In search of the spectral composition of an effective light trap for the mushroom pest Lycoriella ingenua (Diptera: Sciaridae)

Certain fungus gnats, like Lycoriella ingenua are notorious pests in agriculture, especially in mushroom production. While larvae cause mainly direct crop damage, adults are vectors of several dangerous fungal pathogens. To promote the development of pesticide-free management methods, such as light trapping, we measured the spectral sensitivity of L. ingenua compound eyes with electroretinography and performed two different behavioural experiments to reveal the wavelength dependence of phototaxis in this species. The spectral sensitivity of the compound eyes is bimodal with peaks at 370 nm (UV) and 526 nm (green). Behavioural experiments showed that attraction to light as a function of wavelength depends on light intensity. In our first experiment, where the minimal photon flux (10(5)-10(9) photons/cm(2)/s) needed for eliciting a phototactic response was determined wavelength by wavelength, phototaxis was strongest in the green spectral range (similar to 526 nm). In the other behavioural experiment, where wavelength preference was tested under a higher but constant light intensity (similar to 10(13) photons/cm(2)/s), the highest attraction was elicited by UV wavelengths (398 nm). Our results suggest that both UV and green are important spectral regions for L. ingenua thus we recommend to use both UV (similar to 370-398 nm) and green (similar to 526 nm) for trapping these insects.

Automated summary

Fungus gnats like Lycoriella ingenua show strong attraction to both UV and green light, suggesting the use of both UV (around 370-398 nm) and green light (around 526 nm) in traps to capture these insects effectively.