Camera transects as a method to monitor high temporal and spatial ephemerality of flying nocturnal insects

Abstract

The current global decline of insects will have profound cascading effects as insects serve numerous roles in ecosystems. Effective but simple methods are needed to describe spatial and temporal distribution of flying insects in detail. This applies especially to important but short‐lived phenomena such as insect swarms. We developed, tested and implemented a non‐invasive unbiased method with camera transects to measure spatio‐temporal fluctuations in the abundance of nocturnal flying insects in different habitats. To test the sensitivity of the method, we then tested for the influence of environmental factors on this abundance. Our results show that the method is useful for the temporal and spatial comparison of insect abundances. Astonishingly, over 90% of the 63,180 photos lacked insects. We found profound differences in insect abundance and dynamic changes between the studied habitats. Photos with a large number of insects were rare, but occurred predominantly during the warmest period (June/July) and shortly after sunset. Our findings emphasize the importance of quantifying the dynamics of flying insects at a high spatio‐temporal resolution. This method can be expanded to monitor long‐ and short‐term changes in nocturnal insect abundance even at continental scales. With proper development, the camera transects we describe could be used for insect monitoring similar to the way camera traps are used to monitor terrestrial vertebrate populations, and could become an important tool for addressing the current mass disappearances of insects.

A Review of Insect Monitoring Approaches with Special Reference to Radar Techniques

“…Non-intrusive solutions with cameras for insect capturing are the closest remote sensing method to the earlier discussed systems. For instance, Ruczyński et al [ 71 ] described a solution with a sky-oriented camera for nocturnal insect monitoring. These cameras took pictures at 5-min intervals from sunset to sunrise, with only 10% of them containing insects (a median number of 2).…”

Interpreting insect declines: seven challenges and a way forward

“…Stepanian et al ., ). Further advances in technologies such as light detection and ranging (LiDAR; Kirkeby et al ., ) and camera transects (Ruczyński et al ., ) offer the prospect of new tools in the future. In many cases, species‐level identification can be a challenge with remote sensing methods and will require careful validation against conventional measures of insect population change (e.g.…”

Food restriction delays seasonal sexual maturation but does not increase torpor use in male bats

“…As males in eastern Poland stop being social in July (Hałat et al, 2018), we covered periods of both social and solitary lifestyles. In the period of June-July there is a noted high insect abundance in eastern Poland (Ruczynśki et al, 2019). At the beginning of the experiment, we assigned bats to two treatment groups of equal size each containing the same distribution of body conditions (ratio of forearm length to body mass on the first day).…”