title: Drought stress affects plant metabolites and herbivore preference but not host location by its parasitoids.
abstract: One of the main abiotic stresses that strongly affects plant survival and the primary cause of crop loss around the world is drought. Drought stress leads to sequential morphological, physiological, biochemical and molecular changes that can have severe effects on plant growth, development and productivity. As a consequence of these changes, the interaction between plants and insects can be altered. Using cultivated Brassica oleracea plants, the parasitoid Microplitis mediator and its herbivorous host Mamestra brassicae, we studied the effect of drought stress on (1) the emission of plant volatile organic compounds (VOCs), (2) plant hormone titres, (3) preference and performance of the herbivore, and (4) preference of the parasitoid. Higher levels of jasmonic acid (JA) and abscisic acid (ABA) were recorded in response to herbivory, but no significant differences were observed for salicylic acid (SA) and indole-3-acetic acid (IAA). Drought significantly impacted SA level and showed a significant interactive effect with herbivory for IAA levels. A total of 55 VOCs were recorded and the difference among the treatments was influenced largely by herbivory, where the emission rate of fatty acid-derived volatiles, nitriles and (E)-4,8-dimethylnona-1,3,7-triene [(E)-DMNT] was enhanced. Mamestra brassicae moths preferred to lay eggs on drought-stressed over control plants; their offspring performed similarly on plants of both treatments. VOCs due to drought did not affect the choice of M. mediator parasitoids. Overall, our study reveals an influence of drought on plant chemistry and insect-plant interactions.
authors.affiliation: Laboratory of Entomology, Wageningen University, PO Box 8031, 6700 EH, Wageningen, The Netherlands. berhane.weldegergis@wur.nl.
authors.forename: Berhane T
authors.initials: BT
authors.lastname: Weldegergis
authors.affiliation: Laboratory of Entomology, Wageningen University, PO Box 8031, 6700 EH, Wageningen, The Netherlands.
authors.forename: Feng
authors.initials: F
authors.lastname: Zhu
authors.affiliation: Laboratory of Entomology, Wageningen University, PO Box 8031, 6700 EH, Wageningen, The Netherlands.
authors.forename: Erik H
authors.initials: EH
authors.lastname: Poelman
authors.affiliation: Laboratory of Entomology, Wageningen University, PO Box 8031, 6700 EH, Wageningen, The Netherlands.
authors.forename: Marcel
authors.initials: M
authors.lastname: Dicke
mesh_terms: D000040:Abscisic Acid / Q000378:metabolism; D000818:Animals; D001937:Brassica / Q000378:metabolism / Q000469:parasitology* / Q000502:physiology; D003517:Cyclopentanes / Q000378:metabolism; D055864:Droughts; D060434:Herbivory; D006790:Host-Parasite Interactions; D006927:Hymenoptera / Q000502:physiology; D007210:Indoleacetic Acids / Q000378:metabolism; D009036:Moths / Q000469:parasitology*; D054883:Oxylipins / Q000378:metabolism; D010935:Plant Diseases / Q000469:parasitology; D010937:Plant Growth Regulators / Q000378:metabolism*; D020156:Salicylic Acid / Q000378:metabolism; D013312:Stress, Physiological; D055549:Volatile Organic Compounds / Q000378:metabolism*
chemical_list: D003517:Cyclopentanes; D007210:Indoleacetic Acids; D054883:Oxylipins; D010937:Plant Growth Regulators; D055549:Volatile Organic Compounds; C011006:jasmonic acid; C030737:indoleacetic acid; D000040:Abscisic Acid; D020156:Salicylic Acid