ABSTRACT
BACKGROUND: Triatomine bugs are the insect vectors of Trypanosoma cruzi, the etiological agent of Chagas disease. These insects are known to aggregate inside shelters during daylight hours and it has been demonstrated that within shelters, the aggregation is induced by volatiles emitted from bug feces. These signals promote inter-species aggregation among most species studied, but the chemical composition is unknown. METHODOLOGY/PRINCIPAL FINDINGS: In the present work, feces from larvae of the three species were obtained and volatile compounds were identified by solid phase microextraction-gas chromatography-mass spectrometry (SPME-GC-MS). We identified five compounds, all present in feces of all of the three species: Triatoma infestans, Panstrongylus megistus and Triatoma brasiliensis. These substances were tested for attractivity and ability to recruit insects into shelters. Behaviorally active doses of the five substances were obtained for all three triatomine species. The bugs were significantly attracted to shelters baited with blends of 160 ng or 1.6 µg of each substance. CONCLUSIONS/SIGNIFICANCE: Common compounds were found in the feces of vectors of Chagas disease that actively recruited insects into shelters, which suggests that this blend of compounds could be used for the development of baits for early detection of reinfestation with triatomine bugs.
Subject(s)
Chagas Disease/prevention & control , Feces/chemistry , Insect Control/methods , Insect Vectors , Triatoma , Volatile Organic Compounds/pharmacology , Animals , Behavior, Animal/drug effects , Insect Vectors/drug effects , Insect Vectors/physiology , Larva , Panstrongylus/drug effects , Panstrongylus/physiology , Pheromones , Triatoma/drug effects , Triatoma/physiology , Volatile Organic Compounds/chemistryABSTRACT
BACKGROUND: This year-long study evaluated the effectiveness of a strategy involving selective deltamethrin spraying and community education for control of Chagas disease vectors in domestic units located in rural communities of coastal Ecuador. RESULTS: Surveys for triatomines revealed peridomestic infestation with Rhodnius ecuadoriensis and Panstrongylus howardi, with infestation indices remaining high during the study (13%, 17%, and 10%, at initial, 6-month, and 12-month visits, respectively), which indicates a limitation of this strategy for triatomine population control. Infestation was found 6 and 12 months after spraying with deltamethrin. In addition, a large number of previously vector-free domestic units also were found infested at the 6- and 12-month surveys, which indicates new infestations by sylvatic triatomines. The predominance of young nymphs and adults suggests new infestation events, likely from sylvatic foci. In addition, infection with Trypanosoma cruzi was found in 65%, 21% and 29% at initial, 6-month and 12-month visits, respectively. All parasites isolated (n = 20) were identified as TcI. CONCLUSION: New vector control strategies need to be devised and evaluated for reduction of T. cruzi transmission in this region.
Subject(s)
Aerosols/administration & dosage , Disease Vectors , Insect Control/methods , Insecticides/administration & dosage , Nitriles/administration & dosage , Panstrongylus/drug effects , Pyrethrins/administration & dosage , Rhodnius/drug effects , Animals , Ecuador , Education/methods , Family Characteristics , Female , Humans , Male , Panstrongylus/growth & development , Panstrongylus/parasitology , Rhodnius/growth & development , Rhodnius/parasitology , Trypanosoma cruzi/isolation & purificationABSTRACT
A cDNA encoding a trypsin-like protease from the salivary glands of the haematophagous reduviid Panstrongylus megistus was cloned and sequenced. The deduced protein sequence showed similarities to serine proteases of other hemipterans but with substitutions in the catalytic triad and the substrate binding site. The expression of the gene increased more than sixfold after feeding. Saliva showed the highest proteolytic activity at neutral to slightly basic pH. Substrate and inhibitor profiles and zymography indicated the presence of a trypsin-like protease with preference for Arg and Lys at P1. Using chromatography, a fibrinolytic enzyme was purified whose sequence was identified by tandem mass spectrometry as that encoded by the cDNA.
Subject(s)
Feeding Behavior , Panstrongylus/enzymology , Protein Processing, Post-Translational , Salivary Glands/enzymology , Serine Proteases/genetics , Amino Acid Sequence , Animals , Base Sequence , DNA, Complementary/genetics , Electrophoresis, Polyacrylamide Gel , Feeding Behavior/drug effects , Fibrinolysis/drug effects , Gene Expression Profiling , Gene Expression Regulation/drug effects , Hydrolysis/drug effects , Larva/drug effects , Larva/enzymology , Molecular Sequence Data , Molecular Weight , Panstrongylus/drug effects , Panstrongylus/genetics , Protein Processing, Post-Translational/drug effects , Salivary Glands/drug effects , Sequence Alignment , Serine Proteases/chemistry , Serine Proteases/isolation & purification , Serine Proteases/metabolism , Serine Proteinase Inhibitors/pharmacology , Substrate Specificity/drug effects , Time FactorsABSTRACT
The insecticidal action on eggs of triatomine have been little considered in the control activitys of Chagas' disease. With objective [corrected] of to compare the potential of three synthetic pyrethroids (deltamethrin,alphacypermethrin and lambdacyhalothrin) on eggs, the authors realized laboratory tests. The pyretroid lambdacialotrin is more efficient. The following species were used in this experiment: Panstrongylus megistus and Triatoma sordida. The specie Triatoma sordida is more susceptible with the pyrethroids utilized.
Subject(s)
Insect Control/methods , Insecticides , Triatominae/drug effects , Animals , Nitriles , Panstrongylus/drug effects , Pyrethrins , Triatoma/drug effectsABSTRACT
Estudou-se o efeito da deltametrina (K-Othrine Flow SC 50) em 34 unidades habitacionais, domicílio e anexos, em Goianópolis, localizada no município de Pirenópolis, Goiás, Brasil. Estas habitaçÆes estavam infestadas por triatomíneos. As espécies encontradas foram Panstrongylus geniculatos, Rhodnius neglectus, Triatoma pseudomaculata e T. sordida infestando domicílio e/ou anexos. A deltrametrina foi rociada na dose de 25mg/m2, no ambiente domiciliar, nas 34 unidades e locais infestados por triatomíneos mantendo-as livres destes insetos por um período de um ano. Os levantamentos e as buscas de triatomíneos nas unidades habitacionas foram feitos nos 3§, 6§, 9§ e 12§ meses após o tratamento. Deste trabalho pode-se concluir que o efeito residual da deltrametrina persistiu durante um ano e foi letal para as espécies consideradas de pequeno porte, e que R. neglectus e T. sordida foram as espécies que evidenciaram o maior poder de invasåo domiciliar pela dispersåo ativa
Subject(s)
Panstrongylus/drug effects , Rhodnius/drug effects , Triatoma/drug effects , InsecticidesABSTRACT
The epithelial cells of Panstrongylus megistus male accessory glands (MAG) present ultrastructural characteristics of a secretory cell. Their secretory products are accumulated in the lumen of the four MAG lobes. During the first 8 days of adult life a strong secretion activity occurs, accumulating enough material to produce the first spermatophore. Cerebral neurosecretions as well as juvenile hormone are both involved in MAG secretory activity regulation. Juvenile hormone seems to be the responsible for the stimulation of most protein synthesis in male accessory glands. Cerebral neurosecretion seems to be necessary to stimulate juvenile hormone production and release by the corpus allatum. Furthermore, neurosecretion is required for some polypeptides synthesis by MAG. Although topic application of precocene II to adult males does not reproduce the same effects on MAG as does allatectomy, this compound causes strong reduction on male reproductive capacity.
