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ARS Home » Southeast Area » Tifton, Georgia » Crop Protection and Management Research » Research » Publications at this Location » Publication #103365
Title: A COMPARISON OF COLOR-, SHAPE- AND PATTERN-LEARNING BY THE HYMENOPTERAN PARASITOID MICROPLITIS CROCEIPES

Author
item WACKERS, F - SWISS FED.TECH.INSTITUTE
item Lewis, Wallace

Submitted to: Journal of Comparative Physiology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/30/1999
Publication Date: N/A
Citation: Wackers, F.L., Lewis, W.J. 1999. A comparison of color-, shape- and pattern-learning by the hymenopteran parasitoid Microplitis croceipes. Journal of Comparative Physiology. 184:387-393.

Interpretive Summary: Plant feeding insects are costly pests of agricultural crops. Resistance and residue problems with conventional pesticides have caused scientists to seek better ways to harness natural controls for insect pests. Understanding the natural enemies and how they interact with crop pests is essential to their reliable use in pest control. ARS scientists at Tifton, GA are seeking to better understand the host finding mechanisms of Microplitis croceipes, a parasitic wasp which attacks the caterpillar stage of bollworm and tobacco budworm. The ability of this wasp to learn to use various visual cues provided in association with host caterpillars was examined in flight chamber studies. They were able to increase their foraging efficiency by learning all three types of visual cues in association with hosts. However, they learned to distinguish between shapes more readily than between colors or patterns, which is the reverse order of that reported for honey bees. This type of information is central to designing effective biological control programs, since high searching efficiency is crucial to the effectiveness of parasitoids as control agents.

Technical Abstract: Visual learning by the larval parasitoid, Microplitis croceipes Cresson (Hymenoptera: Braconidae) was investigated in flight chamber studies. During conditioning, free-ranging parasitoids were given a choice between two visual alternatives, only one of which offered a host larva. By using alternatives that differed in either color, shape or pattern, parasitoids could be conditioned to distinguish host sites on the basis of each of these visual cues. Tests during which no reward was offered were conducted following six rewards (ovipositions) at one of the two alternative stimuli. The test results reveal that M. croceipes learned to distinguish between shapes more readily than between colors or patterns. This high rate of shape learning in this parasitoid is in strong contrast to the learning capacity of honey bees, which have been shown to learn color better than pattern and pattern better than shapes. It is argued that the difference in learning capacities between M. croceipes and the honey bee may reflect the different selection pressures imposed on these two species by their natural ecological needs. The high rate of shape learning in M. croceipes may be adaptive in dealing with the homochromatic but multishaped environment in which parasitoids have to locate their herbivorous hosts.