title: Impact of UV-A radiation on the performance of aphids and whiteflies and on the leaf chemistry of their host plants.
abstract: Ultraviolet (UV) radiation directly regulates a multitude of herbivore life processes, in addition to indirectly affecting insect success via changes in plant chemistry and morphogenesis. Here we looked at plant and insect (aphid and whitefly) exposure to supplemental UV-A radiation in the glasshouse environment and investigated effects on insect population growth. Glasshouse grown peppers and eggplants were grown from seed inside cages covered by novel plastic filters, one transparent and the other opaque to UV-A radiation. At a 10-true leaf stage for peppers (53 days) and 4-true leaf stage for eggplants (34 days), plants were harvested for chemical analysis and infested by aphids and whiteflies, respectively. Clip-cages were used to introduce and monitor the insect fitness and populations of the pests studied. Insect pre-reproductive period, fecundity, fertility and intrinsic rate of natural increase were assessed. Crop growth was monitored weekly for 7 and 12 weeks throughout the crop cycle of peppers and eggplants, respectively. At the end of the insect fitness experiment, plants were harvested (68 days and 18-true leaf stage for peppers, and 104 days and 12-true leaf stage for eggplants) and leaves analysed for secondary metabolites, soluble carbohydrates, amino acids, total proteins and photosynthetic pigments. Our results demonstrate for the first time, that UV-A modulates plant chemistry with implications for insect pests. Both plant species responded directly to UV-A by producing shorter stems but this effect was only significant in pepper whilst UV-A did not affect the leaf area of either species. Importantly, in pepper, the UV-A treated plants contained higher contents of secondary metabolites, leaf soluble carbohydrates, free amino acids and total content of protein. Such changes in tissue chemistry may have indirectly promoted aphid performance. For eggplants, chlorophylls a and b, and carotenoid levels decreased with supplemental UV-A over the entire crop cycle but UV-A exposure did not affect leaf secondary metabolites. However, exposure to supplemental UV-A had a detrimental effect on whitefly development, fecundity and fertility presumably not mediated by plant cues as compounds implied in pest nutrition - proteins and sugars - were unaltered.
authors.affiliation: Instituto de Ciencias Agrarias-Consejo Superior de Investigaciones Científicas (ICA-CSIC), Calle Serrano 115 dpdo., 28006 Madrid, Spain. Electronic address: beatrizdader@ica.csic.es.
authors.forename: Beatriz
authors.initials: B
authors.lastname: Dáder
authors.affiliation: Institute of Biological, Environmental and Rural Sciences, Aberystwyth University, Aberystwyth, Ceredigion SY23 3DA, United Kingdom. Electronic address: dyj@aber.ac.uk.
authors.forename: Dylan
authors.initials: D
authors.lastname: Gwynn-Jones
authors.affiliation: Instituto de Ciencias Agrarias-Consejo Superior de Investigaciones Científicas (ICA-CSIC), Calle Serrano 115 dpdo., 28006 Madrid, Spain. Electronic address: amoreno@ica.csic.es.
authors.forename: Aránzazu
authors.initials: A
authors.lastname: Moreno
authors.affiliation: Institute of Biological, Environmental and Rural Sciences, Aberystwyth University, Aberystwyth, Ceredigion SY23 3DA, United Kingdom. Electronic address: alg@aber.ac.uk.
authors.forename: Ana
authors.initials: A
authors.lastname: Winters
authors.affiliation: Instituto de Ciencias Agrarias-Consejo Superior de Investigaciones Científicas (ICA-CSIC), Calle Serrano 115 dpdo., 28006 Madrid, Spain. Electronic address: a.fereres@csic.es.
authors.forename: Alberto
authors.initials: A
authors.lastname: Fereres
mesh_terms: D000596:Amino Acids / Q000032:analysis; D000818:Animals; D001042:Aphids / Q000528:radiation effects*; D002212:Capsicum / Q000378:metabolism / Q000469:parasitology / Q000528:radiation effects; D002241:Carbohydrates / Q000032:analysis; D002851:Chromatography, High Pressure Liquid; D005260:Female; D005298:Fertility / Q000528:radiation effects; D006430:Hemiptera / Q000528:radiation effects*; D013058:Mass Spectrometry; D010636:Phenols / Q000032:analysis / Q000737:chemistry; D018515:Plant Leaves / Q000378:metabolism / Q000469:parasitology / Q000528:radiation effects; D010944:Plants / Q000469:parasitology / Q000528:radiation effects*; D011506:Proteins / Q000032:analysis; D032323:Solanum melongena / Q000378:metabolism / Q000469:parasitology / Q000528:radiation effects; D013997:Time Factors; D014466:Ultraviolet Rays
chemical_list: D000596:Amino Acids; D002241:Carbohydrates; D010636:Phenols; D011506:Proteins
keywords: Eggplant; Insect pests; Pepper; Plant–insect interactions; UV-blocking covers