The Effects of Pharmaceuticals and Personal Care Products on Mosquito Oviposition Site Selection

Abstract

The products that humans use every day to shower, drink, prevent sickness, protect their crops, etc. are having an effect on the environment. Pharmaceuticals and personal care products, or PPCPs, have been becoming notable threats to the environment for several decades now. In this study, the effects of caffeine, DEET, triclosan, and a mixture of the three were tested in water with Gambusia kairomones to determine whether the PPCPs are having an effect on a mosquito’s ability detect a predator’s presence in a body of water. The mean population size for all of the treatments decreased when predator kairomones were present except for DEET which increased (p=0.59, f=6, t=0.942). Caffeine present a mildly significant increase from the control when there were no kairomones present (p=0.09, f=6, t=-1.881). The effect sizes varied between treatment groups with the most notable difference presented in DEET whose mean population was 65.9% of the control when the predator was absent, but with the kairomones, the effect size was 148.4% larger than without. This indicated an increase in the mosquito population in the predator treatment when DEET, the insect repellant, is present. This study is attempts to illustrate the effects that PPCPs are having on the surrounding environment and the organisms that inhabit it. Masking a predator’s presence could lead to population depletion of many species (i.e. mosquitoes) causing detrimental damage in the trophic cascade of the local ecosystems.