LAST year, the mealy bug attacked on cotton crop in Sindh and Punjab. In 2006, the bug affected 11 districts in Sindh. Mirpurkhas and Sanghar were the worst affected.

Though some pesticides like profenofos proved effective against the pest, pesticides are not the long-term solution to the problem.

Over-dose of pesticides resulted in developing resistance in the pests and in the long run, they might not be effective. Therefore, methods of pest control, i.e. cultural and biological be applied. Biological control is one of safest and cheapest method.

The pink hibiscus mealy bug is very difficult to control with pesticides, because it hides in crevices on the bark, reproduces very fast and crawls off the host plants. Besides, its feeding distorts the foliage providing some protection from pesticides.

Pesticides cannot easily penetrate the heavy waxy layer on the pink hibiscus mealy bug’s body. Cutting and burning of affected plant can have a little impact on the spread of PHM.

Biological control is the use of natural enemies (parasite/predators) against pest organisms to reduce their population. Parasites are considered the long-term solution to the mealy bug problem. They self-parasite once released into the area and persist even when and continue to attack the bug.

The pest can be suppressed by the importation, rearing, release and by establishing host specific natural enemies (classical biological control). Natural enemies can provide substantial control. Several effective parasites of PHM are known in Asia and else where.

Cryptolaemus: A predacious beetle, some time called the red head lady bird beetle or the mealy bug destroyer, already established in Florida is commercially available. It is dark brown or blackish beetle, has organised head with reddish abdomen. It is small, about 3-4 millimeter long. A female can lay up to 10 eggs in a colony of eggs.

Its adult may live up to two months. It is a voracious feeder on mealy bugs and is capable of eating 3,000-5000 mealy bugs in various life stages during its life time. Its larvae coated with heavy wax are often mistaken for large mealy bugs. They are twice as big as adult mealy bugs and grow up to 1.3 centimeter in length.

Larvae can consume up to 250 mealy bugs. This beetle is considered to be a short-term solution to the mealy bug pest problem and can be used if rapid control of large mealy bug population is necessary within a 6-8 weeks period. Female of this beetle lays her eggs next to mealy bug eggs in “white wool” egg pouches, from eggs larval stage of this beetle emerges and is very similar in appearance to mealy bug, although only larvae of this beetle are mobile.

These beetles are very efficient in searching mealy bugs. Pupation occurs in sheltered places on stem or other substrate. This beetle undergoes complete metamorphosis and has about four germinations per year. These beetles are most effective at controlling mealy bugs, when the mealy bug population is high. Eggs and nymphs of mealy bugs are the preferred food for both adult and larvae.

This beetle can be used against all species of mealy bug and also feed on aphids and soft scale when mealy bugs are scarce. They are raised and released by citrus industry in California and are credited with the complete control of citrus mealy bug.

These are introduced as adults in small glass tubes, but should be released with in 24 hours of receipt. If necessary, hold at 60-65 deg F until release, should not be stored below 50 deg F, as chilling will injure the beetles. Release rates are five beetles per infested plant, or five per square meter of a planted area. In orchards release, 1000-2000 adult beetles per acre mature fruit trees.

Angyrus Kamali: Recently, several parasites from China, Hawaii and Egypt have been released on islands in the Caribbean to control the pink hibiscus mealy bug. This parasite reduced the pink hibiscus population by 80-90 per cent at the sites.

Female of this parasite lays an egg inside the body of adult mealy bug. From the eggs of parasite maggot like larvae emerge that feeds internally on the body of mealy bug and ultimately kills it. After pupation inside the bug’s mummified body, the adult parasite chews an exit hole in one end of mummy to emerge.

During her life time, a Kamali female is capable of parasitising 40-60 mealy bugs. These parasites also kill mealy bug by piercing their bodies and feeding their body fluids. It has ability to complete its life cycle less than half the time required for its host and has 15 days life cycle in tropical climates.

Hypoaspis: It is a tinny mite that feeds on a range of small insects and is particularly fond of mealy bugs. It quickly destroys both adults and eggs. It should be used on plants up to 30 centimeter/1 ft tall as cryptolaemus files to the top of taller plants and is not interested in smaller plants. Hypoaspis is delivered in vermiculite which should be sprinkled over the compost surface.

For getting effective control of mealy bugs on different sizes of crops, parasites and predators should be used accordingly i.e. for larger plants over three feet use lady bird beetles and for plants up to one foot height hypoaspis and for plants between the two heights.