Aphid orientation and performance in glasshouses under different UV‐A/UV‐B radiation regimes

Abstract

Visual cues leading to host selection and landing are of major importance for aphids and evidence suggests that flight activity is very dependent on ultraviolet (UV)-A radiation in the environment. At the same time research on insect plant hosts suggest that the UV-B component can deter some pests via changes in secondary metabolite chemistry. Here, we examine the potential of UV (UV-A/UV-B) radiation to control insect pests in the glasshouse environment. We first examined artificial exposure to UV-B and the potential to trigger morphological and biochemical modifications in pepper (Capsicum annuum L., Solanaceae) with implications for the fitness of green peach aphid, Myzus persicae Sulzer (Hemiptera: Aphididae). UV-B caused accumulation of leaf secondary metabolites and soluble carbohydrates, and stimulated photosynthetic pigments. However, UV-B did not impact on foliar protein content and aphid performance was unaffected. Next, we studied how altering the UV-A/UV-B ratio environment affected aphid orientation and spatial distribution over time, either directly or by exposing plants to supplemental UV before insect introduction. Aphids directly settled and dispersed on their host pepper plants more readily in the presence of supplemental UV-A and UV-B. In the control treatment with ambient glasshouse UV-A and UV-B, insects remained more aggregated. Furthermore, insects were less attracted to peppers pre-exposed to supplemental UV-A and UV-B radiation. Our results suggest that suppression of UV-A and UV-B inside the protected environment reduces aphid colonization and dispersal. Furthermore, application of moderate exposure of young pepper plants to supplemental UV-B radiation could aid in protection from the colonization by phytophagous insectsPeer reviewe

Colour Response in Western Flower Thrips Varies Intraspecifically

“…Thus, it is thought that the response of WFT flying towards the ceiling was mainly caused by the presence of UV-A light and not by the white light illuminating the wind tunnel. UV-light is known to be an important cue in aiding invertebrates in navigation, orientation [ 88 ], and the dispersion of pest insects [ 89 , 90 , 91 ] including thrips [ 92 ]. It also elicits phototaxis in insects [ 93 , 94 ] and is thought to be related to wavelength-specific behaviours [ 88 , 93 , 94 ] such as migration or escape response [ 94 ].…”

Supplementary UV radiation on eggplants indirectly deters Bemisia tabaci settlement without altering the predatory orientation of their biological control agents Nesidiocoris tenuis and Sphaerophoria rueppellii

“…On 42-day-old eggplants (induced effect), any exposure time or supplementary UV combination significantly reduced the number of whiteflies settled. Indirect effects of plants previously exposed to UV radiation on insect avoidance behavior have previously been reported for aphids (Dáder et al 2017;Vänninen et al 2010).…”

“…A 30-min daily dose of UV radiation did not alter the concentration of carbon or nitrogen, nor any of the detectable amino acids or sugars except for galactose. In addition Dáder et al (2014Dáder et al ( , 2017 found out on similar assays conducted on eggplants and peppers, that the content of phenolics and carotenoids increased. Leaves of eggplants harvested for biochemical analysis had been also subjected to the different UV treatments and used for the whitefly orientation assays; therefore, the combination of both might have influence the chemical parameters measured here.…”

Influence of Light on Plant–Phyllosphere Interaction

“…Competitors of insects were reportedly less affected than their targets by altered UV exposure, and UV-exposed plant tissues may be capable of releasing increased levels of volatile compounds that are more efficient in attracting parasitoids ( Foggo et al, 2007 ; Legarrea et al, 2014 ; Dáder et al, 2015 ). Depending on specific target plant–phyllosphere interactions, strategies for plant growth may include moderate exposure of plants to UV-B at early growth stages to induce defense mechanisms and not affect plant growth and yield, and later suppression of UV light to restrict insect entrance and herbivore attack ( Elfadly et al, 2016 ; Dáder et al, 2017 ). Each situation should be evaluated on a case-by-case basis, considering as well plant specific tolerance to UV irradiance and the tight control of UV conditions, including the spectrum provided by selected shading or light bulbs, and the intensity.…”