Bioessays of the effect of commercial grade 5% DEET mosquito repellent on “in vitro” populations of the dinoflagellate Gymnodinium instriatum
In Puerto Rico’s coastal areas, including in bioluminescent bays, it is very common to use mosquito repellents containing DEET. This molecule has been reported to be very toxic to different kinds of human cells. Therefore, we suspect DEET could have adverse effects on marine planktonic populations. The objective of this work is to test the effects of DEET on “in-vitro” populations of the dinoflagellate Gymnodinium instriatum (Freudenthal & J.J.Lee) D.W. Coats. Bioassays were performed on G. instriatum “in-vitro” populations with varying concentrations of commercial grade 5% DEET (Off! family care insect repellent III) dissolved in the culture medium, in order to observe the mortality rate of the populations. Population densities were estimated by fluorometry. Fluorometer measurements were validated by using visual counts.
Results show that a concentration of 10-3 is near the amount that affects more than half of the individuals in the populations. These results suggest that DEET could be a real threat to natural marine planktonic populations.