title: A simulation study on effects of exposure to a combination of pesticides used in an orchard and tuber crop on the recovery time of a vulnerable aquatic invertebrate.
abstract: The aim of the present study was to assess whether population effects and recovery times increase when a population of a vulnerable aquatic invertebrate is exposed to concentrations of 1 or multiple pesticides. The 2 sets of pesticide combinations tested are typical for orchard and tuber crops in The Netherlands. Exposure concentrations were predicted using the FOCUS step 3 modeling framework and the Dutch drainage ditch scenario. Recovery times were assessed using the MASTEP population model. We simulated the population dynamics and pesticide effects in a Monte Carlo style by using median effective concentration values drawn from an arthropod species sensitivity distribution. In the tuber scenario, exposure to λ-cyhalothrin resulted in long-term effects, whereas exposure to the co-occurring compound fluazinam hardly resulted in (additional) effects. In the orchard scenario, 3 pesticides resulted in large effects just after exposure, but pulse exposures to these compounds did not coincide. The probabilities of effects for the single compounds added up for the combination; in contrast, the recovery times were not higher for the combination compared to those associated with exposure to the individual compounds. The conclusion from the present study's simulations is that exposure to the evaluated pesticide packages may lead to increased mortality probabilities and effect sizes of the combination, but does not lead to longer recovery times for populations with synchronized reproduction than when exposed to the individual compounds.
authors.affiliation: Alterra, Wageningen University and Research Centre, Wageningen, The Netherlands; Aquatic Ecology and Water Quality Management Group, Wageningen University, Wageningen University and Research Centre, Wageningen, The Netherlands.
authors.forename: Andreas
authors.initials: A
authors.lastname: Focks
authors.forename: Robert
authors.initials: R
authors.lastname: Luttik
authors.forename: Mathilde
authors.initials: M
authors.lastname: Zorn
authors.forename: Theo
authors.initials: T
authors.lastname: Brock
authors.forename: Erwin
authors.initials: E
authors.lastname: Roex
authors.forename: Ton
authors.initials: T
authors.lastname: Van der Linden
authors.forename: Paul J
authors.initials: PJ
authors.lastname: Van den Brink
mesh_terms: D000818:Animals; D001181:Arthropods / Q000187:drug effects* / Q000502:physiology; D003198:Computer Simulation; D008954:Models, Biological; D009010:Monte Carlo Method; D009426:Netherlands; D010575:Pesticides / Q000633:toxicity*; D011157:Population Dynamics; D014874:Water Pollutants, Chemical / Q000633:toxicity*
chemical_list: D010575:Pesticides; D014874:Water Pollutants, Chemical
keywords: Ecological risk assessment; Individual-based modeling; Pesticide combinations; Recovery