Indian Affairs, he sprayed a virus preparation that was processed from 

 dead caterpillars over long test strips of aspens where tent caterpillar 

 larvae were feeding. The virus gave a good initial kill, and showed that 

 it could overwinter in the egg and give an even larger kill the following 

 year. Laboratory studies indicated that the insect eggs play a significant 

 role in this disease. The eggs can become infected from the outside, if 

 virus spray lands on them. The eggs can also contain the virus initially, 

 if laid by infected adults. 



A different line of attack on the tent caterpillar has been opened up by 

 encouraging tests with Bacillus thuringiensis . In one Forest Service ex- 

 periment in Utah, serviceberry bushes infested with the Great Basin tent 

 caterpillar were sprayed with this bacterial insecticide in late April. The 

 four dosages tried gave kills of 90 percent or higher within a month. 

 Dosages of the same strength in sun and in shade gave a higher kill where 

 pests fed in the sun. 



Gypsy Moth 



Varied disease agents are being tested against larvae of the gypsy 

 moth in a search for an efficient biological weapon suited to large-scale 

 control operations. This pest, that is so destructive to forest and shade 

 trees in the Eastern United States, had many natural parasite and disease 

 enemies in Europe where it came from. In this country a virus that causes 

 a wilt disease in the caterpillars has been the only disease agent known 

 to launch effective attacks on gypsy moth infestations. ARS and Forest 

 Service entomologists jointly have started laboratory and field tests on 

 gypsy moth caterpillars with this virus and some other disease agents, 

 including Bacillus thuringiensis and a bacteria-carrying nematode named 

 DD-136. 



FARM CROP PROTECTION 



ARS entomologists who specialize in farm crop pests include varied 

 microbes in field tests, but are focusing such work mainly on a few 

 promising types. A major problem for growers of many of these crops 

 is the control of destructive insects without an objectionable chemical 

 residue. Some of the microbial field tests include comparison of killing 

 rates with those of chemical insecticides in use. 



The following examples indicate lines along which progress is en- 

 couraging. Some of this work is by ARS scientists alone, some in coopera- 

 tion with State agencies and with industry. 



European Corn Borer 



Considerable disease work with the European corn borer is being 

 done in Iowa, at the USDA Corn Borer Investigations Laboratory in Ankeny 

 and cooperatively at theIowaStateUniversityinAm.es. A fungus ( Beauveria 

 bassiana ), a bacterium ( Bacillus thuringiensis ), and a protozoan ( Perezia 

 pyraustae) are all considered good prospective help. 



The fungus Beauveria bassiana is the one discovered in 1834 by Bassi 

 and named for him. Spores of this fungus work particularly well against 

 newly hatched larvae of first -brood corn borers, because these larvae 



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