Applications of Mesocyclops spp. (Copepoda: Cyclopidae) to control larvae of Aedes aegypti and Ae. albopictus in flooded basements in metropolitan Kaohsiung, Taiwan

Dengue fever is one of the most important mosquito-borne infectious diseases causing great public health concerns in Taiwan. As the global climate warming, Taiwan suffers from severe mosquito nuisance and disease threats. Long-term intensive application of various pesticides has selected mosquitoes with multiple resistance. This study demonstrated an eco-friendly method using indigenous copepods to control mosquito larvae in field. Four species of copepods with highly predatory efficiency, including Mesocyclops aspericornis, M. pehpeiensis, M. woutersi, and M. ogunnus, were collected from native source. These copepods have been confirmed free of pathogenic parasites by light microscopy and molecular diagnosis. Further evaluation on pesticide susceptibility proved that the copepods were less sensitive than mosquito larvae. Artificial cultivation of the copepods were successful in laboratory as well as in field environments. Before releasing of copepods, education courses were held and the study were conducted under the agreement of residents. Forty two flooded basements were selected for routine survey in Kaohsiung. After two years (from March 2012 to May 2014) of intervention, the results showed that the positive rate of larvae breeding sites decreased from 65.0% to 0. Follow-up survival rate of copepods in flooded basements were 5.0%, 10.4%, 45.3%, and 60.0% in small volume of turbid water (TSV), small volume of clear water (CSV), medium volume of clear water (CMV), and large volume of clear water (CLV), respectively. To our knowledge, this is the first study that use copepods to control mosquito larvae in metropolitan city. Considering the breeding behavior of Aedes mosquitoes, utilizing predatory copepods would provide a feasible and sustainable measure for controlling dengue vectors.