Host-specific recognition kairomone for the parasitoidMicroplitis croceipes (Cresson)

Area of Science:

• Chemical Ecology
• Insect Behavior
• Biological Control

Background:

• Parasitoid wasps rely on chemical cues for host location.
• Kairomones, semiochemicals from one trophic level benefiting another, mediate host-parasitoid interactions.
• Understanding these cues is vital for developing effective biological control strategies.

Purpose of the Study:

• To identify the host recognition kairomone in corn earworm (Helicoverpa zea) frass.
• To determine the role of this kairomone in the foraging behavior of the parasitoid wasp (Microplitis croceipes).

Main Methods:

• Collection and extraction of frass from host (H. zea) and nonhost larvae.
• Olfactory stimulation assays using water and hexane extracts.
• Behavioral assays in a flight tunnel to observe wasp responses to odors.

Main Results:

• A water-extractable kairomone in H. zea frass stimulates antennation and flight responses in M. croceipes females.
• Nonhost frass extracts did not elicit similar responses.
• Host frass extract combined with nonhost frass odor induced attraction to the nonhost odor, suggesting a learned association.

Conclusions:

• The host-specific kairomone is water-extractable and crucial for M. croceipes host recognition.
• This kairomone enables parasitoids to identify host frass and learn associated plant odors for efficient foraging.