Many insects harbour facultative endosymbiotic bacteria, often more than one type at a time. These symbionts can have major effects on their hosts' biology, which may be modulated by the presence of other symbiont species and by the host's genetic background. We investigated these effects by transferring two sets of facultative endosymbionts (one Hamiltonella and Rickettsia, the other Hamiltonella and Spiroplasma) from naturally double-infected pea aphid hosts into five novel host genotypes of two aphid species. The symbionts were transferred either together or separately. We then measured aphid fecundity and susceptibility to an entomopathogenic fungus. The pathogen-protective phenotype conferred by the symbionts Rickettsia and Spiroplasma varied among host genotypes, but was not influenced by co-infection with Hamiltonella. Fecundity varied across single and double infections and between symbiont types, aphid genotypes and species. Some host genotypes benefit from harbouring more than one symbiont type.
Fecundity data
Spreadsheet "Fecundity" contains the results of the fecundity assay. The aphids used in this experiment either contained no known secondary symbionts or were artificially infected with different complements of symbiont species. We counted the number of offspring produced by single wingless aphids, representing one of five genotypes and hosting one of seven symbiont complements, during three (grain aphids) or four (pea aphids) consecutive three-day intervals. In the spreadsheet, rows contain offspring counts for individual aphids. Columns are as follows: >>>Species - Aphid species, two levels (A. pisum, S. avenae). >>>Gen - Aphid genotype, five levels (145, J68, J102, Co23, Co26). >>>Sym - Symbiont infection status. Ha / Ri / Sp represent Hamiltonella defensa, Rickettsia sp. or Spiroplasma sp., and the value after underscore represents the genotype of original pea aphid host. >>>Block - The ID number of experimental block. In all cases, lines of a given genotype were tested at the same time (and so have the same block ID number), separately from lines of other genotypes. The fecundity assay for genotype 145 was conducted in two blocks. >>>D10 - number of offspring produced by single wingless aphids before its 10th day of life. >>>D13, D16, D19 - numbers of offspring produced by single aphids during consecutive three-day intervals. >>>Fec_total - total number of offspring produced during 16 days (S. avenae) or 19 days (A. pisum). Missing data are indicated by “NA”.
Lukasik et al - fecundity data.xlsx
Pathogen susceptibility data
Spreadsheet "Susceptibility" contains the results of the pathogen susceptibility assay. The aphids used in this experiment either contained no known secondary symbionts or were artificially infected with different complements of symbiont species. Groups of 20 aphids, representing one of five genotypes and hosting one of seven symbiont complements, were exposed to spores of the pathogenic fungus Pandora neoaphidis. After six days all aphids were scored as a) sporulating; b) dead but not sporulating; or c) alive. In the spreadsheet, each row represents a replicate with 20 aphids. Columns are as follows: >>>Species - Aphid species, two levels (A. pisum, S. avenae). >>>Gen - Aphid genotype, five levels (145, J68, J102, Co23, Co26)
>>>Sym - Symbiont infection status. Ha / Ri / Sp represent Hamiltonella defensa, Rickettsia sp. or Spiroplasma sp., and the value after underscore represents the genotype of original pea aphid host. >>>Fung_D6 - The number of aphids in a replicate which were classified as sporulating six days after the exposure. >>>Dead_D6 - The number of aphids in a replicate which were classified as dead but not sporulating. >>>Alive_D6 - The number of aphids in a replicate which were alive six days after the exposure. >>>Total - The total number of aphids in the three previous categories. Note that in some cases the total is different than 20 – occasionally not all aphids were found six days after the exposure, or the number of the exposed aphids in a replicate may have been miscalculated by 1 or 2.
Lukasik et al - pathogen susceptibility data.xlsx