Pollinator Protection

Residual Time to 25% Bee Mortality (RT25) Data

On this page:

RT25 Data: What They are and Where They Come From

The residual time to 25% mortality (referred to as the RT25) values provided in the table below were compiled from registrant-submitted data submitted in order to fulfill the data requirement for Honey Bee (Apis mellifera) Toxicity of Residues on Foliage study (OCSPP Guideline 850.3030a). This study may be conditionally required if the honey bee acute contact (or oral) median lethal dose (LD50) value (obtained from a honey bee acute toxicity test such as OCSPP Guideline 850.3020b) is less than 11 µg/bee1.

The honey bee toxicity of residues on foliage study is a laboratory test designed to determine the length of time over which field weathered foliar residues remain toxic to honey bees, or other species of terrestrial insects. The test substance (e.g., a representative end-use product) is applied to crop foliage, the foliage is harvested at predetermined post-application intervals (i.e., aged residues), and test adult bees are confined on foliage with aged residues for 24 hours. Three treatment intervals (different durations of time that residues are aged between application and harvest) are typically used (e.g., 3, 8 and 24 hours post-application). At a minimum, the test substance should be evaluated at the maximum application rate specified on the product label. If mortality of bees exposed to the foliage harvested 24 hours after the application is greater than 25%, bees should continue to be exposed to aged residues on foliage samples collected every 24 hours (i.e., 48, 72, 96, 120 hours, etc. after the application) until mortality is 25% or less.

About the RT25 Data Table

The table below represents all available RT25 values from studies submitted to the Agency which have undergone quality assurance reviews to ensure that the data are scientifically sound. Depending on the chemical tested, either the technical grade active ingredient or a specific formulation was tested using either the honey bee, alfalfa leaf cutting bee, or alkali bee; the table lists the test material and species tested. The table also denotes the plant species on which residues were aged.

RT25 values are a function of a number of factors including application rate, physical-chemical properties, dissipation, crop, and pesticide formulation. Thus, there is considerable variability in RT25 values within a single formulation, between formulations, between crops, and across application rates.  The values included in the database are chemical and formulation specific. There are limited RT25 values available in the table below for the numerous pesticide/formulation/use combinations. This table shows all the data submitted to the Agency that meets the EPA’s quality assurance criteria. EPA plans to update this table as a more robust data set becomes available. 

OPP Residual Time to 25% Mortality (RT25)

Active Ingredient

Formulation 2
(% a.i.)

Application Rate
 

Crop 3

Qualifier4

RT255
(hours)

Test Species Name 6
Common
(Scientific)

Abamectin (avermectin)

L 676,

863-28W02

0.0016 lb a.i./tree

citrus

--

60

Honey bee
(Apis mellifera)

0.0008 lb a.i./tree

--

41.5

0.0008 lb a.i./tree

--

30

0.0003 lb a.i./tree

8

0.1 lb a.i./A

seed alfalfa

48

0.05 lb a.i./A

--

15

0.025 lb a.i./A

8

0.0125 lb a.i./A

4

Amitraz

BTS 27419

EC (20)

0.033 lb a.i./gal

apple trees

--

0

Honey bee
(Apis mellifera)

Azinphos-methyl

Guthion® 50

WP (50)

3 lb a.i./A

alfalfa

312

Honey bee
(Apis mellifera)

Bifenazate

Acramite®

50WS (48.8)

0.733 lb a.i./A

alfalfa

3

Honey bee
(Apis mellifera)

Carbaryl

80WP (80)

2 lb a.i./A

white clover

42

Honey bee
(Apis mellifera)

1 lb a.i./A

42

0.5 lb a.i./A

42

0.25 lb a.i./A

42

Chlorantraniliprole

35WG (35)

0.1 lb a.i./A

alfalfa

3

Honey bee
(Apis mellifera)

Chlorfenapyr

PIRATE® 3

SC (29.8)

0.34 lb a.i./A

alfalfa

3

Honey bee
(Apis mellifera)

Chlorpyrifos

Dursban® 4 lb EC

0.25 lb a.i./A

alfalfa

--

16

Honey bee
(Apis mellifera)

0.5 lb a.i./A

24

1 lb a.i./A

24

0.25 lb a.i./A

--

19

Alkali bee
(Nomia melanderi)

0.5 lb a.i./A

24

1 lb a.i./A

24

0.25 lb a.i./A

24

Alfalfa Leafcutting bee
(Megachile rotundata)

0.5 lb a.i./A

24

1 lb a.i./A

24

Clothianidin

V-10066 (49.8)

0.066 lb a.i./A

alfalfa

--

112

Honey bee
(Apis mellifera)

0.132 lb a.i./A

--

179

0.198 lb a.i./A

--

512

Cymoxanil

Cymoxanil/

Famoxadone

50WG (25/25)

0.1875 lb a.i./A

alfalfa

1

Honey bee
(Apis mellifera)

Cypermethrin

Cymbush®

3E (35.6)

0.06 lb a.i./A

oilseed rape

96

Honey bee
(Apis mellifera)

0.14 lb a.i./A

96

Deltamethrin

Decis® EC (20)

0.02 lb a.i./A

alfalfa

--

5.2

Honey bee
(Apis mellifera)

Diazinon

40 WP (40)

1 lb a.i./A

white clover

42

Honey bee
(Apis mellifera)

0.5 lb a.i./A

42

0.25 lb a.i./A

42

0.125 lb a.i./A

42

Dichlorvos

50 EC (50)

0.31 lb a.i./A

white clover

3

Honey bee
(Apis mellifera)

0.155 lb a.i./A

3

0.077 lb a.i./A

3

0.039 lb a.i./A

3

0.019 lb a.i./A

3

DDVP 4E (42.39)

0.5 lb a.i./A

alfalfa

3

Honey bee
(Apis mellifera)

Dicrotophos

9 lb EC

0.5 lb a.i./A

alfalfa

48

Honey bee
(Apis mellifera)

0.5 lb a.i./A

48

Alfalfa Leafcutting bee
(Megachile rotundata)

0.5 lb a.i./A

48

Alkali bee
(Nomia melanderi)

Dimethoate

2.67 lb EC

0.5 lb a.i./A

alfalfa

120

Honey bee
(Apis mellifera)

0.5 lb a.i./A

120

Alfalfa Leafcutting bee
(Megachile rotundata)

0.5 lb a.i./A

72

Alkali bee
(Nomia melanderi)

Dinotefuran

MTI-446 20 SG

0.134 lb a.i./A

alfalfa

--

39

Honey bee
(Apis mellifera)

Disulfoton

Di-System®

8 EC

1 lb a.i./A

alfalfa

--

5.5

Honey bee
(Apis mellifera)

D-phenothrin

Multicide®

2798 D-phenothrin/

Prallethrin/

PBO (5/1/5)

0.0008 lbs a.i./A prallethrin;
0.0036 lb a.i./A d-phenothrin;
and 0.0038 lbs a.i./A PBO

alfalfa

3

Honey bee
(Apis mellifera)

Emamectin benzoate

MK-244

(TGAI, 97.5)

0.015 lb a.i./A

alfalfa

--

11

Honey bee
(Apis mellifera)

Endosulfan

35 EC (35)

0.77 lb a.i./A

clover blossoms

3

Honey bee
(Apis mellifera)

Etofenprox

RF2056 OL (20)

0.007 lb a.i./A

alfalfa

3

Honey bee
(Apis mellifera)

Famoxadone

Cymoxanil/

Famoxadone

50WG (1:1)

(25/25)

0.1875 lb a.i./A

alfalfa

1

Honey bee
(Apis mellifera)

Fenazaquin

GWN-1708 (18.53)

0.45 lb a.i./A

alfalfa

3

Honey bee
(Apis mellifera)

Fenbutatin oxide

SD 14114

50WP (50)

1.75 lb a.i./A

cherry limbs

3

Honey bee
(Apis mellifera)

0.4375 lb a.i./A

3

Fenitrothion

Sumithion®

8 EC

0.5 lb a.i./A

alfalfa

24

Honey bee
(Apis mellifera)

1 lb a.i./A

--

101

0.5 lb a.i./A

--

106

Alfalfa Leafcutting bee
(Megachile rotundata)

1 lb a.i./A

120

0.5 lb a.i./A

--

98

Alkali bee
(Nomia melanderi)

1 lb a.i./A

120

Fenpropathrin

Danitol® 2.4 EC

0.1 lb a.i./200 gal/A

Valencia Orange trees

192

Honey bee
(Apis mellifera)

0.2 lb a.i./200 gal/A

--

276

0.4 lb a.i./200 gal/A

336

Fenvalerate

Pydrin®

2.4 lb/gal EC

0.1 lb a.i./A

alfalfa

--

7

Honey bee
(Apis mellifera)

0.4 lb a.i./A

8

0.4 lb a.i./A

alfalfa

8

Honey bee
(Apis mellifera)

0.1 lb a.i./A

--

7

0.4 lb a.i./A

8

Alkali bee
(Nomia melanderi)

0.1 lb a.i./A

--

7

0.4 lb a.i./A

8

Alfalfa Leafcutting bee
(Megachile pacifica)

0.1 lb a.i./A

8

Flutolanil

Moncut® Dry

Flowable (65)

0.327 lb a.i./A

rapeseed

--

0

Honey bee
(Apis mellifera)

Fonofos

EC

2 lb a.i./A

alfalfa

8

Honey bee
(Apis mellifera)

1 lb a.i./A

3

Gamma cyhalothrin

XR-225.

GF-231 (14.7)

0.015 lb a.i./A

alfalfa

24

Honey bee
(Apis mellifera)

Imidacloprid

NTN 33893

240FS

0.1 lb a.i./A

alfalfa

2

Honey bee
(Apis mellifera)

0.1 lb a.i./A

2

Alfalfa Leafcutting bee
(Megachile rotundata)

0.1 lb a.i./A

8

Alkali bee
(Nomia melanderi)

0.5 lb a.i./A

alfalfa

--

8

Honey bee
(Apis mellifera)

0.167 lb a.i./A

2

0.045 lb a.i./A

2

Indoxacarb

30WG (30.7)

0.15 lb a.i./A

alfalfa

--

24

Honey bee
(Apis mellifera)

Lambda-Cyhalothrin

EC

0.013 lb a.i./A

alfalfa

--

22

Honey bee
(Apis mellifera)

0.031 lb a.i./A

--

54

Lindane

20 EC (20)

1.5 lb a.i./A

alfalfa

--

72

Honey bee
(Apis mellifera)

1 lb a.i./A

--

72

0.5 lb a.i./A

--

24

25WP (25)

1.5 lb a.i./A

--

72

1 lb a.i./A

--

72

0.5 lb a.i./A

--

24

40 F (40)

1.5 lb a.i./A

--

72

1 lb a.i./A

--

72

0.5 lb a.i./A

--

24

Malathion

57 EC (57)

1.6 lb a.i./A

alfalfa

24

Honey bee
(Apis mellifera)

Methidathion

Supracide®

2E (25.2)

5 lb a.i./A

alfalfa

--

114

Honey bee
(Apis mellifera)

Methyl parathion

450g/L CS

0.4 lb a.i./A

alfalfa

--

207

Honey bee
(Apis mellifera)

0.4 lb a.i./A

--

171

Mevinphos

SC (89.5)

0.81 lb a.i./A

alfalfa

4

Honey bee
(Apis mellifera)

Oxamyl

Vydate® L (24)

1 lb a.i./A

alfalfa

144

Honey bee
(Apis mellifera)

24L (24)

1 lb a.i./A

alfalfa

--

22

Honey bee
(Apis mellifera)

2 lb a.i./A

--

75

Parathion

4 lb E

0.5 lb a.i./A

clover

24

Honey bee
(Apis mellifera)

Phosalone

3 lb EC (NA)

1.5 lb a.i./A

alfalfa

3

Alkali bee
(Nomia melanderi)

1.5 lb a.i./A

3

Alfalfa Leafcutting bee
(Megachile rotundata)

Phosmet

50W (50)

0.5 lb a.i./A

alfalfa

--

51

Honey bee
(Apis mellifera)

1 lb a.i./A

24

50WP (50)

1 lb a.i./A

alfalfa

3

Honey bee
(Apis mellifera)

1 lb a.i./A

3

Alfalfa Leafcutting bee
(Megachile rotundata)

1 lb a.i./A

3

Alkali bee
(Nomia melanderi)

Piperonyl butoxide

Multicide®

2798 D-phenothrin/

Prallethrin/

PBO (5/1/5)

0.0008 lbs a.i./A prallethrin; 0.0036 lb a.i./A d-phenothrin; and 0.0038 lbs a.i./A PBO

alfalfa

3

Honey bee
(Apis mellifera)

Scourge®

[Piperonyl butoxide/

Resmethrin mixture] (46/18)

0.007 lb a.i./A

alfalfa

3

Honey bee
(Apis mellifera)

Prallethrin

LX119-04

(ETOC) L (2.45)

0.005 lb a.i./A

alfalfa

8

Honey bee
(Apis mellifera)

Multicide®

2798 D-phenothrin/

Prallethrin/PBO

(5/1/5)

0.0008 lbs a.i./A prallethrin; 0.0036 lb a.i./A d-phenothrin; and 0.0038 lbs a.i./A PBO

alfalfa

3

Honey bee
(Apis mellifera)

Propoxur

50WP (50)

0.75 lb a.i./A

alfalfa

5

Honey bee
(Apis mellifera)

Pyridaben

BAS 300

WP (76.8)

0.5 lb a.i./A

alfalfa

--

20

Honey bee
(Apis mellifera)

Resmethrin

Scourge®

[Piperonyl butoxide/

Resmethrin

mixture] (46/18)

0.007 lb a.i./A

alfalfa

3

Honey bee
(Apis mellifera)

Spinetoram

GF-1640 (24.7)

0.109 lb a.i./A

alfalfa

3

Honey bee
(Apis mellifera)

Spinosad

NAF-315 (23.5)

0.16 lb a.i./A

alfalfa

3

Honey bee
(Apis mellifera)

0.16 lb a.i./A

alfalfa

3

Honey bee
(Apis mellifera)

Spiroxamine

KWG 4168

300CS (32.4)

0.54 lb a.i./A

alfalfa

2

Honey bee
(Apis mellifera)

Thiacloprid

YRC 2894

(41.9)

0.16 lb a.i./A

alfalfa

2

Honey bee
(Apis mellifera)

Thiamethoxam

CGA-293343

(25.5)

0.004 lb a.i./A

alfalfa

24

Honey bee
(Apis mellifera)

0.088 lb a.i./A

72

Tralomethrin

HAG-107

0.3 lb EC

0.015 lb a.i./A

alfalfa

0.5

Honey bee
(Apis mellifera)

Footnotes

1 U.S. CFR 40 Part 158 Subpart G §158.630, Test Note no. 24: Data are required only when the formulation contains one or more active ingredients having an acute LD50 of <11 micrograms per bee as determined in the honey bee acute contact study  [OCSPP 850.3020] and the use pattern(s) indicate(s) that honey bees may be exposed to the pesticide.

2 End use product tested. % active ingredient (a.i.) is provided where available. Product names where specified are listed; otherwise, product codes are listed

3 Agricultural commodity used in study.

4 Less than (<) value indicates that there was less than 25% mortality at the shortest aged foliage tested; greater than (>) value indicates that there was greater than 25% mortality at the longest aged residue tested; equal value (--) indicates that 25% mortality was reported at the time documented in the next column.

5 Residual Time to 25% mortality. This is the length of time post-application that residues of the test substance on foliage are toxic to 25% of honey bees tested.

6 Species tested in the submitted study. Apis mellifera (honey bee); Aphidius rhopalosiphi (parasitic wasp); Aphytis lignanensis (parasitic wasp); Aphytis melinus (parasitic wasp); Chrysoperla carnea (green lacewing); Copidosoma truncatellus (parasitic wasp); Diglyphus intermedius (parasitic wasp); Megachile pacifica (Alfalfa leafcutting bee); Megachile rotundata (Alfalfa leafcutting bee); Metaphycus luteolus (parasitic wasp); Nomia melanderi (alkali bee); Opius bruneipus (parasitic wasp); Stethorus punctum (ladybird beetle); Telenomus remus (parasitic wasp); Typhlodromus pyri (predatory mite).

Definitions

a.i. = active ingredient

CS = capsule suspension

E = emulsifiable

EC = emulsifiable concentrate

F = flowable

L = liquid

OL = liquid formulation

RT25 = residual time to 25% mortality

SC = soluble concentrate

SG = soluble granule

TGAI = technical grade active ingredient

W = wettable powder

WDG = water dispersible granular

WG = wettable granule

WP = wettable powder

WS = water soluble

Other letter/number combinations specified in the formulation column of the table refer to product codes and are not defined.

References

aUSEPA. 2012. Ecological Effects Test Guidelines: OCSPP 850.3030: Honey Bee Toxicity of Residues on Foliage. United States Environmental Protection Agency, Office of Chemical Safety and Pollution Prevention, EPA 712-C-018. January 2012. http://www.epa.gov/ocspp/pubs/frs/home/guidelin.htm

bUSEPA. 2012. Ecological Effects Test Guidelines: OCSPP 850.3020: Honey Bee Acute Contact Toxicity Test. United States Environmental Protection Agency, Office of Chemical Safety and Pollution Prevention, EPA 712-C-019. January 2012. http://www.epa.gov/ocspp/pubs/frs/home/guidelin.htm