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Biological control of insects, mites for safe environs emphasised

KHALID ABBAS SAIF

FAISALABAD: Agriculture Scientists of Faisalabad University of Agriculture have emphasised the need of determining the role of biological control on insects and mites by establishing population levels to safe environment and to curtail the import of pesticides.

Mohammed Afzal, Department of Agri. Entomology, University of Agriculture, Faisalabad said that the Mites are microscopic creatures of the nature having four (4) pairs of legs and cosmopolitan in distribution. These have been recorded from diverse environmental conditions ranging from deserts to oceans, including all other types of habitats, which fall between them.

These tiny animals have been found associated with crops, vegetable fruit plants, pastures ornamental plants and forest trees beside this these also cause diseases in human beings and domestic animals. Asthma and itching diseases are common in human beings living in poor dewellings due to them-Plants are the most vulnerable to them.

Until 1993 these mite have been recorded from all of the economic crops from Baluchistan, Sindh, NWFP, Punjab, Azad Kashmir and Gilgit areas in our country. Their importance can be visualised as one mite belonging tetranychid mite can exhaust 18-20 cells of host plant per minute. Despite their direct feeding on plants they also play pivotal role in transmission pf epidemics of viral, bacterial and fungal diseases.

Various types of synthetic chemicals are being used to control these mites and insects since Second World War and after rediscovery of killing properties of DDT, for arthropods, he added.

He said that the chemicals (pesticides) used to minimise the economic losses have speedy nature of control and high benefit cost ratio if there is no resistance in insects and mites. The import of pesticides have been increased many fold in Pakistan from 1990 to to-date. In 1990, 13030.10 tonnes valuing Rs 1489.43 million and in last year 1999, 17913.00 tonnes valuing Rs 3101.80 million were imported to control agricultural pest in Pakistan. Beside their sole advantages these cause great havoc to environment like persistence and bio-magnification, environmental pollution contamination of water etc. Other discriminations include appearance of secondary pests, which were not harmful in resurgence and resistance, he added.

Muhammed Afzal said that these problems are world-wide as resistance has been reported from all corners of world including Australia, USA, Brazil, Thailand, India and recently Pakistan. On the other hand, biological control (to control life with life) is slow in action, environmental friendly and provides stable ecosystem without creating any disturbance.

He pointed out that the mites have great potential to be used as biological control agents. As these have been found feeding upon the wide variety of the hosts, like insects and mites themselves. Among these, phytoseuds have been recorded feeding from the tetranychids, (spider mites) tenuipalpids, tarsonemids, eriophyids etc. which harm plum, pear, apple, cotton, sugarcane, rice, citrus, squash, grape vine, walnut, mango, loquat, quince, pomegranate and many ornamental plants. These have also been found feeding upon mushrooms, and stored grains. Potential of these mites to control arthropod pest have been recognised world over. These can be incorporated intelligently in pest management programmes. Although these cannot provide control singly, but if conserved only can play great role to minimise economic losses, he added.

He said that correct identification which is an important component of integrated pest management (1PM) programmes is badly needed in developing countries like Pakistan. If we can differentiate among friend and foe it is very easy for us to eliminate enemies of human beings, he added.

He pointed out that the Research has been conducted in University of Agriculture, Faisalabad in the Department of Agriculture Entomology to identify these phytoseud mites. Extensive collection for these mites has been made all over the country for two years (1996-97) and 35 species have been recorded from our country for first time, which are new to the science. They have not been reported in other parts of the world till recently whereas 9 species have been recorded already till 1990. These were found to be feeding upon harmful mites and insects present on crops like peanuts, cotton, rice, vegetables (cucumber, bottle gourd) fruit trees (apple, fig, grape vines, papaya, peach, guava, banana, lasoori, apricot, pear, loquat, walnut, plum, mulberry, persimon and mango) forest trees (Poplar, Sukchain, Chinnar, Sufaida, Dherik, Kilcar and Sishwm) and wild and ornamental plants like Bhang, Swank and Roses. Some have been recorded from unidentified host plants.

There is dire need now to determine their role in biological control of insect and mites by establishing population levels. This will be very safe for our environment, human beings, and also escape us from the hidden dangers of resistance, resurgence and replacement, he concluded.