沙棘主要蛀干害虫危害特性及种群动态变化

Harm characteristics and population dynamics of two important borers in Hippophae rhamnoidea

沙棘木蠹蛾主要危害沙棘栽植树的根部和干部，红缘天牛同时危害沙棘栽植树和根蘖苗的干部，已成为宁夏沙棘林中两大主要蛀干害虫。通过对沙棘树不同高度范围内沙棘木蠹蛾幼虫和红缘天牛幼虫的调查发现，沙棘木蠹蛾幼虫主要分布在地下根部和干部40～120cm的范围内，而红缘天牛主要分布在树干40～120cm的高度内。红缘天牛幼虫数量随时间变化大致呈现向树干上部增加的变化趋势。沙棘木蠹蛾幼虫数量随时间变化呈现明显的向根部转移的趋势，7月末，有近98％的幼虫在根部危害。之后，由于初孵幼虫的大量出现，使干部幼虫数量急剧增加，越冬前，虽然有部分转移至根部危害，但到9月末仍有近43％的幼虫停留在树干40～120cm处越冬，直到次年越冬结束。沙棘木蠹蛾和红缘天牛在沙棘树干部40cm以上危害位置的较大重叠，必然造成它们在时间、空间和营养上的激烈竞争。

Holcocerus hippophaecolus attacking the stems and roots of cultivated seabuckthorn and Asias halodendri attacking the stems of cultivated and root-spouting seedlings of seabuckthorn became 2 important borers in seabuckthorn stands in Pengyang County of Ningxia Hui Autonomous Region. Study on the larva distribution range of the two pests in seabuckhtorn showed that H. hippophaecolus larvae aggregated mainly in the roots and the stems at the height between 40 and 120 cm while A. halodendri distributed mostly in the stems at the same height. As time changed, the population of A. halodendri increased with the height of the stem,however, H. hippophaecolus had an apparent tendency of transferring from stern to root and nearly 98 % of the larvae attacked the roots in the end of July. Then the number of larvae in the stem increased sharply for a great number of newly-hatched larvae appeared. Though some larvae transferred from stem to root before overwintering, about 43 % of the larvae overwintered in tree stems at the height between 40 and 120 cm in the end of September till after the overwintering the next year. The infested position of Hippophae rhamoidea stem by H. hippophaecolus overlapped with that by A. halodendri and that would cause severe competition for time, space and nutrition.