Recipient Organization
UNIVERSITY OF FLORIDA
G022 MCCARTY HALL
GAINESVILLE,FL 32611
Performing Department
(N/A)
Non Technical Summary
Pollinator species include a wide range of arthropods and other organisms that are essential for maintenance of many ecological systems and production of agricultural crops. Losses of pollinator species can significantly reduce yields of open-pollinated crops and negatively impact the ecology of desireable agriculturally-allied and natural systems. Pollinator species losses have been well documented and pesticide-use for crop production/landscape maintenance has been identified as one of several factors potentially contributing to the loss. Little research has focused on contamination of floral resources (nectar and pollen) in ornamental plants. A preliminary study conducted by the PIs found that application methods, rates, and timings can greatly influence contamination of nectar using salvia x 'Indigo Spires' as a model species. Concentrations in nectar greatly exceeded reported toxicity thresholds for native bees/honeybees for some treatments, while others were of less concern, indicating that "safe" application windows may exist but need to be identified. This research project will expand on the preliminary study, with goals of 1) characterizing the influence of pesticide application method, rates, and timing on contamination of floral resources in herbaceous and woody ornamental species; 2) evaluating the potential for identifying windows-of-opportunity when systemic pesticides may be applied with little risk of floral resource contamination relative to sell dates for plants; and 3) determining how quickly pesticide contamination in floral resources dissipates once treated plants are transplanted into the landscape.This project will use cyantraniliprole, flupyradifurone, and thiamethoxam as model systemic insecticides and Mysty salvia and Bloomify lantana as model herbaceous and woody ornamentals, respectively. Rooted liners of the each species will be planted in 3-gallon nursery containers. For determining the effects of application method on floral resource contamination, pesticides will be applied as drenches or as sprays. All of these pesticides are labeled for application through both means, though the rates of application differ. Pesticides will be applied at low, medium, and high rates specified on the labels for each pesticide and application method. All plants for each pesticide-plant combination will be purchased and established at the same time. To evaluate the influence of pesticide application timing on contamination, the pesticides will be applied before the plants form flowers (approximately 1 week after potting the liners in 3 gallon pots) to one set of plants, just before the majority of plants begin to form flower buds for another set, and just before flower buds begin to open for the last set. Once all plants are flowering, nectar and pollen samples will be collected for analysis by uHPLC-MS/MS. Nectar samples will be collected using glass capillaries and anthers will be excised and serve as a proxy for pollen. Following sample collection, half of the replicates within each treatment group will be pruned to evaluate the potential effects of this cultural practice on pesticide concentrations in subsequent flowers. Once the plants are all flowering again samples will be collected as previously described. At the end of this study phase, all plants will be transplanted into the landscape with one to two more samplings to evaluate dissipation of residues once the plants are in the landscape.Each plant-pesticide evaluation will require approximately four months in the shade house from the time the rooted liners are received and an additional two months in the field. Key milestones will be completion studies for of each plant-pesticide combination. Results from the aggregate of study results available at the time will be analyzed and packaged for delivery to stakeholders as abstracts, proceedings, refereed journal articles, presentations (poster and oral) at local and professional meetings, and individual interactions with those interested.
Animal Health Component
100%
Research Effort Categories
Basic
(N/A)
Applied
100%
Developmental
(N/A)
Goals / Objectives
The over-arching goal of this project is to identify management practices that can minimize exposure of pollinator species to pesticides used in ornamental plant production when the plants are market-ready. To achieve this goal, information is needed aboutpesticide applications (how, when, and how much), pesticide transport dynamics within the plants (based on initial application method and partitioning into different tissues), and pesticide dissipation kinetics once plants are established in the landscape.The objectives of this project are to:1) Characterize the influence of pesticide application method, rates, and timing on contamination of floral resources in an herbaceous and a woody ornamental species.2) Evaluate the feasibility of using predictive regression models for characterizing contamination of pollen and nectar with pesticides based on concentrations in leaves to schedule when pesticide applications can be made to minimize contamination in plants going to market.3) Determine how quickly pesticide contamination in floral resources dissipates once treated plants are transplanted into the landscape.
Project Methods
This project will use cyantraniliprole, flupyradifurone, and thiamethoxam as model systemic insecticides and Mysty salvia and Bloomify lantana as model herbaceous and woody ornamentals, respectively. Rooted liners of the each species will be planted in 3-gallon nursery containers. For determining the effects of application method on floral resource contamination, pesticides will be applied as drenches or as sprays. All of these pesticides are labeled for application through both means, though the rates of application differ. Pesticides will be applied at low, medium, and high rates specified on the labels for each pesticide and application method. Drench applications will be made by adding the appropriate amount of diluted pesticide into each pot volumetrically per label specifications. Foliar pesticide applications will be made using hand-held spray bottles. All three pesticide formulations indicate that pesticides should be sprayed to thoroughly cover plants, but not result in runoff from foliage. Prior to applying sprays to treatment plants, spray bottles will be adjusted to optimize spray pattern and calibrated to thoroughly cover the test plants. The same volume and application sequence (e.g. spray from bottom to top while circling the plant at a constant velocity) will be used for each plant. Studies will be conducted in a screenhouse in order to minimize visitation (and possible cross-contamination) by pollinator species. All plants for each plant-pesticide combination will be purchased and established at the same time. To evaluate the influence of pesticide application timing on contamination, the pesticides will be applied before the plants form flowers (approximately 1 week after potting the liners in 3 gallon pots) to one set of plants, just before the majority of plants begin to form flower buds for another set, and just before flower buds begin to open for the last set. Once all plants are flowering, nectar and pollen samples will be collected for analysis. Nectar samples will preferentially be collected using 1, 5, 10 or 25 µL micropipettes (volumes > 1 µL). Microcapillaries will either be inserted into the throat of individual flowers of the flower corollas will be removed and nectar sampled from the base. Nectar samples will be ejected into microcentrifuge tubes and stored on ice in the field and at -20 C in the lab until analysis. Since these plants are not prolific pollen producers, entire anthers will be used as a proxy for pollen. Furthermore, given the small biomass of anthers, these analyses will be restricted to only one of the plant species (i.e. the one that produces the largest anthers and pollen loads). Anthers will be excised from stamens in florets that are just beginning to open to ensure that all pollen is accounted for. Anthers collected will be placed in 1.5 mL microcentrifuge tubes, which will be kept on ice in the field and transferred to -20 C storage until analysis in the lab. The number of anthers to be collected will be determined in preliminary studies to characterize masses, pollen content, and method detection limits. Leaves will be collected from 6 randomly selected positions on the plants, placed in Whirl-Pak bags, and stored at -20°C until analysis. Samplers will use a new pair of gloves for collecting leaves from each plant to minimize cross-contamination.Following sample collection, half of the replicates within each treatment group will be pruned to evaluate the potential effects of this cultural practice on pesticide concentrations in subsequent flowers. Once the plants are all flowering again samples will be collected as previously described. At the end of this study phase, all plants will be transplanted into the ground at the UF/IFAS Plant Science Research and Education Unit (Citra, FL). Plants will be established and maintained in raised beds. Plants will be deadheaded weekly and floral resources will be sampled 1 to 3 months after transplanting depending on flowering status. If residues are still present at high concentrations in floral resources, those plants will be re-sampled again after 1 to 3 months to identify how long exposure risks are significant.Pesticide concentrations in nectar will preferentially be analyzed by direct injection of diluted samples if sensitivity is adequate. If sensitivity is not adequate nectar samples will be diluted with water and extracted using novel or published methods. For analysis by direct-injection, nectar samples will be diluted with 200 µl of H2O:ACN (9:1) followed by thorough mixing using a vortex genie. Samples will be centrifuged (13,000 RCF, 10 min) prior to uHPLC-MS/MS analysis. QuECHERS methods will be adapted for analysis of each target pesticide in pollen and leaves. This method resulted in very good recoveries for thiamethoxam and clothianidin in our preliminary research and is expected to perform equally well with cyantraniliprole and flupyradifurone. Pesticide concentrations in extracts and diluted nectar samples will be analyzed by ultra high-pressure liquid chromatography with tandem mass spectrometer detection (uHPLC/MS/MS). Pesticides will be chromatographed using an Agilent 1290 Infinity II uHPLC System equipped with a C18 reversed-phase column and coupled to an Agilent 6495 tandem mass spectrometer. The MS/MS will be operated in electrospray ionization (ESI) positive or negative mode with nitrogen used as the source and collision gas. Data will be acquired in multiple-reaction monitoring (MRM) mode. Mobile phase for the LC separation may differ depending on the targeted pesticide. We currently have a robust method for extraction and analysis of thiamethoxam and clothianidin, and a base instrument method that includes cyantraniliprole and flupyradifurone. This instrument method will be optimized for cyantraniliprole and flupyradifurone.Pesticide concentrations in nectar, pollen, and leaves will be analyzed by Analysis of Variance (P = 0.05) to identify differences associated with application method (drench or spray), application rate (low, medium, and high), and application timing (at repotting stage, pre-bloom initiation, and post initiation/pre-opening). If differences are identified, Tukeys HSD post hoc analysis will be used to identify treatments that are different. Specific comparisons that will be made include: 1) foliar spray vs. drench at each respective application rate/application timing (e.g., foliar spray/low rate/at potting compared to media drench/low rate/at potting, etc.); 2) within each application method, rates will be compared within each timing (e.g. within foliar spray application method, concentrations in plant matrix will be compared between the low, medium and high application rates within each application timing separately; 3) within each application method and rate, contamination due to timing of application will be assessed. Linear or non-linear regression will be used to characterize relationships between concentrations in leaves and concentrations in nectar and pollen based on the different application rates. Multivariate principal components analysis will be used to further characterize primary factors (timing, rate, application method) associated with contamination of floral resources.Each plant-pesticide evaluation will require approximately four months in the shade house from the time the rooted liners are received and an additional two months in the field. Key milestones will be completion studies for of each plant-pesticide combination. Results from the aggregate of study results available at the time will be analyzed and packaged for delivery to stakeholders as abstracts, proceedings, refereed journal articles, presentations (poster and oral) at local and professional meetings, and individual interactions with those interested.