There have been studies that say that insect populations may have fallen by as much as 75% over the last few decades.

有研究表明，在过去的几十年中，昆虫的数量可能下降了75%。

In this summa, the state-of-the-art in sampling technique of insect populations are reviewed.

本文对昆虫种群抽样技术的研究内容、抽样理论作了概述。