[Influence of temperature and relative humidity on epizootiological features of Zoophthora anhuiensis in Myzus persicae colonies].
The colony of green peach aphid, Myzus persicae(Sulzer), which was initiated with 3 pathogen-free apterae and another 3 ones inoculated with the conidia of the entomophthoraceous fungus, Zoophthora anhuiensis(Li) Humber, was maintained on detached cabbage leaves at the regimes of 10-25 degrees C and 90-100% of relative humidity(RH), and allowed for free reproduction and fungal infection. Based on 26 day observations, it was showed that the development of Z. anhuiensis in the colony was rapid at 15 or 10 degrees C, regardless of the humidity range concerned. The cumulative mortality of the aphids attributed to Z. anhuiensis infection was 72.9-98.2% at 10 degrees C on day 26, and 78.7-94.4% at 15 degrees C on day 24, indicating the occurrence of epizootic in the colony. At 20 degrees C, a high-level epizootic occurred only at 100% RH, with a cumulative mortality of 71.6% on day 24, contrasting to a much lower mortality (5.1-12.8%) at the other three humidity regimes. However, the maximal mortality at 25 degrees C on day 20 was only 27.2% even at 100% RH. Obviously, Z. anhuiensis caused aphid epizootic more easily at lower temperature, and to less degree was affected by the humidity. The disease prevalence (represented by the cumulative mortality) was correlated well to temperature, its interaction with relative humidity, and the days from initiation (r2 = 0.82, alpha < 0.01).
Li
H
H
Institute of Microbiology, Zhejiang University, Hangzhou 310029.
Feng
M
M
D000818:Animals; D001042:Aphids / Q000502:physiology*; D017753:Ecosystem; D020091:Entomophthorales / Q000502:physiology*; D006813:Humidity; D013696:Temperature