CONICET | Buscador de Institutos y Recursos Humanos

In this study we report the results of the first experimental field releases of S. spiculatus in mosquito breeding sites in Argentina. The study area was an experimental garden located in the city of La Plata, Buenos Aires province, Argentina. Nine plastic containers (site 1) and 12 tanks (site 2) were placed to allow mosquitoes to breed, in the month of September (early spring), the best season for mosquito abundance in this region of Argentina. Strelkovimermis spiculatus was introduced into mosquito breeding sites as second-stage juveniles (J2; infective stage) obtained from laboratory cultures maintained at the Centro de Estudios Parasitológicos y de Vectores-CEPAVE. J2 of S. spiculatus were released at a ratio of 10:1 and 20:1 (site 1) and 10:1, 50:1 and 100:1 (site 2) J2/mosquito larva. Three replicates and a control group (under natural conditions without J2 release) were used for each doses and site.The results obtained demonstrate that A. aegypti, C. pipiens and C. apicinus larvae were susceptible to parasitism by S. spiculatus under manipulated natural conditions. The levels of parasitism fluctuated greatly between instars, sites and doses. The number of nematodes per larva did not increase significantly with increase in J2/larva ratios in both sites, maintaining values between 1.2 and 4.7. Therefore, the application of low doses, 10:1 J2/larva (site 1) and 50:1 J2/larva (site 2), could be effective in producing parasitism of 2nd instar larva of between 88-100% and numbers of nematodes per larva of between 1.2 and 4.7, which would reduce the density of mosquito larvae but also would allow the recycling of the nematode in the field. Thus, the results obtained in this study are encouraging and also demonstrate the necessity of evaluating the environment and species beforehand, in order to determine the best doses and the time of application of S. spiculatus for mosquito control.