Convergence in symbiont-induced plant-mediated responses to herbivory: a case study with bracoviruses and ichnoviruses

This dataset describes olfactory responses of insect parasitoids towards herbivore-induced plant volatiles (HIPVs).

Plants were induced with the following caterpillar treatments:

Second-instar Pierisbrassicae were anaesthetized on ice and injected with PBS solutions with components retrieved from Cotesia glomerata (Cg),  or Hyposter ebeninus (He) using the Eppendorf FemtoJet-4x injector equipped with glass capillaries (3.5”, Drummond Scientific. No.3-000-203-G/X). In all experiments, venom, calyx fluid or a mixture of venom and calyx fluid dissolved in 100 nL were injected to prepare the following treatments: 1) C.glomerata calyx fluid containing bracovirus particles (CgBV); 2) C.glomerata venom (V); 3) C.glomerata calyx fluid + venom (CgBV+V); 4) H.ebeninus calyx fluid containing ichnovirus particles (HeIV). Additional treatments were used as controls to test whether the microinjection treatment per se affected the interaction of the caterpillars with the food plant: 5) un-parasitized caterpillars injected with 100 nL of PBS (PBS) (negative controls) and 6) parasitized caterpillars injected with 100 nL of PBS (Cg-PBS, He-PBS) (positive controls).

Wind tunnel and olfactometer assays

To investigate whether different injection treatments of caterpillars affect the plant-mediated foraging behavior of parasitoid females, we carried out olfactory assays using a wind tunnel for C.glomerata and a static two-chamber olfactometer for H.ebeninus.

Cotesia glomerata responses to Herbivore-induced plant volatiles (HIPVs) triggered by micro-injected caterpillars in wind tunnel dual-choice set-up. Parasitoid preference for one of the two offered plants was assessed in terms of first choice, which was considered to be made when the wasp landed on a plant. Each treatment combination was replicated with 10 plant pairs and 10 wasps per plant pair.

Hyposoter ebeninus responses to Herbivore-induced plant volatiles (HIPVs) triggered by micro-injected caterpillars in static olfactometer dual-choice set-up Parasitoid preference for one of the two offered plants was assessed in terms of residence time, over a total time of 300 seconds.. In each bioassay testing a specific leaf pair combination, the response of three female wasps was monitored. To avoid pseudoreplication, the mean response of these 3 wasps was considered a replicate and this procedure was repeated 8 times for each pairwise combination.