Chemical and Biological Characterizationof Venom of the Ant Solenopsis Xyloni McCook

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. [I957]), 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 chem,ical and biological properties of these Sole, nopsis venom in order to possibly determine what is responsible for their different dermatological effects. Materials and lethodsVenom was collected from major .ormedia workers, employing a previously described method (Blum et al. 958).The chemical and biological properties of S. xyloni venom were studied by procedures described elsewhere (Blum et al. 958; Blum and Callahan 96o).A crystalline derivative of the main com,ponent in S. xyloni venom was prepared from an ether extract of 45o poison glands, dissected from major workers.The derivative was isolated by the method of Blum and Callahan (96o).The dermatological effects of the sting of S. xyloni to human beings were studied by observing reactions at sting sites. Results and DisoussionThe 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. xylo,ni, the venomous secretion o S. saevissima consists of an alkaline two-phase system in which the suspended droplets represent the m,inor phase (Blum et al. 958).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. 959; Blum and Callahan 96o).The infrared spectrum of the venom o S. saevissima is virtually superimposable on the spectrum of the venom of S. xyloni and it is probable that the amine.constituentswhich these