Monday, December 10, 2007 - 9:53 AM

Praying mantids: A new training protocol and a first look at mantid mushroom bodies

Heather S. Mallory, and Martha R. Weiss, Georgetown University, Biology, 37th and O Streets NW Reiss 406, Washington, DC

Learning in insects has been well documented, particularly for bees and other holometabolous insects. Less is known about the learning abilities of the praying mantis, a hemimetabolous sit-and-wait predator. Previous studies of the Chinese praying mantis (Tenodera sinensis) have demonstrated that sixth instar nymphs can learn to avoid eating toxic milkweed bugs (Oncopeltus fasciatus) after sampling the noxious prey. Other studies have shown that third instar nymphs still eat toxic prey despite previous sampling. It is not clear whether third instar nymphs truly cannot learn, or whether high levels of variance mask learning. The use of milkweed bugs introduces several levels of variance to the system, including activity level of the bug during a trial, toxicity of the seeds fed upon, and individual variation in bug toxicity. We have developed an aversive learning task that utilizes artificial diet and thus allows us to control for movement patterns and toxicity levels. Pilot studies with sixth instar and adult mantids show that they learn to reject salty artificial diet, but not plain artificial diet, within five days. This new training protocol will be used to test third, fourth, and fifth instars in order to establish definitively the onset of learning ability. Additionally, we describe for the first time mantid mushroom bodies. Mushroom bodies are the putative location of learning and memory in insect brains. Future experiments will use the new training protocol and brain imaging to explore the connection between rearing environment, learning ability and mushroom body morphology.