Leucaena psyllid is a sucking insect native to the area of Central America where the tree, Leucaena leucocephala, originated. Since the first sighting of the pest in Hawaii in 1984, the psyllid has spread over 3 million square miles, spanning the region between China and Australia. The psyllid's invasion, now reaching western India, is defoliating and, especially when followed by drought, killing leucaena plantings.
For example, when the psyllid first appeared in Hawaii, it provoked the growth of large populations of Curinus coeruleus, and Olla v-nigrum. These beetles were effective only after the psyllid population had already reached damaging levels. At the Winrock International conference Dr. Ida Nyoman Oka of Indonesia announced results of research to enhance the effect of Curinus. The mass production and release of the beetle in restricted areas of a tea estate controlled the psyllid population even at pre-damaging levels.
Two kinds of parasitic wasps from tropical America were found wherever the psyllid was present: a species of Psyllaephagus, and a species new to science; Tamarixia leucaenae. The more abundant Tamarixia may be a useful addition to a complex of natural enemies for controlling the psyllid in Asia.
Dr. George Funasaki of the Hawaiian Department of Agriculture announced at the Winrock International conference in Bogor that a Psyllaephagus wasp has reduced psyllid populations in Hawaii even in small incipient populations which the beetles do not find. Dr. Banpot Napompeth of Thailand's National Biological Control Research Centre, is directing efforts to establish this wasp in Asia.
As Africa prepares itself for the appearance of the Leucaena psyllid, the International Centre for Research on Agroforestry, together with CAB International and other regional organizations, are establishing an early-warning system to detect the pest's first appearance on the continent. While it may not be possible to halt the spread of the pest into leucaena-based African alley cropping systems, continuing research on biological control and resistant species may eventually present solutions for Africa.
For more information, write to:
International Development Research Center for their
Sustainable Agriculture Newsletter, Vol 1 (2)
Tanglin P.O. Box 101
Republic of Singapore.