Stage-Dependent Expression of Deltamethrin Toxicity and Resistance in Triatoma infestans (Hemiptera: Reduviidae) From Argentina

GERMANO, MÓNICA D; PICOLLO, MARÍA I

JOURNAL OF MEDICAL ENTOMOLOGY

ENTOMOLOGICAL SOC AMER

Año: 2018

0022-2585

Triatoma infestans Klug (Hemiptera: Reduviidae) is the main vector of Chagas disease in Latin America. This insecthas been controlled with pyrethroids since the 1980s, although the emergence of resistance to deltamethrin hasdecreased control success in some areas of the Gran Chaco ecoregion. The response of T. infestans to deltamethrinwas evaluated per developmental stage. In addition, we evaluated the possible stage-dependent expression ofdeltamethrin resistance. The bioassays were conducted by topical application of the insecticide in acetone. The dropsize, age at the time of exposure, and mortality measuring time were standardized per stage. The lethal dose ofdeltamethrin moderately increased with the developmental stage. The resistance to deltamethrin was expressed inevery instar, and was the highest in the fourth- and fifth-instar nymphs. While increasing, weight plays a relevant rolein lethal dose stage dependency, a number of contributing factors such as degradative metabolism are probablyinvolved in the variability of insecticide effect and resistance described for different T. infestans developmentalstages. Possible explanations for these differences and their implications on resistance management and chemicalcontrol are discussed.