Survival and Lt50 after exposures at constant low temperature were compared to the values obtained at alternating temperatures in two active (summer acclimated) temperate terrestrial arthropods. The experimental regimes used interruptions - daily transfers from the lower temperature to various higher temperatures for two hours or to one high temperature for Various durations. In both species the alternating conditions improved survival, implying reparation of the chill injury. In the collembolan Orchesella cincta, there was a maximum Lt50 when the higher exposure temperature was equal to the temperature of rearing (19°C). In the bug Pyrrhocoris apterus, Lt50 increased strongly with increasing higher temperature from 0 to 15°C, and was subsequently constant over the entire physiological range suitable for development (to 35°C). Exposure at 0°C was harmful if continuously applied, but survival increased, relative to a constant exposure at -5°C, if the temperature alternated between -5 and 0°C., Zdeněk Hanč, Oldřich Nedvěd, and Lit
The cold hardiness of individuals from overwintering populations of a freeze susceptible bug Pyrrhocoris apterus from central and southern Europe differed significantly. Supercooling point (SCP) correlated well with both lethal temperature (LT50) and lethal time (Lt50), and is agood index of cold hardiness of adults during and after diapause. In January, diapause terminated, but cold hardiness was similar to that recorded in November; cold hardiness decreased slightly in March and markedly in May. Short exposure (less than a week) to higher temperatures before termination of diapause did not reduce the cold hardiness. Cold hardiness did not closely follow air temperatures.The Bulgarian bugs retained lower cold hardiness regardless of acclimation to harsh field conditions in the Czech Republic. The interpopulation difference is therefore a heritable character representing an adjustment to local climates.
Vnitrodruhová variabilita ve zbarvení mnoha druhů slunéček (Coleoptera, Coccinellidae) nám umožňuje porozumět mechanismům, jak je vzor s tečkami tvořen a jak se dědí. Adaptivní termální melanismus, který nalézáme u kukel a dospělých slunéček, je výsledkem dědičného polymorfismu nebo fenotypové plasticity. and Intraspecific variability in the colour pattern of many ladybird beetles (Coccinellidae) enables us to understand the mechanisms behind how the spotted pattern is made and inherited. Adaptive thermal melanism in pupae and adults is driven by genetic polymorphism in some species and phenotypic plasticity in others.