Nutrition in termites: Effect of macronutrient ratio on intake, longevity, digging activity and gut bacteria
Laure-Anne Poissonnier, Audrey Dussutour , Jerome Buhl
School of Agriculture, Food and Wine, The University of Adelaide, AUSTRALIA; CRCA, universite paul sabatier, FRANCE ; School of Agriculture, Food and Wine, The Univeristy of Adelaide, AUSTRALIA
Recent advances in nutritional ecology have led to a better understanding of collective regulation of nutrition in ants and bees. Termites, despite their economic and ecological importance, have on the contrary received almost no attention. Termite nutrition is nonetheless unique and fascinating, due to their social structure and their efficient digestion of recalcitrant complex of ligno-cellulose inaccessible to other species. However, almost nothing is known about their nutritional requirements or the behavioural rules they use to select their food. I constrained groups of the Australian termite Nasutitermes exitiosus to one of 11 artificial diets varying in their macronutrient content (using cellulose, protein and sterols powders). I found that the ratio of macronutrient in the diet did not obviously affect the intake, contrary to other insects studied so far. Lifespan was affected: the strongest effect was the amount of carbohydrate eaten, a specific value leading to the longest lifespan. Too much protein was detrimental, as well as a too high amount of cellulose plus lipid. Digging activity was influenced as well: cellulose intake had the biggest impact (positive); protein also positively affected the activity, but lipid intake had no effect. Regarding body composition, soldiers (fed only by trophallaxis) were not affected by the diet, but worker protein content was affected by the amount of cellulose and protein, as well as their interaction. Lipid proportion was not affected. Using the same diets, I explored how the gut bacteria (essential for termite metabolism) were affected by the diet. I sampled individuals at different time points during a month, and used 16S rRNA gene sequencing to characterise bacteria communities. This is the first time termite nutritional requirements, feeding decision rules and their impact have been studied in termites in such details. This research could be applied to improve pest control and bait formulation.