The study, published in Biological Conservation, shows that over 40% of insect species are threatened worldwide.
The study reviewed a total of 73 historical reports of insect declines worldwide.
It found that habitat loss by conversion to intensive agriculture is the main driver of the declines.
Climate change was also listed as a contributing factor, particularly in tropical regions.
The study warned: "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."