@article{KaechMatheHubertDennisetal.2018,
  author    = {K{\"a}ch, Heidi and Mathe-Hubert, Hugo and Dennis, Alice B. and Vorburger, Christoph},
  title     = {Rapid evolution of symbiont-mediated resistance compromises biological control of aphids by parasitoids},
  series = {Evolutionary applications},
  volume    = {11},
  journal   = {Evolutionary applications},
  number    = {2},
  publisher = {Wiley},
  address   = {Hoboken},
  issn      = {1752-4571},
  doi       = {10.1111/eva.12532},
  pages     = {220 -- 230},
  year      = {2018},
  abstract  = {There is growing interest in biological control as a sustainable and environmentally friendly way to control pest insects. Aphids are among the most detrimental agricultural pests worldwide, and parasitoid wasps are frequently employed for their control. The use of asexual parasitoids may improve the effectiveness of biological control because only females kill hosts and because asexual populations have a higher growth rate than sexuals. However, asexuals may have a reduced capacity to track evolutionary change in their host populations. We used a factorial experiment to compare the ability of sexual and asexual populations of the parasitoid Lysiphlebus fabarum to control caged populations of black bean aphids (Aphis fabae) of high and low clonal diversity. The aphids came from a natural population, and one-third of the aphid clones harbored Hamiltonella defensa, a heritable bacterial endosymbiont that increases resistance to parasitoids. We followed aphid and parasitoid population dynamics for 3months but found no evidence that the reproductive mode of parasitoids affected their effectiveness as biocontrol agents, independent of host clonal diversity. Parasitoids failed to control aphids in most cases, because their introduction resulted in strong selection for clones protected by H.defensa. The increasingly resistant aphid populations escaped control by parasitoids, and we even observed parasitoid extinctions in many cages. The rapid evolution of symbiont-conferred resistance in turn imposed selection on parasitoids. In cages where asexual parasitoids persisted until the end of the experiment, they became dominated by a single genotype able to overcome the protection provided by H.defensa. Thus, there was evidence for parasitoid counteradaptation, but it was generally too slow for parasitoids to regain control over aphid populations. It appears that when pest aphids possess defensive symbionts, the presence of parasitoid genotypes able to overcome symbiont-conferred resistance is more important for biocontrol success than their reproductive mode.},
  language  = {en}
}
@article{DennisPatelOliveretal.2017,
  author    = {Dennis, Alice B. and Patel, Vilas and Oliver, Kerry M. and Vorburger, Christoph},
  title     = {Parasitoid gene expression changes after adaptation to symbiont-protected hosts},
  series = {Evolution},
  volume    = {71},
  journal   = {Evolution},
  publisher = {Wiley},
  address   = {Hoboken},
  issn      = {0014-3820},
  doi       = {10.1111/evo.13333},
  pages     = {2599 -- 2617},
  year      = {2017},
  abstract  = {Reciprocal selection between aphids, their protective endosymbionts, and the parasitoid wasps that prey upon them offers an opportunity to study the basis of their coevolution. We investigated adaptation to symbiont\&\#8208;conferred defense by rearing the parasitoid wasp Lysiphlebus fabarum on aphids (Aphis fabae) possessing different defensive symbiont strains (Hamiltonella defensa). After ten generations of experimental evolution, wasps showed increased abilities to parasitize aphids possessing the H. defensa strain they evolved with, but not aphids possessing the other strain. We show that the two symbiont strains encode different toxins, potentially creating different targets for counter\&\#8208;adaptation. Phenotypic and behavioral comparisons suggest that neither life\&\#8208;history traits nor oviposition behavior differed among evolved parasitoid lineages. In contrast, comparative transcriptomics of adult female wasps identified a suite of differentially expressed genes among lineages, even when reared in a common, symbiont\&\#8208;free, aphid host. In concurrence with the specificity of each parasitoid lineages' infectivity, most differentially expressed parasitoid transcripts were also lineage\&\#8208;specific. These transcripts are enriched with putative venom toxins and contain highly expressed, potentially defensive viral particles. Together, these results suggest that wild populations of L. fabarum employ a complicated offensive arsenal with sufficient genetic variation for wasps to adapt rapidly and specifically to their hosts' microbial defenses.},
  language  = {en}
}