Invertebrate Numbers Nearly Halve as Human Population Doubles: Bees and Butterflies at Risk

The human population is spreading out across the globe. Unfortunately, this spread is destroying habitat and ecosystems for other animals. Now, scientists have taken a closer look at some of the smaller denizens on our planet: invertebrates. They've found that the number of invertebrates has decreased by 45 percent on average over a 35 year period during which the human population doubled.

This decline is a huge issue. There are enormous benefits from invertebrates such as insects, spiders, crustaceans, and slugs. For example, invertebrates pollinate and provide pest control for crops, cycle nutrients, and even filter water.

The decrease in invertebrate numbers can be largely attributed to two main factors: habitat loss and climate disruption. For example, in the UK alone, areas inhabited by common insects saw a 30 to 60 percent decline over just the last 40 years.

"We were shocked to find similar losses in invertebrates as with larger animals, as we previously thought invertebrates to be more resilient," said Ben Collen, one of the researchers, in a news release. "While we don't fully understand what the long-term impact of these declining numbers will be, currently we are in the potentially dangerous position of losing integral parts of ecosystems without knowing what roles they play within it."

Currently, scientists hope to increase understanding of how ecosystems are changing. With this decline in invertebrates, it's crucial to target species that are most at risk.

"Prevention of further declines will require us to better understand what species are winning and losing in the fight for survival and from studying the winners, apply what we learn to improve conservation projects," said Collen. "We also need to develop predictive tools for modeling the impact of changes to the ecosystem so we can prioritize conservation efforts, working with governments globally to create supportive policy to reverse the worrying trends we are seeing."

The findings are published in the journal Science.