温湿度对安徽虫瘟霉在桃蚜居群中流行的影响

用安徽虫瘟霉(Zoopphthoraanhuiensis)接种桃蚜(Myzuspersicae)无翅成蚜3头和健蚜3头组成新的蚜群若干,在不同温湿组合条件下任其繁殖、发病和传染,以评价温湿度对该菌在蚜群中流行的影响.持续26d观察,在偏低温与各湿度(90～100%RH)的组合中均成功诱发了蚜病流行,其程度受湿度影响较小.在10℃与各湿度组合中,最终感病死亡率为72.9%～98.2%,15℃下为78.7%～94.4%,流行强度极大.而20℃下仅100%RH诱发了高强度流行病,其余湿度下感病死亡率仅为5.1%～12.8%.在25℃,100%RH下死亡率仅27.2%.与所有湿度组合中的对照蚜群相比,10℃下流行病控蚜效果为89.5%～96.9%,15℃下为96.1%～98.2%,20℃下为45.9%～85.7%,25℃下为56.4%～69.7%.逐步回归分析表明,安徽虫瘟霉引发的蚜病流行与温度及其相对湿度和蚜群带菌后天数的互作项密切相关(r2=0.82,a＜0.01),这些变量在很大程度上决定了安徽虫瘟霉是否在蚜群中流行.

Influence of temperature and relative humidity on epizootiological features of Zoophthora anhuiensis in Myzus persi cae 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).