Table 2.

Physiological parameters in the laboratory-reared adults of Pyrrhocoris apterus, and the effects of diapause progression, desiccation and cold acclimation

ParameterInitial state (day 0)After diapause progression (2 months)After desiccation (14 days)After cold acclimation (2 months)
Dry mass (mg)21.2±9.124.6±8.019.4±7.321.7±6.5
Hydration (mg water mg-1 DM)1.72±0.211.60±0.330.85±0.15***1.13±0.14***
Haemolymph osmolality (mosmol kg-1)342±27373±40750±121***1128±370***
Conc. of ribitol (μg mg-1 DM)tracetrace0.34±0.2715.94±6.54
Conc. of sorbitol (μg mg-1 DM)tracetrace0.11±0.0711.40±2.20
Supercooling point (°C)-13.9 (-12.2, -14.8)-12.9 (-6.2, -15.0)-11.7 (-7.8. -14.3)-18.9*** (-14.9, -19.6)
Lt50 at -15°C (days)<1<1<114.6±4.1
  • DM, dry mass.

    Each value represents either a mean ± s.d. or, in the case of supercooling points, median (25%, 75% percentile); (see text for N). The differences between the initial state and the treatments were statistically analyzed using unpaired two-tailed t-tests or two-tailed Mann—Whitney U-tests, respectively (*P<0.05; **P<0.001; ***P<0.0001).