Trypanosomes Modify the Behavior of Their Insect Hosts: Effects on Locomotion and on the Expression of a Related Gene.
BACKGROUND
As a result of evolution, the biology of triatomines must have been significantly adapted to accommodate trypanosome infection in a complex network of vector-vertebrate-parasite interactions. Arthropod-borne parasites have probably developed mechanisms, largely still unknown, to exploit the vector-vertebrate host interactions to ensure their transmission to suitable hosts. Triatomines exhibit a strong negative phototaxis and nocturnal activity, believed to be important for insect survival against its predators.


RESULTS
In this study we quantified phototaxis and locomotion in starved fifth instar nymphs of Rhodnius prolixus infected with Trypanosoma cruzi or Trypanosoma rangeli. T. cruzi infection did not alter insect phototaxis, but induced an overall 20% decrease in the number of bug locomotory events. Furthermore, the significant differences induced by this parasite were concentrated at the beginning of the scotophase. Conversely, T. rangeli modified both behaviors, as it significantly decreased bug negative phototaxis, while it induced a 23% increase in the number of locomotory events in infected bugs. In this case, the significant effects were observed during the photophase. We also investigated the expression of Rpfor, the triatomine ortholog of the foraging gene known to modulate locomotion in other insects, and found a 4.8 fold increase for T. rangeli infected insects.


CONCLUSIONS
We demonstrated for the first time that trypanosome infection modulates the locomotory activity of the invertebrate host. T. rangeli infection seems to be more broadly effective, as besides affecting the intensity of locomotion this parasite also diminished negative phototaxis and the expression of a behavior-associated gene in the triatomine vector.
Centro de Pesquisas René Rachou, Avenida Augusto de Lima, Belo Horizonte, Minas Gerais, Brazil.
Newmar Pinto
NP
Marliére
Centro de Pesquisas René Rachou, Avenida Augusto de Lima, Belo Horizonte, Minas Gerais, Brazil.
José Manuel
JM
Latorre-Estivalis
Centro de Pesquisas René Rachou, Avenida Augusto de Lima, Belo Horizonte, Minas Gerais, Brazil.
Marcelo Gustavo
MG
Lorenzo
Chemical Ecology Group, Department of Plant Protection Biology, Swedish University of Agricultural Sciences, Alnarp, Sweden.
David
D
Carrasco
Centro de Pesquisas René Rachou, Avenida Augusto de Lima, Belo Horizonte, Minas Gerais, Brazil; Departamento de Bioquímica e Imunologia, Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais, Belo Horizonte, Minas Gerais, Brazil.
Juliana
J
Alves-Silva
Centro de Pesquisas René Rachou, Avenida Augusto de Lima, Belo Horizonte, Minas Gerais, Brazil.
Juliana de Oliveira
Jde O
Rodrigues
Centro de Pesquisas René Rachou, Avenida Augusto de Lima, Belo Horizonte, Minas Gerais, Brazil.
Luciana de Lima
Lde L
Ferreira
Centro de Pesquisas René Rachou, Avenida Augusto de Lima, Belo Horizonte, Minas Gerais, Brazil.
Luisa de Melo
Lde M
Lara
Department of Biological Sciences, Simon Fraser University, Burnaby, British Columbia, Canada.
Carl
C
Lowenberger
Centro de Pesquisas René Rachou, Avenida Augusto de Lima, Belo Horizonte, Minas Gerais, Brazil; Department of Biological Sciences, Simon Fraser University, Burnaby, British Columbia, Canada.
Alessandra Aparecida
AA
Guarneri
D000595:Amino Acid Sequence; D000818:Animals; D001522:Behavior, Animal; D005786:Gene Expression Regulation; D006790:Host-Parasite Interactions; D019476:Insect Proteins / Q000235:genetics / Q000378:metabolism; D007303:Insect Vectors / Q000235:genetics / Q000469:parasitology* / Q000502:physiology; D008027:Light; D008969:Molecular Sequence Data; D009043:Motor Activity / Q000235:genetics; D012239:Rhodnius / Q000235:genetics / Q000469:parasitology* / Q000502:physiology; D014345:Trypanosoma / Q000502:physiology*; D014349:Trypanosoma cruzi / Q000502:physiology; D057509:Trypanosoma rangeli / Q000502:physiology
D019476:Insect Proteins