DIAPAUSE AND PHOTOPERIODIC RESPONSE IN COCCINELLA-SEPTEMPUNCTATA-BRUCKI MULSANT (COLEOPTERA, COCCINELLIDAE) IN HOKKAIDO, JAPAN

The regulatory function of photoperiod and temperature on the life-cyc le of Coccinella septempunctata brucki Mulsant in Hokkaido populations was investigated. Dissection of adults from Sapporo (43-degrees-N) in mid-October showed diapausing adults (partly hidden in grass tussocks ) possessing enlarged fat body, ovaria without vitellinized oocytes an d at a beginning of regression of testicular follicle tissue. Some of the females had sperm in their spermathecae. Experimental rearings und er contrasting photoperiods (12L-12D, 16L-8D) and three temperatures ( 20, 25 and 30-degrees-C) of insects sampled in early September, and of their offspring, showed that the Sapporo population has a long-day ph otoperiodic response adequate for the induction of winter diapause. Th is is in contrast to short-day response inducing summer diapause in th e Nagoya (35-degrees-N) and Kanto (36-degrees-N) plains, but similar t o C. septempunctata septempunctata in France and central and northern Europe, i.e. regions with climate similar to Hokkaido.