Storage tests are included in production research, to learn the condi- 

 tions in which a microbial material can be kept for future use and what 

 storage life to expect. Some pathogens retain virulence well in storage; 

 some do not. Many viruses that stand both dryness and cold can be air- 

 dried and refrigerated, either in purified form or in dried larvae. Among 

 viruses thus stored, some have remained virulent for 25 years. On the 

 other hand, a virus used to kill the European spruce sawfly showed loss 

 of virulence after 2 years in storage- -indicating that keeping up fresh 

 supply of this virus may be advisable, perhaps on a yearly basis. 



COMMERCIAL PRODUCTS 



At present, two kinds of microbial insecticides are produced com- 

 mercially and registered with the USDAfor specifieduses. Here is general 

 information on the commercial status and background of each. 



A Japanese Beetle Killer 



Preparations containing milky disease spores for killing Japanese 

 beetle grubs are available to the public. When applied to soil or turf, the 

 spores sicken and kill the grubs --the young of the beetle - -where the 

 grubs feed on plant roots underground. The preparations are sold under 

 trade names through garden supply houses and similar outlets for soil or 

 sod application by farmers, gardeners, and homeowners. 



This spore material was developed and put to use years ago, and its 

 history is one of the success stories of microbial pest control. 



In Orient homelands, the Japanese beetle has never been a serious 

 problem. But when it found its way to New Jersey, about 1916, the beetle 

 seemed for a long time to have escaped natural enemies and it found some 

 275 kinds of trees, shrubs, field crops, and garden plants, and grass suited 

 to its voracious appetite. Chemicals, quarantines, traps, and other con- 

 trols curbed the beetle to some extent, but it crawled, flew, and ate its 

 way into 14 Eastern States. 



A disease was added to useful controls when, in the 1930's, some 

 grubs of the beetle in New Jersey were found to be dying of a disease 

 agent in the soil. A USDA research team identified two rather similar 

 sporeforming bacteria. Both bacteria cause milky diseases, so named 

 because the blood of the grubs, normally clear, turns milky white. A 

 single disease-killed grub releases to the soil several billion milky 

 disease spores. However, the disease in nature was found only in a small 

 area. The fast-spreading beetle had mainly escaped this fatal disease. 



The research team developed a method of getting quantity supplies of 

 the spores by inoculating grubs and grinding up and otherwise processing 

 the diseased insects. Government patents for producing this spore mate- 

 rial were obtained in 1941 and 1942 by S. R. Dutky, a USDA leader in this 

 research. Extensive tests showed that the spores do not harm man, domes- 

 tic or wild animals or birds, or earthworms. The spores can kill only the 

 Japanese beetle and a few related species. 



In 1939, a systematic program of treating beetle-infested soil was 

 started under guidance of USDAandState scientists, and by 1952 the spores 

 were established in 14 Eastern States. Meanwhile, in the 1940's under 



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