Energetic underpinnings of yellow dung fly mating success in the field

Foraging provides the basis for animal reproduction, but requires energy and time to be sustained, entailing a trade-off. Whereas females should maximize their foraging resources, males minimize by optimizing budgets access mating partners. Mark-resight field studies are difficult hence uncommon small insects. Yellow dung flies ( Scathophaga stercoraria L.) abound on pastures in cold-temperate regions across northern hemisphere. Adult lick nectar from flowers energy, require insect prey produce eggs sperm. Males wait around fresh cow dung, at one point also need replenish and/or sperm reserves surrounding vegetation. Their depend body size, nutritional reserves, availability of sperm, competitor female density. Marked male whose status was experimentally manipulated – water only (null control); + sugar (energy replenishment); or water, Drosophila replenishment) were repeatedly observed an experimental pasture entire day. Both nutrient types expected increase success especially large males. The total number resighted seen copulating lowest water-treated flies. Mating positively related size. distance travelled between pats greater fed increased with while pat residence times decreased No differences found sugar- prey-fed groups. Crucially however, there no evidence budget advantage when nutrients limited.