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ARS Home » Southeast Area » Tifton, Georgia » Crop Protection and Management Research » Research » Publications at this Location » Publication #152302
Title: ASSOCIATIVE LEARNING OF COMPLEX ODOURS IN PARASITOID HOST LOCATION

Author
item MEINERS, TORSTEN - FREIE UNIV/BERLIN
item WACKERS, FELIX - NIOO CTO/NETHERLANDS
item Lewis, Wallace

Submitted to: Chemical Senses
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/14/2003
Publication Date: 7/1/2003
Citation: Meiners, T. Wackers, F., Lewis, W.J. 2003. Associative learning of complex odours in parasitoid host location. Chemical Senses. 28:231-236.

Interpretive Summary: A better understanding and use of natural enemies of agricultural pests is important to developing effective alternatives to the economic costs and environmental hazards of conventional pesticides. ARS scientists at Tifton, GA, together with their cooperators, are studying how the parasitic wasp, Microplitis croceipes, a natural enemy of the bollworm/ corn earworm, detects and tracks chemical cues to optimize their host/pest-finding effeciency. They demonstrated that this wasp can learn and subsequently recognize individual and combinations of chemicals associated with host presence and plant-feeding activities, even when present in complex bouquets. However, for certain compounds of a mixture, learning can be blocked by other mixture components. This knowledge of the keen chemical sensing and learning abilities of parasitic wasps is an important step in developing improved strategies for biologically-based pest management of agricultural crops.

Technical Abstract: In this paper we address the question how hymenopteran parasitoids deal with complex odour bouquets, using Microplitis croceipes (Cresson) (Hymenoptera: Braconidae) as a model. We examined the capacity of Microplitis croceipes to respond to individual compounds in flight chamber experiments after conditioning parasitoids with a mixture consisting of 2-octanone, methyl jasmonate, and B-caryophyllene. Parasitoids were given a choice between single compounds from the training mixture and B-ocimene as an unrewarded alternative. When compared with control individuals lacking experience with the odour mixture, parasitoids trained to the odour blend showed an increased preference for 2-octanone and B-caryophyllene, but not for methyl jasmonate. However, when trained with methyl jasmonate alone, parasitoids were able to respond to this compound. This demonstrates that parasitoids can learn to respond to individual compounds following experience with an odour mixture. However, for certain compounds of a mixture, learning can be blocked by other mixture components. Further experiments in which parasitoids were conditioned and challenged with two compound mixes confirmed that the olfactory background can affect recognition of individual compounds.