A 40 year legacy depleted, once magnificent trees in bloom are now skeleton like, having no leaves or flowers. These trees have been at Galle Face Hotel for as long as anyone of our generation can remember. Witnessing their degradation, as a result of their branches being chopped off, over the course of mere months, makes one realize the tight grip which mealy bugs have had on sappy trees and plants across the nation.

The Agriculture Department has taken comprehensive measures against the mealy bugs. The importation of a parasitoid wasp, a natural predator of the mealy bug, completes the list of measures for the integrated pest management of the mealy bug.

For a quick review of these measures, I met up with Mr. G. M. Gamage, general manager of Hayleys Agro. To help raise awareness on the mealy bug, Hayleys Agro has distributed several leaflets. They have also set up a help desk with round the clock assistance.

"We used to get calls as late as 12 at night and distressed people came to us almost every day with infected plant samples," says Mr. Gamage. Their leaflets outline the basic measures of mealy bug control such as cutting and burning infected plants, spraying plants with pressurized jets of water, or soap water with a mixture of kerosene for non edible plants and a shampoo mixture for edible plants. Application of grease on tree barks is recommended to prevent reinfestation.

Chemical control is recommended only as a last resort and usually only for large scale cash crops. On a domestic level, choices are limited to those simple measures mentioned above. On the other hand, biological control using the parasitoid wasp is the most promising method and the government hopes to permanently control mealy bugs in this country with it.

In previous cases of pest infestation in Sri Lanka, never has there been a pest with such a wide host range. Therefore, the only effective long term solution of controlling the pest is biological control says Dr. K.A.N. P. Bandara, a research officer attached to the Agriculture Department in Gannnoruwa.

The wasp (Acerophagus papayae) affects only the papaya mealy bug. Many people are not aware that there are many different species of mealy bugs that are still being identified. This wasp lays eggs inside the papaya mealy bug, during the second and third instar stages, thus killing the bug.

The wasps arrived in Sri Lanka from the U.S. in small test tubes packaged under controlled conditions. Half of them are being reared in laboratories and the rest are to be released in carefully selected locations.

Dr. Bandara had just returned from Polonnaruwa, where the wasps were released on Saturday 16th of May. "We will continue to monitor the areas where the wasps were released to observe their progress", he said.

Wasps are due to be released in ten locations in the districts of Colombo, Kurunegala, Gampaha and Kegalle, all areas with perennial trees such as Araliya, Jak fruit etc. After the release of wasps, pesticides must not be sprayed on plants in these designated areas. Following continued observation and repeated periodical release of wasps, it is expected that the mealy bug problem would be permanently under control within six-months to one year.

"Fears of non-target organisms being in danger are unfounded," says Dr. Bandara. "The wasps do not harm humans, other plants or animals. The only other scenario is the wasp attacking another species of mealy bugs. In addition, we are also observing local parasitoids for evidence suggesting that they may be attacking certain mealy bug species. All this can only be confirmed with further research."

Up until these attempts of biological control, most farmers were using toxic pesticides in their attempts to control the infestations. During the usage of pesticides, Admire SL 200 was recommended by Hayleys Agro. Although its toxicity is low, being a synthetic pesticide, it is naturally frowned upon by environmentalists.

A plant extract from neem oil (kohomba), whose active principle is azadiractin, a natural bio-pesticide, is also available although it is mostly effective on a small scale. But the Department of Agriculture is still conducting research on its pesticidal effects with regards to the mealy bug. This solution has been overlooked and has not received much publicity, however internationally many in the scientific community feel that the neem plant extract used for thousands of years by easterners could be a promising environmentally friendly pesticide in the future.