Do age and mating status affect olfactory response of the parasitoid, Microplitis croceipes (Hymenoptera: Braconidae) to host-related plant odors? [version 1; referees: 2 approved]

• Main Authors: Matthew Burrows, Tolulope Morawo, Henry Fadamiro
• Format: Article
• Language: English
• Published: F1000 Research Ltd 2018-11-01
• Series: F1000Research
• Online Access: https://f1000research.com/articles/7-1817/v1

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.