Mealy Bug meets it’s match

By Nizla Naizer

Close to 4000 parasitoids brought down from Puerto Rico have been released to various locations in Sri Lanka to control the spread of the alien papaya mealy bug (Paracoccus marginatus) or ‘piti makuna’ that has been devastating plants across the island.
Officials at the Department of Agriculture, pointed out that although the heavy rains in the West and South of the island has restricted the spread of the pest; the mealy bug has reached the drier zones in the North Western and North Central Provinces, from Puttalam to Ambilipitiya and Sooriyawewa. However, they are closely monitoring the progress of the recently released parasitoids, and are in the process of culturing more in an attempt to biologically control the pest before it reaches the commercial papaya cultivations in the dry zone.
The parasitoid’s journey
The 5000 parasitoids (Acerophagus papayae) were flown in to the country on May 15 after an elaborate diplomatic process to ensure that the miniscule bugs survived the long journey from Los Angeles to Colombo. The parasitoids which were developed at the Puerto Rico Department of Agriculture, have been established as the most successful way of negating the mealy bug menace. However, the entire process of obtaining the parasitoids was initiated by the Consul General for Sri Lanka in Los Angeles, Ananda Wickremasinghe who having served at the Department of Agriculture Sri Lanka, was keen to assist our agriculturists as the bug kept spreading in the country.
The tiny parasitoid is an insect less than 0.5 mm in length and has already proven to be a successful controller of the PM in other parts of the world. However scientists at the U.S. Department of Agriculture had warned that it would be susceptible to x-ray scans and rough handling en route to Sri Lanka, so the 36 hour Los Angeles-Dubai-Colombo route for the creatures were filled with prior stamps of approval to let the insects enter Sri Lanka as soon as possible, with less interference as possible.
Feeding on the mealy bug
The parasitoids were brought into the country as adults, which meant less time was required for quarantine, Department of Agriculture, Horticulture Research and Development Institute Research Officer, Anura Wijesekara explained. “They were checked at the Department of Agriculture in Gannoruwa, and then released to areas in the Colombo, Kegalle, Kurunegala and Polonnaruwa Districts on May 16.” The parasitoids were released in sets of 400 and he informed that the Institute was carefully monitoring their progress to see if they adapt to the Sri Lankan environment.
Out of the initial batch of 5000, the Department kept 1000 to culture and breed, in order to release them in larger batches to the heavily affected areas. “It will take another month to see the results of the parasitoid introduction,” he continued, “These insects lay their eggs on the mealy bug. The larvae then develop inside the mealy bug for a bout two weeks, feeding off the pest and eventually destroying it.”
Meanwhile, Wijesekara also informed that they have been monitoring the development of a natural predator that is emerging in the environment. “There is a type of butterfly larvae which we have observed feeds on the mealy bug, and has emerged as a local predator for the pest. However, they are only suitable for certain areas where the spread of the mealy bug isn’t too rampant like Colombo or Gampaha.”