Susceptibility characterization of residual Brazilian populations of Triatoma infestans Klug, 1834 (Hemiptera: Reduviidae) to deltamethrin pyrethroid

Grasielle Caldas D`avila Pessoa, Aline Cristine Luiz Rosa, Cleonara Bedin, Tânia Wilhelms, Fernanda de Mello, Helder Silveira Coutinho, Eduardo Oyama Lins Fonseca, Roberto Fonseca dos Santos, Liléia Diotaiuti
2015 Revista da Sociedade Brasileira de Medicina Tropical  
Despite years of efforts towards the elimination of Triatoma infestans in Brazil, residual foci still persist in some areas of the States of Bahia and Rio Grande do Sul. The persistence of these T. infestans populations in the country has two different origins of equal concern: operational failures or insecticide resistance. Thus, the objective of this study was to characterize the susceptibility profi le of the residual Brazilian populations of T. infestans to deltamethrin. Methods: The
more » ... ibility reference lineage was derived from Cipein/Argentina. The populations studied were manually collected using a dislodging agent in peridomiciles in the States of Bahia (Novo Horizonte) and of Rio Grande do Sul (Santa Rosa and Doutor Maurício Cardoso). Serial dilutions of deltamethrin were prepared and applied at the dorsal abdomen of fi rst instar nymphs. The control group received only pure acetone. Mortality was evaluated after 72h. Qualitative tests assessed the mortality of a diagnostic dose of 1xLD 99 (2.76ng a.i./nymph) determined for the susceptibility reference lineage. Results: The susceptibility profi le characterization of the T. infestans populations revealed an RR 50 ranging from 1.73 to 3.26. The mortality percentage in response to a diagnostic dose was 100%. The results obtained in the quantitative and qualitative assays corresponded for all populations. Conclusions: The results of this study indicate that the persistence of residual foci of T. infestans in Bahia and Rio Grande do Sul is not related to insecticide resistance but may be associated with operational failures. In Rio Grande do Sul, we must consider the possibility of continuous reinfestation by Argentinian individuals, which justifi es active and effi cient epidemiological surveillance.
doi:10.1590/0037-8682-0011-2015 pmid:25992929 fatcat:vd4ooots3vh3pgmyrj3ffmxc6m