title: Conditional fitness benefits of the Rickettsia bacterial symbiont in an insect pest.
abstract: Inherited bacterial symbionts are common in arthropods and can have strong effects on the biology of their hosts. These effects are often mediated by host ecology. The Rickettsia symbiont can provide strong fitness benefits to its insect host, Bemisia tabaci, under laboratory and field conditions. However, the frequency of the symbiont is heterogeneous among field collection sites across the USA, suggesting that the benefits of the symbiont are contingent on additional factors. In two whitefly genetic lines collected from the same location, we tested the effect of Rickettsia on whitefly survival after heat shock, on whitefly competitiveness at different temperatures, and on whitefly competitiveness at different starting frequencies of Rickettsia. Rickettsia did not provide protection against heat shock nor affect the competitiveness of whiteflies at different temperatures or starting frequencies. However, there was a strong interaction between Rickettsia infection and whitefly genetic line. Performance measures indicated that Rickettsia was associated with significant female bias in both whitefly genetic lines, but in the second whitefly genetic line it conferred no significant fitness benefits nor conferred any competitive advantage to its host over uninfected whiteflies in population cages. These results help to explain other reports of variation in the phenotype of the symbiosis. Furthermore, they demonstrate the complex nature of these close symbiotic associations and the need to consider these interactions in the context of host population structure.
authors.affiliation: Graduate Interdisciplinary Program in Entomology and Insect Science, University of Arizona, 410 Forbes, Tucson, AZ, 85721, USA.
authors.forename: Bodil N
authors.initials: BN
authors.lastname: Cass
authors.affiliation: Department of Entomology, University of Arizona, 410 Forbes, Tucson, AZ, 85721, USA.|Department of Biology, The College of Idaho, 2112 Cleveland Blvd., Box 44, Caldwell, ID, 83605, USA.
authors.forename: Anna G
authors.initials: AG
authors.lastname: Himler
authors.affiliation: Department of Entomology, University of Arizona, 410 Forbes, Tucson, AZ, 85721, USA.
authors.forename: Elizabeth C
authors.initials: EC
authors.lastname: Bondy
authors.affiliation: Department of Entomology, University of Arizona, 410 Forbes, Tucson, AZ, 85721, USA.
authors.forename: Jacquelyn E
authors.initials: JE
authors.lastname: Bergen
authors.affiliation: Department of Entomology, University of Arizona, 410 Forbes, Tucson, AZ, 85721, USA.
authors.forename: Sierra K
authors.initials: SK
authors.lastname: Fung
authors.affiliation: Department of Entomology, University of Arizona, 410 Forbes, Tucson, AZ, 85721, USA.
authors.forename: Suzanne E
authors.initials: SE
authors.lastname: Kelly
authors.affiliation: Department of Entomology, University of Arizona, 410 Forbes, Tucson, AZ, 85721, USA. mhunter@ag.arizona.edu.
authors.forename: Martha S
authors.initials: MS
authors.lastname: Hunter
mesh_terms: D000818:Animals; D005260:Female; D056084:Genetic Fitness; D006430:Hemiptera / Q000235:genetics / Q000254:growth & development / Q000382:microbiology*; D006358:Hot Temperature; D008297:Male; D010641:Phenotype; D012281:Rickettsia / Q000254:growth & development*; D012744:Sex Ratio; D013312:Stress, Physiological; D013559:Symbiosis; D014481:United States
keywords: Bemisia tabaci; Frequency dependence; Genetic line; Heat shock; Temperature