冀中苹果园苹果绵蚜及其寄生性天敌发生消长动态调查

Investigation of the population dynamics of Eriosoma lanigerum and its parasitoids Aphelinus mali in apple orchards in central Hebei

为了明确苹果绵蚜及其主要寄生性天敌-苹果绵蚜蚜小蜂在冀中苹果园的种群消长动态,分析苹果绵蚜蚜小蜂对苹果绵蚜的控害作用,本试验采用田间定点、定株调查统计了苹果树不同部位苹果绵蚜的虫落数量、虫落面积、虫落中的活蚜数及苹果绵蚜蚜小蜂的寄生率。结果表明,在河北中部苹果园苹果绵蚜和苹果绵蚜蚜小蜂发生的种群数量1年中均有2个高峰,在6月中下旬苹果绵蚜虫落数量达到第1个高峰期,树干、主枝、侧枝和新梢上虫落数量最高分别为123,95,20和36个;然后虫落数量逐渐减少,至8月10日左右最少,之后虫落数量又逐渐回升,9月21日达到第2个高峰,此时主干、主枝、侧枝和新梢上虫落的数量分别为40,62,21和3个。主干上第2个高峰虫落数量明显低于第1个高峰,主枝、侧枝的虫落数量均与第1个高峰差异不显著,新梢上仅6月底1个高峰。苹果绵蚜蚜小蜂种群数量的两个发生高峰分别在7月27日和8月31日,其20个虫落中的平均数量分别为40.95和41.40头;7-10月中旬,苹果绵蚜蚜小蜂的田间自然寄生率在40%～70%左右,表明其在生长季节后期寄生率明显提高,对苹果绵蚜的危害可起到较好的控制作用。

The objective of this work was to investigate the population dynamics of Eriosoma lanigerum and its parasitoids Aphelinus rnali in apple orchards in central Hebei province, and analyze the natural control efficiency of A. mall. A system investigate methods was used in ap- ple orchards to count the numbers and area of aphid colonies on different part in fixed apple trees, and the parasitized E. lanigerum by A. mall in the colonies were calculated. The results indicated that two peaks of the aphid and its parasitoid enemy population occurred in Hebei ap- ple orchards. The Eriosoma lanigerum population reached the first peak in late June with the average numbers of 123, 95, 20 and 36 on the tree trunk, bough, branch and twig respectively.From early July to August the number of E. lanigerurn drop off and reached its lowest point at August 10. Then the number of E. lanigerum increased gradually and reached the second peak at September 21. The numbers of E. lanigerum in the second peak were 40, 62, 21 and 3 on tree trunk, bough, branch and twig which were much lower than that of the first peak. Only one population peak was fund on twig. Two peaks in the average numbers of Aphelinus mali on 20 patches occurred, with a peak population number of 40.95 in late July, and a second peak of 41.10 in late August. The natural parasitism rate was lowest in May and reached the peak up to 40% to 70% from early July to late October. The parasitoid Aphelinus mall showed a better control efficiency to the population densities of E. lanigerurn in Hebei apple orchards during the late season.