1982] Howard, McDaniel, Blomquist — Three Termitophiles 159 
previously obtained from R. virginicus cuticular hydrocarbons 
(Howard et al., 1982). Likewise, concurrently obtained 
AgN0 3 TLC retention values (Rf) were identical for all beetle 
derived alkenes and R. virginicus alkenes. Components which were 
identified include n-alkanes, 2-, 3-, 1 1-, 13-, and 15-methylalkanes, 
1 1, 15-dimethylalkanes, Z-9-alkenes, Z,Z-7,9-dienes, and E/Z-6,9- 
dienes ranging in carbon number from C 2] to C 40 (Table 1). Double 
bond location and stereochemistries of the beetle derived alkenes 
were inferred solely from GC and GC-MS retention time data, 
and AgN0 3 -TLC Rf data, since insufficient sample was available 
for infrared analysis and methoxymercuration-demercuration (Blom- 
quist et al., 1980). Early eluting components not identified by a 
number in Figures 1 to 4 are unidentified, but have retention times 
consistent with a homologous series of /7-alkanes. 
The relative abundance of individual hydrocarbon components 
varied from species-to-species, but no more so than that of their 
termite host, whose percent composition varies considerably by 
caste (Howard et al., 1982). 
The in vitro radioisotope incorporation experiment was con- 
ducted with X. hexagonalis to determine if this species can biosyn- 
thesize its cuticular hydrocarbons de novo. Howard (1978) reported 
that this species engages in frequent allogrooming with its termite 
host, with the resulting possibility of acquiring host hydrocarbons 
by mechanical transfer rather than by de novo biosynthesis. A com- 
bination of these two alternatives is also possible. After 2 hours of 
incubating beetle cuticular tissues with 10 ^uCi of [1— 14 C]-acetate, 
19.6 ± 8.8 pmole (mean ± SD) of [1— 14 C]-acetate was incorporated 
into hydrocarbon. About 87.8 ± 5.3 percent of the radioactivity was 
in the alkane fraction, 10.2 ± 4.0 percent was in the alkene fraction, 
and 1.9 ± 1.3 percent was in the alkadiene fraction. This closely 
approximates the distribution of alkanes and olefins in X. hexago- 
nalis, suggesting that this species can de novo biosynthesize its 
cuticular hydrocarbons. In vitro biosynthesis experiments were not 
conducted with T. depressus and P. howardi because we were 
unable to collect enough beetles simultaneously. 
Discussion 
The striking mimicry of hydrocarbon components observed 
among these three beetles (representing two subfamilies) and their 
