Effects of environmentally realistic concentrations of neonicotinoid insecticides on an aquatic invertebrate community

Neonicotinoid insecticides represent 24 % of the global market, and their use is increasing globally. Among them, clothianidin, imidacloprid, and thiamethoxam are widely used systemic insecticides, but are also used for lawn and garden care, and pest control. Residential usage has been linked to the occurrence of toxic level of pesticides in urban water bodies. Neonicotinoids are highly soluble in water and persistent in soil, and even though they are not intended for use in water bodies, they may enter in the aquatic compartment via spray drift, runoff or leaching, and contribute to downstream aquatic toxicity. Neonicotinoids interfere with the insect nervous system, and exhibit very high selectivity for insect nicotinic acetylcholine receptors. However, although insects appear to be the most sensitive, some studies have shown effects of neonicotinoids on the crustaceans Ceriodaphnia dubia and Daphnia magna, but also on honeybees and bumble bees, flies, and birds. Moreover, neonicotinoid contamination is likely to induce a top-down trophic cascade in a community dominated by invertebrate predators. Very little is known concerning the impact of neonicotinoid mixtures on the environment, and their combined toxicity on invertebrate community. Thus, our study aimed to test the effect of a mixture of imidachloprid, clothianidin and thiamethoxam on an aquatic invertebrate community at concentrations measured in the environment, and explore the community-level effects. The experiment was conducted in outdoor microcosms. The community was sampled before the insecticide application and throughout the month following the treatment. Environmental parameters (water temperature, pH, conductivity, chlorophyll a) were measured in every microcosm on each sampling date. Results will be discussed during the presentation. Keywords: neonicotinoid insecticides, mixture, aquatic invertebrates, community-leve

Effects of Bacillus thuringiensis israelensis and spinosad on adult emergence of the non-biting midges Polypedilum nubifer (Skuse) and Tanytarsus curticornis Kieffer (Diptera: Chironomidae) in coastal wetlands

International audienceTo optimize their efficacy, some insecticides used for mosquito control are introduced into aquatic ecosystems where mosquito larvae develop (marshes, ponds, sanitation devices) and cannot escape from the treated water. However, this raises the question of possible effects of mosquito larvicides on nontarget aquatic species. Bacillus thuringiensis var. israelensis (Bti), which is well-known for its selectivity for Nematocera dipterans, is widely used for mosquito control all over the world. Spinosad, a mixture of spinosyns A and D known as fermentation products of a soil actinomycete (Saccharopolyspora spinosa), is a biological neurotoxic insecticide with a broader action spectrum. It is a candidate larvicide for mosquito control, but some studies showed that it may be toxic to beneficial or non-target species, including non-biting midges. The present study was therefore undertaken to assess the impact of Bti and spinosad on natural populations of Polypedilum nubifer (Skuse) and Tanytarsus curticornis Kieffer (Diptera: Chironomidae) in field enclosures implemented in Mediterranean coastal wetlands. Unlike Bti, spinosad had a strong lethal effect on Polypedilum nubifer and seems to affect Tanytarsus curticornis at presumed recommended rates for field application. Differences in the sensitivity of these two species to spinosad confirm that population dynamics need to be known for a proper assessment of the risk encountered by chironomids in wetlands where larvicide-based mosquito control occurs. (C) 2015 Elsevier Inc. All rights reserved

Influence of environmental factors on the response of a natural population of Daphnia magna (Crustacea: Cladocera) to spinosad and Bacillus thuringiensis israelensis in Mediterranean coastal wetlands

The present study was undertaken to assess the impact of a candidate mosquito larvicide, spinosad (8, 17 and 33 μg L−1) on a field population of Daphnia magna under natural variations of water temperature and salinity, using Bti (0.16 and 0.50 μL L−1) as the reference larvicide. Microcosms (125 L) were placed in a shallow temporary marsh where D. magna was naturally present. The peak of salinity observed during the 21-day observation period may have been partly responsible for the decrease of daphnid population density in all the microcosms. It is also probably responsible for the absence of recovery in the microcosms treated with spinosad which caused a sharp decrease of D. magna abundance within the first two days following treatment whereas Bti had no effect. These results suggest that it may be difficult for a field population of daphnids to cope simultaneously with natural (water salinity and temperature) and anthropogenic (larvicides) stressors. Significant interaction between salinity and spinosad exposure impairs the recovery of a natural population of Daphnia magn

Population-level effects of spinosad and Bacillus thuringiensis israelensis in Daphnia pulex and Daphnia magna: comparison of laboratory and field microcosm exposure conditions

Because exposure to toxicants not only results in mortality but also in multiple sublethal effects, the use of life-table data appears particularly suitable to assess global effects on exposed populations. The present study uses a life table response approach to assess population-level effects of two insecticides used against mosquito larvae, spinosad (8 mu g/l) and Bacillus thuringiensis var. israelensis (Bti, 0.5 mu l/l), on two non target species, Daphnia pulex and Daphnia magna (Crustacea: Cladocera), under laboratory versus field microcosms conditions. Population growth rates were inferred from life table data and Leslie matrices under a model with resource limitation (ceiling). These were further used to estimate population risks of extinction under each tested condition, using stochastic simulations. In laboratory conditions, analyses performed for each species confirmed the significant negative effect of spinosad on survival, mean time at death, and fecundity as compared to controls and Bti-treated groups; for both species, population growth rate lambda was lower under exposure to spinosad. In field microcosms, 2 days after larvicide application, differences in population growth rates were observed between spinosad exposure conditions, and control and Bti exposure conditions. Simulations performed on spinosad-exposed organisms led to population extinction (minimum abundance = 0, extinction risk = 1), and this was extremely rapid (time to quasi-extinction = 4.1 one-week long steps, i.e. one month). Finally, D. magna was shown to be more sensitive than D. pulex to spinosad in the laboratory, and the effects were also detectable through field population demographic simulations

Effects of spinosad and Bacillus thuringiensis israelensis on a natural population of Daphnia pulex in field microcosms

Spinosad, a candidate biological larvicide for mosquito control, was evaluated for its effects on a field population of Daphnia pulex, using Bacillus thuringiensis serovar israelensis (Bti) as a reference larvicide. Microcosms (125 L enclosures) were placed in a shallow temporary oligohaline marsh where D. pulex was present. Three concentrations of spinosad (8, 17 and 33 μg L−1) and two concentrations of Bti (0.16 and 0.50 μL L−1) were applied (5 replicates per concentration, including the controls). Effects of larvicides on D. pulex were evaluated after 2, 4, 7, 14 and 21 d of exposure, through measurements of abundance and individual size. Dissipation of spinosad from the water phase was rapid. Four days after treatment, residue concentration represented 11.8%, 3.9% and 12.7% of the initial exposure level for the nominal concentrations of 8, 17 and 33 μg L−1, respectively. Spinosyns A and D dissipated at similar rates. Analysis of abundance and size structure of the D. pulex population showed an impact of spinosad. Both survival and size structure were affected. However, at the lowest concentration (8 μg L−1), population recovered after the first week. In microcosms treated with Bti, the abundance of D. pulex was not affected but the size structure of the population changed after 21 d. As compared to laboratory tests, the use of in situ microcosms improved the environmental risk assessment of larvicides, taking into account the influence of environmental factors (e.g., temperature, light, salinity) and intrinsic capacity of recovery of D. pulex under field conditions

Molecular identification of Aedes phoeniciae (Diptera: Culicidae) in rockpools along the northern Israeli coast

Mosquitoes inhabiting rockpools within supra‐littoral zones along the Mediterranean coast belong to the Aedes mariae complex (Coluzzi and Sabatini 1968, Coluzzi et al. 1974b, Schaffner et al. 2001, Mastrantonio et al. 2015). The species in the Ae. mariae complex can be responsible for vectoring bird malaria as vectors of Plasmodium relictum (Clements 1999). Furthermore, they are a biting nuisance for humans in areas densely populated by tourists from spring through autumn

Chitobiase activity as an indicator of altered survival, growth and reproduction in Daphnia pulex and Daphnia magna (Crustacea: Cladocera) exposed to spinosad and diflubenzuron

Chitobiase is involved in exoskeleton degradation and recycling during the moulting process in arthropods. In aquatic species, the moulting fluid is released into the aqueous environment, and chitobiase activity present therein can be used to follow the dynamics of arthropod populations. Here, chitobiase activity was used for monitoring the impact of mosquito candidate larvicides on Daphnia pulex and Daphnia magna under laboratory conditions. Both species were exposed to spinosad (2, 4, 8 mu g L-1) and diflubenzuron (0.2, 0.4, 0.8 mu g L-1) for 14 days. Bacillus thuringiensis var. israelensis (Bti: 0.25, 0.5, 1 mu L L-1) was used as the reference larvicide. Chitobiase activity, adult survival, individual growth and fecundity, expressed as the number of neonates produced, were measured every 2 days. Average Exposure Concentrations of spinosad were ten-fold lower than the nominal concentrations, whereas only a slight deviation was observed for diflubenzuron. In contrast to Bti, spinosad and diflubenzuron significantly affected both species in terms of adult survival, and production of neonates. As compared to D. pulex, D. magna was more severely affected by diflubenzuron, at low and medium concentrations, with reduced adult growth and much lower chitobiase activity. Chitobiase activity was positively correlated with the individual body length, number of neonates produced between two consecutive observation dates, and number of females and neonates. In addition, the significant positive correlations between chitobiase activity measured on the last sampling date before the first emission of neonates and the cumulative number of neonates produced during the whole observation period strongly support the potential of the activity of this chitinolytic enzyme as a proxy for assessing the dynamics of arthropod populations exposed to larvicides used for mosquito control. (C) 2010 Elsevier Inc. All rights reserved

Pratiques technologiques d'adolescents et modes de vie

Financement de la numérisation : fonds propres IIAC UMR8177 CNRS/EHESS ; tous mes remerciements à Jean-François Gossiaux, directeur de l'UMR8177 pour sa générosité.Rapport de recherche (94 p.) de l'équipe "Science Technique Société" de l'INRP (Institut national de la recherche pédagogique), département "Nouvelles technologies". Equipe dirigée par Jacques Perriault, dans le cadre du contrat CNRS ATP Science Technique Société n°033871, réunissant des enseignants détachés à l'INRP et des chercheurs hors-statuts.Cette recherche trouve son origine dans un questionnement sur la raison d'être de nombreuses formations d'adolescents autour de pratiques technologiques (groupes de rock, clubs informatiques...). Une étude antérieure, conduite par le Centre de Recherche sur la Culture Technique et 1'INRP, avait abouti à la mise en évidence de quelques cinq cents groupements sur le territoire, essentiellement d'ailleurs dans les domaines parascolaires et périscolaires. I1 avait semblé que le phénomène, de par son importance numérique, prenait une dimension qu'il n'avait pas connue par le passé, même si existent depuis très longtemps des pratiques associatives en matière, par exemple, d'aéromodélisme, d'astronomie ou de radio-amateurisme

Persistence and Recycling of Bioinsecticidal Bacillus thuringiensis subsp. israelensis Spores in Contrasting Environments: Evidence from Field Monitoring and Laboratory Experiments

International audienceSprays of commercial preparations of the bacterium Bacillus thuringiensis subsp. israelensis (Bti) are widely used for the control of mosquito larvae. Despite an abundant literature on Bti field efficiency on mosquito control, few studies have evaluated the fate of spores in the environment after treatments. In the present article, two complementary experiments were conducted to study the effect of different parameters on Bti persistence and recycling, in field conditions and in the laboratory. First, we monitored Bti persistence in the field in two contrasting regions in France: the Rhône-Alpes region, where mosquito breeding sites are temporary ponds under forest cover with large amounts of decaying leaf matter on the ground, and the Mediterranean region characterized by open breeding sites such as brackish marshes. Viable Bti spores can persist for months after a treatment, and their quantity is explained both by the vegetation type and by the number of local treatments. We found no evidence of Bti recycling in the field. Then, we tested the effect of water level, substrate type, salinity, and presence of mosquito larvae on the persistence/recycling of Bti spores in controlled laboratory conditions (microcosms). We found no effect of change in water level or salinity on Bti persistence over time (75 days). Bti spores tended to persist longer in substrates containing organic matter compared to sand-only substrates. Bti recycling only occurred in presence of mosquito larvae, but was unrelated to the presence of organic matter