INVESTIGADORES
GIROTTI Juan Roberto
artículos
Título:
Epicuticular lipids induce aggregation in Chagas disease vectors
Autor/es:
ALICIA N LORENZO FIGUEIRAS; JUAN R GIROTTI; SERGIO J MIJAILOVSKY; M PATRICIA JUAREZ
Revista:
PARASITES AND VECTORS
Editorial:
BioMed Central Ltd
Referencias:
Lugar: London, United Kingdom; Año: 2009 vol. 2 p. 1 - 7
ISSN:
1756-3305
Resumen:
Abstract
Background: The triatomine bugs are vectors of the protozoan parasite Trypanosoma cruzi, the
causative agent of Chagas disease. Aggregation behavior plays an important role in their survival by
facilitating the location of refuges and cohesion of aggregates, helping to keep them safely assembled
into shelters during daylight time, when they are vulnerable to predators. There are evidences that
aggregation is mediated by thigmotaxis, by volatile cues from their faeces, and by hexaneextractable
contact chemoreceptive signals from their cuticle surface. The epicuticular lipids of
Triatoma infestans include a complex mixture of hydrocarbons, free and esterified fatty acids,
alcohols, and sterols.
Results: We analyzed the response of T. infestans fifth instar nymphs after exposure to different
amounts either of total epicuticular lipid extracts or individual lipid fractions. Assays were
performed in a circular arena, employing a binary choice test with filter papers acting as aggregation
attractive sites; papers were either impregnated with a hexane-extract of the total lipids, or lipid
fraction; or with the solvent. Insects were significantly aggregated around papers impregnated with
the epicuticular lipid extracts. Among the lipid fractions separately tested, only the free fatty acid
fraction promoted significant bug aggregation. We also investigated the response to different
amounts of selected fatty acid components of this fraction; receptiveness varied with the fatty acid
chain length. No response was elicited by hexadecanoic acid (C16:0), the major fatty acid
component. Octadecanoic acid (C18:0) showed a significant assembling effect in the concentration
range tested (0.1 to 2 insect equivalents). The very long chain hexacosanoic acid (C26:0) was
significantly attractant at low doses (≤ 1 equivalent), although a repellent effect was observed at
higher doses.
Conclusion: The detection of contact aggregation pheromones has practical application in Chagas
disease vector control. These data may be used to help design new tools against triatomine bugs.