Effect of temperature on development and reproduction in Gastrophysa viridula (Coleoptera: Chrysomelidae)

The duration of development, reproduction and longevity of Gastrophysa viridula (DeGeer) was measured at constant temperatures and a long day photoperiod. At 18, 21.5, 25, and 28degreesC the average duration of development of the egg, larval and pupal stages and total development time (28.2, 21.6, 16.1, 15.0 days) decreased with temperature but the proportion of time spent in the egg, larval and pupal stages did not significantly change with temperature. Total development required 304.6 day degrees above the lower development threshold of 7.1degreesC. Pre-adult mortality and the rate of oviposition increased, and the duration of oviposition decreased with increasing temperature. Net reproduction rate R. decreased (from 157 female eggs at 18degreesC to 75 female eggs at 28degreesC) and mean generation time T also decreased (from 45.5 days at 18degreesC to 24.1 days at 28degreesC) with increasing temperature. The intrinsic rate of population increase r(m) increased with temperature (from 0.111 at 18degreesC to 0.179 at 28degreesC). On a physiological time scale the average generation time T was 496 day degrees.