A study of the internal morphology of the alimentary canal of Chrysoperla rufilabris adults in relation to yeast symbionts was conducted utilizing scanning and transmission electron, and epifluorescence microscopy. The alimentary canal of field-collected adults possessed a single large diverticulum at the posterior end of the foregut. Although yeast cells were distributed throughout the gut, large numbers of yeasts were observed to accumulate within the diverticulum. Large tracheal trunks were attached to the lateral side of the diverticulum suggesting a high demand for gas exchange within this organ. However, the diverticulum was lined with cuticle, and the underlying tissues indicated that minimal absorption occurs within this gut region. This suggests that the high potential for gas exchange in the diverticulum is primarily to support yeast metabolic activity. Observation with fluorescence particles indicated that the foregut and/or diverticulum do not possess an absolute mechanism for retaining particles based on size. The presence of large numbers of yeast cells in between hairs of proventriculus suggests that the proventriculus may play a role in retention of yeast cells. The midgut possessed typical absorptive structures. Since evidence indicated no or minimal absorption of nutrients within the diverticulum, nutrients provided by the yeasts must be transferred to the midgut where absorption occurs. Morphological evidence obtained in this study supports the hypothesis that chrysopid adults form a mutualistic symbiosis with the yeasts and the diverticulum is a specialized structure for housing yeasts.
Species 1: Neuroptera Chrysopidae Chrysoperla rufilabris (green lacewing)
Keywords: gut morphology, yeasts
Back to Student Competition Display Presentations, Section Cd. Behavior and Ecology
Back to Student Competition Posters
Back to The 2003 ESA Annual Meeting and Exhibition