Since their discovery in the late 1980s, neonicotinoid pesticides have become the most widely used class of insecticides worldwide, with large-scale applications ranging from plant protection (crops, vegetables, fruits), veterinary products, and biocides to invertebrate pest control in fish farming. In this review, we address the phenyl-pyrazole fipronil together with neonicotinoids because of similarities in their toxicity, physicochemical profiles, and presence in the environment. Neonicotinoids and fipronil currently account for approximately one third of the world insecticide market; the annual world production of the archetype neonicotinoid, imidacloprid, was estimated to be ca. 20,000 tonnes active substance in 2010. There were several reasons for the initial success of neonicotinoids and fipronil: (1) there was no known pesticide resistance in target pests, mainly because of their recent development, (2) their physicochemical properties included many advantages over previous generations of insecticides (i.e., organophosphates, carbamates, pyrethroids, etc.), and (3) they shared an assumed reduced operator and consumer risk. Due to their systemic nature, they are taken up by the roots or leaves and translocated to all parts of the plant, which, in turn, makes them effectively toxic to herbivorous insects. The toxicity persists for a variable period of time—depending on the plant, its growth stage, and the amount of pesticide applied. A wide variety of applications are available, including the most common prophylactic non-Good Agricultural Practices (GAP) application by seed coating. As a result of their extensive use and physicochemical properties, these substances can be found in all environmental compartments including soil, water, and air. Neonicotinoids and fipronil operate by disrupting neural transmission in the central nervous system of invertebrates. Neonicotinoids mimic the action of neurotransmitters, while fipronil inhibits neuronal receptors. In doing so, they continuously stimulate neurons leading ultimately to death of target invertebrates. Like virtually all insecticides, they can also have lethal and sublethal impacts on non-target organisms, including insect predators and vertebrates. Furthermore, a range of synergistic effects with other stressors have been documented. Here, we review extensively their metabolic pathways, showing how they form both compound-specific and common metabolites which can themselves be toxic. These may result in prolonged toxicity. Considering their wide commercial expansion, mode of action, the systemic properties in plants, persistence and environmental fate, coupled with limited information about the toxicity profiles of these compounds and their metabolites, neonicotinoids and fipronil may entail significant risks to the environment. A global evaluation of the potential collateral effects of their use is therefore timely. The present paper and subsequent chapters in this review of the global literature explore these risks and show a growing body of evidence t...

We assessed the state of knowledge regarding the effects of large-scale pollution with neonicotinoid insecticides and fipronil on non-target invertebrate species of terrestrial, freshwater and marine environments. A large section of the assessment is dedicated to the state of knowledge on sublethal effects on honeybees (Apis mellifera) because this important pollinator is the most studied non-target invertebrate species. Lepidoptera (butterflies and moths), Lumbricidae (earthworms), Apoidae sensu lato (bumblebees, solitary bees) and the section “other invertebrates” review available studies on the other terrestrial species. The sections on freshwater and marine species are rather short as little is known so far about the impact of neonicotinoid insecticides and fipronil on the diverse invertebrate fauna of these widely exposed habitats. For terrestrial and aquatic invertebrate species, the known effects of neonicotinoid pesticides and fipronil are described ranging from organismal toxicology and behavioural effects to population-level effects. For earthworms, freshwater and marine species, the relation of findings to regulatory risk assessment is described. Neonicotinoid insecticides exhibit very high toxicity to a wide range of invertebrates, particularly insects, and field-realistic exposure is likely to result in both lethal and a broad range of important sublethal impacts. There is a major knowledge gap regarding impacts on the grand majority of invertebrates, many of which perform essential roles enabling healthy ecosystem functioning. The data on the few non-target species on which field tests have been performed are limited by major flaws in the outdated test protocols. Despite large knowledge gaps and uncertainties, enough knowledge exists to conclude that existing levels of pollution with neonicotinoids and fipronil resulting from presently authorized uses frequently exceed the lowest observed adverse effect concentrations and are thus likely to have large-scale and wide ranging negative biological and ecological impacts on a wide range of non-target invertebrates in terrestrial, aquatic, marine and benthic habitats.

Toxicity persistence to the nontarget amphipod Hyalella curvispina in runoff events following chlorpyrifos applications to soy experimental plots was compared in conventional and no-till management. Two application scenarios were compared: an early-season application with the soil almost bare and a late-season application after the foliage had attained complete soil cover. H. curvispina was exposed to chlorpyrifos using two different test systems: a short-term (48 h) runoff water exposure and a long-term (10 days) soil exposure. Both commonly used crop management practices for soybean production resulted in runoff toxicity following pesticide applications and represent a toxicity risk for adjacent inland waters. Toxicity persistence was longer after the earlier than the late season application, likely because of higher volatilization and photodecomposition losses from the soy canopy than from the soil. For the early-season application, toxicity persisted longer in the no-till plots than in the conventional tillage plots. Suspended matter was higher in the conventional treatment. Chlorpyrifos sorption to suspended matter likely contributed to the shorter persistence. For the late-season application, toxicity persisted longer in the conventional treatment. The causes remain conjectural. The soil organic carbon content was higher in the no-till treatment. Sorption to organic matter might have contributed to the shorter chlorpyrifos toxicity persistence in no-till management. Late applications are more frequent and prevail longer throughout the soy growing season. Overall, the no-till management practice seems preferably because shorter toxicity persistence in runoff represents a lower environmental risk for the adjacent inland waters.

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Evidence suggests that the small chloroplast heat-shock protein (Hsp) is involved in plant thermotolerance but its site of action is unknown. Functional disruption of this Hsp using anti-Hsp antibodies or addition of purified Hsp to chloroplasts indicated that (a) this Hsp protects thermolabile photosystem II and, consequently, whole-chain electron transport during heat stress; and (b) this Hsp completely accounted for heat acclimation of electron transport in pre-heat-stressed plants. Therefore, this Hsp is a major adaptation to acute heat stress in plants.PSII (the H 2 O-oxidizing, quinone-reducing complex) is usually the most heat sensitive of the chloroplast thylakoid-membrane protein complexes involved in photosynthetic electron transfer and ATP synthesis and is one of the most thermolabile photosynthetic processes in general (Berry and Bjö rkman, 1980;Weis and Berry, 1988; Havaux, 1993). Within PSII, the O 2 -evolving-complex proteins are frequently the most susceptible to heat stress, although both the reaction center and the light-harvesting complexes can be disrupted by high temperatures as well (Berry and Bjö rkman, 1980;Weis and Berry, 1988; Havaux, 1993). Thermotolerance of PSII varies widely among species and there is also variation in the extent of acclimation of PSII to heat stress (Berry and Bjö rkman, 1980;Weis and Berry, 1988). With the exception of the probable protective effect of xanthophyll-cycle carotenoids (Havaux et al., 1996) and isoprene (Sharkey and Singaas, 1995) on membrane stability and PSII function, little is known about the protective adaptations of PSII to heat stress. However, accumulating evidence suggests that chloroplast Hsps are involved in photosynthetic and PSII thermotolerance.For example, when phenotypic variation in the production of the major chloroplast lmw Hsp is induced (e.g. by manipulating N availability), increased levels of the lmw Hsp are positively correlated with increased thermotolerance of PSII (Stapel et al., 1993; Clarke and Critchley, 1994; Heckathorn et al., 1996). Additionally, greater production of the chloroplast lmw Hsp, both within (Park et al., 1996) and among species (Downs et al., 1997), is positively correlated with whole-plant thermotolerance. Also in support of this, several chloroplast fractionation studies indicate that the lmw Hsp is a stromal protein that associates with the thylakoid membranes in response to heat stress (Restivo et al., 1986; Glaczinski and Kloppstech, 1988; Adamska and Kloppstech, 1991; Debel et al., 1997; also see Vierling, 1991; Clark and Critchley, 1994). However, a definite role of this or other Hsps in photosynthetic thermotolerance has not been demonstrated.In contrast to most hmw Hsps, which are constitutively expressed and are essential for protein folding and import into organelles (i.e. they are molecular chaperones) (Gatenby and Viitanen, 1994; Hartl, 1996), lmw Hsps (approximately 17-30 kD) are generally produced only in response to environmental stress and little is known about their function (Vier...

Using a novel molecular biomaker system (MBS), we assessed the physiological status of coral (Montastraea faveolata) challenged by heat stress by assaying specific cellular and molecular parameters. This technology is particularly relevant for corals because heat stress is thought to be an essential component of coral bleaching. This phenomenon is widely believed to be responsible for coral mortality worldwide, particularly during 1997-1998. Specific parameters of coral cellular physiology were assayed using the MBS that are indicative of a nonstressed or stressed condition. The MBS distinguished the separate and combined effects of heat and light on the 2 coral symbionts, a scleractinian coral and a dinoflagellate algae (zooxanthellae). This technology aids in the accurate diagnosis of coral condition because each parameter is physiologically well understood. Finally, the MBS technology is relatively inexpensive, easy to implement, and precise, and it can be quickly adapted to a high-throughout robotic system for mass sample analysis.

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Additional co-authors: M. Liess, E. Long, M. McField, P. Mineau, E. A. D. Mitchell, C. A. Morrissey, D. A. Noome, L. Pisa, J. Settele, N. Simon-Delso, J. D. Stark, A. Tapparo, H. Van Dyck, J. van Praagh, M. Wiemer