Effects of two common fungicides on the reproduction of Aporrectodea caliginosa in natural soil

The use of pesticides in agroecosystems can have negative effects on earthworms, which play key roles in soil functioning such as organic matter decomposition. The aim of this study was to assess the effects of two fungicides (Cuprafor micro®, composed of copper oxychloride, and Swing Gold®, composed of epoxiconazole (EPX) and dimoxystrobin (DMX)) on earthworm reproduction by exposing adults and cocoons. First, adult Aporrectodea caliginosa individuals were exposed for 28 days to 3.33, 10 and 30 times the recommended dose (RD) of Cuprafor micro® corresponding to 25.8, 77.5 and 232.5 mg kg−1 dry soil of copper, respectively, and 0.33, 1 and 3 times the RD of Swing Gold® (corresponding to 5.2 × 10−2 mg DMX kg−1 + 1.94 × 10−2 mg EPX kg−1, 1.55 × 10−1 mg DMX kg−1 + 5.81 × 10−2 mg EPX kg−1 and 4.62 × 10−1 mg DMX kg−1 + 1.74 × 10−1 mg EPX kg−1 respectively), in addition to a control soil with no fungicide treatment. Cocoon variables (production, weight, hatching success, hatching time) were monitored. Second, “naïve” cocoons produced by uncontaminated earthworms were exposed to soils contaminated by the same concentrations of the two fungicides, and we assessed hatching success and hatching time. In the first experiment, cocoon production was halved at the highest copper concentration (232.5 mg Cu kg−1 of dry soil) as compared to the control. Cocoons took 5 more days to hatch, and the hatching success decreased by 35% as compared to the control. In the Swing Gold® treatments, cocoon production was reduced by 63% at 3 times the RD, and the hatching success significantly decreased by 16% at the RD. In the second experiment, only the hatching success of cocoons was impacted by Swing Gold® at 3 times the RD (30% less hatching). It is concluded that the cocoon stock in the soil is crucial for the renewal of populations in the field. The most sensitive endpoint was the hatching success of the cocoons produced by exposed adults. This endpoint and the effects observed on the “naïve” cocoons could be taken into account in pesticide risk assessment

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WOS:000346545800018International audienceThe presence of plants induces strong accelerations in soil organic matter (SOM) mineralization by stimulating soil microbial activity a phenomenon known as the rhizosphere priming effect (RPE). The RPE could be induced by several mechanisms including root exudates, arbuscular mycorrhizal fungi (AMF) and root litter. However the contribution of each of these to rhizosphere priming is unknown due to the complexity involved in studying rhizospheric processes. In order to determine the role of each of these mechanisms, we incubated soils enclosed in nylon meshes that were permeable to exudates, or exudates & AMF or exudates, AMP and roots under three grassland plant species grown on sand. Plants were continuously labeled with C-13 depleted CO2 that allowed distinguishing plant-derived CO2 from soil-derived CO2. We show that root exudation was the main way by which plants induced RPE (58-96% of total RPE) followed by root litter. AMP did not contribute to rhizosphere priming under the two species that were significantly colonized by them i.e. Poa trivialis and Trifolium repens. Root exudates and root litter differed with respect to their mechanism of inducing RPE. Exudates induced RPE without increasing microbial biomass whereas root litter increased microbial biomass and raised the RPE mediating saprophytic fungi. The RPE efficiency (RPE/unit plant-C assimilated into microbes) was 3-7 times higher for exudates than for root litter. This efficiency of exudates is explained by a microbial allocation of fresh carbon to mineralization activity rather than to growth. These results suggest that root exudation is the main way by which plants stimulated mineralization of soil organic matter. Moreover, the plants through their exudates not only provide energy to soil microorganisms but also seem to control the way the energy is used in order to maximize soil organic matter mineralization and drive their own nutrient supply. (C) 2014 Elsevier Ltd. All rights reserved

Démographie du Puffin cendré Calonectris diomedea de Selvagem Grande (30° 09' n, 15° 52' w)

The breeding numbers of the Cory ' s Shearwaters Calonectris diomedea of Selvagem Grande (30° 09' N, 15 ° 52' W) have shown important variations during the last three decades, decreasing from about 100,000 birds at the beginning of the seventies to 5,000 only in 1 977 following depredations, and increasing regularly since then to reach nowadays about 30,000. The mean age at first breeding is 8.9 years. Every year, 11.8 % of the breeders temporarily stop breeding, these sabbatical leaves lasting 1.7 years on average and 7 years at most. 56.6 % of the eggs laid produce fledglings, with significant variations between years. The mean annual survival rate of the adults is comparatively low, 92.7 %, higher for females (93.5 %) than for males (91.9 %) and varying significantly between years (min. : 84.1 %, max.: 98.0 % ). The survival rate of the immatures between fledging and first breeding is 32.8 % at !east. Selvagem Grande population, which numbered an important proportion of young inexperienced birds at the beginning of the eighties, following the depredations of the seventies, has gained age and experience during the eighties and the nineties. But the relatively low annual survival rate of the adults, which is probably linked to the development of new fishing methods, is an alarming sign for the future of the population of Cory' s Shearwaters, notwithstanding the conservation actions engaged in the breeding localitiesLes effectifs des Puffins cendrés Calonectris diomedea de Selvagem Grande (30° 09' N, 15° 52' W) ont montré au cours des trois dernières décennies des variations considérables, passant de 100 000 reproducteurs environ au début des années 70 à 5 000 seulement en 1977 à la suite de déprédations, et augmentant régulièrement depuis lors pour atteindre aujourd'hui environ 30 000. La reproduction s'établit en moyenne à 8,9 années. Chaque année, 11,8 % des reproducteurs ne nichent pas, les interruptions temporaires de la reproduction durant en moyenne 1,7 années et au maximum 7 ans. 56,6 % des oeufs pondus produisent des poussins en fin de croissance, des variations significatives existant d'une année à l'autre. Le taux de survie annuel des adultes est relativement faible, 92,7 %. Il est plus élevé chez les femelles (93,5 %) que chez les mâles (91,9 %) et il varie significativement d'une année à l'autre (min.: 84,1 %, max. : 98,0 %). Enfin, le taux de survie des immatures entre l'envol en fin de croissance et la première reproduction est au moins égal à 32,8 %. La population de Selvagem Grande, qui comptait une proportion importante de jeunes oiseaux inexpérimentés au début des années 80, à la suite des massacres de reproducteurs de la fin-des années 70, a acquis de l'âge et de l'expérience au cours des décennies 80 et 90. Mais la relative faiblesse du taux de survie annuel des adultes, qu'il faut sans doute mettre en relation avec le développement de nouvelles méthodes de pêche, est un signe inquiétant pour l'avenir des populations de Puffins cendrés, malgré les mesures de protection prises sur les lieux de reproduction

Fate of Pesticides in Soils: Toward an Integrated Approach of Influential Factors

Chapitre 29absen

Earthworms mitigate pesticide effects on soil microbial activities

Earthworms act synergistically with microorganisms in soils. They are ecosystem engineers involved in soil organic matter degradation and nutrient cycling, leading to the modulation of resource availability for all soil organisms. Using a soil microcosm approach, we aimed to assess the influence of the earthworm Aporrectodea caliginosa on the response of soil microbial activities against two fungicides, i.e. Cuprafor micro® (copper oxychloride, a metal) and Swing® Gold (epoxiconazole and dimoxystrobin, synthetic organic compounds). The potential nitrification activity (PNA) and soil enzyme activities (glucosidase, phosphatase, arylamidase, and urease) involved in biogeochemical cycling were measured at the end of the incubation period, together with earthworm biomass. Two common indices of the soil biochemistry were used to aggregate the response of the soil microbial functioning: the geometric mean (Gmean) and the Soil Quality Index (SQI). At the end of the experiment, the earthworm biomass was not impacted by the fungicide treatments. Overall, in the earthworm-free soil microcosms, the two fungicides significantly increased several soil enzyme and nitrification activities, leading to a higher GMean Index as compared to the non-treated control soils. The microbial activity responses depended on the type of activity (nitrification was the most sensitive one), on the fungicide (Swing® Gold or Cuprafor micro®), and on the doses. The SQI indices revealed higher effects of both fungicides on the soil microbial activity in the absence of earthworms. The presence of earthworms enhanced all soil microbial activities in both the control and fungicide-contaminated soils. Moreover, the magnitude of the fungicide impact, integrated through the SQI index, was mitigated by the presence of earthworms, conferring a higher stability of microbial functional diversity. Our results highlight the importance of biotic interactions in the response of indicators of soil functioning (i.e., microbial activity) to pesticides

Aporrectodea caliginosa, a relevant earthworm species for a posteriori pesticide risk assessment: current knowledge and recommendations for culture and experimental design

Ecotoxicological tests with earthworms are widely used and are mandatory for the risk assessment of pesticides prior to registration and commercial use. The current model species for standardized tests is Eisenia fetida or Eisenia andrei. However, these species are absent from agricultural soils and often less sensitive to pesticides than other earthworm species found in mineral soils. To move towards a better assessment of pesticide effects on non-target organisms, there is a need to performaposterioritestsusingrelevantspecies.TheendogeicspeciesAporrectodeacaliginosa(Savigny,1826)isrepresentative of cultivated fields in temperate regions and is suggested as a relevant model test species. After providing information on its taxonomy, biology, and ecology, we reviewed current knowledge concerning its sensitivity towards pesticides. Moreover, we highlighted research gaps and promising perspectives. Finally, advice and recommendations are given for the establishment of laboratory cultures and experiments using this soil-dwelling earthworm species