Vulnerability and behavioral response to ultraviolet radiation in the components of a foliar mite prey–predator system

Abstract

Ambient ultraviolet-B (UVB) radiation impacts plant-dwelling arthropods including herbivorous and predatory mites. However, the effects of UVB on prey-predator systems, such as that between the herbivorous spider mite and predatory phytoseiid mite, are poorly understood. A comparative study was conducted to determine the vulnerability and behavioral responses of these mites to ultraviolet (UV) radiation. First, we analyzed dose-response (cumulative irradiance-mortality) curves for the eggs of phytoseiid mites (Neoseiulus californicus, Neoseiulus womersleyi, and Phytoseiulus persimilis) and the spider mite (Tetranychus urticae) to UVB radiation from a UV lamp. This indicated that the phytoseiid mites were more vulnerable than the spider mite, although P. persimilis was slightly more tolerant than the other two phytoseiid mites. Second, we compared the avoidance behavior of adult female N. californicus and two spider mite species (T. urticae, a lower leaf surface user; Panonychus citri, an upper leaf surface user) in response to solar UV and visible light. N. californicus actively avoided both types of radiation, whereas P. citri showed only minimal avoidance behavior. T. urticae actively avoided UV as well as N. californicus but exhibited a slow response to visible light as well as P. citri. Such variation in vulnerability and avoidance behavior accounts for differences in the species adaptations to solar UVB radiation. This may be the primary factor determining habitat use among these mites on host plant leaves, subsequently affecting accessibility by predators and also intraguild competition.

Spectrum-Specific Uv Egg Damage and Dispersal Responses in the Phytoseiid Predatory MiteNeoseiulus californicus(Acari: Phytoseiidae)

“…These authors irradiated eggs and mites with UVB lamps at a high intensity, 6.8 W m Ϫ2 , for 30 Ð300 min (Onzo et al 2010), resulting in much higher cumulative doses of UVB (12.2Ð122.4 kJ m Ϫ2 ) than the LD 50 values in phytoseiid mite eggs (Ͻ0.3 kJ m Ϫ2 ; Tachi and Osakabe 2012). If the UVB lamp emitted spectra of relatively broad wavelengths, the tails of spectra below 300 nm would have had deleterious effects on the survival of phytoseiid mites, which is frequently true in such equipment (Tachi and Osakabe 2012).…”

“…The observed differences in UV avoidance response rates among monochromatic radiation at different wavelengths indicate the capacity of N. californicus females to discern variation in wavelengths of UV radiation, such as UVB from UVA. Tachi and Osakabe (2012) reported that N. californicus escaped from solar UV radiation more quickly than visible radiation. However, UVB recognition by N. californicus has never been reported so far.…”

“…The LD 50 values (50% lethal cumulative UVB dose) of T. urticae eggs and adult females were 0.58 and 26.12 kJ m Ϫ2 , respectively, in a laboratory whose interior was illuminated with ßuo-rescent lamps (Murata and Osakabe 2013). Tachi and Osakabe (2012) reported that eggs of N. californicus were more vulnerable than those of T. urticae; the LD 50 value was Ͻ0.3 kJ m Ϫ2 (eggs were exposed to UVB without visible light and moved to a laboratory condition illuminated with ßuorescent lamps immediately). In the present experiment, the cumulative UV doses for 60 min were 4.54 kJ m Ϫ2 (1.26 W m Ϫ2 ) and 5.29 kJ m Ϫ2 (1.47 W m Ϫ2 ).…”

“…The citrus red mite, Panonychus citri (McGregor) (Acari: Tetranychidae), one of a few spider mites that use upper leaf surfaces, exhibits higher tolerance to UVB radiation (Fukaya et al 2013) and escapes from solar UV radiation more slowly than the twospotted spider mite, Tetranychus urticae Koch (Acari: Tetranychidae), which resides on the lower leaf surfaces (Tachi and Osakabe 2012). In a preyÐpredator system composed of herbivorous spider mites and predacious phytoseiid mites, the predators are more vulnerable to ambient UVB radiation than the prey, resulting in rapid emigration from places irradiated with solar UV radiation (Tachi and Osakabe 2012).…”

“…In a preyÐpredator system composed of herbivorous spider mites and predacious phytoseiid mites, the predators are more vulnerable to ambient UVB radiation than the prey, resulting in rapid emigration from places irradiated with solar UV radiation (Tachi and Osakabe 2012). Phytoseiid mites escape from not only solar UV radiation but also visible light radiation (Weintraub et al 2007, Tachi and.…”