5种植物对薇甘菊化感作用研究

用水作为溶剂对云南省薇甘菊发生地伴生的常见本地物种异型莎草(Cyperus difformis)、水蓼(Polygonum hydropiper)和外来物种空心莲子草(Alternanthera philoxcroides)、三叶鬼针草(Bidens pilosaL.)以及农粮作物红薯(Ipomoea batatas)地上部分进行提取,后将各提取液配制成一定质量浓度的营养液培养薇甘菊幼苗,12 d后测其对薇甘菊幼苗的生长抑制情况。结果表明,5种供试植物的水提取物均能抑制薇甘菊幼苗的生长,且彼此间存在一定的差异。5种植物化感作用的综合抑制效应总体表现为:空心莲子草>异型莎草>三叶鬼针草,水蓼和红薯对薇甘菊幼苗生长的抑制程度相似,但强度明显弱于前3种植物;不同供试植物的水提取物对薇甘菊幼苗新增质量的受抑制程度均大于茎长和根长的受抑制程度。说明入侵地许多与薇甘菊伴生的物种具有抑制薇甘菊幼苗生长的化感作用,其中外来种群的抑制作用总体强于本地种群。

不同马铃薯品种对桃蚜发育和繁殖的影响

为探索不同马铃薯品种对桃蚜生命表参数的影响,为马铃薯品种抗蚜性评价及桃蚜预测预报与综合防治提供依据,在室内观察了桃蚜在“荷兰15号”、“陇薯10号”及“陇薯14号”三个马铃薯品种上的生长发育参数;通过建立特定年龄-阶段两性生命表,分析了不同马铃薯品种对桃蚜生长发育、存活率、繁殖力、寿命期望值(e_(xj))、繁殖值(v_(xj))及种群参数的影响。结果表明:与桃蚜取食“陇薯14号”相比,取食“荷兰15号”后的发育历期较长、寿命较短、繁殖力较低、寿命期望值较短、繁殖值较低;取食“荷兰15号”的蚜虫净增殖率、内禀增长率与周限增长率均低于取食“陇薯10号”和“陇薯14号”,平均世代周期和种群加倍时间则长于取食“陇薯10号”、“陇薯14号”;桃蚜对不同马铃薯品种适应能力不同,“荷兰15号”对桃蚜的抗性显著强于“陇薯10号”和“陇薯14号”。

SEASONAL PERFORMANCE AFFECTING POPULATION DYNAMICS OF CITRUS RED MITE, PANONYCHUS CITRI (MCGREGOR) (ACARI: TETRANYCHIDAE), ON PEAR

The population of the citrus red mite, Panonychus citri (McGregor), does not increase on pear from spring to mid summer but thereafter increases abruptly. To elucidate this phenomenon, we compared the performance of the mites on pear leaves with that on citrus leaves, at different time throughout the pear growing season. No significant difference was detected between the oviposition rate on pear and that on citrus throughout the season. However, the survival rate of ovipositing females that had fed on pear and the hatch rate of eggs laid by those females were significantly lower than those for females that had fed on citrus, until August. However, no significant difference was observed thereafter. The results showed that the decline of the population of citrus red mite before autumn is due to the high mortality of adult females that had fed on pear leaves and the low hatch rate of the eggs produced by those females.