The Effects of Residual IGRs on Aedes Albopictus and Aedes Aegypti

| July 12, 2015

K. C. Donovan, R. M. Pereira and P.G. Koehler

Urban Entomology Lab. – Univ. of Florida

Abstract: Mosquito-borne viruses, namely chikungunya and dengue, are quickly becoming an increasing problem in the western hemisphere. A. aegypti and A. albopictus mosquitoes, the principle vectors of these viruses, are vigorously breeding in water containers around people’s homes. Unlike other mosquitoes, they are daytime biters and good disease vectors.

Insect growth regulators (IGRs) are known to impact the juvenile hormones of insects, effectively preventing them from reaching adulthood. The purpose of this experiment was to record the effect of the insect growth regulator pyriproxyfen on mosquito development and to classify how mortality occurs.

A. aegypti and A. albopictus were exposed to water containing flooring tiles treated with pyriproxyfen (Nyguard) in a polymer coating to produce 0.01% (30 PPB), 0.001% (3 PPB) and 0.0001% (0.3 PPB) concentrations of pyriproxfen in 350 ml of clean, unchlorinated water contained in 500 ml polypropylene cups.

Mosquitoes were observed daily until two days after all control mosquitoes had emerged as adults. Mosquitoes were classified and given a number ranging 0-4 according to the stage when they died: larva (0), deformed pupae (1), healthy pupae (2), deformed adult (3) and living adult (4). Results showed that the 0.01% and 0.001% doses of pyriproxfen were most effective at killing mosquitoes at the larval and pupal stages, thereby preventing them from reaching adulthood.

In this study, the 0.0001% dose of pyriproxfen allowed some adults to live while others died half-enclosed in their pupal case. The IGR hindered the mosquito’s ability to completely form new cuticle in the larval and pupal stages, preventing normal development and causing death before adult mosquito development.

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