New slow release formulations containing pyripoxyfen used as lethal ovitraps for Aedes aegypti (L.) control

SECCACINI EMILIA; JUAN LAURA; ZERBA EDUARDO; LICASTRO SUSANA

Encuentro; THIRD PANAMERICAN DENGUE RESEARCH NETWORK MEETING; 2012

Aedes aegypti (L.) is the main vector of dengue and yellow fever in Latin America. It usually inhabits urban areas (indoors) and deposits its eggs in man-made containers. Ovitraps were developed as a surveillance tool and in few cases they have been used for mosquito control, incorporating an insecticide-impregnated strip. The present study evaluates the performance of new designed lethal ovitraps incorporating pyriproxyfen in natural materials as new slow release devices that avoids Aedes aegypti (L.) adults to emerge. Hollow candles (10cm diameter x 9.5cm height) made of beeswax and a paraffin:stearin 1:1 mixture containing pyriproxyfen 0.01 and 0.05%, quickly released the insecticide into the larvae breeding water. After the addition of Ae.aegypti larvae III/IV, 80 -100% inhibition of adult emergence of the exposed larvae was found after 1h. The residual activity obtained with pyriproxyfen 0.01 and 0.05% released from beeswax or paraffin:stearin hollow candles was higher than 360 d with 100% inhibition of adult emergence. In another bioassay beeswax and paraffin:stearin 1:1 mixture discs (6.5cm diameter and 0.5cm height) containing different amounts of pyriproxyfen from 10-5  to 10-1  % were used as bottom of 500 ml plastic jars and evaluated for larvae mortality and residual activity. For beeswax larvae mortality never reached 100% for 10-4 and 10-5 % pyriroxyfen while for paraffin:stearin mixture there was an initial total larvae mortality but began to fall at 30d. For concentrations 10-3 % and higher both discs remain 100% active during at least 240d.      The results here presented suggest that natural materials containing pyriproxyfen represent a new long lasting material with a long residual larvicide activity with a very low environmental impact. The hollow candles impregnated with pyriproxyfen could be used as safe autocidal ovitraps inside the houses for Aedes control while the long lasting release of pyriproxyfen from small pieces could convert any breeding container in a lethal ovitrap. Our laboratory is currently working in pieces of different sizes, made of different materials, including biodegradable polymers, containing pyriproxyfen, to be used inside standard ovitraps or sticked on the wall under the water surface of breeding containers (water storage tanks, pots, etc).