淮北地区农田金龟子三种优势种在土壤中垂直活动规律观察

在安徽省淮北地区,暗黑金龟子Holotrichia parallela Motsehulsky和铜绿金龟子Anomala corpulenta MotschuIsky 1年发生1代,一般以三龄幼虫越冬;大黑金龟子Holotrichia oblita Faldermann两年发生1代,以成虫和三龄幼虫交替越冬。三种金龟子相同虫态(龄、期)在地下的垂直分布基本一致。3月下旬至4月上旬,铜绿、大黑金龟子越冬幼虫上升为害,而暗黑金龟子越冬幼虫则停留在越冬土室内直至化蛹。大黑金龟子成虫羽化后蛰伏至翌年4月,然后出土;另两种成虫羽化后于当年5月下旬开始出土。从成虫出土后至三龄幼虫下蛰前,群体分布在浅土层。幼虫为害夏季作物,并在下蛰前为害秋播小麦。土温决定了幼、成虫春季的上升和秋季的下蛰。群体在浅土层活动期,土壤湿度是群体升降的主要因素。土壤结构、寄主植物成熟期和幼虫龄期均能影响群体的垂直分布。暗黑金龟子从三龄幼虫下蛰至羽化成虫上升,这期间群体垂直分布不变,呈正态分布。

ANNUAL SUBTERRANEAN VERTICAL MOVEMENT OF THREE DOMINANT SPECIES OF SCARABAEIDS IN HUAIBEI REGION

In Huaibei Region, Anhui Province, Holotrichia parallela Motschulsky and Anomala corpulenta Motschulsky complete one generation per year, and overwinter generally with 3rd-instar larvae. Holotrichia oblita Faldermann needs two years to complete one generation, and overwinters alternately by 3rd-instar larvae and adults. Vertical distributions of their populations in soil are similar in the same stages or instars. In late March and early April overwintering 3rd-instar larvae of A. corpulenta and H. oblita rise up and injure crops, while those of H. parallela stay in overwintering cells until pupation. After emergence of adults H. oblita stays in soil and rises up onto the ground until April of the next year,while the other two species begin to appear on the ground in late May. During the period from adult having appeared on the ground to 3rd-instar larvae, they distribute in shallow layers of soil. The larvae attack summer crops,and autumn-sown wheat before they descend to overwinter. Soil temperature determines the spring-ascent and autumn-descent of larvae and adults.while the insects live in surface soil,soil moisture becomes a main factor affecting the vertical movement.Rainfall has an effect on vertical movement of the populations by changing soil moisture. Vertical distribution of the populations is also affected by soil structure, ripe date of host plants, and instar of larvae. From descent of 3rd-instar larvae for overwintering to ascent of emerged adults, vertical distribution of H. parallela remains steady and shows statistically normal distribution.