The history of Hymenopteran parasitoid research in Germany

For many centuries, the detection of the true nature of Hymenopteran parasitism was greatly hindered by the prevalence of the ideas of Aristoteles, in particular his assumption of a Generatio Spontaneum. It was Conrad Gessner (1516-1565), the forerunner of modern zoology, who emancipated natural sciences from a medieval deadlock and opened up new aspects of viewing natural objects through his own observations. He greatly influenced the German flower painter Maria Sybilla Merian (1647-1717), who started to rear the insects she was painting herself to be able to observe them under natural conditions. When she exactly recognised the significance of the parasitoid is difficult to assess, but in the preface of the 1717 version of her “caterpillar” book she made clear that she knew the whole cycle of parasitoid development. So the first publication by a German, Merian, with a correct interpretation dates from 1717, although she might have discovered the phenomenon already 30 years earlier. Merian's studies may have inspired Johann Leonhard Frisch (1666-1743) and August Johann Roesel von Rosenhof (1705-1759) to study insects in detail. Roesel von Rosenhof accurately described several behavioural aspects related to the life history of parasitoids. The first taxonomists working specifically on Hymenopteran parasitoids in Germany were Johann Ludwig Christian Gravenhorst (1777-1857) and Christian Godfried Nees von Esenbeck (1776-1856). The forestry entomologist Julius Theodor Christian Ratzeburg (1801-1871) was the first to describe the ecological relationships of parasitoids in detail. He influenced many other entomologists in the 19th century and founded the long tradition of Hymenopteran parasitoid research in Germany.