Low parasitoid success on a myrmecophilous host is maintained in the absence of ants

1. Studies of Dinocampus coccinellae, a parasitoid of ladybird beetles, have generally shown congruence between field parasitism rates of different host species and parasitoid preference and/or host suitability in the laboratory, suggesting that host intrinsic factors rather than habitat-related extrinsic factors are of greatest importance in determining D. coccinellae occurrence.

2. The myrmecophilous Coccinella magnifica exhibits much lower D. coccinellae prevalence in the field than most other Coccinella species: it has been suggested that this is a manifestation of enemy-free space provided by the predatory Formica rufa group ants with which the C. magnifica occurs.

3. Coccinella magnifica collected at the same time and locality as parasitised Coccinella septempunctata were unparasitised by D. coccinellae. In the laboratory, in the absence of ants, although the parasitoid attacked C. magnifica as readily as C. septempunctata, C. magnifica was not parasitised successfully.

4. Such results are consistent with those from other ladybirds and C. magnifica does not now benefit directly from any putative D. coccinellae-free space provided by aggressive ants. Because its close relatives exhibit high levels of D. coccinellae parasitism, C. magnifica may be useful in determining some elements important in the evolution of host protection against parasitoid attack.