The characteristics of hatching and infection of Heterodera microulae

To clarify the biological characteristics of Heterodera microulae, the effects of temperature and incubation solutions on egg hatching of H. microulae were examined by immersion of Microula sikkimensis into soils five times, 10 times, and 20 times with root juice and 4 mmol·L⁻¹ ZnCl₂ solution. The effects of temperature on the activity of second-stage juvenile (J2) and the viability of J2 were determined in vitro using the one-way variable principle. The infection process of this cyst-forming nematode was examined by inoculating seedlings of M. sikkimensis with eggs. The results showed that 15 ℃ was the optimal temperature for H. microulae hatching. The immersion of M. sikkimensis into soils 20 times and 10 times with root juice significantly increased the hatching rates of this nematode, with hatching rates 2.96 times, 2.11 times, and 1.61 times that of the control, respectively. Additionally, 4 mmol·L⁻¹ zinc chloride solution had no significant promotion effect. Moreover, immersion five times in root juice inhibited hatching significantly. At 10～15 ℃, the survival rate of J2 was as high as 67.22%～76.25%. The survival rate at 4 ℃ was better for J2 preservation, while 15 ℃ was suitable for retaining activity. J2 was discovered in the root system of H. microulae three days after egg inoculation at 15 ℃. White females were present 24 d later. The white females turned into light brown cysts 27 d later, according to the results of investigations and observations. Overall, the results showed that M. sikkimensis soil immersion at 15 ℃ was more conducive to hatching of H. microulae and it took 27 d for the completion of one generation of reproduction at 15 ℃. These findings have elucidated the biological properties of H. microulae and serve as a foundation for future studies on its control.