An improved space-saving system for testing photoperiodic responses of insects and mites: its use for diapause experiments in the two-spotted spider mite, Tetranychus urticae (Acari: Tetranychidae)

摘要

We developed an improved space-saving system consisting of a netbook computer, microcontrollers, aluminum bottles with white light-emitting diodes (LEDs), and an incubator. In this system, light and dark periods, light intensity, and night-interrupting light conditions (i.e., period, intensity, and timing) can be independently controlled in each bottle with a pulse-width modulator (PWM). Scheduled photoperiodic conditions with less fluctuation in air temperature were successfully realized with this system. Night-interrupting light conditions that may prevent diapause induction and subsequent overwintering were examined using this system to establish a novel strategy for nonchemical control of the two-spotted spider mite, Tetranychus urticae Koch. The results show that diapause incidence decreased as the cumulative intensity of night-interrupting light increased. Taken together, data show that this system can provide an accurate and space-efficient means of investigating the photoperiodic responses of insects and mites without unwanted fluctuations in air temperature, thus contributing to development of a lighting-based pest-control method in commercial agricultural fields.