Effect of temperature on the hatch of two German populations of the beet cyst nematodes, Heterodera schachtii and Heterodera betae

Beet cyst nematodes, Heterodera schachtii and H. betae, cause damage to sugar beet production and could become even more important with an increase in soil temperatures. In northern Germany, temperatures are expected to rise by 4°C by 2100. In this study we investigated the hatch of two beet cyst nematode species at constant temperatures as well as simulated temperature conditions set to be 4°C higher than the standard temperature regime. The effect of different constant temperatures on the emergence of second- stage juveniles of H. schachtii and H. betae was investigated using six incubators set at 5, 10, 15, 20, 25 and 30°C for a period of 6 weeks. In a second experiment, the effect of increased and standard temperature regimes on the emergence of second-stage juveniles of H. schachtii and H. betae was investigated in climate chambers for 12 weeks. The highest cumulative hatching rates for H. schachtii were observed at temperatures between 15 and 30°C and for H. betae between 20 and 30°C, suggesting that this can be considered as the optimal temperature range for hatch. The emergence of juveniles of both beet cyst nematode species started at 5°C, but cumulative hatch percentages were less than 1%. Differences in final cumulative hatching rate of H. schachtii and H. betae between the increased and standard temperature regime were not significant.