Author
Okuda T; Hodek I
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‰œ“c@—²EHodek I
Title
Diapause and photoperiodic response in Coccinella septempunctata brucki Mulsant (Coleoptera: Coccinellidae) in Hokkaido, Japan
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Keywords
Coccinella septempunctata brucki, diapause, photoperiodic response, Hokkaido
Abstract
The regulatory function of photoperiod and temperature on the life-cycle 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 and at a beginning of regression of testicular follicle tissue. Some of the females had sperm in their spermathecae. Experimental rearings under 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 photoperiodic response adequate for the induction of winter diapause. This is in contrast to short-day response inducing summer diapause in the Nagoya (35-degrees-N) and Kanto (36-degrees-N) plains, but similar to C. septempunctata septempunctata in France and central and northern Europe, i.e. regions with climate similar to Hokkaido.
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Journal
Appl.Ent.Zool., 29(4), 1994, p.549-554.


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