GLANDULAR SOURCES AND SPECIFICITY OF SOME 
CHEMICAL RELEASERS OF SOCIAL BEHAVIOR IN 
DOLICHODERINE ANTS 1 
By Edward O. Wilson 2 and Mario Pavan 3 
Introduction 
Species of the ant subfamily Dolichoderinae are excellent subjects 
for the experimental analysis of chemical communication. The group 
is advanced evolutionarily, and large, complex societies are the rule. 
During foraging, workers of many species form long, conspicuous 
columns tightly bound to persistent odor trails. When disturbed they 
void volatile secretions that seem likely to function, at least in part, 
as olfactory releasers of alarm behavior. Furthermore, the dolicho- 
derines have recently been the object of extensive biochemical research 
by Pavan, Cavill and their associates (cf. Pavan, 1950; Pavan and 
Ronchetti, 1955; Pavan and Trave, 1958; Cavill, Ford, and Locks- 
ley, 1956; Cavill and Locksley, 1957). Several terpenoids including 
the previously unknown iridomyrmecin, iso-iridomyrmecin, and irido- 
dial, have been identified as components of the anal gland secretion of 
various species. T he availability of these substances in purified form 
has made possible for the first time the precise behavioral assay ol 
natural secretory products in ants. 
Trail Substances 
Applying the artificial trail technique used earlier by one of us 
(Wilson, 1959) in studies of the myrmicine Solenopsis saevissima , an 
attempt was made to determine the glandular source of the trail sub- 
stance in workers of Iridomyrmex humilis Mayr. Groups of workers 
from laboratory colonies (grown from stocks originating from Baton 
Rouge, Louisiana) were attracted to drops of 1 M sucrose solution, 
about 6 mm in diameter, on glass feeding tables. Selected body parts 
of freshly killed workers were made into artificial trails directed at 
the feeding workers. The number of workers following the trails be- 
yond the trail midpoint, i.e., 15 cm. from the sucrose bait, were re- 
corded. When positive responses were obtained, the duration of 
biological activity was timed to the nearest half-minute. Preliminary 
experiments showed that the trail substance is limited to the abdomen, 
^ased on research supported in part by a grant from the U. S. National 
Science Foundation. 
^Biological Laboratories, Harvard University, Cambridge, Mass., U. S. A. 
3 Istituto di Anatomia Comparata and Istituto di Entomologia Agraria 
delPUniversita di Pavia, Italy. 
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