Visual learning and spatial orientation in the whirligig beetle Dineutus sublineatus
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1
University of Arizona, Graduate Interdisciplinary Program in Entomology & Insect Science, United States
Whirligig beetles (Coleoptera: Gyrinidae) are aquatic insects living in groups on the water surface. When disturbed, they swim rapidly in circles. Each beetle is equipped with two completely separate pairs of compound eyes, an upper pair sampling the airspace above the water line and a lower pair sampling the water below the surface. The beetles also show aggregate behaviors: groups of tens to sometimes hundreds of individuals are usually found at the same place in a pond or stream all year round. In addition, each individual within a group is thought to have its own positional preference in relation to others depending on a combination of factors including size, sex, age, nutritional state, recent predator exposure. How individual beetles recognize their own positions relative to other group members and to their surroundings is unknown, however. It has been previously found that in the whirligig beetle Dineutus sublineatus, the paired mushroom bodies are exclusively supplied by visual neurons from the upper eyes (Lin and Strausfeld, 2012). It is the only insect taxon found to be equipped with exclusively visual mushroom bodies. In other terrestrial insects mushroom bodies are predominantly supplied by olfactory neurons and are higher olfactory and multimodal processing centers involved in mediating olfactory learning and memory. Our published study confirmed the neural arrangement in the whirligig beetle using fluorescent tracer injections into the upper and lower optic lobes respectively. The calyces, the major input regions of the mushroom bodies, are exclusively supplied by dye-filled neurons relaying from the upper aerial eyes, but not the lower aquatic eyes. I have now developed a vision-based spatial learning paradigm, in which groups of whirligig beetles are trained to associate a terrestrial landmark with a negative reinforcement mimicking a bird attack. After training, the landmark was presented in random locations in the arena and beetles in the treatment group rapidly reoriented themselves accordingly and significantly further away from the landmark than the control group that did not experience bird attacks. In addition, after reorientation with regard to the landmark, each individual beetle in the treatment group maintained its own position in relation to other members of the group throughout the testing period. These results suggest that visual information from above the water line (such as landmarks on the bank) is sufficient for the whirligig beetles to achieve their spatial orientation in relation to the surroundings and to other group members. As suggested by our anatomical data, this visual-based spatial learning and place memory may be formed and mediated by the beetles’ mushroom bodies, which receive direct and exclusive visual inputs from the upper aerial eyes, but not the lower aquatic eyes.
Lin, C, Strausfeld, NJ. 2012. Visual inputs to the mushroom body calyces of the whirligig beetle Dineutus sublineatus: Modality switching in an insect. DOI: 10.1002/cne.23092
Keywords:
Gyrinidae,
mushroom body,
place memory,
Vision
Conference:
Tenth International Congress of Neuroethology, College Park. Maryland USA, United States, 5 Aug - 10 Aug, 2012.
Presentation Type:
Poster (but consider for participant symposium and student poster award)
Topic:
Orientation and Navigation
Citation:
Lin
C
(2012). Visual learning and spatial orientation in the whirligig beetle Dineutus sublineatus.
Conference Abstract:
Tenth International Congress of Neuroethology.
doi: 10.3389/conf.fnbeh.2012.27.00229
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Received:
30 Apr 2012;
Published Online:
07 Jul 2012.
*
Correspondence:
Mr. Chan Lin, University of Arizona, Graduate Interdisciplinary Program in Entomology & Insect Science, Tucson, Arizona, 85721, United States, linch@si.edu