Wolbachia infection in Argentinean populations of Anastrepha fraterculus sp1: preliminary evidence of sex ratio distortion by one of two strains

Abstract

AbstractBackgroundWolbachia,one of the most abundant taxa of intracellular Alphaproteobacteria, is widespread among arthropods and filarial nematodes. The presence of these maternally inherited bacteria is associated with modifications of host fitness, including a variety of reproductive abnormalities, such as cytoplasmic incompatibility, thelytokous parthenogenesis, host feminization and male-killing.Wolbachiahas attracted much interest for its role in biological, ecological and evolutionary processes as well as for its potential use in novel and environmentally-friendly strategies for the control of insect pests and disease vectors including a major agricultural pest, the South American fruit fly,Anastrepha fraterculusWiedemann (Diptera: Tephritidae).ResultsWe usedwsp,16S rRNAand a multilocus sequence typing (MLST) scheme includinggatB,coxA,hcpA,fbpA, andftsZ genes to detect and characterize theWolbachiainfection in laboratory strains and wild populations ofA. fraterculusfrom Argentina. Wolbachiawas found in allA. fraterculusindividuals studied.Nucleotide sequences analysis ofwspgene allowed the identification of twoWolbachianucleotide variants (namedwAfraCast1_A andwAfraCast2_A). After the analysis of 76 individuals, a high prevalence of thewAfraCast2_A variant was found both, in laboratory (82%) and wild populations (95%). MLST analysis identified bothWolbachiagenetic variants as sequence type 13. Phylogenetic analysis of concatenated MLST datasets clusteredwAfraCast1/2_A in the supergroup A. Paired-crossing experiments among single infected laboratory strains showed a phenotype specifically associated towAfraCast1_A that includes slight detrimental effects on larval survival, a female-biased sex ratio; suggesting the induction of male-killing phenomena, and a decreased proportion of females producing descendants that appears attributable to the lack of sperm in their spermathecae.ConclusionsWe detected and characterized at the molecular level twowspgene sequence variants ofWolbachiaboth in laboratory and wild populations ofA. fraterculus sp.1 from Argentina. Crossing experiments on singly-infectedA. fraterculusstrains showed evidence of a male killing-like mechanism potentially associated to thewAfraCast1_A -A. fraterculusinteractions. Further mating experiments including antibiotic treatments and the analysis of early and late immature stages of descendants will contribute to our understanding of the phenotypes elicited by theWolbachiavariantwAfraCast1_A inA. fraterculus sp.1.