Project HYPERWASP: Rapid adaptation to a novel competitor of Nasonia vitripennis

Mark Lammers, Post-Doc in GA 661/4-1

Fitness landscapes of resident species can change upon the introduction of new species into their habitat,
leading to new ecological interactions and opportunities, significant life history shifts, local extinction, and
trophic cascades. Hundreds of parasitoid wasps have been brought repeatedly to new continents as biocontrol
agents to combat agricultural pests. If niches of introduced and native parasitoids overlap, species will compete
over resources, in particular, hosts. In some cases that might lead to the extinction of either species. However, if
there is no evidence for competitive exclusion, coexistence is inferred, which means that the native species
adapted to the new competitor. This often happens within decades, implying rapid adaptation as an underlying
mechanism. I have established a new model system to study the effects of introduced biocontrol agents; the
introduced parasitoid Tachinaephagus zealandicus and native Nasonia vitripennis in Europe. This system is
tractable in the wild and can readily be brought into the laboratory. I discovered that N. vitripennis is able to
hyperparasitize on T. zealandicus, i.e. feed on T. zealandicus larvae when those have already consumed the
hosts (fly pupae). Hyperparasitism on T. zealandicus represents a novel fitness peak for N. vitripennis.
However, the number of offspring produced through hyperparasitism is significantly lower than on
unparasitized hosts. I will test in the laboratory and field whether selection can or has over the last decades
already increased the efficiency of N. vitripennis to hyperparasitize T. zealandicus. Using evolve and
resequence I try to induce increased hyperparasitic abilities and subsequently screen for loci linked to this
adaptation. Furthermore, I will sample wild populations of both species from the same sites, spanning from the
original introduction site in Denmark to recently invaded areas in Europe. These population samples will be
cultured in the laboratory where I will measure the efficiency of hyperparasitism by all collected strains of N.
vitripennis on all T. zealandicus populations and resistance of T. zelandicus to hyperparasitism. This project will
measure the potential for rapid adaptation of N. vitripennis in the laboratory as well as the actual status and
efficiency of hyperparasitism in the field.