Temperature affects performance of Lymantria dispar larvae feeding on leaves of Quercus robur
2007
Karolewski, P. | Grzebyta, J. | Oleksyn, J. | Giertych, M.J.,Polish Academy of Sciences, Kornik (Poland). Inst. of Dendrology
Future climatic warming maymodifyinsect development, sex ratio, quantitative changes in populations that could affect the frequency of outbreaks. Here we analysed the influence of temperature on larval growth and development in the gypsy moth (Lymantria dispar L.). The larvae were reared at three constant temperatures: 15, 20 or 25 deg C, and fed with leaves of the English oak (Quercus robur L.). Larval mortality, duration of development (DD), relative growth rate (RGR), total mass of food eaten (TFE), and pupal mass (PM) were estimated. Larval mortality was lowest at 20 deg C, higher at 25 deg C, and highest at 15 deg C. DD significantly decreased with increasing temperature and depended on sex. The influence of temperature on the shortening of DD was stronger in males than in females. RGR significantly depended on temperature and was the highest at 25 deg C, and lowest at 15 deg C. At 15 deg C, RGR did not change markedly with time. In contrast, RGR at 20 deg C was characterized by a continuous decreasing trend. At 25 deg C, RGR was very high for 2 weeks but quickly declined afterwards. Temperature did not affect the TFE. PM was significantly correlated with temperature and sex. PM of females was higher at 20 deg C than at 15 and 25 deg C, in contrast to that of males, which was similar at 20 and 25 deg C, and higher than at 15 deg C. For larval growth and development, the most favourable was the medium temperature (20 deg C). The least favourable temperature for females was 25 deg C, for males 15 deg C. The results suggest that global warming may modify the future sex ratio of gypsy moths that may affect insect development and outbreaks
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