The development of resistance to pesticides is generally acknowledged as one of the most serious obstacles to effective pest control today. Since house flies first developed resistance to DDT in 1946, more than 428 species of arthropods, at least 91 species of plant pathogens, five species of noxious weeds and two species of nematodes were reported to have developed strains resistant to on or more pesticides. A seminar of U. S. and Japanese scientists was held in Palm Springs, California, during December 3-7, 1979, under the U. S. -Japan Cooperative Science Program, in order to evaluate the...