Summary: S H O R T C O M M U N I C A T I O N
Does parasitoid attack strategy influence host
specificity? A test with New World braconids
D A V I D M . A L T H O F F Department of Biological Sciences, University of Idaho, U.S.A.
Abstract. 1. Parasitoid attack strategy has been divided into two broad cat-
egories, koinobiosis and idiobiosis, based on the arrest of host development and
the intimacy of larval contact. Koinobionts allow the host to continue developing
and larvae usually feed within the host body, whereas idiobionts stop host
development and larvae usually feed externally.
2. Comparisons of host ranges from rearings of parasitoids from specific host
communities have shown that koinobionts are more host specific than idiobionts.
These tests suggested that parasitoid attack strategy influenced specialisation in
parasitoidhost interactions within certain host communities.
3. To determine whether this pattern was consistent within a single parasitoid
lineage that utilises hosts from many different communities, the host ranges of
koinobiont and idiobiont braconid genera of the New World were compared.
Koinobiont genera utilised fewer host families than idiobionts, suggesting that
parasitoid attack strategy may direct the evolution of host specificity throughout
the evolutionary history of parasitoid lineages.
Key words. Braconidae, host range, idiobiosis, koinobiosis, specialisation.