An LED-based UV-B irradiation system for tiny organisms: System description and demonstration experiment to determine the hatchability of eggs from four Tetranychus spider mite species from Okinawa.
We developed a computer-based system for controlling the photoperiod and irradiance of UV-B and white light from a 5×5 light-emitting diode (LED) matrix (100×100mm). In this system, the LED matrix was installed in each of four irradiation boxes and controlled by pulse-width modulators so that each box can independently emit UV-B and white light at irradiances of up to 1.5 and 4.0Wm(-2), respectively, or a combination of both light types. We used this system to examine the hatchabilities of the eggs of four Tetranychus spider mite species (T. urticae, T. kanzawai, T. piercei and T. okinawanus) collected from Okinawa Island under UV-B irradiation alone or simultaneous irradiation with white light for 12hd(-1) at 25°C. Although no eggs of any species hatched under the UV-B irradiation, even when the irradiance was as low as 0.02Wm(-2), the hatchabilities increased to >90% under simultaneous irradiation with 4.0Wm(-2) white light. At 0.06Wm(-2) UV-B, T. okinawanus eggs hatched (15% hatchability) under simultaneous irradiation with white light, whereas other species showed hatchabilities <1%. These results suggest that photolyases activated by white light may reduce UV-B-induced DNA damage in spider mite eggs and that the greater UV-B tolerance of T. okinawanus may explain its dominance on plants in seashore environments, which have a higher risk of exposure to reflected UV-B even on the undersurface of leaves. Our system will be useful for further examination of photophysiological responses of tiny organisms because of its ability to precisely control radiation conditions.
Faculty of Agriculture, Ibaraki University, Ami, Ibaraki 300-0393, Japan; Faculty of Agriculture, Aristotle University of Thessaloniki, 541 24 Thessaloniki, Greece; Center for Environment, Health and Field Sciences, Chiba University, Kashiwa, Chiba 277-0882, Japan; Graduate School of Agricultural Science, Kobe University, Nada, Kobe 657-8501, Japan; Japan Society for the Promotion of Science, Chiyoda, Tokyo 102-0083, Japan. Electronic address: suzukit@mx.ibaraki.ac.jp.
Takeshi
T
Suzuki
Faculty of Agriculture, Ibaraki University, Ami, Ibaraki 300-0393, Japan.
Yoshio
Y
Yoshioka
Faculty of Agriculture, Aristotle University of Thessaloniki, 541 24 Thessaloniki, Greece.
Olga
O
Tsarsitalidou
Faculty of Agriculture, Aristotle University of Thessaloniki, 541 24 Thessaloniki, Greece.
Vivi
V
Ntalia
Ishigaki Branch, Okinawa Prefectural Agricultural Research Center, Ishigaki, Okinawa 907-0003, Japan.
Suguru
S
Ohno
Center for Environment, Health and Field Sciences, Chiba University, Kashiwa, Chiba 277-0882, Japan.
Katsumi
K
Ohyama
Faculty of Agriculture, Ibaraki University, Ami, Ibaraki 300-0393, Japan.
Yasuki
Y
Kitashima
Faculty of Agriculture, Ibaraki University, Ami, Ibaraki 300-0393, Japan.
Tetsuo
T
Gotoh
Graduate School of Agricultural Science, Kobe University, Nada, Kobe 657-8501, Japan.
Makio
M
Takeda
Faculty of Agriculture, Aristotle University of Thessaloniki, 541 24 Thessaloniki, Greece.
Dimitris S
DS
Koveos
D000818:Animals; D058507:Host Specificity; D007564:Japan; D008027:Light; D010063:Ovum / Q000502:physiology / Q000528:radiation effects; D010935:Plant Diseases / Q000469:parasitology; D061066:Plant Pathology; D010944:Plants / Q000469:parasitology; D040102:Tetranychidae / Q000502:physiology* / Q000528:radiation effects*; D014466:Ultraviolet Rays; D015046:Zoology / Q000295:instrumentation / Q000379:methods*
Irradiance; Photolyase; Photoreactivation; Pulse-width modulator; UV-B irradiation