Biological control of coffee berry borer

By Our Agricultural Correspondent

COFFEE BERRY borer Hypothenemus hampei, one of the most dreaded pests of coffee, has been found to be effectively managed by biological control agents and an integrated pest management strategy. The white muscardine fungus, Beauveria bassiana, has been found to be effective in checking the population of the dreaded insect pest.

Various governmental and non-governmental organisations have contributed significantly in identifying and mass propagation of the bio- control agent for managing this scourge of coffee. The Directorate of Biological Control Laboratory, Bangalore, the Coffee Board, University of Mysore and some active NGO's in Madikere are some of the agencies engaged in the research and popularisation of the bio-control methods.

Virulent strains of Beauvaria bassiana, an entomophagus fungus, have been identified and extensively field tested. The mass propagation technology has been developed and it is being adopted by various agencies to distribute this effective fungal culture to all the coffee growers in the country.

The white muscardine fungus is sprayed on the infested plants, and it gradually kills the larvas of the pest, which is the most destructive stage of the pest. The effectiveness of this fungus in managing the pest depends on the environmental factors, which are conducive for its quick establishment and rapid spread. A high humidity of over 80 per cent and a temperature ranging between 25 to 30 degrees Celsius will be offer the best condition for the proliferation of this beneficial organism, according to the scientists.

In addition to this fungus, some parasitoids introduced from Mexico are also being evaluated. The bio-control method should be backed up by phytosanitary measures in the plantations. All dried, blackened and infested berried on the trees and on the ground should be gathered and burnt. They may also be buried at least 20 cm deep in the soil.

All the remaining berries should be collected after the harvest season to prevent infestation. Proper pruning should be done to avoid heavy shading, and in the well ventilated plantations, the pest incidence will be less. When the berries attain the size of a mungbean, botanical insecticides may be sprayed, and it should be repeated at fortnightly intervals.

The adult coffee berry borer is a black beetle. Much of the damage is caused by the female beetles. The insect feeds by boring into the berries. They also breed inside, and the emerging larvae continue to destroy one or more seeds. When they feed on tender fruits, the damaged berries either fall off or get infected by fungus and rot.

Most damage is suffered by the endosperms of matured beans. Even slightly bored beans turn distinctively blue-green, which reduces market value. By rigorously adopting the biological and cultural methods and restoring to the spraying of botanical insecticides at the appropriate time, the pest can be effectively managed, according to the scientists.

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