Contents - Faperta

8
Genetic Engineering of Entomopathogenic
Microbes for Pest Management
Introduction
Entomopathogenic bacteria, viruses, fungi, nematodes, and protozoa have a great potential
as a component of integrated pest management. However, they still account for 3% of
the total pesticide market, and formulations based on the bacterium, Bacillus thuringiensis
(Berliner) account for 80% to 90% of the commercial microbial pesticides. The commercial
value of microbial pesticides is estimated at US$100 million per year (Meadows, 1990;
Neale, 1997). The major constraint to the use of biopesticides is the need for simultaneous
management of three biological systems: the pathogen, the prey, and the crop. Their greatest
application is in vegetables, gardens, and orchard crops. Despite several advantages of
biological insecticides, many factors have hindered their commercial success and practical
effectiveness. Some of the problems associated with the use of microbial pesticides for pest
management include:
• Quality and effectiveness;
• Unstable formulations and delivery systems;
• Sensitivity to light, relative humidity, and heat;
• Short shelf-life, especially in hot and humid conditions; and
• Limited host range and specifi city to a particular stage of the insect.
Effective use of microbial pesticides often requires a more complex infrastructure than
is needed for conventional pesticides. These include control of environmental conditions
in the production area, an effi cient system to deliver the product to the farmers, and training
the farmers on the effi cient use of biopesticides. With the exception of fungi, microbial
insecticides do not kill the target insect on contact, but need to be ingested. The insect
must feed on some plant tissue carrying the biopesticide before the agent can cause the