U. Gehrken et L. Somme, TOLERANCE OF DESICCATION IN BEETLES FROM THE HIGH ATLAS MOUNTAINS, Comparative biochemistry and physiology. Part A, Physiology, 109(4), 1994, pp. 913-922
Resistance to desiccation was studied in eight species of beetles from
Oukaimeden at 2600-3200 m in the High Atlas Mountains, Morocco. Lowes
t water loss rates and high tolerance to water losses were found in fi
ve species of tenebrionids. Seven of the eight species were diurnal, a
nd only the tenebrionid Pimeli thomsoni was seen to be active in direc
t sunlight. The carabid Harpalus dissitus had a high water loss rate a
nd low tolerance to water loss. The chrysomelid Timarcha mairei and th
e curculionid Gonocleonus insculpturatus represented an intermediate p
osition. The tenebrionids Pimelia sp., P. thomsoni and Opatrum rhaticu
m were non-regulators and tolerated dehydration of more than 50%. Tima
rcha spp regulated haemolymph osmolality which remained almost unchang
ed for water losses up to 46%. In nocturnal O. rhaticum, the O-2 consu
mption was highest during the night and higher in beetles from 3100 m
than from 2600 m. Pimelia sp., P. thomsoni and T. mairei displayed the
highest respiratory rates during the day. A smaller rise in O-2 consu
mption between 15 and 20 degrees C than between 10 and 15 degrees C wa
s seen in the diurnal species. This may also be of adaptive significan
ce in a hot and dry environment. It was also concluded that respiratio
n is the main source of water loss in most of the species.