Fenitrothion: an Alternative Insecticide for the Control of Deltamethrin-resistant Populations of Triatoma infestans in Northern Argentina

GERMANO M; PICOLLO M I; SPILLMANN C; MOUGABURE CUETO G

MEDICAL AND VETERINARY ENTOMOLOGY

WILEY-BLACKWELL PUBLISHING, INC

Lugar: Londres; Año: 2014 vol. 28 p. 21 - 25

0269-283X

Deltamethrin-based campaigns to control Triatoma infestans (Klug)(Hemiptera: Reduviidae) have decreased in success as a result of the development ofinsecticide resistance. We compared the in vitro effects of the pyrethroid deltamethrinand two doses of the organophosphate fenitrothion, presented on different materials, onT. infestans from La Esperanza, Argentina. Laboratory tests demonstrated a decreasein susceptibility to deltamethrin in the field population [LD50: 30.32 nanograms perinsect (ng/i)] compared with the reference population (LD50: 0.13 ng/i), giving ahigh resistance ratio of 233.42. By contrast, similar susceptibility to fenitrothionwas assessed in both the field and reference populations (LD50: 21.65 ng/i and21.38 ng/i, respectively). The effectiveness of the formulated insecticides variedaccording to the surfaces to which they were applied. The application of fenitrothionformulations to glass or brick resulted in mortality of 90?100%. The applicationof fenitrothion formulations to wood or mud caused mortality in the range of6.7?56.7%. Resistant insects presented low mortality when exposed to the deltamethrinformulation and high mortality when exposed to fenitrothion formulations. Moreover,the insecticides demonstrated residual activity only when applied to glass. The presentwork demonstrates that fenitrothion is an alternative to pyrethroids for the managementof deltamethrin-resistant insects in La Esperanza. However, this effectiveness is notsustained over time.