sometimes a secondary fungus called black sooty mold that grows on it and reduces the quality of the lint. Study carried out in Punjab of the Pakistan during 2007-08 indicated losses to the tune of 3.1 million bales from the targeted output of 14.3 million bales due to mealy bug attack. Management of mealybug is difficult due to its wide host range, presence of waxy coating on the body and high reproductive potential. But the crawler stage is the most fragile and easily controllable stage in its life history. Recently some organophosphates, insect growth regulators (IGRs) and Bio-pesticides have been recommended for the control of mealybug. Predaceous coccinellids are important entomophagous predators of arthropod pests’, including whiteflies, aphids, scales and mites and has been using continuously for decades because of their easy collection. Alternative control of cotton mealybug is through their  predators and among them coccinellid beetles like  all the predaceous life stage of M. sexmaculatus, C. septempunctata, B. suturalis, H. convergens, especially C. septempunctata, B. suturalis, are found potential  predaceous stages/predator for first instar nymphs of cotton mealybug and hence, should be evaluated in the field. This is one of the very effective ways of controlling mealybug.