Is there any alternative insecticide to control pyrethroid-resistant Triatoma infestans (Hemiptera: Reduviidae) populations in the Gran Chaco Ecoregion?

G. CARVAJAL; M. I. PICOLLO; A. TOLOZA

Austin

Congreso; ESA Annual Meetings; 2013

Entomological Society of America

The prevention of Chagas Disease is based on the chemical control of the vector using pyrethroid insecticides. In the last decade, high resistance levels to these insecticides have been detected. Actually, the only alternative insecticides to control pyrethroid resistant populations are based in the use of organophosphate compound. We analyze the toxicity of 7 non-pyrethorid insecticides against two T. infestans populations, a susceptible (S) and a deltamethrin-resistant (R) population with a resistant level (RL) of 1,031. There was no significant variation in the LD50s after 24, 48 and 72 h of initial topical application on both S (LD50=5.2 ng/insect) and R (LD50= 9.2 ng/insect) populations. This could indicate that the toxicological effect of the active ingredient remains stable through the time. The nutritional condition (starvation/feeding) of the insects had no significant influence on the insecticidal activity of the imidacloprid on either populations S (LD50starved = 5.2 ng/I and LD50feeded = 3.9 ng/i) or R (LD50starved = 9.2 ng/I and LD50feeded = 10.8 ng/i). Thus, the rate of penetration associated with physicochemical modifications of cuticle after feeding seems not to alter the relatively fast-acting effect after topical application. The above results indicate that the neonicotinoid imidacloprid seems to be a possible alternative to pyrethroid insecticides in areas where T. infestans developed resistance. However, the adequate formulation of the active ingredient is essential in their effectiveness. Finally, the implementation of an integrative control strategy is also discussed