Wolbachia wSinvictaA infections in natural populations of the fire ant Solenopsis invicta: Testing for phenotypic effects
1Department of Entomology and Nematology, University of Florida, Bldg. 970 Natural Area Drive, Gainesville, FL
32611, USA.
2USDA-ARS, Center for Medical, Agricultural, and Veterinary Entomology, Gainesville, FL, 32608, USA
Abstract
Wolbachia are intracellular bacteria that commonly infect many arthropods and some nematodes. In arthropods, these maternally transmitted bacteria often induce a variety of phenotypic effects to enhance their own spread within host populations. Wolbachia phenotypic effects generally either provide benefits to infected host females (cytoplasmic incompatibility, positive fitness effects) or bias host sex ratio in favor of females (male-killing, parthenogenesis, feminization), all of which increase the relative production of infected females in host populations. Wolbachia surveys have found infections to be exceedingly common in ants, but little is known at this juncture as to what phenotypic effects, if any, they induce in this group. Previous studies have demonstrated that individuals from native populations of the invasive fire ant Solenopsis invicta commonly harbor one or more of three Wolbachia variants. One of the variants, wSinvictaA, typically occurs at low prevalence in S. invicta populations, appears to have been transmitted horizontally into S. invicta three or more times, and has been lost repeatedly from host lineages over time. In order to determine the phenotypic effects and likely population dynamics of wSinvictaA infections in these ants, brood production patterns of newly mated fire ant queens were studied during simulated claustral founding and measured wSinvictaA transmission fidelity within mature single-queen families. No clear evidence was found for Wolbachia-induced cytoplasmic incompatibility, significant fitness effects, or male-killing. Maternal transmission was perfect to both virgin queens and males. Possible mechanisms for how this variant could be maintained in host populations are discussed.
Keywords: cytoplasmic incompatibility, fitness, social insects, Solenopsis invicta, Wolbachia
Abbreviations: CI, cytoplasmic incompatibility; FM, female mortality; M, monogyne; MD, male development; MK, male-killing; mtDNA, mitochondrial DNA; P, polygyne
Correspondence:
a*andrew.bg@uky.edu,
bdewayne.shoemaker@ars.usda.gov, *Corresponding author
Editor: Thomas Miller was editor of this paper.
Received: 1 December 2009 | Accepted: 12 February 2010 | Published: 4 February 2011
Copyright: This is an open access paper. We use the Creative Commons Attribution 3.0 license that permits unrestricted use, provided that the paper is properly attributed.
ISSN: 1536-2442 | Volume 11, Number 11
Bouwma AM, Shoemaker D. 2011. Wolbachia wSinvictaA infections in natural populations of the fire ant Solenopsis invicta: Testing for phenotypic effects. Journal of Insect Science 11:11 available online: insectscience.org/11.11
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