The continued widespread use of larvicides in Aedes aegypti control programs is still a necessary strategy, since there are no apparent efficient vaccines against arboviruses. However, chemical approaches may affect nontarget organisms and produce detrimental effects to environmental health. Therefore, the aim of this study was to conduct toxicity testing for pyriproxyfen at different concentrations using Daphnia magna and Artemia salina as model organisms to evaluate the ecotoxicological parameters. This study describes the toxicological effects of pyriproxyfen on both microcrustaceans, which are widely used in bioassays because of their sensitivity to changes in hydrosphere. Data demonstrated that the calculated EC_50-48h value of pyriproxyfen was 2.5 μg/for D. magna and A. salina; the no-observed-effect concentration (NOEC) and the lowest-observed-effect concentration (LOEC) of pyriproxyfen were found to be 0.63 and 1.25 μg/L for Artemia salina and Daphnia magna, respectively. In chronic toxicity and reproduction tests on D. magna, a calculated CL_50-7day (lethality on 50% of daphnids after 7 days of chronic test) and an EC_50-21day (50% reduction in the reproductive output of parental daphnids after 21 days of exposure) higher than 1.25 μg/L pyriproxyfen were observed. The time of first reproduction was significantly increased in D. magna after exposure to environmentally relevant concentrations of pyriproxyfen, but other reproduction parameters were not markedly altered. Environmental risk assessment revealed that pyriproxyfen is highly toxic for both branchiopods. Data demonstrated that pyriproxyfen may produce adverse effects on the aquatic ecosystem at concentrations required to control Ae. aegypti.

There is increasing concern to control Aedes aegypti mosquito exposure in developing countries such as Brazil. Thus, integrated approaches using a combination of chemical, pyriproxyfen larvicide, and biological, Xiphophorus maculatus, larvivorous fish species approaches are necessary and important to initiate more effective control against mosquito borne diseases. This study describes the toxicological effects of pyriproxyfen larvicide on the fish Xiphophorus maculatus, the larvivorous fish species employed to destroy A. aegypti larvae mosquito species. The toxicological profile of pyriproxyfen was evaluated to determine compatible concentrations for the use of this chemical in conjunction with X. maculatus as an integrated approach against A. aegypti mosquito larvae. According to the behavioral responses of fish, the no-observed-effect concentration (NOEC) and lowest-observed-effect concentration (LOEC) of pyriproxyfen were determined to be 2.5 and 5 µg/L, respectively. Bioassays indicated that although pyriproxyfen was not lethal to X. maculatus, the application of this compound at a concentration reported to control the emergence of A. aegypti larvae may decrease the swimming performance of larvivorous fish and their ability to ingest A. aegypti L4 larvae. Data show that integration of biological larvivorous fish and chemical larvicides is more effective when the appropriate larvicide concentration is utilized.

Integration of larvivorous fish and biolarvicides at low concentrations to control of mosquito larvae in field situations may result in a safer and more effective tool. However, the usefulness of integrated approach depends upon survival and ecological fitness of fish employed. Thus, the aim of this study was to examine the genotoxic effects of combining different sublethal concentrations of spinosad, a naturally occurring neurotoxic insecticide, with male adult poecilid larvivorous guppy (Poecilia reticulata) and platy (Xiphophorus maculatus) fish on Aedes larvae mosquitos. Both fish species have been used for biological control of Aedes larvae in Brazil. Sublethal spinosad exposures were predetermined based on CL_50-96hr. Nuclear abnormalities (NA) and micronucleus (MN) frequency in gill cells were measured after 14 d of exposure. Behavioral changes were monitored over 96 h. Although genotoxic effects were not markedly different from control, behavioral changes evaluated based upon the no-observable-effect concentration (NOEC) and lowest-observable-effect concentration (LOEC). Adverse effects were noted at concentrations of 12.6 mg/L (NOEC) and 25.3 mg/L (LOEC) spinosad. Therefore, these insecticide concentrations may be considered as being safe to these fish species and have important implications for integrated approach to control Aedes larvae using natural larvicides and larvivorous fish.