USE OF DISEASES TO KILL PLANT INSECT PESTS 

 A Research Progress Report 



Man is learning, through scientific methods, to get more dependable 

 benefit from a kind of pest control observed in nature: the killing of 

 insects by their own diseases. 



This control in nature is uncertain. Now and again, a pest-ridden 

 forest or farm crop is rescued from destruction by a virus or other in- 

 fectious disease organism that spreads and kills the ravaging insect. But 

 many voracious insects wander or are carried about, and leave their fatal 

 diseases behind. And when a pest does meet up with a disease agent, the 

 kill of the pest is often too little or too late to be of much use to man. 

 Over the years, nature's help with insect diseases falls short of what man 

 may achieve by applying the right disease agents in a scientific way. 



A scientific approach is to apply a disease organism in large quanti- 

 ties, in a spray or dust, at the proper time, with due regard for insect 

 habits, weather, and other conditions on which a successful kill depends. 

 In research with this method, scientists have employed varied pathogens 

 (disease-causing organisms) --including bacteria, fungi, protozoa, viruses, 

 and bacteria-carrying nematodes. As an informal word for any of the 

 disease agents so used, many scientists accept the term "microbe." And 

 the sprays and dusts containing microbial material are often called 

 microbial insecticides. 



A scientist's concept of the ideal microbial insecticide has been put 

 in these terms: It should be highly infectious for at least one pest insect, 

 preferably for a large number of kinds. It should be easily and inexpen- 

 sively produced. It should be capable of being stored for a long period. It 

 should pose no hazard to man, or to animals including beneficial insects. 



Carefully tested microbes are now produced in research laboratories 

 on a quantity scale and used under scientific guidance against some forest 

 and farm pests in the United States and other countries. In addition, the 

 public in this country can buy two bacterial insecticides commercially 

 produced for uses designated on registered labels. 



There is prospect of further uses for microbial materials through 

 agricultural and forestry research under way. Interest in this use of insect 

 diseases has been spurred by the resistance that many serious pests have 

 been developing to chemical insecticides. Alternate chemicals have been 

 introduced in some instances, and such adjustments will undoubtedly 

 continue. At the same time, there is recognized need to gain command of 

 varied pest-fighting tactics and weapons. Microbial materials also have 

 possibilities for use in some situations where chemical residues would be 

 objectionable. 



Entomologists are hopeful that the microbial method can be used in 

 protecting livestock and man against harmful insects, such as some flies 

 and mosquitoes. Work toward this goal is under way by some research 

 agencies, including those of the U. S. Department of Agriculture. 



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