12. QUINONES: STRUCTURE AND DISTRIBUTION
679
and Myriapoda, sometimes along with other quinones. The most notable
mixture is the material gonyleptidine, a yellow, aqueous, antibiotic fluid,
containing 2,3- and 2,5-dimethyl-, and 2,3,5-trimethylbenzoquinone,
secreted by a South American arachnid of the Gonyleptidae family. The
antibiotic nature of the secretion from Tribolium confusum and T.
castaneum had been noted (200) previously, and the examination of
gonyleptidine by Fieser et al. (201) revealed inter alia that simple
alkylbenzoquinones are more potent than any other type of quinone (cf.
202).
It appears that the function of the simple quinones listed in Table V
is to provide a means of defense for these animals (202a). They are
discharged when the animals are disturbed, and advantage is taken of
this behavior in laboratory procedures for their detection and isolation.
Roth (203) showed that a blue color could be obtained on acidified
starch iodide paper merely by holding a beetle (e.g., Tribolium confusum) over it. Tenebrionids generally respond to this simple test, although a negative reaction does not necessarily mean that odoriferous
glands are absent, and a positive test is not specific for quinones (as
distinct from other oxidizing agents) (204). The most remarkable example is the bombardier beetle Brachinus crepitans (= explodens),
which discharges its quinones explosively in an acrid cloud when irritated. The secretion [pH 4.2, but not nitric acid, as first suggested
(205)] is a mixture of benzoquinone and toluquinone in a fatty oil
(with occasional traces of uric acid), which is ejected together with
a gas consisting mostly of oxygen, with lesser amounts of carbon
dioxide and nitrogen (195). Schildknecht (206) and Barbier (207)
have recently devised techniques whereby the quinones discharged
from a single animal can be collected and identified by chromatography.
On a larger scale, the odorous secretion from batches of insects can be
isolated by direct vacuum sublimation. In this way Loconti and Roth
(208) obtained 30 gm. of mixed quinones from over 1.5 million flour
beetles (Tribolium
castaneum).
The odoriferous glands of a number of beetles (Tenebrionidae)
(203, 204) and of the cockroach Diploptera punctata (196) have been
studied in detail by Roth. Infrared analysis of the secretion from the
latter showed that the relative concentrations were methylbenzoquinone
> ethylbenzoquinone > benzoquinone, males having a slightly higher
proportion of methylbenzoquinone than females, but in the last and
next-to-last instar nymphs of both series, the order of relative concentrations was ethylbenzoquinone > methylbenzoquinone > benzoquinone. D. punctata differs from the tenebrionids in that immature stages,
as well as the adults, produce quinones. In both the cockroach and the
beetles, quinone biosynthesis develops rapidly after emergence of the
679
and Myriapoda, sometimes along with other quinones. The most notable
mixture is the material gonyleptidine, a yellow, aqueous, antibiotic fluid,
containing 2,3- and 2,5-dimethyl-, and 2,3,5-trimethylbenzoquinone,
secreted by a South American arachnid of the Gonyleptidae family. The
antibiotic nature of the secretion from Tribolium confusum and T.
castaneum had been noted (200) previously, and the examination of
gonyleptidine by Fieser et al. (201) revealed inter alia that simple
alkylbenzoquinones are more potent than any other type of quinone (cf.
202).
It appears that the function of the simple quinones listed in Table V
is to provide a means of defense for these animals (202a). They are
discharged when the animals are disturbed, and advantage is taken of
this behavior in laboratory procedures for their detection and isolation.
Roth (203) showed that a blue color could be obtained on acidified
starch iodide paper merely by holding a beetle (e.g., Tribolium confusum) over it. Tenebrionids generally respond to this simple test, although a negative reaction does not necessarily mean that odoriferous
glands are absent, and a positive test is not specific for quinones (as
distinct from other oxidizing agents) (204). The most remarkable example is the bombardier beetle Brachinus crepitans (= explodens),
which discharges its quinones explosively in an acrid cloud when irritated. The secretion [pH 4.2, but not nitric acid, as first suggested
(205)] is a mixture of benzoquinone and toluquinone in a fatty oil
(with occasional traces of uric acid), which is ejected together with
a gas consisting mostly of oxygen, with lesser amounts of carbon
dioxide and nitrogen (195). Schildknecht (206) and Barbier (207)
have recently devised techniques whereby the quinones discharged
from a single animal can be collected and identified by chromatography.
On a larger scale, the odorous secretion from batches of insects can be
isolated by direct vacuum sublimation. In this way Loconti and Roth
(208) obtained 30 gm. of mixed quinones from over 1.5 million flour
beetles (Tribolium
castaneum).
The odoriferous glands of a number of beetles (Tenebrionidae)
(203, 204) and of the cockroach Diploptera punctata (196) have been
studied in detail by Roth. Infrared analysis of the secretion from the
latter showed that the relative concentrations were methylbenzoquinone
> ethylbenzoquinone > benzoquinone, males having a slightly higher
proportion of methylbenzoquinone than females, but in the last and
next-to-last instar nymphs of both series, the order of relative concentrations was ethylbenzoquinone > methylbenzoquinone > benzoquinone. D. punctata differs from the tenebrionids in that immature stages,
as well as the adults, produce quinones. In both the cockroach and the
beetles, quinone biosynthesis develops rapidly after emergence of the