140 
Psyche 
[Vol. 89 
In these and several other encounters that night, aggressive interac- 
tions among colonies were similar to those described earlier. 
B. Intra- and Interspecific Laboratory Experiments: 
Termite-Termite Interactions Among Four 
Panamanian Species 
To examine conflicts among colonies and species of sympatric 
termites I staged laboratory encounters in pairwise tests: soldiers vs 
soldiers, soldiers vs workers, and workers vs workers. Characteris- 
tics of the four species used in these experiments are summarized in 
Table I. Amitermes beaumonti soldiers have curved mandibles; 
Armitermes chagresi soldiers have long, curved mandibles and a 
prolonged nasus; and soldiers of Nasutitermes corniger and N. 
ephratae are nasutoid with vestigal mandibles (Fig. 3). 
METHODS 
Experimental trials were conducted in March and April, 1981 in 
the Smithsonian Tropical Research Institute laboratory on Barro 
Colorado Island (BCI), Panama (9° 09' N, 79° 51' W). All Ami- 
termes beaumonti and Armitermes chagresi were collected from 
nests on BCI; samples of Nasutitermes corniger and N. ephratae 
were from colonies in Frijoles, Panama (4km east of BCI). Pairwise 
encounters were staged in petri dish arenas (4.6cm diameter) lined 
with moist filter paper. Equal numbers of termites, soldiers or 
workers, from each colony were introduced to an arena simultane- 
ously. Dishes were then covered and left undisturbed in darkness for 
12 hours. After the interaction period survivors were counted: con- 
spicuously injured individuals were considered as dead. Most 
worker-worker trials involved 50 individuals from each colony (only 
large workers ($) were used from Nasutitermes colonies; Amitermes 
and Armitermes have monomorphic worker castes). When soldiers 
of Amitermes or Armitermes were involved in a trial, and in occa- 
sional trials involving Amitermes or Armitermes workers, fewer 
individuals were available so experiments proceeded with less than 
50 termites from each colony. In Table II the number of individuals 
from each colony used in each trial is indicated in parentheses fol- 
lowing the survival percentages. A minimum of three trials were 
conducted for each intra- and interspecific interaction. Each such 
