Keeping track of mosquitoes: a review of tools to track, record and analyse mosquito flight

Abstract

The health impact of mosquito-borne diseases causes a huge burden on human societies. Recent vector control campaigns have resulted in promising declines in incidence and prevalence of these diseases, notably malaria, but resistance to insecticides and drugs are on the rise, threatening to overturn these gains. Moreover, several vector-borne diseases have re-emerged, requiring prompt and effective response measures. To improve and properly implement vector control interventions, the behaviour of the vectors must be well understood with detailed examination of mosquito flight being an essential component. Current knowledge on mosquito behaviour across its life history is briefly presented, followed by an overview of recent developments in automated tracking techniques for detailed interpretation of mosquito behaviour. These techniques allow highly accurate recording and observation of mating, feeding and oviposition behaviour. Software programmes built with specific algorithms enable quantification of these behaviours. For example, the crucial role of heat on host landing and the multimodal integration of carbon dioxide (CO2) with other host cues, has been unravelled based on three-dimensional tracking of mosquito flight behaviour. Furthermore, the behavioural processes underlying house entry and subsequent host searching and finding can be better understood by analysis of detailed flight recordings. Further potential of these technologies to solve knowledge gaps is discussed. The use of tracking techniques can support or replace existing monitoring tools and provide insights on mosquito behaviour that can lead to innovative and more effective vector-control measures.

Video Recording Can Conveniently Assay Mosquito Locomotor Activity

“…Developments in automated tracking techniques allow recording and observation of some important mosquito behaviors, and software programs can quantify them. These techniques therefore produce data that can aid in the interpretation of mosquito behavioral details 12,13 .Laboratory measurement of mosquito locomotor patterns was initiated with acoustic measurements in sound-proof flight cages [14][15][16] and has recently been done with break-beam technology [17][18][19] . To monitor more precisely the movement and sleep of adult Drosophila flies, Guo et al 20 used an automated video recording assay instead of the beam-break Drosophila activity monitor (DAM) system.…”

“…Developments in automated tracking techniques allow recording and observation of some important mosquito behaviors, and software programs can quantify them. These techniques therefore produce data that can aid in the interpretation of mosquito behavioral details 12,13 .…”

Mosquito counting system based on optical sensing

“…Images of insects are recorded at different angles by a camera followed by identification based on the characteristics features [7][8][9]. This method not only requires a high acquisition speed of the camera to quickly acquire insect images in flight, but also requires sufficient contrast of the background [10,11]. Using infrared radiation in the recordings, the insects are thought to be less affected by the detection procedure [12,13].…”

“…When insects flap their wings, sound with a special frequency is produced, and the pitch of the sound is related to the type of insect [14]. Using a microphone to monitor insects provides a simple and less costly method than image tracking [11]. However, it is difficult to use the microphone efficiently due to environmental influences and because of the limited range of sound propagation [15].…”

Diffuse retro-reflective imaging for improved video tracking of mosquitoes at human baited bednets

“…Optical imaging techniques have been used for decades in entomological studies in diverse settings in the laboratory and field, and recently a tracking system was used to characterise in detail how Anopheles gambiae mosquitoes, the vectors of human malaria in sub-Saharan Africa, interact with human-occupied bednet [1,2,5]. Offering high spatial and temporal resolution, optical imaging has clear advantages for quantifying vector behaviour [6,7], but their application in typical sub-Saharan Africa dwellings present particular challenges. In order to understand better how hungry host-seeking mosquitoes are affected by the bednet, or how net alterations (physical as well as chemical) might improve net performance, entomologists are most interested in visualizing activity around the sleeping space, the bednet suspended above it and the regions around this in order to examine details of approach, attack and departure [8,9].…”