Influence of green light illumination at night on biological characteristics of the oriental armyworm,Mythimna separata(Lepidoptera: Noctuidae)

Abstract

The oriental armyworm, Mythimna separata is an important crop pest in eastern Asia. Nocturnal insects, including nocturnal moths, have phototactic behavior to an artificial light source. Phototactic behavior in insects is species-specific in response to different wavelengths of light sources. Our previous study showed that green (520 nm) light emitting diode (LED) light resulted in a significantly higher phototactic behavior in M. separata moths compared to the other wavelength LED lights. The goal of the present study is to investigate the influence of green light illumination on biological characteristics of different developmental stages in M. separata. Our results revealed that when different developmental stages of M. separata were exposed to the green light illumination in a dark period, several biological characteristics in all developmental stages except for egg stage were positively changed, but those of F1 generation M. separata which are next generation of the adults exposed to the green light did not significantly change compared with the control level. These findings suggest that green light illumination at night (or dark period) has a positive effect on the development and longevity of M. separata.

Influence of green light at night on Juvenile hormone in the oriental armyworm Mythimna separata (Lepidoptera: Noctuidae)

“…When M. separata larvae are reared under the green LED light in the dark period (10 h), the larval period is significantly shortened compared with the control (Kim et al ., ). The results of the present study show that, when M. separata larvae are reared under green (520 nm) LED light for 22 days, comprising the larval period during which the fifth instar develops into the sixth instar, the JH titres of these larvae decrease with an extension of the exposure time of the green light.…”

“…The pupal period of M. separata under laboratory condition is approximately 9–10 days (Ali, ). When M. separata pupae are reared under the green LED light in the dark period (10 h), the pupal period is significantly shortened compared with the control (Kim et al ., ). The results of the present study reveal that, when M. separata pupae are reared under the green light, the JH titre is elevated in middle pupal age, whereas it is reduced in at final pupal age as the exposure time is prolonged.…”

“…The lifespan of M. separata adult under laboratory conditions is approximately 9–11 days (Ali, ). When M. separata adults are reared under the green LED light in the dark period (10 h), the lifespan of the adult is significantly prolonged compared with the control (Kim et al ., ). The results of the present study show that the JH titres of M. separata adult moths reared under the green light are significantly elevated with an extension of the exposure time of the green light, and the JH titres of all groups in 3‐day‐old adult moths are higher than those of the corresponding groups in moths of other ages.…”

“…Light traps equipped with LEDs of green wavelength can be used to monitor and control the moths, although the green light emitting from the light trap at night can affect some of the biological characteristics of M. separata . In M. separata reared under the green LED light at night, larval period and pupal period are significantly shortened, and the adult lifespan is significantly prolonged, with an extension of the exposure period of the green light in the dark period (Kim et al ., , ).…”

“…The green light emitting from the light traps at night can affect the life of M. separata and so identifying the effect of the green light on the biology of M. separata is important with respect to the potential use of the light trap. Green light at night has a positive effect on some of the biological characters of M. separata living under the green light environment, such as a shortening of the larval and pupal periods, as well as an increase in larval survival and adult lifespan (Kim et al ., ). However, whether the green light can affect the JH level of M. separata still remains unknown.…”