Background: Parasitic wasps (parasitoids) use volatile organic compounds released by herbivore-infested plants to locate their hosts. Response of parasitoids to plant odors may be plastic and dependent on their physiological state. Using
Microplitis croceipes (Hymenoptera: Braconidae), a relatively specialized larval endoparasitoid of
Heliothis virescens (Lepidoptera: Noctuidae), we asked whether age and mating status of parasitoids affect their olfactory response to host-related odors.
Methods: Four odor stimuli of varying complexity were selected based on previous reports of parasitoid response to cotton volatiles:
cis-3-hexenol (a green leaf volatile), α-pinene (a constitutive monoterpene), a 50/50 v/v binary mixture (
cis-3-hexenol + α-pinene), and
H. virescens-infested cotton odors. Female
M. croceipes used in Y-tube olfactometer bioassays were either mated or unmated, and grouped 1–3, 4–6, and 7–9 d-old. Female parasitoids used in electroantennogram (EAG) recording were mated and grouped 1–3, 4–6, 7–9 and 10–12 d-old.
Results: In Y-tube olfactometer bioassays, neither age nor mating status played a major role in the attraction of parasitoids to test odor stimuli, with two exceptions: 4–6 d-old mated parasitoids showed attraction to the binary mixture, and 1–3 d-old mated parasitoids showed attraction to
H. virescens-infested cotton. Age did not affect EAG response of parasitoids to test stimuli.
Conclusions: The present results suggest that age and mating status do not play a major role in modulating olfactory responses of
M. croceipes to host-related plant odors. Instead, plasticity of olfactory response may be limited in
M. croceipes due to strong innate sensitivity to host-related odor cues.