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Lethal effects of short-wavelength visible light on insects.

Hori M, Shibuya K, Sato M, Saito Y - Sci Rep (2014)

Bottom Line: We investigated the lethal effects of visible light on insects by using light-emitting diodes (LEDs).Blue light was also lethal to mosquitoes and flour beetles, but the effective wavelength at which mortality occurred differed among the insect species.For some animals, such as insects, blue light is more harmful than UV light.

View Article: PubMed Central - PubMed

Affiliation: Graduate School of Agricultural Science, Tohoku University, Sendai 981-8555, Japan.

ABSTRACT
We investigated the lethal effects of visible light on insects by using light-emitting diodes (LEDs). The toxic effects of ultraviolet (UV) light, particularly shortwave (i.e., UVB and UVC) light, on organisms are well known. However, the effects of irradiation with visible light remain unclear, although shorter wavelengths are known to be more lethal. Irradiation with visible light is not thought to cause mortality in complex animals including insects. Here, however, we found that irradiation with short-wavelength visible (blue) light killed eggs, larvae, pupae, and adults of Drosophila melanogaster. Blue light was also lethal to mosquitoes and flour beetles, but the effective wavelength at which mortality occurred differed among the insect species. Our findings suggest that highly toxic wavelengths of visible light are species-specific in insects, and that shorter wavelengths are not always more toxic. For some animals, such as insects, blue light is more harmful than UV light.

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Lethal effects of blue-light irradiation on the mosquito Culex pipiensmolestus and the confused flour beetle Tribolium confusum.(a) Mortality of C. pipiensmolestus pupae irradiated with various wavelengths of blue light at 10.0 × 1018 photons·m−2·s−1 during the pupal stage. Data are means ± standard error (SE). Different lowercase letters next to bars indicate significant differences (Steel–Dwass test, P < 0.05). DD indicates the 24-h dark condition. (b) Dose–response relationships for lethal effects of irradiation with each wavelength of light on pupae. Data are mean values. (c) Mortality of C. pipiensmolestus that were irradiated with 417-nm light for 48 h at 10.0 × 1018 photons·m−2·s−1 during the egg stage. Data are means ± SE. Hours in parentheses show the elapsed time after discontinuation of irradiation. Different lowercase or capital letters next to bars indicate significant differences among the three treatments for each time period (Steel–Dwass test, P < 0.05). LL and DD indicate 24-h light and 24-h dark conditions, respectively. (d) Mortality of T. confusum pupae irradiated with various wavelengths of light at 2.0 × 1018 photons·m−2·s−1 during the pupal stage. Data are means ± SE. Different lowercase letters next to bars indicate significant differences (Steel–Dwass test, P < 0.05). LD indicates 16L:8D photoperiod condition.
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f3: Lethal effects of blue-light irradiation on the mosquito Culex pipiensmolestus and the confused flour beetle Tribolium confusum.(a) Mortality of C. pipiensmolestus pupae irradiated with various wavelengths of blue light at 10.0 × 1018 photons·m−2·s−1 during the pupal stage. Data are means ± standard error (SE). Different lowercase letters next to bars indicate significant differences (Steel–Dwass test, P < 0.05). DD indicates the 24-h dark condition. (b) Dose–response relationships for lethal effects of irradiation with each wavelength of light on pupae. Data are mean values. (c) Mortality of C. pipiensmolestus that were irradiated with 417-nm light for 48 h at 10.0 × 1018 photons·m−2·s−1 during the egg stage. Data are means ± SE. Hours in parentheses show the elapsed time after discontinuation of irradiation. Different lowercase or capital letters next to bars indicate significant differences among the three treatments for each time period (Steel–Dwass test, P < 0.05). LL and DD indicate 24-h light and 24-h dark conditions, respectively. (d) Mortality of T. confusum pupae irradiated with various wavelengths of light at 2.0 × 1018 photons·m−2·s−1 during the pupal stage. Data are means ± SE. Different lowercase letters next to bars indicate significant differences (Steel–Dwass test, P < 0.05). LD indicates 16L:8D photoperiod condition.

Mentions: We also investigated the lethal effects of various blue-light wavelengths (404–508 nm) on pupae of the mosquito Culex pipiensmolestus. Blue light irradiation was lethal to mosquito pupae, although their tolerance was higher than that of D. melanogaster pupae (Fig. 3a, b). Compared with DD conditions, irradiation with wavelengths of 404, 417, and 456 nm at 10.0 × 1018 photons·m−2·s−1 throughout the pupal stage significantly increased the mortality of C. pipiens molestus (Supplementary Table 3); the peak wavelength of 417 nm was highly lethal (Fig. 3a). Wavelengths of 404 and 417 nm killed substantial proportions of pupae before adult emergence, whereas wavelengths ≥ 440 nm were non- or negligibly lethal (Fig. 3a). The lethal effect of 417 nm increased with increasing numbers of photons; in contrast, the lethal effect of 404 nm was nominal, and the lethal effects of 440-, 456-, and 467-nm wavelengths increased only slightly with increasing numbers of photons (Fig. 3b). Irradiation with a wavelength of 417 nm was lethal to mosquito eggs, and the mortality increased over time (Fig. 3c, Supplementary Table 4). Whereas only 34% of mosquitos died before hatching following 48 h of irradiation at 10.0 × 1018 photons·m−2·s−1, approximately 90% of hatchlings from the irradiated eggs died within 72 h after irradiation; this is compared with a 2% mortality rate of hatchlings from the eggs maintained under dark conditions. Accordingly, even if irradiated eggs hatched, most hatchlings died soon thereafter. These results show that the lethal effect of blue light is not confined to flies; however, the effective wavelength at which mortality occurs is species-specific, and tolerance to blue-light irradiation differs among insect species.


Lethal effects of short-wavelength visible light on insects.

Hori M, Shibuya K, Sato M, Saito Y - Sci Rep (2014)

Lethal effects of blue-light irradiation on the mosquito Culex pipiensmolestus and the confused flour beetle Tribolium confusum.(a) Mortality of C. pipiensmolestus pupae irradiated with various wavelengths of blue light at 10.0 × 1018 photons·m−2·s−1 during the pupal stage. Data are means ± standard error (SE). Different lowercase letters next to bars indicate significant differences (Steel–Dwass test, P < 0.05). DD indicates the 24-h dark condition. (b) Dose–response relationships for lethal effects of irradiation with each wavelength of light on pupae. Data are mean values. (c) Mortality of C. pipiensmolestus that were irradiated with 417-nm light for 48 h at 10.0 × 1018 photons·m−2·s−1 during the egg stage. Data are means ± SE. Hours in parentheses show the elapsed time after discontinuation of irradiation. Different lowercase or capital letters next to bars indicate significant differences among the three treatments for each time period (Steel–Dwass test, P < 0.05). LL and DD indicate 24-h light and 24-h dark conditions, respectively. (d) Mortality of T. confusum pupae irradiated with various wavelengths of light at 2.0 × 1018 photons·m−2·s−1 during the pupal stage. Data are means ± SE. Different lowercase letters next to bars indicate significant differences (Steel–Dwass test, P < 0.05). LD indicates 16L:8D photoperiod condition.
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f3: Lethal effects of blue-light irradiation on the mosquito Culex pipiensmolestus and the confused flour beetle Tribolium confusum.(a) Mortality of C. pipiensmolestus pupae irradiated with various wavelengths of blue light at 10.0 × 1018 photons·m−2·s−1 during the pupal stage. Data are means ± standard error (SE). Different lowercase letters next to bars indicate significant differences (Steel–Dwass test, P < 0.05). DD indicates the 24-h dark condition. (b) Dose–response relationships for lethal effects of irradiation with each wavelength of light on pupae. Data are mean values. (c) Mortality of C. pipiensmolestus that were irradiated with 417-nm light for 48 h at 10.0 × 1018 photons·m−2·s−1 during the egg stage. Data are means ± SE. Hours in parentheses show the elapsed time after discontinuation of irradiation. Different lowercase or capital letters next to bars indicate significant differences among the three treatments for each time period (Steel–Dwass test, P < 0.05). LL and DD indicate 24-h light and 24-h dark conditions, respectively. (d) Mortality of T. confusum pupae irradiated with various wavelengths of light at 2.0 × 1018 photons·m−2·s−1 during the pupal stage. Data are means ± SE. Different lowercase letters next to bars indicate significant differences (Steel–Dwass test, P < 0.05). LD indicates 16L:8D photoperiod condition.
Mentions: We also investigated the lethal effects of various blue-light wavelengths (404–508 nm) on pupae of the mosquito Culex pipiensmolestus. Blue light irradiation was lethal to mosquito pupae, although their tolerance was higher than that of D. melanogaster pupae (Fig. 3a, b). Compared with DD conditions, irradiation with wavelengths of 404, 417, and 456 nm at 10.0 × 1018 photons·m−2·s−1 throughout the pupal stage significantly increased the mortality of C. pipiens molestus (Supplementary Table 3); the peak wavelength of 417 nm was highly lethal (Fig. 3a). Wavelengths of 404 and 417 nm killed substantial proportions of pupae before adult emergence, whereas wavelengths ≥ 440 nm were non- or negligibly lethal (Fig. 3a). The lethal effect of 417 nm increased with increasing numbers of photons; in contrast, the lethal effect of 404 nm was nominal, and the lethal effects of 440-, 456-, and 467-nm wavelengths increased only slightly with increasing numbers of photons (Fig. 3b). Irradiation with a wavelength of 417 nm was lethal to mosquito eggs, and the mortality increased over time (Fig. 3c, Supplementary Table 4). Whereas only 34% of mosquitos died before hatching following 48 h of irradiation at 10.0 × 1018 photons·m−2·s−1, approximately 90% of hatchlings from the irradiated eggs died within 72 h after irradiation; this is compared with a 2% mortality rate of hatchlings from the eggs maintained under dark conditions. Accordingly, even if irradiated eggs hatched, most hatchlings died soon thereafter. These results show that the lethal effect of blue light is not confined to flies; however, the effective wavelength at which mortality occurs is species-specific, and tolerance to blue-light irradiation differs among insect species.

Bottom Line: We investigated the lethal effects of visible light on insects by using light-emitting diodes (LEDs).Blue light was also lethal to mosquitoes and flour beetles, but the effective wavelength at which mortality occurred differed among the insect species.For some animals, such as insects, blue light is more harmful than UV light.

View Article: PubMed Central - PubMed

Affiliation: Graduate School of Agricultural Science, Tohoku University, Sendai 981-8555, Japan.

ABSTRACT
We investigated the lethal effects of visible light on insects by using light-emitting diodes (LEDs). The toxic effects of ultraviolet (UV) light, particularly shortwave (i.e., UVB and UVC) light, on organisms are well known. However, the effects of irradiation with visible light remain unclear, although shorter wavelengths are known to be more lethal. Irradiation with visible light is not thought to cause mortality in complex animals including insects. Here, however, we found that irradiation with short-wavelength visible (blue) light killed eggs, larvae, pupae, and adults of Drosophila melanogaster. Blue light was also lethal to mosquitoes and flour beetles, but the effective wavelength at which mortality occurred differed among the insect species. Our findings suggest that highly toxic wavelengths of visible light are species-specific in insects, and that shorter wavelengths are not always more toxic. For some animals, such as insects, blue light is more harmful than UV light.

Show MeSH
Related in: MedlinePlus