柑桔爆皮虫羽化孔的空间分布

Spatial distribution pattern of Agrilus auriventris Saunders (Coleoptera:Buprestidae)

通过调查柑桔爆皮虫成虫羽化孔的分布,经空间分布型检验和聚集度指标的测定以及Taylor幂法则和m*-m(Iwao)回归分析,结果表明,柑桔爆皮虫的羽化孔在柑桔树树体内和桔园内均呈聚集分布:在枯树内呈负二项分布,在半枯树内呈负二项分布或奈曼A型分布,在桔园内呈负二项分布,在树体内和桔园内分布的基本成分均为为个体群,个体间相互吸引。树势较差的柑桔树容易受柑桔爆皮虫危害,在树势强的树体内不能完成世代发育。因此,柑桔爆皮虫采用多次聚集攻击的策略攻击寄主。在桔园内聚集危害部分寄主,在树体内聚集危害寄主主枝的中下部,主枝的死亡导致整株树势下降,下一代虫源进而再次攻击寄主,在树势下降的树体内柑桔爆皮虫完成世代发育并羽化出孔,成虫继续为害健康的柑桔树。

In order to examine the interaction between pest population and environment as well as biology and ecology of the citrus flat-headed borer, Agrilus auriventris Saunders, spatial distribution pattern of the borer was studied by investigating the distribution of adult emergence holes in citrus plants. The results showed that the emergence holes of the borer were distributed in crowds both in trees and in orchards. The fitting tests for spatial distribution pattern, analysis of the aggregative indexes and the Taylar＇ s law showed that the emergence holes revealed an aggregative negative-binomial distribution pattern in died trees, negative-binomial distribution or Neyman type A distribution in half died trees, and negative-binomial distribution in orchards. Based on Iwao regression, the basic element for the distribution was clusters of individuals both within trees and within orchards, and the individuals attracted each other. Trees with low growth vigor were vulnerable to the pest, while healthy trees could kill the larvae by gummosis. Therefore, aggregative multi-attacking strategy was used by the pest to conquer the host plants. In general, the beetle attacked in crowds a part of the trees in the orchards and the middle or basal part of the trunks in trees, and then next generations attacked the wounded trees again and again as the growth vigor of citrus trees descended, where larvae could succeed in completing development, and finally conquered the host plants.