OFFICE OF

CHEMICAL SAFETY AND

POLLUTION PREVENTION

UNITED STATES ENVIRONMENTAL PROTECTION AGENCY

WASHINGTON D.C., 20460

PC Code: 125501

DP Barcode: D423151

October 9, 2014

MEMORANDUM 

SUBJECT: Response to Request for Waiver of Honey Bee Larval Toxicity Testing for Clofentezine

FROM: Nicholas Mastrota, Wildlife Biologist

Environmental Risk Branch 3

Environmental Fate and Effect Division

Office of Pesticide Programs

THROUGH: Dana Spatz, Branch Chief 

Environmental Risk Branch 3

Environmental Fate and Effects Division (7507P)

TO: Kevin Costello, Branch Chief

Wilhelmena Livingston, Chemical Review Manager

Risk Management and Implementation Branch 4

Pesticide Re-Evaluation Division (7508P)

As part of the Clofentezine Proposed Interim Registration Review Decision (July 2014), EPA noted that 

the available toxicity data do not inform on the potential chronic risk to terrestrial insects, i.e.

pollinators, and as such, was noted as a data gap. In response, Irvita Plant Protection has submitted a 

request for the Agency to waive the requirement for additional honey bee toxicity testing, including 

honey bee larval testing, with clofentezine (MRID 49467600). To support their request, they also

submitted the following two nonguideline studies on the toxicity of Apollo 50 SC (42% clofentezine) to

insects:

 Apollo 50 SC: Evaluation of the Effect on the Rove Beetle Aleochara bilineata in an Extended 

Laboratory Study. (MRID 49467601)

 Apollo 50 SC: Toxicity to the Predatory Bug Orius laevigatus Fieber (Heteroptera, Anthocoridae) 

Using an Extended Laboratory Test including Assessment of Effects on Sprayed Eggs (Limit Test).

(MRID 49467602)

The EPA has conducted a cursory review of these studies. The studies appear to be scientifically sound 

and useful to inform on the toxicity of clofentezine to predatory bugs and beetles. We agree that these 
2

studies show that environmentally relevant exposure to clofentezine does not cause significant effects 

on the survival or reproduction of these two insect species. However, these studies do not provide 

adequate information for the EPA to assess the potential risk of bee brood effects from the use of 

clofentezine. To address this uncertainty, a chronic honey bee larval toxicity test is needed to conduct a 

tier 1 risk assessment (Guidance for Assessing Pesticide Risk to Bees, Environmental Fate and Effects 

Division, June 23, 2014).

The major shortcomings of the two submitted insect studies for addressing the uncertainty with 

potential effects to insect pollinators are described below:

1. One study (MRID 49467601) with a beetle (Order Coleoptera) and the other (MRID 49467602) is 

with a true bug (Order Heteroptera). Neither provide toxicity information on Order 

Hymenoptera, the order of insects which includes the vast majority of insect pollinators (bees, 

wasps, and ants).

2. Both studies expose the insects only one time; however, these studies do not inform on 

potential effects from chronic exposure, as would a study with repeated dosing.

3. Neither study provides a toxicity endpoint in terms of dose to the bee (microgram a.i./g 

bodyweight) and therefore cannot be used to calculate a tier-1 RQ for insect pollinators.

4. Both studies were conducted with an application rate of 200 g a.i./ha. This is less than the 

maximum registered application rate, 0.26 lb a.i./A, which is equivalent to 291 g a.i./ha.

5. One of the studies (Toxicity to the Predatory Bug, 49467602) measures only acute toxicity to 

eggs and to juvenile insects, but rather than toxicity to all of the early life-stages through the 

emergence of adult bees, as is recommended by the EFED guidance.

Because of these shortcomings with the submitted studies, EFED recommends that the requirement of

honeybee larvae toxicity testing with clofentezine not be waived at this time.