Differential Patterns of insecticide Resistance in eggs and first instars of Triatoma infestans (Hemiptera: Reduviidae) from Argentina and Bolivia. J. Med. Entomol. 45, 421- 426 (6)

TOLOZA A., M. GERMANO, G. MOUGABURE CUETO, C. VASSENA, E. ZERBA & M.I. PICOLLO

Journal of Medical Entomology

Entomological Society of America

Lugar: Lanham, Maryland; Año: 2008 vol. 45 p. 421 - 426

Previous works of our laboratory have reported high resistance levels to deltamethrin correlated with failures of chemical control in the field from populations of Northern Argentina and Southern Bolivia. The aim of this work was to study the resistance pattern in either eggs or first instars of T.infestans Klug populations from Argentina and Bolivia. Concerning ovicidal action, Salvador Mazza showed the highest resistant ratio to deltamethrin and lambda-cyhalothrin (RR=114.3 and 14.2, respectively), and was susceptible to fipronil and fenitrothion. About Bolivian populations Mataral showed very low resistant ratios to deltamethrin and lambda-cyhalothrin (RR=2.3 and 2.1, respectively) and was susceptible to fipronil and fenitrothion, Sucre was susceptible to deltamethrin and fenitrothion, and showed very low resistant ratios to lambda-cyhalothrin and fipronil (RR=2.5 and 2.0, respectively); and Yacuiba was susceptible to deltamethrin. With respect to first instar toxicity, Salvador Mazza was susceptible to fipronil while Mataral and Sucre were susceptible to fenitrothion, and showed very low resistant ratios to lambda-cyhalothrin (RR= 2.9 and 2.8, respectively) but high levels to fipronil (RR= 386.8 and 585.5, respectively). Salvador Mazza possessed eggs as resistant to deltamethrin as larvae stage. Remarkable differences were found in the resistant-profile to fipronil in first instars and eggs from Sucre and Mataral. These indicated that the expression of insecticide resistance in eggs is population dependent, and that the pyrethroid resistance diagnosed in T.infestans first instar is not indicative of resistance in the egg stage. More work is required to identify the insecticide resistance profile in T.infestans eggs and first instars.    Key words. Triatoma infestans, insecticide resistance, egg, first instar, Argentina, Bolivia