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A constant pressure microrespirometer for measurements of
Oz-consumption in Collembola
ELSE-MARGRETE CONRADI-LARSEN
Conradi-Larsen, E.-M. 1974. A constant pressure microrespirometer for measurements
of 02-consumption in Collembola. Norsk ent. Tidsskr. 21, 187-190.
In order to determine 02-consumption in individual collemboles, a modified constant
pressure respirometer was constructed. The respirometer consists of 0.1 mm
and 2 mm glass capillaries, glued together. The 2 mm capillary is the respiration
chamber and is sealed with a Vaseline coated cover slip. The small capillary and
a part of the respiration chamber is filled with KOH, so that a pressure reduction
in the chamber will draw the KOH column downwards.
Measurements of 02-consumption were carried out on Isotoma violacea Tullberg
and T etrachantella wahlgreni Linnaniemi collected at Finse, 1200 m a.s.l. in the
winter. In T. wahlgreni the increase of the 02-consumption was linear for the
temperatures 10°, 20°, and 25° C. At 10° C the 02-consumption in both species
was 0.3 mm 3 02lmg/h. The present results seem to be in agreement with 02-consumption
measurements carried out on coliemboles by use of Cartesian diver and
Warburg respirometers.
Else-Margrete Conradi-Larsen, Zoological Institute, University of Oslo, P.B. 1050
Blindern, Oslo 3, Norway.
The Engelmann constant pressure respiro­ The respiration chamber is a 2 cm long piece
meter (Engelmann 1963) can be used to mea­ of a 2 mm capillary. To this is fastened a 0.1
sure O 2 -consumption in small insects (Dixon mm capillary of about 5 cm length. The
1971). An Engelmann respirometer with a ends of the capillaries are ground so that
0.3 mm capillary makes it possible to mea­ they fit together and no glue is allowed to
sure O2-consumption in insects of about 1 mg penetrate into the small capillary. Constant
fresh weight. The respirometer did not func­ temperature is obtained in a water bath with
tion sufficiently accurately when smaller cap­ a Braun thermomixer. For temperatures beillaries
than 0.3 mm were used. To measure low 20° C a Colora immersion cooler is used.
02-consumption in high mountain species
of collemboles, 10-20 animals have to be
used in one respirometer. In order to determine
the O 2 -uptake of single collemboles, it
PROCEDURE
is necessary to use capillaries of 0.1 mm or The respirometer IS cleaned by drawing a
smaller. For this reason attempts were made mixture of soap (Deconex 11) and water
to construct a modified respirometer. This through it, followed by distilled water and
was based partly on the Engelmann method acetone. Dry air is then drawn through the
and partly on a respirometer according to respirometer until it is completely dry. 0.3 M
Cunningham and Kirk (Kirk 1959).
KOH is drawn up through the small capillary
and about 4 mm into the respiration chamber.
A small piece of dry cotton wool is introduced
THE APPARATUS
into the respiration chamber so that no fibre
will come in contact with the KOH meniscus.
The design of the respirometer shown in Fig. The animal is now introduced and then
1 is very simple. It consists of two glass another small piece of cotton wool which
capillaries fastened together with epoxy glue. has been slightly moistened with water.