Fitness of pyrethroid resistance in Triatoma infestans, a vector of Chagas disease

PICOLLO, MARÍA INÉS; MOUGABURE CUETO, GASTÓN; GERMANO, MÓNICA

Orlando Florida

Congreso; XXV International Congress of Entomology; 2016

Entomological Society of America

Triatomines are large blood-sucking bugs that occur mainly in Latin America countries and are vectors of Chagas´ disease. Chemical control by using pyrethroid insecticides has been successful for the elimination of domestic infestation. However, at the beginning of the 2000s a decrease in the effectiveness of pyrethroids was detected in Argentina and Bolivia, particularly in the Gran Chaco eco-region. Actually, it is known the wide widespread and mechanisms of resistance in Triatoma infestans and the expression of deltamethrin resistance thoroughout the embryonic development. In this work, the fitness of resistant T. infestans from Aguaray, Salta, Argentina (22°14?S 63°43?W), an area of the Gran Chaco eco-region, was measured in comparison to susceptible insects by using a demographic approach based on matrix population models. The length of each developmental stage and complete life cycle, mating rate, and fecundity were evaluated. A survival life table was constructed and parameters were calculated to achieve a stage-structured model of population growth. The results showed that the total fecundity of susceptible females resulted significantly higher than resistant and crossed ones and was expressed as the highest reproductive value. Moreover, the proportion of individuals in the younger stages was lower in the resistant than in the susceptible colony, and the opposite was found for the older stages (IV to adult). The described differences in reproductive output and development were associated with lower growth rates in the resistant insects, which could delay resistance evolution or allow its reversion in heterogeneous populations.