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Lyme disease bacterium does not affect attraction to rodent odour in the tick vector.

Berret J, Voordouw MJ - Parasit Vectors (2015)

Bottom Line: Nymphs were significantly attracted to questing perches that had been scented with mouse odours.However, there was no difference in questing behaviour between nymphs infected with rodent- versus bird-specialized Borrelia genospecies.Our study suggests that the tick, and not the pathogen, controls the early stages of host choice behaviour.

View Article: PubMed Central - PubMed

Affiliation: Laboratory of Ecology and Evolution of Parasites, Institute of Biology, University of Neuchâtel, Rue Emile-Argand 11, 2000, Neuchâtel, Switzerland. jeremy.berret@unine.ch.

ABSTRACT

Background: Vector-borne pathogens experience a conflict of interest when the arthropod vector chooses a vertebrate host that is incompetent for pathogen transmission. The qualitative manipulation hypothesis suggests that vector-borne pathogens can resolve this conflict in their favour by manipulating the host choice behaviour of the arthropod vector.

Methods: European Lyme disease is a model system for studying this conflict because Ixodes ricinus is a generalist tick species that vectors Borrelia pathogens that are specialized on different classes of vertebrate hosts. Avian specialists like B. garinii cannot survive in rodent reservoir hosts and vice versa for rodent specialists like B. afzelii. The present study tested whether Borrelia genospecies influenced the attraction of field-collected I. ricinus nymphs to rodent odours.

Results: Nymphs were significantly attracted to questing perches that had been scented with mouse odours. However, there was no difference in questing behaviour between nymphs infected with rodent- versus bird-specialized Borrelia genospecies.

Conclusion: Our study suggests that the tick, and not the pathogen, controls the early stages of host choice behaviour.

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Related in: MedlinePlus

Proportion of active nymphs that chose the scented focal stick for each Borrelia ecotype. The proportion of active I. ricinus nymphs that chose the focal stick scented with mouse odours is shown for each of the three groups of nymphs. The three groups were: uninfected nymphs (16.20% = 29/179), nymphs infected with the bird-specialist ecotype (21.05% = 16/76), and nymphs infected with the rodent-specialist ecotype (23.08% = 3/13). The differences in attraction to rodent odour between the three groups of nymphs were not statistically significant. Shown are the means and the 95% confidence limits.
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Fig2: Proportion of active nymphs that chose the scented focal stick for each Borrelia ecotype. The proportion of active I. ricinus nymphs that chose the focal stick scented with mouse odours is shown for each of the three groups of nymphs. The three groups were: uninfected nymphs (16.20% = 29/179), nymphs infected with the bird-specialist ecotype (21.05% = 16/76), and nymphs infected with the rodent-specialist ecotype (23.08% = 3/13). The differences in attraction to rodent odour between the three groups of nymphs were not statistically significant. Shown are the means and the 95% confidence limits.

Mentions: The preference for the focal perch scented with mouse odour was highest for the nymphs infected with the rodent-specialist ecotype (3 focal ticks/13 active ticks; mean = 23.08%; 95% CL = 5.04–53.81%), intermediate for the nymphs infected with the bird-specialist ecotype (16 focal ticks/76 active ticks; mean = 21.05%; 95% CL = 12.54–31.92%), and lowest for the uninfected nymphs (29 focal ticks/179 active ticks; mean = 16.20%; 95% CL = 11.12–22.43%; Figure 2). However, there was no significant effect of Borrelia ecotype on tick attraction to rodent odour (Δ df = 2, Δ dev = 0.983, p = 0.611).Figure 2


Lyme disease bacterium does not affect attraction to rodent odour in the tick vector.

Berret J, Voordouw MJ - Parasit Vectors (2015)

Proportion of active nymphs that chose the scented focal stick for each Borrelia ecotype. The proportion of active I. ricinus nymphs that chose the focal stick scented with mouse odours is shown for each of the three groups of nymphs. The three groups were: uninfected nymphs (16.20% = 29/179), nymphs infected with the bird-specialist ecotype (21.05% = 16/76), and nymphs infected with the rodent-specialist ecotype (23.08% = 3/13). The differences in attraction to rodent odour between the three groups of nymphs were not statistically significant. Shown are the means and the 95% confidence limits.
© Copyright Policy - open-access
Related In: Results  -  Collection

License 1 - License 2
Show All Figures
getmorefigures.php?uid=PMC4417542&req=5

Fig2: Proportion of active nymphs that chose the scented focal stick for each Borrelia ecotype. The proportion of active I. ricinus nymphs that chose the focal stick scented with mouse odours is shown for each of the three groups of nymphs. The three groups were: uninfected nymphs (16.20% = 29/179), nymphs infected with the bird-specialist ecotype (21.05% = 16/76), and nymphs infected with the rodent-specialist ecotype (23.08% = 3/13). The differences in attraction to rodent odour between the three groups of nymphs were not statistically significant. Shown are the means and the 95% confidence limits.
Mentions: The preference for the focal perch scented with mouse odour was highest for the nymphs infected with the rodent-specialist ecotype (3 focal ticks/13 active ticks; mean = 23.08%; 95% CL = 5.04–53.81%), intermediate for the nymphs infected with the bird-specialist ecotype (16 focal ticks/76 active ticks; mean = 21.05%; 95% CL = 12.54–31.92%), and lowest for the uninfected nymphs (29 focal ticks/179 active ticks; mean = 16.20%; 95% CL = 11.12–22.43%; Figure 2). However, there was no significant effect of Borrelia ecotype on tick attraction to rodent odour (Δ df = 2, Δ dev = 0.983, p = 0.611).Figure 2

Bottom Line: Nymphs were significantly attracted to questing perches that had been scented with mouse odours.However, there was no difference in questing behaviour between nymphs infected with rodent- versus bird-specialized Borrelia genospecies.Our study suggests that the tick, and not the pathogen, controls the early stages of host choice behaviour.

View Article: PubMed Central - PubMed

Affiliation: Laboratory of Ecology and Evolution of Parasites, Institute of Biology, University of Neuchâtel, Rue Emile-Argand 11, 2000, Neuchâtel, Switzerland. jeremy.berret@unine.ch.

ABSTRACT

Background: Vector-borne pathogens experience a conflict of interest when the arthropod vector chooses a vertebrate host that is incompetent for pathogen transmission. The qualitative manipulation hypothesis suggests that vector-borne pathogens can resolve this conflict in their favour by manipulating the host choice behaviour of the arthropod vector.

Methods: European Lyme disease is a model system for studying this conflict because Ixodes ricinus is a generalist tick species that vectors Borrelia pathogens that are specialized on different classes of vertebrate hosts. Avian specialists like B. garinii cannot survive in rodent reservoir hosts and vice versa for rodent specialists like B. afzelii. The present study tested whether Borrelia genospecies influenced the attraction of field-collected I. ricinus nymphs to rodent odours.

Results: Nymphs were significantly attracted to questing perches that had been scented with mouse odours. However, there was no difference in questing behaviour between nymphs infected with rodent- versus bird-specialized Borrelia genospecies.

Conclusion: Our study suggests that the tick, and not the pathogen, controls the early stages of host choice behaviour.

Show MeSH
Related in: MedlinePlus