title: Effect of Carbohydrate Supplementation on Investment into Offspring Number, Size, and Condition in a Social Insect.
abstract: Resource availability can determine an organism's investment strategies for growth and reproduction. When nutrients are limited, there are potential tradeoffs between investing into offspring number versus individual offspring size. In social insects, colony investment in offspring size and number may shift in response to colony needs and the availability of food resources. We experimentally manipulated the diet of a polymorphic ant species (Solenopsis invicta) to test how access to the carbohydrate and amino acid components of nectar resources affect colony investment in worker number, body size, size distributions, and individual percent fat mass. We reared field-collected colonies on one of four macronutrient treatment supplements: water, amino acids, carbohydrates, and amino acid and carbohydrates. Having access to carbohydrates nearly doubled colony biomass after 60 days. This increase in biomass resulted from an increase in worker number and mean worker size. Access to carbohydrates also altered worker body size distributions. Finally, we found a negative relationship between worker number and size, suggesting a tradeoff in colony investment strategies. This tradeoff was more pronounced for colonies without access to carbohydrate resources. The monopolization of plant-based resources has been implicated in the ecological success of ants. Our results shed light on a possible mechanism for this success, and also have implications for the success of introduced species. In addition to increases in colony size, our results suggest that having access to plant-based carbohydrates can also result in larger workers that may have better individual fighting ability, and that can withstand greater temperature fluctuations and periods of food deprivation.
authors.affiliation: Department of Animal Biology, University of Illinois, Urbana, Illinois, United States of America.
authors.forename: Bill D
authors.initials: BD
authors.lastname: Wills
authors.affiliation: School of Integrative Biology, University of Illinois, Urbana, Illinois, United States of America.
authors.forename: Cody D
authors.initials: CD
authors.lastname: Chong
authors.affiliation: Department of Entomology, Texas A&M University, College Station, Texas, United States of America.
authors.forename: Shawn M
authors.initials: SM
authors.lastname: Wilder
authors.affiliation: Department of Entomology, Texas A&M University, College Station, Texas, United States of America.
authors.forename: Micky D
authors.initials: MD
authors.lastname: Eubanks
authors.affiliation: Divisison of Biological Sciences, University of California at San Diego, La Jolla, California, United States of America.
authors.forename: David A
authors.initials: DA
authors.lastname: Holway
authors.affiliation: Department of Animal Biology, University of Illinois, Urbana, Illinois, United States of America; Department of Entomology; Program in Ecology, Evolution and Conservation Biology, University of Illinois, Urbana, Illinois, United States of America.
authors.forename: Andrew V
authors.initials: AV
authors.lastname: Suarez
mesh_terms: D000596:Amino Acids / Q000378:metabolism; D000818:Animals; D001000:Ants / Q000033:anatomy & histology / Q000254:growth & development / Q000502:physiology*; D001522:Behavior, Animal; D049628:Body Size; D004040:Dietary Carbohydrates / Q000378:metabolism*; D011156:Population Density; D012098:Reproduction
chemical_list: D000596:Amino Acids; D004040:Dietary Carbohydrates