title: Action of photoperiod at cold in diapausing Chrysopa carnea females (Chrysopidae, Neuroptera).
abstract: To reveal the effect of photoperiod on insects under low temperatures, dormant females of Chrysopa carnea were exposed for 3 months (November-January) to cold (7°±2.5°C) and to long- or short-day conditions (18L:6D or 12L:12D). They were thereafter activated under short-day conditions at 25°C.The samples differed considerably in the incidence of ovipositing females, duration of pre- and post-oviposition period, and fecundity. All parameters evidenced a considerably higher reproductive activity of insects chilled under short-day conditions. It was thus confirmed that adults of C. carnea perceive photoperiod at cold. The action of short photoperiod at cold does not impair the subsequent oviposition; by contrast it promotes future reproduction, apparently also due to photoperiod changes. Although short-day photoperiod inhibits the activation at warm temperatures, it enables diapause development under cold temperatures.
authors.affiliation: Institute of Entomology, Czechoslovak Academy of Science, Viniěná 7, 12800, Prague 2, Czechoslovakia.
authors.forename: I
authors.initials: I
authors.lastname: Hodek
authors.affiliation: Institute of Plant Protection, Research Institute of Crop Production, 16106, Prague, Czechoslovakia.
authors.forename: A
authors.initials: A
authors.lastname: Honěk