title: Night-interrupting light inhibits diapause induction in the Kanzawa spider mite, Tetranychus kanzawai Kishida (Acari: Tetranychidae).
abstract: The inhibitory effects of the timing, intensity (I(I)) and period (I(T)) of night-interrupting light on diapause induction of the Kanzawa spider mite (Tetranychus kanzawai) were investigated in a series of laboratory experiments. During a light and dark period of 8 and 16 h d(-1), respectively, a single 1-h night-interrupting light was applied at early (E), middle (M), and late (L) parts of the dark period: i.e., at 3, 7.5, and 12h after the start of the dark period, respectively. No interrupting light was applied in the control treatment. The incidence of diapause was significantly lower in the M treatment (63%) compared to the control treatment (100%). In the E and L treatments, more than 90% of females entered diapause, which was comparable to the control treatment. Since the longest consecutive dark period during the E and L treatments was longer than the critical dark period (CDP) of 10.5-11 hd(-1), during which 50% of females entered diapause, the night-interrupting light probably failed to prevent diapause induction. However, in the M treatment, the longest consecutive dark period was shorter than the CDP; therefore, the night-interrupting light inhibited diapause induction. Moreover, the inhibitory effects of night-interrupting light in the M treatment increased as I(I) and I(T) increased. The dose of night-interrupting light (I(I)×I(T)) was significantly negatively related to the incidence of diapause. The median effective dose for 50% disturbance of diapause induction was 2.5 kJ m(-2) at wavelengths between 350 and 1050 nm. Our results suggest that the longest consecutive dark period and the dose of night-interrupting light should both be considered when a lighting-based physical control is applied to inhibit diapause induction and consequent overwintering of T. kanzawai in commercial agricultural fields.
authors.affiliation: Graduate School of Horticulture, Chiba University, Matsudo 648, Matsudo, Chiba, Japan.
authors.forename: Maqsood
authors.initials: M
authors.lastname: Shah
authors.forename: Takeshi
authors.initials: T
authors.lastname: Suzuki
authors.forename: Noureldin Abuelfadl
authors.initials: NA
authors.lastname: Ghazy
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Amano
authors.forename: Katsumi
authors.initials: K
authors.lastname: Ohyama
mesh_terms: D000818:Animals; D005260:Female; D008027:Light; D017440:Photoperiod; D040102:Tetranychidae / Q000528:radiation effects*; D013983:Tick Control / Q000379:methods*