Laboratory testing of very low-copper-treated water to prolong pupation and emerging time of mosquito larvae: an alternative method to delay mosquito breeding capability
ABSTRACTIntroductionLarvicide application in ovitrap is one of the currently available methods used in mosquito eradication campaign because they eliminate the larval stage. We previously reported that copper in liquid form is a promising candidate due to its potent larvicide properties in a laboratory setting and even in the field. In the field study, several larvae survived in the ovitrap due to the dilution of copper concentration by the rain. The surviving larvae were smaller and less motile. This led our interest to study the effect of a sub-lethal dose of copper in ovitrap on larvae development, pupation time and lifespan in the adult stage.MethodsFirst instar larvae of three species of mosquito (Aedes albopictus, Culex pipiens and Anopheles stephensi) were bred in copper-treated water at a concentration of 0.60 ppm, 0.30 ppm, and 0.15 ppm and compared with the control group. The surviving larvae were recorded every day in terms of pupa emerging time and adult emerging time. The number of adult mortality was recorded and compared with the control.ResultsCopper showed potent larvicide effect in the 0.60 ppm concentration and prolonged pupation time and caused a significantly lower number of emerging mosquitoes down to the lowest concentration of 0.15 ppm. The adult lifespan was not different compared to the control.ConclusionThis study demonstrates the capability of copper below 1 ppm to prolong the pupation time and the emerging time of mosquito larvae. Our findings open the possibility of copper application to cut mosquito breeding capacity that eventually will reduce disease transmission.