Date of this Version
Muona J. 2021. How do Vanhorniidae (Hymenoptera) parasitize Eucnemidae (Coleoptera)? Insecta Mundi 0867: 1–10.
The relationship between the beetle family Eucnemidae and the parasitic proctotrupoid family Vanhorniidae is discussed. The only proven host for Vanhornia eucnemidarum Crawford in North America is an undetermined species of the genus Isorhipis Boisduval and Lacordaire. In Europe, the only known host for Vanhornia leileri Hedqvist is Hylis cariniceps (Reitter). The biologies of the hosts differ radically and it appears unlikely that they could be parasitized in a typical proctotrupoid fashion in which eggs are placed in or on the host larva. This supports the hypothesis that small Vanhorniidae larvae attach themselves to the newly hatched beetle larvae, before they enter the wood on which they feed. The taxonomy of the genus Vanhornia Crawford is briefly discussed.
The close association between Eucnemidae beetles and Vanhorniidae parasitic wasps remains a dilemma. Although the idea of a highly specialized beetle family having its “own” parasitic wasp family suggests a great evolutionary story, this relationship is still poorly known. Many new records of Vanhorniidae have been published recently (He and Chu 1990, China; Kozlov 1998, Far Eastern Russia; Choi and Lee 2012, South Korea; Doczkal 2017, Germany; Artmann-Graf 2017, Switzerland; Hogan et al. 2019, USA; Belgers et al. 2020, the Netherlands). Further new records are known from Sweden (Forshage i. l.) and Finland (FiBIF).
Most of the new articles discuss the biology of the vanhorniids. These discussions are based mainly on Deyrup (1985) and do not provide new information on the subject. My aim is to introduce the other half of the puzzle into this discussion, the biology of the beetles parasitized.
Two definite host species are known, Isorhipis sp. and Hylis cariniceps (Reitter). A fair amount is known of the biology of these eucnemids, but that information has not been considered in this context before. In addition, the old host species associations are partly suspect and some of the new records of Vanhornia spp. may refer to undescribed wasp species. The overlooked fossil information is pointed out as well.