ADAPTATIONS OF INSECTS AT HIGH-ALTITUDES OF CHIMBORAZO, ECUADOR

Carabid beetles (Coleoptera: Carabidae) were collected from an altitud inal gradient at Chimboraze, Ecuador, in March 1994. Bembidion andinum Bates was the dominant species at 4,800 m, Pelmatellus andium Bates a t 4,500 m and Agraphoderus integer Bates at 4,250 m. During daytime, t he beetles were sheltering under rocks, but were caught in pitfall tra ps on open ground during the night. At 0.5 cm depth, soil temperatures from -4 to 41 degrees C were recorded at 4,800 m and from -3 to 52 de grees C at 4,500 m, but fluctuations were greatly buffered at 2 and 5 cm depths. All three species had mean supercooling points of -5 to -6 degrees C. Rates of water loss at 18 degrees C and 5% RH were 4.4, 1.2 and 1.1% of fresh weight per hour, respectively. Apparently, the cara bid beetles are poorly adapted to low temperatures and aridity. To sur vive the harsh climatic conditions at high altitudes on Chimborazo, th ey depend on sheltered microhabitats under rocks or below vegetation. Surface activity is restricted to certain periods during the night whe n conditions are more favorable. In comparison, lower rates of water l oss were found in an unidentified species of Dermaptera and a curculio nid beetle.