Pollinator Protection

Residual Time to 25% Bee Mortality (RT25) Data

On this page:

RT₂₅ Data: What They are and Where They Come From
About the RT₂₅ Data Table
OPP Residual Time to 25% Mortality (RT₂₅)
Footnotes
Definitions
References

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 850.3030^a). 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 850.3020^b) 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)
Cypermethrin	Cymbush^® 3E (35.6)	0.14 lb a.i./A	oilseed rape	>	96	Honey bee (Apis mellifera)
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)
Fenbutatin oxide	SD 14114 50WP (50)	0.4375 lb a.i./A	cherry limbs	<	3	Honey bee (Apis mellifera)
Fenitrothion	Sumithion^® 8 EC	0.5 lb a.i./A	alfalfa	<	24	Honey bee (Apis mellifera)
		1 lb a.i./A		--	101	Honey bee (Apis mellifera)
		0.5 lb a.i./A		--	106	Alfalfa Leafcutting bee (Megachile rotundata)
		1 lb a.i./A		>	120	Alfalfa Leafcutting bee (Megachile rotundata)
		0.5 lb a.i./A		--	98	Alkali bee (Nomia melanderi)
		1 lb a.i./A		>	120	Alkali bee (Nomia melanderi)
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	alfalfa	>	8	Honey bee (Apis mellifera)
		0.4 lb a.i./A	alfalfa	>	8	Honey bee (Apis mellifera)
		0.1 lb a.i./A		--	7	Honey bee (Apis mellifera)
		0.4 lb a.i./A		>	8	Alkali bee (Nomia melanderi)
		0.1 lb a.i./A		--	7	Alkali bee (Nomia melanderi)
		0.4 lb a.i./A		>	8	Alfalfa Leafcutting bee (Megachile pacifica)
		0.1 lb a.i./A		>	8	Alfalfa Leafcutting bee (Megachile pacifica)
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)
Fonofos	EC	1 lb a.i./A	alfalfa	<	3	Honey bee (Apis mellifera)
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)
Lambda-Cyhalothrin	EC	0.031 lb a.i./A	alfalfa	--	54	Honey bee (Apis mellifera)
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)
Methyl parathion	450g/L CS	0.4 lb a.i./A	alfalfa	--	171	Honey bee (Apis mellifera)
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)
	24L (24)	2 lb a.i./A	alfalfa	--	75	Honey bee (Apis mellifera)
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)
Phosalone	3 lb EC (NA)	1.5 lb a.i./A	alfalfa	<	3	Alfalfa Leafcutting bee (Megachile rotundata)
Phosmet	50W (50)	0.5 lb a.i./A	alfalfa	--	51	Honey bee (Apis mellifera)
	50W (50)	1 lb a.i./A	alfalfa	>	24	Honey bee (Apis mellifera)
	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)
Piperonyl butoxide	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)
Prallethrin	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)
Spinosad	NAF-315 (23.5)	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)
Thiamethoxam	CGA-293343 (25.5)	0.088 lb a.i./A	alfalfa	>	72	Honey bee (Apis mellifera)
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.

^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.