Recognition of foreign oviposition-marking pheromone in a multi-trophic context

Area of Science:

• Insect chemical ecology
• Behavioral ecology
• Chemical eavesdropping

Background:

• Insects use oviposition-marking pheromones (OMPs) to signal host suitability to conspecifics.
• The blueberry maggot fly (Rhagoletis mendax) uses OMPs to deter conspecifics from previously oviposited fruit.
• Diachasma alloeum is a parasitoid wasp that attacks R. mendax larvae.

Purpose of the Study:

• To investigate if the OMP of the parasitic wasp Diachasma alloeum influences the oviposition behavior of its host, the blueberry maggot fly Rhagoletis mendax.
• To determine if Rhagoletis mendax can recognize and respond to the OMP deposited by Diachasma alloeum.

Main Methods:

• Behavioral assays were conducted to observe the oviposition choices of female Rhagoletis mendax.
• Experimental setup involved presenting flies with both unmarked and wasp-marked blueberries.
• Quantification of fly rejection rates for wasp-marked versus unmarked fruit.

Main Results:

• Rhagoletis mendax females demonstrated recognition of the Diachasma alloeum OMP.
• Female flies significantly rejected blueberries previously marked by the parasitic wasp for oviposition.
• This indicates a behavioral modification in the host fly due to the parasitoid's pheromone signal.

Conclusions:

• The OMP of Diachasma alloeum effectively deters oviposition by its host, Rhagoletis mendax.
• This represents a rare instance of interspecific chemical recognition across different insect orders and trophic levels.
• This chemical eavesdropping mechanism may aid the fly in avoiding parasitized hosts, enhancing larval survival.