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首页> 外文期刊>Journal of Insect Conservation >The decline of native coccinellids (Coleoptera: Coccinellidae) in the United States and Canada.
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The decline of native coccinellids (Coleoptera: Coccinellidae) in the United States and Canada.

机译：美国和加拿大的天然球虫（鞘翅目：球虫）数量下降。

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Reviewing published coccinellid surveys we found that the number of adventive species has increased steadily over the last century while the average proportion of native individuals has remained fairly constant until 1987 followed by a rapid decrease between 1987 and 2006. Seven long-term studies indicated that the total density of coccinellids increased by an average of 14% following establishment of adventive species, but this increase was not significant and in 4 of 7 cases the total density of coccinellids actually decreased following establishment. Similarly, no significant difference was found in comparisons of diversity across all studies. These results illustrate that even with multiple long-term data sets it is currently difficult to make any general conclusions regarding the impact adventive coccinellids have had on native coccinellid assemblages. However, it is clear that specific systems and species have seen major shifts in recent years. For example, adventives have become the dominant species in a third of the assemblages where they are found. Focusing on two formerly common native species, Adalia bipunctata and Coccinella novemnotata, we show they have become rare in their former ranges and discuss potential explanations for this phenomenon.
机译：回顾已发表的球虫调查，我们发现外来物种的数量在上个世纪稳定增长，而本地个体的平均比例一直保持稳定，直到1987年，然后在1987年至2006年间迅速下降。七项长期研究表明建立外来种后，球菌的总密度平均增加了14％，但这种增加并不显着，在7个病例中有4例中，球菌的总密度实际上下降了。同样，在所有研究的多样性比较中也没有发现显着差异。这些结果说明，即使有多个长期数据集，目前也很难得出关于外来球虫对天然球虫组合的影响的任何一般性结论。但是，很明显，近年来特定的系统和物种发生了重大变化。例如，外来剂已成为发现它们的组合中的三分之一。着眼于两个以前常见的本地物种Adalia bipunctata和Coccinella novemnotata，我们显示它们在其先前的范围内已变得稀有，并讨论了对此现象的潜在解释。

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