野苹果枝条主要营养成分对苹小吉丁幼虫发育的影响

【目的】研究苹小吉丁(Agrilus mali Matsumura)幼虫生长发育对野苹果被害枝条韧皮部主要营养成分影响及其变化规律。【方法】研究苹小吉丁与野苹果枝条营养成分之间的关系,对野苹果枝条韧皮部和木质部的苹小吉丁幼虫定点定时调查其不同时间段的发育情况,测定幼虫所处的不同部位主要营养成分含量。【结果】在枝条韧皮部内越冬的幼虫5月下旬至6月初开始蛀入木质部化蛹,未蛀入木质部的部分幼虫从6月下旬至8月下旬期间出现自然死亡,尤其是7月中旬后自然死亡率上升到45%以上;经对幼虫所处韧皮部不同阶段主要营养成分含量测定发现,受害韧皮部主要营养成分含量均低于健康韧皮部,幼虫危害期的延续可溶性糖、还原性糖、淀粉、可溶性蛋白含量分别从6月下旬的38.68、18.37、9.47、19.57 mg/g下降到8月下旬的17.5、12.15、9.47、16.6 mg/g,幼虫自然死亡率与韧皮部主要营养成分含量进行相关性分析(P＜0.05),两者为负相关性;而受害木质部主要营养成分含量均高于健康韧皮部,幼虫危害期的延续可溶性糖、还原性糖、淀粉、可溶性蛋白含量分别从6月下旬的12.13、3.91、3.73、12.2 mg/g上升到8月下旬的19.26、14.10、4.20、17.50 mg/g,幼虫自然死亡率与木质部主要营养成分含量相关性分析(P＜0.05),两者为正相关。【结论】野苹果受害部位枝条韧皮部的可溶性糖、还原性糖、可溶性蛋白含量下降是影响幼虫正常发育的主要因素,致使6月下旬至8月下旬幼虫难以蛀入木质部而大量死亡,可作为苹小吉丁林间种群数量变动的重要参数。

Effects of Main Nutrients of Wild Apple Branches on the Development of Agrilus mali Matsumura Larvae

【Objective】 To reveal the effects of the growth and development of the larvae of Agrilus mali Matsumura on the main nutrients of the phloem of the infected apples. 【Methods】 In this paper, the development of larvae was investigated at fixed point for 2 years, and the content of main nutrients in different damaged parts of Agrilus mali Matsumura branches was determined. 【Results】 The results showed that the total larval mortality of phloem increased significantly, especially after mid-July, and the total mortality was much higher than that of xylem. The content of main nutrients (soluble sugar, reducing sugar, starch and soluble protein) in bast phloem was lower than that in healthy phloem. The content of persistent soluble sugar, reducing sugar, starch and soluble protein in the larval stage decreased from 38.68, 18.37, 9.47 mg/g and 19.57 mg/g in late June to 17.5, 12.15, 9.47 mg/g and 16.6 mg/g in late August, respectively. Correlation analysis showed that there was negative correlation between larva natural mortality and the content of main nutrients in phloem. The main nutrient content of affected xylem was higher than that of healthy phloem. The content of persistent soluble sugar, reducing sugar, starch and soluble protein in the larvae harm period rose from 12.13, 3.91, 3.73, 12.2 mg/g and 12.26, 14.10, 4.20 mg/g and 17.50 mg/g in late June to that in late August, respectively. Correlation analysis showed that there was a positive correlation between the larval natural mortality and the content of main nutrients in xylem(P＜0.05). 【Conclusion】 It can be seen that the decrease of soluble sugar, reducing sugar and soluble protein content in phloem of branches of Agrilus mali Matsumura was the main factor affecting the normal development of larvae, as result, it was difficult for larvae to decay into the phloem from late June to late August, resulting in a large number of deaths. This can be used as an important parameter for the population change of Agrilus mali Matsumura.