He was a professor of general and comparative animal physiology and later entomology at Wageningen University and Research between 1972 and 1991.
In 1962 he obtained his PhD under professor Jan de Wilde with a thesis titled: "Diapause and the physiology of hostparasite synchronization in Bupalus piniarius L. [Geometridae] and Eucarcelia rutilla Vill.
[2] In his research he confirmed De Wilde's theory that the relationship between the moth Bupalus piniaria and the parasite Eucarcelia rutilla was based on hormones.
Schoonhoven subsequently moved to the United States where he was a postdoctoral researcher under Vincent Dethier in Philadelphia.
Back in the Netherlands De Wilde encouraged Schoonhoven to study insect-plant relations.
[2] In 1998 he wrote the book Insect-Plant Biology together with Joop van Loon and Tibor Jermy.
[7] In 2015 he was the winner of the Jan Wolkers Prijs [nl] for the book Niet zonder elkaar - bloemen en insecten.