Night Catcher™: an automated mechanical trap to replace human-baited trapping methods for Anopheles surveillance

Background The human landing catch (HLC) method is considered the “gold standard” for the collection of Anopheles vectors to establish entomological indices for malaria surveillance and control. Similar to HLC, Human Baited Net Trap (HBNT) is another method in surveying Anopheles vectors where human bait(s) sits within a protective net. Both methods allow collection of live mosquitoes for further analysis and research but are manpower intensive and pose ethical concerns with regards to exposing field staff to inherent risk of malaria and other vector-borne disease transmission. In this study, we report a new automated trap, Night Catcher™ (NC), for Anopheles surveillance that addresses these issues. The NC modifies the Centers of Disease Control and Prevention (CDC) light trap to incorporate a programmable, adjustable collection module and platform. This allows for the segregation and collection of live and intact mosquitoes to characterise species-specific temporal activity. In this study, we evaluated the performance of NC relative to HBNT and HLC. Methods We conducted our study at forests and urban parks in Singapore with reported Anopheles vectors. Paired comparisons of NC with HBNT or HLC were conducted at selected locations from 7 pm to 6 am the next morning. Collected mosquitoes were morphologically identified. Abundance and diversity of Anophelines and all mosquito species collected were compared. Results A total of 1,770 and 6,034 mosquitoes were collected in the NC with HLC, and NC with HBNT comparisons, respectively. There were no significant differences in the abundance of all mosquitoes and in the species richness between the methods. Similarly, there were no significant differences in Anopheles abundance across comparisons. Although NC collected more Anopheles species than both HBNT ( p = 0.31) and HLC ( p = 0.176), neither difference was statistically significant. Conclusions This study demonstrated that NC is a viable alternative to human baited methods for Anopheles surveillance. It is simple to use, requires less manpower, and eliminates the variability that comes from individual human attractiveness. These features make the NC an excellent tool for long term systematic surveillance programme to be put in place.