products containing cyantraniliprole are optimized for foliar or soil ... be conducted for demonstrating pollinator safety and good product stewardship. Abstract.
Cyantraniliprole (Cyazypyr™) – A testing program for honey bees Bridget F. O’Neill, Axel Dinter, and Alan Samel
Abstract
Extensive product testing allows for comprehensive knowledge of a product’s risks, and how those risks may be mitigated in our modern agricultural landscape. Recent focus on global honey bee health has resulted in regulators from multiple countries requesting additional data to assess risk to bees. The result of these requests is a very conservative risk assessment methodology for crop protection products. Cyantraniliprole is an anthranilic diamide insecticide and DuPont formulations are now registered globally and in the US for a variety of crops. As part of product development, over 50 laboratory and field studies were performed to demonstrate honey bee safety for cyantraniliprole. These studies investigated the effects of the active ingredient, metabolites and formulated products on honey bees, and quantified residues in bee matrices, like pollen and nectar. Semi-field and field studies, and higher tier risk assessments indicate an acceptable risk for bees resulting from field-realistic exposure to DuPont cyantraniliprole uses.
Introduction Cyantraniliprole (DPX-HGW86, DuPont™ Cyazypyr™ insecticide) is the second anthranilic diamide insecticide discovered by E. I. du Pont de Nemours and Company, Inc. activating ryanodine receptors via stimulation of the release of calcium stores from the sarcoplasmic reticulum of muscle cells (e.g. for chewing insect pests) causing impaired regulation, paralysis and ultimately death of sensitive species (Cordova et al. 2006). Cyantraniliprole is a systemic insecticide and products containing cyantraniliprole are optimized for foliar or soil applications and are effective on a wide range of crops (e.g. vegetables and top fruits). Application rates may vary for different pests and crops between 0.07 to 0.4 lbs. cyantraniliprole/Acre/year with up to 3 applications per crop. Cyantraniliprole registration dossiers were submitted initially in 2011. Currently DuPont cyantraniliprole products for spray and/or and drip uses are registered in many countries, e.g. USA, Canada, Australia, New Zealand, China and India. DuPont cyantraniliprole products for seed treatment uses are registered for use in canola in USA and Canada. Because of the wide range of application rates, products, crops, and countries, an aggressive bee testing strategy was developed for cyantraniliprole to demonstrate safe uses with good agricultural practice methods and adherence to the product labels. More than 50 studies were conducted, including 10 acute laboratory oral and contact honey bee tests on technical, formulated products, and metabolites, a foliage residue test, two plant translocation studies, more than 10 semi-field tunnel studies some of which included brood assessments, eight field studies some of which included overwintering of the bee colonies, a bumble bee greenhouse study, and more than 20 field residue trials. We present an overview of this testing strategy in this poster.
Cyantraniliprole and the three formulations are equally toxic to honey bees with the OD (oil dispersed) formulation having the lowest acute values. We used the acute values for cyantraniliprole technical in the new US EPA honey bee risk assessment foliar spray calculations (with the highest single use foliar rate for the US, 0.133 lb./A) for tier I: Adult acute oral Risk Quotient (RQ) = Estimated Environmental Concentration (EEC)/oral LD50 (32 x 0.133)/0.11 = 38.69 Adult acute contact RQ = EEC/contact LD50 (2.7 X 0.133)/0.09 = 3.99 The estimated environmental concentration is a shortcut value multiplied by the maximum single use application rate in pounds/acre. Both of these RQ values are greater than the level of concern of 0.4 for tier I acute risk assessment, so tier II studies were conducted to help refine the risk assessment. Figure 1 – Tier II Semi-Field Tunnel Tests Mortality. In this study design, a small honey bee colony forages on a treated crop grown in a mesh tunnel. Exposure in tunnel for 7 days, then hive moved to an untreated crop outside tunnel and observed for several weeks. Mortality, foraging activity, brood development, behavior, and residues in pollen, nectar, and bee matrices (honey, bee bread, wax) may all be recorded or measured. More than 10 semi-field studies have been conducted to date for multiple cyantraniliprole formulations in multiple crops. Here is an example from one such study with cyantraniliprole OD done with the bee-attractive plant Phacelia. There were two treatments, T1 was applied at a rate of 10 g active ingredient/ha, T2 was applied at a rate of 100 g active ingredient/ha. A reference compound was applied as a positive control, and water was sprayed as a negative control. Cyantraniliprole was sprayed twice, once before the plants had flowered and the second time while the plants were blooming and bees were present (second spray marked by an arrow below). Asterisks denote significant differences from water control (p ≤ 0.05).
Table 1a and b – Tier I acute LD50 values. For tier I there are currently two acute tests performed with adult worker bees. An oral toxicity study for honey bees and a contact toxicity study for honey bees. Both tests have one time exposure, then observation for 48-96 hours. Both studies result in an LD50 value, median lethal dose of 50% of the population tested. Any abnormal behavioral effects are also noted in study reports (e.g. twitching, abdominal contractions) as they may possibly indicate sub-lethal effects. Table 1a -Test material Cyantraniliprole technical (max. water sol.) Cyantraniliprole OD Cyantraniliprole SE Cyantraniliprole SC Table 1b - Test material Cyantraniliprole technical (max. water sol.) Cyantraniliprole OD Cyantraniliprole SE Cyantraniliprole SC
Duration (hour) 48 h 72 h 96 h 96 h
Oral LD50 ( g Cyantraniliprole/bee) >0.11 0.39 0.92 0.40
Duration (hour) 72 h
Contact LD50 ( g Cyantraniliprole/bee) >0.09
96 h 96 h 96 h
0.65 2.78 0.66
A foliar residue study was also conducted with alfalfa foliage sprayed with cyantraniliprole OD at a rate of 150 g a.s./ha. The foliage was then allowed to dry for 3, 8, 24, 48, or 72 hours and honey bees were exposed to the dried foliage for a period of 24 hours. No adverse effects were noted for any of the treatments.
Figure 2 – Tier II Semi-Field Tunnel Tests Brood Assessments. In this example, the one treatment, T was applied at a rate of 150 g active ingredient/ha plus 2.5 L codacide oil/ha as a surfactant. A reference compound was applied as a positive control, and water was sprayed as a negative control. Cyantraniliprole was sprayed twice, once before the plants had flowered and the second time while the plants were blooming and bees were present. BFD stands for brood fixing day, or the day developmental stage was first checked, with subsequent checks being in weekly or so intervals after that date.
Summing up the two examples of Tier II semi-field tunnel studies presented, bee colonies exposed to cyantraniliprole OD treated foliage in tunnels at 10 g/ha showed only a slight reduction in flight and minor intoxication on the day of the second application. Bee colonies exposed to cyantraniliprole OD treated foliage in tunnels at 100 g/ha showed only a slight mortality increase, a slight reduction of flight, and minor intoxication on the day of the second application. And honey bee colonies exposed to cyantraniliprole OD at 150 g/ha plus codacide Oil did not have brood termination rates significantly different from the control colonies. There are no simple formulas to use to see if a pesticide passes the risk assessment at tier II or if tier III testing is required. Generally with tier II and tier III studies you want to see if effects witnessed for individual bees translate to colony-level effects at fieldrealistic dose levels. Tier III studies may also be conducted if there are specific concerns that may not be answerable with the tier II study structure. Figure 3 – Tier III – Full Field Test. In this study design, a normal-sized honey bee colony forages on a treated crop grown in an open field and is observed for several weeks to months. Mortality, foraging activity, brood development, behavior, and residues in pollen, nectar, and bee matrices (honey, bee bread, wax) may all be recorded or measured. Eight full field studies have been conducted to date for multiple cyantraniliprole formulations in multiple crops. Here is an example from one such study with Cyantraniliprole OD conducted in canola. There was one treatment, T1 was applied at a rate of 90 g active ingredient/ha in the evening after bees had returned to the hive for the night. A reference compound was applied as a positive control, and water was sprayed as a negative control. Cyantraniliprole was sprayed twice, once before the plants had flowered and the second time while the plants were blooming and bees were present (second spray marked by an arrow below). Colonies were observed through the winter to assess overwintering success.
In this study there was no negative impact in treatment group T1 on flight activity. There was no negative impact in treatment group T1 on mortality. No short-term or long-term effects were observed for the honey bee colonies and their brood development throughout the whole season until start of over-wintering in October in T1 at which point brood observations were halted for the winter. In T1 in early spring (after over-wintering) the colonies were in good overall condition to support further growth in ongoing season.
Conclusions The studies presented on this poster are a small selection of the >50 bee studies completed to date for the cyantraniliprole data package. Overall, it was found that the intended uses of DuPont cyantraniliprole products, according to good agricultural practice, pose no unacceptable risks for pollinators. Any potential issues may be mitigated by the label statements to only apply cyantraniliprole products when bees are not actively foraging. DuPont‘s experiences with the cyantraniliprole product registrations is informing our future planning needs for new active ingredients and the types and amounts of pollinator testing that should be conducted for demonstrating pollinator safety and good product stewardship.
References Cordova, D., Benner, E.A., Sacher, M.D., Rauh, J.J., Sopa, J.S., Lahm, G.P., Selby, T.P., Stevenson, T.M., Flexner, L., Gutteridge, S., Rhoades, D.F., Wu, L., Smith, R.M. & Tao, Y. 2006. Anthranilic diamides: A new class of insecticides with a novel mode of action, ryanodine receptor activation. Pesticide Biochemistry and Physiology, 84, 196-214.
