Attractivity of various artificial light sources to caddisfly (Trichoptera) species and its importance in their sampling and conservation

Abstract

The artificial light sources are useful tools for sampling night active insects, however, they also possess potential environmental risks in their habitats. To test their applicability and evaluate environmental risk for caddisflies (Trichoptera), the attractivity of different portable light traps working with LED, UV and mixed-white light sources was studied and compared with attractivity of traditionally used mercury-vapour lamp (in Jermy-type light trap), which is tool of sampling and street-light. Analysing 1135 caught individuals of 19 species light sources emitting different wavelength spectra showed different attractivity and selectivity on caddisflies both on species and family levels. Attractivity of mercury-vapour lamp was generally lower than the other tested light sources. We found that the most attractive wavelength range for caddisflies is between 360 and 407 nm. One of the tested LED and mixed-white lamps together could cover this spectrum and a high and wide spectral peak of mixed-white light source between 375 and 391 nm resulted additional catches considering both species and number of individuals. Lamps emitting between 360 and 407 nm may be both a useful tool for sampling caddisflies and dangerous source of light pollution along lowland water courses where the sampled species are common and widespread.