Dataset Information

Clothianidin in agricultural soils and uptake into corn pollen and canola nectar after multiyear seed treatment applications.

ABSTRACT: Limited data are available on the fate of clothianidin under realistic agricultural production conditions. The present study is the first large-scale assessment of clothianidin residues in soil and bee-relevant matrices from corn and canola fields after multiple years of seed-treatment use. The average soil concentration from 50 Midwest US corn fields with 2 yr to 11 yr of planting clothianidin-treated seeds was 7.0?ng/g, similar to predicted concentrations from a single planting of Poncho 250-treated corn seeds (6.3?ng/g). The water-extractable (i.e., plant-bioavailable) clothianidin residues in soil were only 10% of total residues. Clothianidin concentrations in soil reached a plateau concentration (amount applied equals amount dissipated) in fields with 4 or more application years. Concentrations in corn pollen from these fields were low (mean: 1.8?ng/g) with no correlation to total years of use or soil concentrations. For canola, soil concentrations from 27 Canadian fields with 2 yr to 4 yr of seed treatment use (mean?=?5.7?ng/g) were not correlated with use history, and plant bioavailability was 6% of clothianidin soil residues. Average canola nectar concentrations were 0.6?ng/g and not correlated to use history or soil concentrations. Under typical cropping practices, therefore, clothianidin residues are not accumulating significantly in soil, plant bioavailability of residues in soil is limited, and exposure to pollinators will not increase over time in fields receiving multiple applications of clothianidin.

SUBMITTER: Xu T

PROVIDER: S-EPMC4736462 | biostudies-literature | 2016 Feb

REPOSITORIES: biostudies-literature

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Clothianidin in agricultural soils and uptake into corn pollen and canola nectar after multiyear seed treatment applications.

Xu Tianbo T Dyer Dan G DG McConnell Laura L LL Bondarenko Svetlana S Allen Richard R Heinemann Oliver O

Environmental toxicology and chemistry 20160108 2

Limited data are available on the fate of clothianidin under realistic agricultural production conditions. The present study is the first large-scale assessment of clothianidin residues in soil and bee-relevant matrices from corn and canola fields after multiple years of seed-treatment use. The average soil concentration from 50 Midwest US corn fields with 2 yr to 11 yr of planting clothianidin-treated seeds was 7.0 ng/g, similar to predicted concentrations from a single planting of Poncho 250-t ...[more]

PMID: 26467536

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Project description:The objective of this study was to quantify consumption of clothianidin-treated corn seed by birds following standard planting practices. Based on post-planting seed counts on 21 fields in southwestern Ontario, Canada, between 29 and 813 seeds/ha (mean of 224 ± 167 (SD)) were estimated to remain on the soil surface immediately post planting (i.e., less than one seed per 10 m2). This represents between 0.03 and 1.2% of the total sown seeds. The number of seeds missing on each field on the third day after planting as a result of any process (e.g., removal by foraging birds or mammals or burial as a result of heavy rains) ranged from 0 to 136 seeds/ha (0 to 0.0136 seeds/m2). Behavior monitoring of individual birds and 24 h remote video surveillance were deployed to investigate how much of the treated seed remaining on the soil surface was consumed by birds. Spotting scopes were used to monitor the full duration of the field visits of 596 individual birds during morning hours for three consecutive days after planting on the 21 fields. Two birds were observed consuming treated seeds (one seed each) and three birds consumed seeds for which the treatment status could not be visually confirmed. Additionally, constant (24 h) video surveillance for 2-4 days immediately after planting was deployed at 24 areas where multiple treated seeds were found on the soil surface. Across 1,380 h of collected video footage (including both day and night periods), no birds were observed to consume any treated seeds. This study provides field evidence of two factors that determine exposure of birds to clothianidin-treated corn seeds: (1) standard sowing practices in Ontario are effective at burying treated seeds such that the proportion of sown seeds that remain on the soil surface after planting is low, and (2) birds monitored on these fields consumed very few of the clothianidin-treated corn seeds remaining on the soil surface after planting. As these results are dependent on planting techniques and seed characteristics, they are not necessarily applicable to other types of clothianidin treated seed.

Project description:There is growing concern that some bee populations are in decline, potentially threatening pollination security in agricultural and non-agricultural landscapes. Among the numerous causes associated with this trend, nutritional stress resulting from a mismatch between bee nutritional needs and plant community provisioning has been suggested as one potential driver. To ease nutritional stress on bee populations in agricultural habitats, agri-environmental protection schemes aim to provide alternative nutritional resources for bee populations during times of need. However, such efforts have focused mainly on quantity (providing flowering plants) and timing (during flower-scarce periods), while largely ignoring the quality of the offered flower resources. In a first step to start addressing this information gap, we have used literature data to compile a comprehensive geographically explicit dataset on nectar quality (i.e., total sugar concentration), offered to bees both within fields (crop and weed species) as well as outside fields (wild species) around the globe. Social bees are particularly sensitive to nectar sugar concentrations, which directly impact calorie influx into the colony and consequently their fitness making it an important resource quality marker. We find that the total nectar sugar concentrations in general do not differ between the three plant communities studied. In contrast we find increased variability in nectar quality in the wild plant community compared to crop and weed community, which is likely explained by the increased phylogenetic diversity in this category of plants. In a second step we explore the influence of local habitat on nectar quality and its variability utilizing a detailed sunflower (Helianthus annuus L.) data set and find that geography has a small, but significant influence on these parameters. In a third step we identify crop groups (genera), which provide sub-optimal nectar resources for bees and suggest high quality alternatives as potential nectar supplements. In the long term this data set could serve as a starting point to systematically collect more quality characteristics of plant provided resources to bees, which ultimately can be utilized by scientist, regulators, NGOs and farmers to improve the flower resources offered to bees. We hope that ultimately this data will help to ease nutritional stress for bee populations and foster a data informed discussion about pollinator conservation in modern agricultural landscapes.

Dataset Information

Clothianidin in agricultural soils and uptake into corn pollen and canola nectar after multiyear seed treatment applications.

Publications

Clothianidin in agricultural soils and uptake into corn pollen and canola nectar after multiyear seed treatment applications.

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