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Effects of anoxia and hypoxia on the two-spotted spider mite, Tetranychus urticae (Acari: Tetranychidae)

Yamakawa, Sota, Ohyama, Katsumi, Yamori, Wataru, Suzuki, Takeshi
Applied entomology and zoology 2018 v.53 no.4 pp. 535-541
Tetranychus urticae, adults, buds, carbon dioxide, cucumbers, cultivars, fecundity, females, host plants, hypoxia, kidney beans, leaves, lethal concentration 50, oxygen, seedlings, tomatoes
We investigated the potential use of anoxic (0% O₂) and hypoxic (lower O₂ concentration than in the atmosphere) conditions for controlling the two-spotted spider mite, Tetranychus urticae Koch (Acari: Tetranychidae). Adult T. urticae females were exposed to O₂ concentrations of 0, 0.5, 1, 2, or 21% (control) with a constant CO₂ concentration of 0.05% at 1 atm and 25 °C under continuous darkness for 24 h. The survival and fecundity at 8 days after treatment significantly decreased when the O₂ concentration was lower than 0.5% and 1%, respectively; the lethal concentration at 50% survival (LC₅₀) was 0.55%. The miticidal hypoxic condition (0.5% O₂) led to physiological disorders in host plants. The degree of physiological disorders differed among the plant species tested. Although tomato seedlings died after the hypoxia treatment, in kidney bean and cucumber seedlings the primary leaves remained and lateral buds developed instead of the apical buds that ceased. Hypoxia treatment could be useful as a physical measure for controlling spider mites depending on plant species or cultivars.