Lidar reveals activity anomaly of malaria vectors during pan-African eclipse

Abstract

Yearly, a quarter billion people are infected and a half a million killed by the mosquito-borne disease malaria. Lack of real-time observational tools for continuously assessing the unperturbed mosquito flight activity in situ limits progress toward improved vector control. We deployed a high-resolution entomological lidar to monitor a half-kilometer static transect adjacent to a Tanzanian village. We evaluated one-third million insect observations during five nights, four days, and one annular solar eclipse. We demonstrate in situ lidar classification of several insect families and their sexes based on their modulation signatures. We were able to compare the fine-scale spatiotemporal activity patterns of malaria vectors during ordinary days and an eclipse to disentangle phototactic activity patterns from the circadian mechanism. We observed an increased insect activity during the eclipse attributable to mosquitoes. These unprecedented findings demonstrate how lidar-based monitoring of distinct mosquito activities could advance our understanding of vector ecology.

Real-time dispersal of malaria vectors in rural Africa monitored with lidar

“…However, accurately and robustly estimating the fundamental frequency of 233,660 time-series signal segments of varying duration and quality is a challenging task. Two methods were developed to tackle this problem [ 23 , 24 ], and are explained below.…”

Bark beetles as lidar targets and prospects of photonic surveillance

“…Several beetles were released in the dual‐band polarimetric flight chamber to determine the WBF and dynamic properties of flying beetles. When laser light interacts with free‐flying bark beetles, the recorded signal can be decomposed into a non‐oscillatory and oscillatory scatter contribution [21, 22, 24, 25]. The oscillatory signal is contributed from the wing throughout many wingbeats, and the non‐oscillatory scattered signal is contributed from the body and elytra.…”

“…An RG780 long‐pass filter and a bandpass filter (808 nm, FWHM: 3 nm) were used to block background light. The baseline of expander and collector are separated by 814 mm, and the CMOS array was tilted 45° in Scheimpflug configuration to achieve infinite focal depth [17, 18, 22, 35–38]. The laser and the CMOS camera were connected to a multiplexer and a laser driver, and the laser was controlled by a strobe signal sent from the CMOS sensor to switch on and off alternately, the sensor line rate was 3.5 kHz, and the sampling rate for both backscattered signal and background were 1.75 kHz [37].…”

“…Therefore, surveillance of the population density of beetles is crucial. Several methods have been used by researchers to access the population dynamic of insects, such as e‐traps [12, 13], entomological radar [14, 15], and lidar [16–22]. Existing aerial topographic lidar has primarily been used for damage assessment [23].…”

“…E‐trap provides a limited assessment of insects fluxes and no dispersal estimation, and radar is unable to monitor untagged insects imbedded in the forest due to ground clutter. To overcome the limitations of those photonic surveillance methods, our group developed a kHz entomological lidar for non‐intrusive remote sensing [17, 19, 22, 24, 25]. It provides optical oscillatory and microstructure information of the in‐flight target, based on the retrieved spectral and polarization information.…”