The main cause of variety decline was due to the loss of its resistance.

品种衰退的主要原因是抗性的丧失；

youdao

Despite repeated global pledges to protect the planet's species and habitats -and the goods and services they provide -the variety of life on Earth continues to decline at an unprecedented rate.

尽管一再做出全球承诺，要保护地球上的物种和生境及其提供的货物和服务，但生物种类继续以史无前例的速度减少。

youdao

Despite repeated global pledges to protect the planet's species and habitats - and the goods and services they provide - the variety of life on Earth continues to decline at an unprecedented rate.

尽管一再做出全球承诺，要保护地球上的物种和生境及其提供的货物和服务，但生物种类继续以史无前例的速度减少。

youdao

The decline resulted from a variety of factors, but losing the gun ban certainly did not produce the rise in murders that many might have expected.

WSJ: Jeffrey Scott Shapiro: A Gun Ban That Misfired

He said the main cause of decline in wild bees, such as mining and mason species, was loss of habitat due to a variety of reasons including urban development.

BBC: Oxford's The Kidneys Jubilee flower meadow for bees