Biological Control of Mealy Bug Is the Need of Future
Cotton is a major fiber crop of Pakistan. Among sixty cotton growing countries of the world, Pakistan stands at 4th position and third largest consumer of the cotton.
It plays pivotal role by providing food, fiber and fuel that earns foreign exchange. The cotton provides raw material to all oil mills, textile mills and ginning factories as well. It is also used for edible oil and 80% of national oil production also. Cotton is regarded as the mother of civilization because it has much more important utilization in our economy as well as in our culture.
It contributes 5.1% in value addition in agriculture, 1.0% in gross domestic product making up to 60% of the total export income. Because in Pakistan 55% of domestic cooking oil comes from cotton seeds.
Each year the cotton growers of Pakistan are suffering enormous losses in yield and quality of cotton crop due to attack of various insect pests and diseases.
In Pakistan, cotton crop is attacked by about 150 types of insect pests; which act as significant limiting factor in increasing its production. As compared to other cotton producing countries of the world, Pakistan cotton production is very low due to their inadequate or un-integrated management.
Cotton growers are always looking for ways to protect their crops from pest especially the present situation of cotton field in Punjab and Sindh provinces, where the crop is suffering from an emerging problem of mealy bug pest. Mealy bug (Maconellicoccus hirsutus) is a small insect having the size of about a small red ant, it gets its name due to its appearance.
It is wingless and have piercing–sucking mouthparts. Its female body is reddish but covered by the white cotton-like wax. When female’s body puncture the fluid is also reddish. Mealy bug belongs to order Hemiptera. Mealy bugs hibernate as eggs on stems, in soil, in cracks and gaps in the stem, and inside wrinkled leaves. The colour of freshly laid eggs are orange but turn into pink just prior to hatch. The nymphs need approximately 30 days to develop into adults. The insect has a life cycle of 24 to 30 days. The female mealy bug produces 10-15 generations per year in colonies of 500-600 eggs.
Mealy bug causes serious damage to a variety of crops due to that way it became a serious pest in many parts of the world, it attacks more than 300 plant species including sugarcane, cotton etc.
It feeds on the sap of the plant and after feeding it releases toxic material that causing injury, curling the leaves and as a result leaves dried, it also damages the vegetables, fruits drastically and decrease the yield badly. Mealy bug start attack especially where the root and the stem meet, mean just above the roots and just below the level of the soil.
Mealy bug also emits large quantities of honeydew on to the plants that attracts ants and sooty mould. During September 2005, a severe damage of mealy bug was recorded first time in Pakistan on an area of about 3000 acres in Sindh. During 2007 it destroyed the crop and caused a loss of Rs.159 crore in Pakistan in several districts of Punjab and Sindh.
This problem was appeared late when cotton crop was mature. But since last many years the attack of mealy bug has been observed in early stages of cotton crop that spreading very fast. About mealy bug it is stated that once mealy bug pests become recognized, it is particularly difficult to achieve acceptable control.
There are different signs of Mealy bug Infestation
Presence of honeydew, black sooty mold, and ants Unopened flowers which often shrivel and die Small distorted fruits, crumpled or twisted leaves and shoots.
For mealy bug in recent experiments in the district Sindh has shown that only the chemical control is not enough because it is not much control by chemically. No proper chemical was developed to control it. The other reason is that when mealy bug attack it produce large amounts of honeydew like whiteflies and aphids, which can coat plants and surrounding surface with a sticky or waxy layer of honeydew.
Pesticides cannot easily penetrate through the heavy wax layers. Therefore against the mealy bug pest the application of pesticides only is an ineffective control technique. Therefore a biological control is emerging for mealy bug.
Aenasius bambawalei is used against mealy bug. It is a solitary endo-parasite that kill the mealy bug naturally without use of any chemical. Aenasius bambawalei is a good biological control agent of the pest. Compatibleness is important in any IPM program, and the insecticide used must have little or no effects on the biological control agent. It can kill more than 40% of mealy bug nymphs. Its female laid eggs into the abdomen of mealy bug, when mealy bug female laid eggs the nymph of Aenasius bambawalei are produced.
After laying eggs mealy bug female are died the nymph feed the mealy bug nymph and adult as a result mealy bug population are controlled. So without using chemical we can control mealy bug attack bitterly. Biological control is the safes and most economical and long term solution to this problem. The expected cost to control of 25 mealy bug attack is just ten thousand rupees only.
This article is collectively authored by Kamran Akhtar, Narjis Ashfaq and Tauqeer Qadir.