The fungi in insect pathology are anenigma, 
These organisms kill countless insects yearly. 
Apparently they select their own time and 
place to do so, Attempts to use these orga- 
nisms have not been universally successful 
and, without a doubt, the pathology of ento- 
mogenous fungi is one area in which basic 
research is absolutely essential. Extensive 
studies on entomogenous fungi have been 
progressing for some years now under the 
direction of D. M. MacLeod of Canada, 
Miller-Kogler of Germany, M. F. Madelin 
of England, and J, N. Couch in the United 
States, yet many problems of the most basic 
nature still exist. For example, the fungi 
usually invade through the integument; yet 
our knowledge is negligible of the precise 
means of invasion, the enzymes used, the 
optimum conditions for invasion, and the 
mechanics of this operation. 
We are aware that fungi are likely affected 
by temperature and humidity, yet conflicting 
reports of the effect of these parameters on 
insect attack by the organisms leave us 
helpless to use these agents with knowledge. 
We are aware that fungi are variable, that 
they mutate readily; but we know nothing of 
the relative insecticidal and invasive ability 
of the strains that are selected by environ- 
mental conditions. Here indeed is a rich field 
of endeavor; and until we obtain more knowl- 
edge of this type, we are unable to make full 
use of these promising agents in microbial 
control, 
The Rickettsiales have until recently been 
of more concern to medical entomologists 
than to insect pathologists. These are fas- 
tidious organisms that usually have a long 
developmental period in the host and thus 
likely are not so useful for rapid, decisive 
control as some pathogens from other groups. 
The suspicion that the Rickettsiales isolated 
from insects may have the ability to grow in 
animal cells makes them unlikely candidates 
for general insect control at present. Never- 
theless, several investigators, including 
A. Krieg, A. Huger of Germany, andS, R, Dutky 
of the United States, continue their investiga- 
tions of this group. 
There are over 100 species of nematodes 
associated with insects. These animals could 
be developed into desirable control agents; 
however, their requirements in the field are 
71 
just beginning to become understood through 
research by S. R. Dutky, H. E. Welch in 
Canada, and J. Weiser in Czechoslovakia. 
More extensive research in field application 
and assessment is required along with sup- 
porting basic research on nutrition and effect 
of environment. 
The first successful attempt on this con- 
tinent to use micro-organisms was carried 
out by Dutky, who used the bacterium Bacillus 
popilliae Dutky to control the Japanese beetle 
(Popillia japonica Newman). After intensive 
basic research on the disease and the disease 
organisms, Dutky devised a method of pro- 
ducing the organism by using the insect as a 
living culture medium. Through his efforts 
the project developed into a massive control 
program between 1939-52 that was carried 
on in 14 States and the District of Columbia 
and involved the distribution of 184,000 pounds 
of spore-bearing preparation at 140,973 sites 
on 109,119 acres,1 One company is still pro- 
ducing the spore preparation according to 
Dutky's method, while intensive research is 
being conducted on alternative methods of 
producing this bacterium by the fermentation 
process at the Northern Utilization and De- 
velopment Laboratory at Peoria, IIl. 
Dutky gave us more by this classical ex- 
ample of research and development than is 
first apparent. He delineated the route we 
must follow in the development of a microbial 
agent from the original isolation to the appli- 
cation of a competent insect-control prepara- 
tion. Most of his findings have been summarized 
in a recent publication (Dutky 1963). 
The key Dutky gave us to increased use 
of insect pathogens, today and in the future, 
is production of large amounts of the pathogens 
now available. There are now in existence 
many fine bacterial, viral, and protozoal 
pathogens, and most of these grow only in 
insect tissue. Several of these available micro- 
organisms have been laboriously produced 
in gram quantities for limited field trials by 
Government agencies throughout the world. 
As a result of these trials, we are certain 
that the potential of these organisms is 
enormous; yet no further progress will be 
made and large-scale use will not be possible 

1 Report of Chief of former U,S, Bureau of Entomology 
and Plant Quarantine, 1953, 
