title: Protein and carbohydrate intake influence sperm number and fertility in male cockroaches, but not sperm viability.
abstract: It is commonly assumed that because males produce many, tiny sperm, they are cheap to produce. Recent work, however, suggests that sperm production is not cost-free. If sperm are costly to produce, sperm number and/or viability should be influenced by diet, and this has been documented in numerous species. Yet few studies have examined the exact nutrients responsible for mediating these effects. Here, we quantify the effects of protein (P) and carbohydrate (C) intake on sperm number and viability in the cockroach Nauphoeta cinerea, as well as the consequences for male fertility. We found the intake of P and C influenced sperm number, being maximized at a high intake of diets with a P : C ratio of 1 : 2, but not sperm viability. The nutritional landscapes for male fertility and sperm number were closely aligned, suggesting that sperm number is the major determinant of male fertility in N. cinerea. Under dietary choice, males regulate nutrient intake at a P : C ratio of 1 : 4.95, which is midway between the ratios needed to maximize sperm production and pre-copulatory attractiveness in this species. This raises the possibility that males regulate nutrient intake to balance the trade-off between pre- and post-copulatory traits in this species.
authors.affiliation: Centre for Ecology and Conservation, College of Life and Environmental Sciences, University of Exeter, Tremough Campus, Penryn TR10 9EZ, UK.
authors.forename: Harriet
authors.initials: H
authors.lastname: Bunning
authors.affiliation: Centre for Ecology and Conservation, College of Life and Environmental Sciences, University of Exeter, Tremough Campus, Penryn TR10 9EZ, UK.
authors.forename: James
authors.initials: J
authors.lastname: Rapkin
authors.affiliation: Centre for Ecology and Conservation, College of Life and Environmental Sciences, University of Exeter, Tremough Campus, Penryn TR10 9EZ, UK.
authors.forename: Laurence
authors.initials: L
authors.lastname: Belcher
authors.affiliation: Centre for Ecology and Conservation, College of Life and Environmental Sciences, University of Exeter, Tremough Campus, Penryn TR10 9EZ, UK Max Planck Institute for Demographic Research, Konrad-Zuse-Strasse 1, 18057 Rostock, Germany.
authors.forename: C Ruth
authors.initials: CR
authors.lastname: Archer
authors.affiliation: Centre for Ecology and Conservation, College of Life and Environmental Sciences, University of Exeter, Tremough Campus, Penryn TR10 9EZ, UK Department of Entomology, North Carolina State University, Gardner Hall, Raleigh, NC 27695-7613, USA.
authors.forename: Kim
authors.initials: K
authors.lastname: Jensen
authors.affiliation: Centre for Ecology and Conservation, College of Life and Environmental Sciences, University of Exeter, Tremough Campus, Penryn TR10 9EZ, UK j.hunt@exeter.ac.uk.
authors.forename: John
authors.initials: J
authors.lastname: Hunt
mesh_terms: D000824:Animal Nutritional Physiological Phenomena; D000818:Animals; D020048:Blattellidae / Q000502:physiology*; D004040:Dietary Carbohydrates / Q000008:administration & dosage; D004044:Dietary Proteins / Q000008:administration & dosage; D005298:Fertility; D005518:Food Preferences; D008297:Male; D013076:Sperm Count; D013094:Spermatozoa / Q000502:physiology
chemical_list: D004040:Dietary Carbohydrates; D004044:Dietary Proteins
keywords: Nauphoeta cinerea; cost of sperm production; ejaculate; nutritional geometry