Bee Sting: The Chemistry of an Insect
Venom Rod O'Connor and Larry Peck Texas A8M University College Station, TX 77843 From ancient times. bee venom has held a dual interest for and sometimes fatal, reactions to bee man. While the stines have develooed a healthy . resoect . for the bee as an adversary, potential therapeutic uses for the venom were recognized even in very early civilizations. Both interests have stimulated chemical research into the composition and activity of the venom. The first crude investigation of bee venom, in 1897, led to the erroneous report that it was principally formic acid. Although this was disproved many years ago, it is not uncommon to find a chemistry textbook still describing formic acid as the main component of the venom, and the principal venom source is still referred to as the "acid gland," although the venom is actually quite alkaline. We know today that the venom contains only a trace, a t most, of formic acid. Bee venom actually consists of a highly complex mixture of enzymes, peptides, and smaller molecules, many of which exhihit potent physiological activity (I). The venom is produced in a rather complex apparatus (Figure 1) consisting of a glandular system, a venom sac (reservoir), the sting shaft, and associated tissue. The sting shaft is normally retracted into the lower abdomen of the bee. For the act of stinging, it is protruded by a complex plate-
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the victim. The shaft consists of three segments (Fig. 1,lower right), which taper together to form a sharp, hollow point. The venom is injected through the poison canal, located near the center of the shaft. The two lancets slide hack and forth, alternatelv. ,. alone a track-and-eroove connection to the stvlet. As thc i~incc~rs move rapidly back and forth, they prrfvrm t a u funct~ms. 'l'hr hnrhs cm the underidesoithe lancets prevent their retraction from the wound, so that each successive lancet ~ e n e t r a t i o ndrives the stine, shaft deeper. A t the same time, ;enom is pouring from the-sac into the cavity of the stylet bulb. The stylet bulb is open on the side adjoining the poison canal, and the venom is pumped through the poison canal by a successive valve action of lobes a t the lancet bases. Since the harhed lancets hold the stinger tightly in skin, the struggles of the bee to escape normally rip the entire venom apparatus from its abdomen. T h e damaged bee soon dies, Rod O'Connor is the editor of our new "Brain Tinglers" feature. Besides his involvement with Chemical Education, Dr. O'Connor is actively involved in the research area of the chemistry of insect venoms. His development of a method for obtaining ultrapure venoms was featured in the science news section of T I M E magazine and he has made significant cantrihutions tu the study of venom composition and insect sting allerm. He has published more than forty technical papers, including the chapter on Apidne Venoms for the International Encyclopedia of Pharmacology, which was ea-authored with Larry Peek. Larry Peek received his PhD in 1971from Montana State University. Before joining the First Year Chemistry team at Texas A&M five years ago, he worked at the ACS Department of Educational Activities, where he was primarily responsible for the ACS audio course program. Dr. Peck was a co-discoverer of the first natural peptide containing histamine. His most recent research haa heen in the use of glycylhistamineasa radioprotective drug, which has resulted in a series of further studies by the Atomic Energy groups in eleven countries, including Russia, West Germany, England, South Africa and Canada. 206 1 Journal of Chemical Education
while the removed stinger continues its function of penetration and envenomation. Contrarv to oooular belief, venom is not continuously "squeezed" from thesac by cont'raction of surrounding muscles, although the sac may he squeezed by the victim an attempt tu withdran thr imhedded stmgr;. 11 is thc continuinc action ofthe musclescontn)llinr: the lancet movements that maintain the ~wrm;llpumping O i the wnom and the ever-deeper penetration ot the stinx ih;~tt'I'his a c u r s even after the sting apparatus is detached from the bee.
Physiological Activities The reactions of humans to bee stings vary widely, deoending on the numher of stines, the location of stina sites on ;he h d " , and the general healih and ant ilwds c l ~ o r ~ t e r i s t i c s o i t h e indivioual stung. Heekeepers ilrnlcar to suffer the lrasr discomfort from stings, possihl;becauie of the presence in the serum of the beekeeper of antibodies specific to venom antigens. The responsesbf nonprotected individuals to bee sting may be considered in five basic categories: 1) the normal response to one, or a few, stings 2) a local reaction in the vicinity of sting sites 3) a toxic reaction to a large number of stings 4)
delaved ohvsioloeic resoonse , .
5 ; the gtncr:tlta~d&mion, nnvit frequently nsscmnted with h ~ pcr\pnsn~ut)tc, w m m nmp,>ncnt
