Final report covering period September 1988-December 1992 : screening of new B. thuringiensis strains for integrated pest management in Costa Rica

in Jerusalem, Israel, and a team of scientists at the University of San Jose, Costa Rica. Ecological hazards due to use of chemicals, particularly pesticides, have made the search for biological replacements a global decree. In response, a variety of biopesticides have been proposed. The two research teams involved in this program sought to develop a whole family of cost-effective Bt-based products. Efforts were focused on three major pests of vegetable crops, and primarily on old-world bollworm (Heliothis armigera), Egyptian leafworm (Spodoptera littoralis), and diamondback moth (Plutella xylostella), which are devastating pests of cruciferous and solaneous vegetables. At the outset it was clear that in order to attain cost-effective pest control it is possible to use naturally occurring Bt strains that are isolated from different niches in the environment. However, such isolates required significant improvements before they could be turned into commercial products. Within four years the program resulted in the isolation of three highly potent Bt strains, each against one of the above mentioned pests. This was followed by intense research using sophisticated techniques in molecular biology. The naturally occurring strains were manipulated so as to enhance the expression of toxin plasmid genes as well as broaden the pest spectrum. The main accomplishments of the project were the identification of useful Bt-based biopesticides, their improvement by genetic manipulation, and the targeting of those strains towards major pests that in the future will have to be controlled by biorational means. The close collaboration between the two teams will create the foundation for highly qualified research in Costa Rica where scientists are eager to make progress in such a prominent area. (Author abstract)