Ecotoxicology emerged following the publication of Rachel Carson’s “Silent Spring” in 1962 as the environmental branch of the field of toxicology. Its major focus was on investigating the impacts of chemicals on individuals rather than populations, communities, or ecosystems (Van den Brink 2008). Ecotoxicological research has evolved considerably over the past decades, resulting in several new concepts, trends, and methodologies. Studies into the ecotoxicological assessment of pesticides have also been following this trend considering their unique properties and their intentional design and release into the environment to affect specific biological targets.

This special issue was initiated to compile current research trends and advances in the field of pesticide ecotoxicology. To this end, the Guest Editors and the Editor-in-Chief of this journal initiated a dialogue to define contemporary and emerging research topics based on those discussed in scientific (e.g. Breitholtz et al. 2006; Cedergreen et al. 2017; Schiesari et al. 2018) and legislative (e.g. EFSA 2013, 2016) sources. Based on this, papers were invited dealing with one or more advances and/or challenges in pesticide ecotoxicology, including, but not limited to (see bold text below; Shugart 2017):

More ecological ecotoxicological test approaches, e.g. extrapolating pesticide effects from the laboratory to the field

  1. 1.

    de Lima e Silva et al. (this issue) Assessing the toxicity of thiamethoxam, in natural LUFA 2.2 soil, through three generations of Folsomia candida.

  2. 2.

    Siede et al. (this issue) A long-term field study on the effects of dietary exposure of clothianidin to varroosis-weakened honey bee colonies.

Population and food-web modelling

  1. 3.

    Reno et al. (this issue) Effects of glyphosate formulations on the population dynamics of two freshwater cladoceran species.

Influence of species interactions and environmental parameters on pesticide ecotoxicity

  1. 4.

    Rodrigues et al. (this issue) Combined effects of insecticide exposure and predation risk on freshwater detritivores.

The choice of representative test species and life stages

  1. 5.

    Beiras and Tato (this issue) Marine environmental risk assessment and acute water quality criterion for pentachlorophenol in coastal waters.

  2. 6.

    Mallmann et al. (this issue) Placing arbuscular mycorrhizal fungi on the risk assessment test battery of plant protection products (PPPs).

  3. 7.

    Ortiz-Santaliestra et al. (this issue) Validity of fish, birds and mammals as surrogates for amphibians and reptiles in pesticide toxicity assessment.

Spatial-temporal extrapolation of ecotoxicological research, e.g. the influence of environmental conditions on pesticide ecotoxicity

  1. 8.

    Rocha et al. (this issue) Sensitivities of three tropical indigenous freshwater invertebrates to single and mixture exposures of diuron and carbofuran and their commercial formulations.

The influence of climate change on pesticide ecotoxicity

  1. 9.

    Hasenbein et al. (this issue) Contaminant exposure effects in a changing climate: How multiple stressors can multiply exposure effects in the amphipod Hyalella Azteca.

New sub-lethal test parameters, e.g. biomarkers, ecotoxicogenomics

  1. 10.

    Esteves et al. (this issue) Sensitive vs. tolerant Nitzschia palea (Ku¨tzing) W. Smith strains to atrazine: a biochemical perspective.

  2. 11.

    Gill et al. (this issue) Comparative analysis of transcriptomic responses to sub-lethal levels of six environmentally relevant pesticides in Saccharomyces cerevisiae.

  3. 12.

    Sanchez-Hernandez et al. (this issue) Response of digestive enzymes and esterases of ecotoxicological concern in earthworms exposed to chlorpyrifos-treated soils.

  4. 13.

    Sohn et al. (this issue) Exposure to a nicotinoid pesticide reduces defensive behaviors in a non-target organism, the rusty crayfish Orconectes rusticus.

  5. 14.

    Costa et al. (this issue) The role of contamination history and gender on the genotoxic responses of the crayfish Procambarus clarkii to a penoxsulam-based herbicide.

  6. 15.

    Shakir et al. (this issue) Pesticide-induced oxidative stress and antioxidant responses in tomato (Solanum lycopersicum) seedlings.

Pesticide mixture toxicity

  1. 16.

    Coors et al. (this issue) Is there synergistic interaction between fungicides inhibiting different enzymes in the ergosterol biosynthesis pathway in toxicity tests with the green alga Raphidocelis subcapitata?

  2. 17.

    Queiro´s et al. (this issue) Ecotoxicological assessment of the herbicide Winner Top and its active substances—are the other formulants truly inert?

  3. 18.

    Silva et al. (this issue) Toxicity prediction and assessment of an environmentally realistic pesticide mixture to Daphnia magna and Raphidocelis subcapitata.

  4. 19.

    Aca et al. (this issue) Lethal and sublethal responses in the fish, Odontesthes bonariensis, exposed to chlorpyrifos alone or under mixtures with endosulfa´n and lambda-cyhalothrin.

Landscape and ecosystem ecotoxicology

  1. 20.

    Streissl et al. (this issue) Linking pesticide marketing authorisations with environmental impact assessments through realistic landscape risk assessment paradigms.

Toxicokinetics/dynamics in pesticide ecotoxicology

  1. 21.

    Focks et al. (this issue) Calibration and validation of toxicokinetic-toxicodynamic models for three neonicotinoids and some aquatic macroinvertebrates.

Getting more out of old data, e.g. reviewing existing information, meta-analysis, trait-based analysis, multivariate statistical analysis

  1. 22.

    Cuevas et al. (this issue) Risk assessment of pesticides in estuaries: A review addressing the persistence of an old problem in complex environments.

    After an independent peer-reviewing process, a total of 25 papers were accepted for publication in this special issue. As indicated by the references of these papers above (enumerated in the order in which they appear in this special issue), all topics were at least partly covered. In addition, two papers are included that deal with ecotoxicological approaches assisting integrated pest management:

  2. 23.

    Muslim et al. (this issue) Non-target toxicity of synthetic insecticides on the biological performance and population growth of Bracon hebetor (Say).

  3. 24.

    u et al. (thisW issue) A decade of a thrips invasion in China: Lessons learned.

    The last paper of this special issue provides an evaluation of citation bias in the pesticide ecotoxicology literature:

  4. 25.

    Hanson et al. (this issue) Evidence of citation bias in the pesticide ecotoxicology literature.

In November 2016, the European Food Safety Authority (EFSA) organized the conference “Environmental risk assessment of pesticides: 25 years of scientific advancements”. In this conference, the progress made in the regulation of pesticides in the EU, advances in guidance and assessment methodologies, as well as new challenges and emerging trends were discussed. The Head of EFSA’s Pesticides Unit (Jose Tarazona) closed this meeting by stating: “We started with the challenges and achievements of the past and have now shared thoughts and ideas that can hopefully inspire our work over the next 25 years” (EFSA 2016). In line with these words, we trust that the papers in this special issue provide a valuable contribution to address current challenges in pesticide ecotoxicology.