Chill tolerance in the tropical beetle Stenotarsus rotundus.

The tropical beetle Stenotarsus rotundus (Endomychidae) survived chilling at mildly low temperatures (above +5 degree C). With upper limit of cold injury zone (ULCIZ, the highest temperature that causes cold injury) well above freezing point, the supercooling ability (mean supercooling point - SCP; -11 degree C) has no cryoprotective importance. Mortality increases rapidly between -9 and +5 degree C, dependent on accumulated dose of chilling (sum of injurious temperatures - SIT; 2 degree-days below ULCIZ). The cold hardiness traits found in this species are by-products of deep diapause, and may serve as pre-adaptation for expansion into cooler regions.