Potential of insect pathogens in the tropics

In North America and Europe, the slow shift in emphasis from the use of chemical insecticides to ecologically-based integrated pest management programmes had stimulated research into exploitation of insect pathogens as well as other biotic agents. So far, the greatest progress in using pathogens had been made in the following area -forests, vegetables and protected crops. Tt present, several species of pathogens were mass-produced commercially and formulated to a consistent quality. These were viruses (9), bacteria (2), protozoa (1) and very likely in the near future, nematodes. More pathogens were mass-produced along non-commercial lines in several countries but information on the quality and effectiveness of these products was generally lacking and in some cases quality was known to be very variable. Few pathogens were exploited in tropical countries. Possibly meteorological conditions, and the germicidal effect of sunlight and insect phenology, and overlapping generations, in the tropics reduces the chances of success compared to those in temperate zones, but in some cases the possibilities of success were enhanced e.g. tropical humidity would favour fungi. Probably, the main limitation on the use of pathogens was that little research in this area had been undertaken so far in the tropics. Effort should be made to train personnel in techniques of pathogen identification, isolation, manipulation, production and use. The methodologies were usually not difficult and adapted to meet the needs of agriculture in most situations. Commercial exploitation of pathogens was not always relevant and production at a local level is the only feasible option. This aspect raised problems concerning the purity and therefore, safety and efficacy of microbial insecticides. With these caveats in mind, this paper attempts to assess realistically the prospects of using pathogens in the tropics