The review, Worldwide decline of the entomofauna: A review of its drivers, cites habitat loss due to intensive agriculture as the main driver of the decline.
In addition, agro-chemical pollutants, invasive species, and climate change are listed as additional causes.
The study says that more than 40 percent of insect species are threatened with extinction - with the rate of extinction eight times faster than that of mammals, birds, and reptiles. Overall, the number of insects is falling by 2.5 percent annually - which could lead to their extinction within 100 years
This is a major issue, as insects play an essential role in biodiversity and the proper functioning of all ecosystems, according to the review's authors, who add that insects are food for other creatures, pollinators, and recyclers of nutrients.
Insects are dying out
"The main drivers of species declines appear to be in order of importance: i) habitat loss and conversion to intensive agriculture and urbanisation; ii) pollution, mainly that by synthetic pesticides and fertilisers; iii) biological factors, including pathogens and introduced species; and iv) climate change," says the review.
"The latter factor is particularly important in tropical regions, but only affects a minority of species in colder climes and mountain settings of temperate zones.
"A rethinking of current agricultural practices, in particular a serious reduction in pesticide usage and its substitution with more sustainable, ecologically-based practices, is urgently needed to slow or reverse current trends, allow the recovery of declining insect populations and safeguard the vital ecosystem services they provide."