CHEMICAL AND BIOLOGICAL CHARACTERIZATION 
OL VENOM OE THE ANT SOLENOPSIS XYLONI 
McCOOK 
By Murray S. Blum 1 , J. E. Roberts, Jr. 2 , and A. F. Novak 3 
The reaction of human beings to the sting of the indigenous southern 
fire ant ( Solenopsis xyloni McCook) is in marked contrast to that 
produced by the sting of the closely related imported fire ant 
( Solenopsis saevissima [Fr. Smith]). Whereas the sting of S. saevis- 
sima is characterized by a painful edema and marked necrosis (Caro 
et al. [1957]), we have found that the sting of S. xyloni seldom 
results in more than a mild prurience. These facts strongly indicate 
that the venoms of these two species of Solenopsis differ chemically. 
The purpose of this present paper is to compare the chemical and 
biological properties of these Solenopsis venoms in order to possibly 
determine what is responsible for their different dermatological effects. 
Materials and Methods 
Venom was collected from major or media workers employing a 
previously described method (Blum et al. 1958). The chemical and 
biological properties of S. xyloni venom were studied by procedures 
described elsewhere (Blum et al. 1958; Blum and Callahan i960). 
A crystalline derivative of the main component in S. xyloni venom was 
prepared from an ether extract of 450 poison glands dissected from 
major workers. The derivative was isolated by the method of Blum 
and Callahan (i960). 
The dermatological effects of the sting of S. xyloni to human beings 
were studied by observing reactions at sting sites. 
Results and Discussion 
The chemical properties of the venom of S. xyloni parallel those of 
the venom of S. saevissima in nearly all respects. Like the venom of 
S. xyloni , the venomous secretion of S. saevissima consists of an alkaline 
two-phase system in which the suspended droplets represent the minor 
phase (Blum et al. 1958). The main constituent in the venom of 
S. xyloni is an amine which is chemically comparable to the amine 
isolated from the venom of S. saevissima (Adrouny et al. 1959; Blum 
and Callahan i960). The infrared spectrum of the venom of 
S. saevissima is virtually superimposable on the spectrum of the venom 
of S. xyloni and it is probable that the amine constituents which these 
department of Entomology, Louisiana State University. 
department of Entomology, Louisiana State University. Present Address: 
Louisville General Hospital, Louisville, Kentucky. 
department of Agricultural Chemistry and Biochemistry, Louisiana State 
University. 
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