Alongside British naturalist David Attenborough, Wilson was considered one of the world's leading authorities on natural history and conservation.
Wilson's Half-Earth Project calls for protecting half the planet's land and sea so there are enough diverse and well-connected ecosystems to reverse the course of species extinction, which is happening at a rate not seen in 10 million years.
The United Nations has urged countries to commit to conserving 30% of their land and water – almost double the area now under some form of protection - by 2030, a target known as "30 by 30" and inspired in part by Wilson.
Born in the southern US state of Alabama, Wilson's trajectory as an entomologist, someone who studies insects, was set at the age of 10, when he spent hours in the woods collecting bugs and butterflies.
He went on to spend 70 years as a scientist at Harvard University, putting in time as a professor and curator in entomology. Through his career, Wilson discovered more than 400 species of ants. He said one of his greatest achievements was working out how ants communicate danger and food trails, for example, by emitting chemicals.
Wilson attracted controversy when his 1975 book "Sociobiology: the New Synthesis" was interpreted by some scientists as implying that human behaviours like altruism or hostility are determined by genes, or "nature", rather than environment, or "nurture". Critics at the time decried the theory as carrying echoes of eugenics.
He had been living in a retirement community in the northeastern United States and had recently published the latest in a long series of books on biodiversity.