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PLoS Negl Trop Dis. 2009;3(5):e434. doi: 10.1371/journal.pntd.0000434. Epub 2009 May 12.

Control of pyrethroid-resistant Chagas disease vectors with entomopathogenic fungi.

Author information

1
Instituto de Investigaciones Bioquímicas de La Plata (CCT La Plata CONICET-UNLP), Facultad de Ciencias Médicas, Universidad Nacional de La Plata, La Plata, Argentina.

Abstract

BACKGROUND:

Triatoma infestans-mediated transmission of Tripanosoma cruzi, the causative agent of Chagas disease, remains as a major health issue in southern South America. Key factors of T. infestans prevalence in specific areas of the geographic Gran Chaco region-which extends through northern Argentina, Bolivia, and Paraguay-are both recurrent reinfestations after insecticide spraying and emerging pyrethroid-resistance over the past ten years. Among alternative control tools, the pathogenicity of entomopathogenic fungi against triatomines is already known; furthermore, these fungi have the ability to fully degrade hydrocarbons from T. infestans cuticle and to utilize them as fuel and for incorporation into cellular components.

METHODOLOGY AND FINDINGS:

Here we provide evidence of resistance-related cuticle differences; capillary gas chromatography coupled to mass spectrometry analyses revealed that pyrethroid-resistant bugs have significantly larger amounts of surface hydrocarbons, peaking 56.2+/-6.4% higher than susceptible specimens. Also, a thicker cuticle was detected by scanning electron microscopy (32.1+/-5.9 microm and 17.8+/-5.4 microm for pyrethroid-resistant and pyrethroid-susceptible, respectively). In laboratory bioassays, we showed that the virulence of the entomopathogenic fungi Beauveria bassiana against T. infestans was significantly enhanced after fungal adaptation to grow on a medium containing insect-like hydrocarbons as the carbon source, regardless of bug susceptibility to pyrethroids. We designed an attraction-infection trap based on manipulating T. infestans behavior in order to facilitate close contact with B. bassiana. Field assays performed in rural village houses infested with pyrethroid-resistant insects showed 52.4% bug mortality. Using available mathematical models, we predicted that further fungal applications could eventually halt infection transmission.

CONCLUSIONS:

This low cost, low tech, ecologically friendly methodology could help in controlling the spread of pyrethroid-resistant bugs.

PMID:
19434231
PMCID:
PMC2674565
DOI:
10.1371/journal.pntd.0000434
[Indexed for MEDLINE]
Free PMC Article

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