Japanese Journal of Applied Entomology and Zoology

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We aimed to clarify the pulse conditions of a yellow LED that can be pulsed at the high speed required to control noctuid moths without suppressing the blooming of chrysanthemum. We used a lemon-yellow LED (central wavelength: 571 nm) of similar wavelength to yellow fluorescent light, with an intensity of 20 mW/m² and pulsed-LED light period of 20 ms. We measured the flight activity of adult Helicoverpa armigera (Hübner) under various light to dark period ratios of the LED pulse: 20 ms : 0 ms (continuous lighting), 20 ms : 40 ms, 20 ms : 80 ms, 20 ms : 160 ms, 20 ms : 400 ms and these were compared with dark conditions 0 ms : 0 ms without illumination, using an actograph system. As a result, Helicoverpa armigera became accustomed to the LED lighting conditions over time and the number of flight activities gradually increased in unmated females in 20 : 0, 20 : 160 and 20 : 400 groups and in unmated males in 20 : 0 and 20 : 400 groups over one day. However, in the 20 : 40 and 20 : 80 groups, Helicoverpa armigera adults, either unmated females or males, did not become accustomed, but flight activity was clearly controlled over five continuous days. It was found that the flight of adult moths was strongly suppressed under the conditions of 20 : 40 ms and 20 : 80 ms pulsed-LED light.

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Native predatory mites (Acari: Gamasina) and saprophagous arthropods—an acarid mite Tyrophagus similis Volgin (Acari: Acaridae) and springtails (Entognatha: Collembola) —were collected from spinach-cultivated soils of 6 greenhouses located in Hokkaido at 7–10 day intervals from April to September in 2010 and 2011. Of the 16 species of predator mites collected, Ascidae sp.1, Ascidae sp.2, Hypoaspis (Gaeolaelaps) praesternalis Willmann, Macrocheles sp., Cycetogamasus diviortus (Athias-Henriot), and Parholaspulus alstoni Evans most frequently occurred. Positive correlations were observed between the population dynamics of H. praesternalis and T. similis, and that of Macrocheles sp. and springtails. Therefore, we suggest that H. praesternalis and Macrocheles sp. prey on the saprophagous arthropods T. similis and springtails, respectively.

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The abundance of larvae of midge and mayfly, Cloeon dipterum (Linnaeus), in paddy plots with conventional release granular formulation corresponding to before transplanting treatment in nursery boxes (BT treatment), was significantly lower than in control plots 14 days after transplanting (DAT), but species abundance in BT plots was significantly higher than in control plots at 28 DAT. On the other hand, there were no significant differences in the abundance of aquatic insects, including midge and mayfly larvae, in paddy plots with controlled release granular formulation, corresponding to at sowing treatment in nursery boxes (AS treatment), and control plots at 14 and 28 DAT. Moreover, for introduced nymphs of ferocious water bug, Appasus japonicas Vuillefroy, paralysis occurred in greater frequency in BT plots than in AS plots.

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The sweetpotato whitefly, Bemisia tabaci biotype B, laid eggs on tea leaves in both no-choice and choice tests. However, the number of eggs laid on tea leaves was significantly less than oviposition on cucumber, eggplant and cabbage. The survival rates of eggs and nymphs on tea leaves were extremely low compared to survival on cucumbers, but egg-to-adult development time on both plants was similar.

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