COLD HARDINESS IN THE JAPANESE BEETLE, POPILLIA JAPONICA NEWMAN

Abstract

Larvae of the 2nd and 3rd instar are cold-hardy to the quantity factor of low temp., except directly after molting or when the digestive tract is clear. Wilt disease, relative humidity, temp. of environment, and nutritional state influence cold-hardiness to the intensity factor of low temp. [rho][ETA] does not appear to be important. After long exposure to low temp., cold-hardiness to the intensity factor decreases. Adults and cold-hardy to the intensity factor of low temp. A proteolytic enzyme may be 1 factor in determining cold-hardiness. Larvae have been kept for 2 years below their developmental temp.