Attraction to different wavelength light emitting diodes (LEDs), the compound eye structure, and opsin genes in Nilaparvata lugens

Abstract

We studied the wavelength dependency of phototactic behavior, the eye structure, and opsin genes of the brown planthopper, Nilaparvata lugens (Stål) (Hemiptera: Delphacidae). The action spectrum showed that N. lugens was attracted to wide wavelength range of light; i.e. from 365 nm to 735 nm. The preference test between two wavelengths indicated that they were attracted to the wavelength in the following sequence; 365 nm=385 nm>470 nm= 525 nm>white LED=590 nm>660 nm=735 nm>850 nm. The spectral sensitivity of the eyes, determined by electroretinogram (ERG), exhibited peaks at 520 nm and 360 nm, while the sensitivity was negligible at the wavelength longer than 660 nm. Three opsin genes were cloned; one long wavelength (LW), and two UV-absorbing types (UV1 and UV2). In situ hybridization showed that LW opsin mRNA was widely expressed in the compound eyes and the ocelli. The UV1 opsin mRNA was expressed in the ventral periphery, while the mRNA of the UV2 opsin was expressed throughout the eye. Eight photoreceptor cells were observed to form a rhabdom in the compound eyes.