Control of preimaginal development by photoperiod and temperature in the dock leaf beetle Gastrophysa viridula (De Geer) (Coleoptera, Chrysomelidae)

Abstract

Development times of preimaginal stages and immature adult body mass of the dock leaf beetle Gastrophysa viridula from Bryansk (53°N, 34°E) were determined at six constant temperatures ranging from 16 to 26°C and at two photoperiods, 12L: 12D or 22L: 2D. The lower developmental threshold (LDT) and sum of degreedays (SDD) were calculated for eggs, larvae, and pupae; the values for the total preimaginal development were 7.9°C and 274.8 °C×d, respectively. The thermal reaction norms for preimaginal development were not affected by photoperiod, although the adult body mass was on average greater under short-day conditions. Our results confirm the previously published data on G. viridula concerning diapause induction by shorter daylengths, greater body mass under lower temperatures, and narrowing of the thermal optimum range during preimaginal development. The thermal reaction norms for larval development were shown to be the same in individuals that died during the pupal stage, and in those that successfully emerged as adults. Our results are more precise than the previous data on this species due to a larger sample size, careful control of rearing conditions, and the use of an alternative method for calculating LDT and SDD. In particular, a more accurate estimation of LDTs allowed us to demonstrate that rate isomorphy was violated in this species, contrary to what had been stated by Honěk and co-authors (2003).