1974] 
Eisner et al. — Tenebrionid Beetles 
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a 
b 
c 
Fig. 1. Compounds in defensive secretion of Adelium percatum and A. 
pustolosum. a; 2-methyl-l,4-benzoquinone ; b; 2,3-dimethyl-l,4-benzoquinone ; 
c; 1-pentadecene. 
property of tanning human skin. Our fingertips were always darkly 
mottled after handling a quantity of the beetles. 
Secretion for analysis was obtained by seizing and squeezing in- 
dividual beetles in forceps and wiping the fluid from the everted 
glands with small pieces of filter paper. The chemical procedure and 
the findings were the same for both species. Extraction of the papers 
with methylene chloride, followed by gas chromatography of the 
extract (1% OV-i on Gas Chrom. Q, 4' X 50° to 240°C), 
revealed the presence of three major components. Analysis by gas 
chromatography-mass spectrometry showed two of the components to 
have mass spectra identical to the published spectra ( Budzikiewicz 
et al., 1967) of 2-methyl- 1,4-benzoquinone and 2, 3-dimethyl- 1,4- 
benzoquinone (Fig. 1 a, b). The third component had a mass spec- 
trum matching that of i-pentadecene (Stenhagen et al., 1969) 
(Fig. 1 c). Definitive confirmation of the position of the double 
bond in this compound was obtained by ozonolysis. A small sample 
of the third component was collected from the gas chromatograph 
and dissolved in methylene chloride, and the cooled solution ( — 70°C) 
was subjected to a slow bubbled stream of ozone in oxygen until the 
blue color persisted. Addition of a small crystal of triphenylphos- 
phine, followed by gas chromatography-mass spectrometry, showed 
the higher molecular weight product to have a mass spectrum identi- 
cal to that of tetradecanal (Stenhagen et al., 1969). 
One interesting point in connection with these analyses was the 
observation of a fourth component in the initial sample of secretion 
obtained from both species. This component was guessed to be 1,2- 
dichloropentadecane on the basis of its mass spectrum, and the iden- 
tification was confirmed by direct comparison of the isolated material 
with an authentic sample prepared by addition of chlorine to i-penta- 
decene. However, since additional milkings taken from the same 
