pymetrozine (ISO); (E)-4,5-dihydro-6-methyl-4-(3-pyridylmethyleneamino)-1,2,4-triazin-3(2H)-one

Toxicity to terrestrial arthropods

Link to relevant study record(s)

Reference

Reference 1

Endpoint:

toxicity to terrestrial arthropods: short-term

Type of information:

experimental study

Adequacy of study:

supporting study

Study period:

20 Sep 1990 to 23 Sep 1990

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

comparable to guideline study with acceptable restrictions

Qualifier:

according to guideline

Guideline:

other: Environmental Protection Agency (EPA) Pesticide Assessment Guidelines, Subdivision L, Hazard Evaluation Nontarget Insect.

Deviations:

no

Qualifier:

according to guideline

Guideline:

other: Pesticides Safety Precautions Scheme, Working Document 03, issued by the United Kingdom, 1979

Deviations:

no

GLP compliance:

yes

Test organisms (species):

Apis mellifera

Animal group:

Hymenoptera (honeybees)

Study type:

laboratory study

Duration:

48 h

Dose descriptor:

LD50

Remarks:

oral

Effect conc.:

> 100 µg per animal

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

mortality

Duration:

48 h

Dose descriptor:

LD50

Remarks:

contact

Effect conc.:

> 100 µg per animal

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

mortality

Preliminary dose range-finding tests indicated that the test item had a low toxicity to bees, with an LD50 > 100/µg per bee by both contact and oral application. This was confirmed in a final test using 10 groups of 10 bees all dosed at 100/µg per bee and therefore the test substance would not represent a hazard to bees.

 

Mortality of bees after oral and contact treatment with the test substance

Group	oral		contact
Treated	24h	48h	24h	48h
1	0	2	0	2
2	4	4	0	0
3	5	8	0	2
4	3	3	0	1
5	1	1	0	3
6	2	2	0	0
7	0	1	3	3
8	3	5	0	0
9	0	4	4	4
10	0	0	0	1
	18%	30%	7%	16%
Controls
1	3	4	0	1
2	0	0	2	3
3	0	0	0	0
4	0	0	2	2
5	0	0	0	0
6	1	1	0	0
7	0	0	0	0
8	0	2	0	1
9	0	0	1	1
10	0	0	3	3
	4%	7%	8%	11%

 

Validity criteria fulfilled:

yes

Conclusions:

The test item had a low toxicity to bees, with an LD50 > 100/µg per bee by both contact and oral application.Therefore the test substance would not represent a hazard to bees.

Executive summary:

This study was conducted to determine the toxicity to honey bees of the test item according to the United Kingdom Pesticide Safety Precautions Scheme protocol. Preliminary dose range-finding tests indicated that the test item had a low toxicity to bees (Apis mellifera), with an LD50 greater than 100/µg per bee by both contact and oral application. Therefore the final test was at 100/µg per bee only. 10 groups of 10 bees and 10 control groups were used for the oral test and the same for the contact test.

Dose administration in contact toxicity test:One cage of bees at a time were lightlyanaesthetised with carbon dioxide and a 2/µL droplet of the appropriate dilutionof test material was placed on the ventral surface of the thorax of each bee using a microapplicator (Burkard) and a micrometer syringe. The bees were then replaced in the cage. Control groups were treated with a 2/µL droplet of dimethylformamide only.

Dose administration in oral toxicity test:The appropriate concentration was administered as a single dose of 0.2 mL to each group of 10 bees in a cage. The dose was introduced with a syringe into the feeder place. The bees are known to share the 0.2 mL among themselves and so would have received similar amounts of 20/µL each. When the bees had taken all the test solution after 4 hours the bees were fed with honey again during the test.

Observations: The final test mortalities were recorded after 24 and 48 hours.

Results: Preliminary dose range-finding tests indicated that the test item had a low toxicity to bees, with an LD50 > 100/µg per bee by both contact and oral application.This was confirmed in a final test using 10 groups of 10 bees all dosed at 100/µg per bee and therefore the test substance would not represent a hazard to bees.

Reference 2

Endpoint:

toxicity to terrestrial arthropods: short-term

Type of information:

experimental study

Adequacy of study:

supporting study

Study period:

10 Jul 2001 to 14 Jul 2001

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

other: EPPO Guideline No. 170

Version / remarks:

1992

Deviations:

no

GLP compliance:

yes

Test organisms (species):

Apis mellifera

Study type:

laboratory study

Duration:

96 h

Dose descriptor:

LD50

Remarks:

oral

Effect conc.:

> 62.71 µg per animal

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

mortality

Remarks on result:

other: organism: bees (Apis mellifera L.)

Duration:

96 h

Dose descriptor:

LD50

Remarks:

contact

Effect conc.:

> 100 µg per animal

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

mortality

Remarks on result:

other: organism: bees (Apis mellifera L.)

Oral toxicity test:

In the control group fed with pure sugar solution a mortality of 7.5 % was observed 96 h after treatment application. Bees in the control group fed with sugar solution mixed with acetone showed a mortality of 10 % 96h after treatment application. In the toxic standard treatment a corrected mortality of 86.5 % was observed 96h after application. The maximum corrected bee mortality in the tested dose range from 0.01 to 62.71 μg/bee of the test substance observed 96h after treatment application was 8.3 %. The oral LD50/96h of the test item was determined as> 62.71μg/bee. Bees which showed abnormal behaviours 24h after treatment application in the 0.01 and 0.12 μg /bee treatment levels (32.5 % and 77 .5 % of the bees were affected in the respective treatment levels), did recover within 72h after treatment application. Bees which showed abnormal behaviours 24h after treatment application in the 1.01 μg /bee treatment level (90 % of the bees were affected), only partially recovered until test termination (57.5 % of the bees were healthy 96 h after treatment application). Most of the bees which showed abnormal behaviours 24h after treatment application in the 8.77 and 62.71 μg/bee treatment level (90 % of the bees were affected in both treatments), did not recover until test termination (30 % and 10 % of the bees were healthy in the respective treatments 96h after treatment application). Oral treatment of the test item at a dose of 0.01 μg/bee did not affect food consumption of the bees during the 96h observation period. A reduction in feeding rate was observed after oral feeding at higher doses of the test item tested: 16.50 %, 47.40 %, 45.91 % and 48.67 % lower feeding rates were observed during the 96h observation period in the treatment level 0.12, 1.01, 8.77 and 62.71 μg/bee, respectively when compared to control.

Contact toxicity test:

In the water treated control group a mortality of 2.5 % was observed 96 h after treatment application. Bees in the acetone treated control group showed a mortality of 12.5 %, 96h after treatment application. In the toxic standard treatment a corrected mortality of 79.5 % was observed 96h after application. The maximum corrected bee mortality in the tested test item dose range of 0.01 to 100 μg/bee was 11 .4 % observed 96h after treatment application. The contact LD50 (96h) of the test item was determined as >100 μg/bee. Bees which showed abnormal behaviours 24h after treatment application in the 0.01 and 0.10 μg /bee treatment levels (30 % and 95 % of the bees were affected in the respective treatment levels), did recover within 96h after treatment application. Bees which showed abnormal behaviours 24h after treatment application in the 1 and 10 μg a.i./bee treatment level (90 % and 95 % of the bees were affected in the respective treatment levels), only partially recovered until test termination (62.5 % and 45.0 % of the bees were healthy 96h after treatment application). Most of the surviving bees, which showed abnormal behaviours 24h after treatment application in the 100 μg /bee treatment level (87.5 % of the bees were affected), did not recover until test termination (5 % of the bees were healthy 96h after treatment application). Contact treatment of the test item at doses of 0.01 and 0.1 μg /bee did not affect negatively food consumption of the bees during the 96h observation period. A reduction in feeding rate was observed after contact treatment at higher doses of the test item tested. 30.60 %, 44.40 % and 39.13 % lower feeding rate was observed during the 96h observation period in the treatment level 1, 10 and 100μg /bee, respectively when compared to control.

Conclusions

The 96 hour contact and oral LD50 values for the test substance are >100 μg as/bee and >62.71 μg as/bee respectively. However, the test material caused sub-lethal effects in the form of abnormal behaviour, which lasted until the end of the tests at the higher dose rates. An antifeedant effect was also observed at oral dose rates of 0.12 mg as/bee and above and contact dose rates of 1.00 mg as/bee and above.

Validity criteria fulfilled:

yes

Conclusions:

The 96 hour contact and oral LD50 values for the test substance are >100 μg as/bee and >62.71 μg as/bee respectively. However, the test material caused sub-lethal effects in the form of abnormal behaviour, which lasted until the end of the tests at the higher dose rates. An antifeedant effect was also observed at oral dose rates of 0.12 μg as/bee and above and contact dose rates of 1.00 g as/bee and above.

Executive summary:

The oral and contact toxicity of the test item to the honey bee (Apis melliferaL.) was determined in a dose-response test according to the EPPO Guideline No. 170 (EPPO, 1992). The test was conducted under GLP compliance. Mortality, behaviour and food consumption were the endpoints considered over a 96h observation period. In the laboratory, the bees were exposed to the following doses of the test substance: 100.0, 10.0, 1.00, 0.10 and 0.01 mg as/bee (Contact test) and 100.0, 10.0, 1.00, 0.10 and 0.01 mg as/bee (Oral test).

Oral Toxicity Test: Feeding solution, which is consisted of the test substance dissolved in acetone and mixed with a 50% aqueous sucrose solution, was offered, as a quantity of 250 μL, for 6 hours to each cage of 10 bees to ensure a sufficient intake of test substance. The bees in one cage shared the test solution and so received similar doses. After the test substance was taken up, the bees in the test cages were supplied ad libitum with a 50 % aqueous sucrose solution without the test item.The amount of test item solution consumed for each replicate (mean value of 10 bees) was determined by weighing the feeders before and after feeding.

Contact toxicity test: After the bees had been anaesthetised with carbon dioxide they were treated individually by topical application with a microapplicator. 2 μL of test substance or toxic standard solution were applied to the ventral side of the thorax of each bee. After application the bees were returned to the test cages and fed with a 50 % aqueous sucrose solution ad libitum.

The number of dead bees and sublethal effects on the bees in the individual test cages were observed after 3 h, 6 h, 24 h, 48 h, 72 hand 96 h.The food consumption was assessed by weighing the syringes containing the 50 % sucrose solution before and after feeding every 24 hours. The intake per bee was calculated by dividing the amount of sucrose solution consumed per replicate (test cage) by the number of living bees at the time of assessment. The syringes were refilled with sucrose solution after 48 hours.

In the control group fed with pure sugar solution a mortality of 7.5 % was observed 96 h after treatment application. Bees in the control group fed with sugar solution mixed with acetone showed a mortality of 10 % 96h after treatment application. In the toxic standard treatment a corrected mortality of 86.5 % was observed 96h after application.The maximum corrected bee mortality in the tested dose range from 0.01 to 62.71μg/bee of the test substance observed 96h after treatment application was 8.3 %. The oral LD50/96h of the test item was determined as> 62.71μg/bee. Bees which showed abnormal behaviours 24h after treatment application in the 0.01 and 0.12μg /bee treatment levels (32.5 % and 77 .5 % of the bees were affected in the respective treatment levels), did recover within 72h after treatment application. Bees which showed abnormal behaviours 24h after treatment application in the 1.01 μg /bee treatment level (90 % of the bees were affected), only partially recovered until test termination (57.5 % of the bees were healthy 96 h after treatment application). Most of the bees which showed abnormal behaviours 24h after treatment application in the 8.77 and 62.71 μg/bee treatment level (90 % of the bees were affected in both treatments), did not recover until test termination (30 % and 10 % of the bees were healthy in the respective treatments 96h after treatment application). Oral treatment of the test item at a dose of 0.01 μg/bee did not affect food consumption of the bees during the 96h observation period. A reduction in feeding rate was observed after oral feeding at higher doses of the test item tested: 16.50 %, 47.40 %, 45.91 % and 48.67 % lower feeding rates were observed during the 96h observation period in the treatment level 0.12, 1.01, 8.77 and 62.71 μg/bee, respectively when compared to control.

In the water treated control group a mortality of 2.5 % was observed 96 h after treatment application. Bees in the acetone treated control group showed a mortality of 12.5 %, 96h after treatment application. In the toxic standard treatment a corrected mortality of 79.5 % was observed 96h after application. The maximum corrected bee mortality in the tested test item dose range of 0.01 to 100 μg/bee was 11 .4 % observed 96h after treatment application. The contact LD50 (96h) of the test item was determined as >100 μg/bee. Bees which showed abnormal behaviours 24h after treatment application in the 0.01 and 0.10 μg /bee treatment levels (30 % and 95 % of the bees were affected in the respective treatment levels), did recover within 96h after treatment application. Bees which showed abnormal behaviours 24h after treatment application in the 1 and 10 μg a.i./bee treatment level (90 % and 95 % of the bees were affected in the respective treatment levels), only partially recovered until test termination (62.5 % and 45.0 % of the bees were healthy 96h after treatment application). Most of the surviving bees, which showed abnormal behaviours 24h after treatment application in the 100 μg /bee treatment level (87.5 % of the bees were affected), did not recover until test termination (5 % of the bees were healthy 96h after treatment application). Contact treatment of the test item at doses of 0.01 and 0.1μg /bee did not affect negatively food consumption of the bees during the 96h observation period. A reduction in feeding rate was observed after contact treatment at higher doses of the test item tested. 30.60 %, 44.40 % and 39.13 % lower feeding rate was observed during the 96h observation period in the treatment level 1, 10 and 100μg /bee, respectively when compared to control.

The 96 hour contact and oral LD50 values for the test substance are >100 μg as/bee and >62.71 μg as/bee respectively. However, the test material caused sub-lethal effects in the form of abnormal behaviour, which lasted until the end of the tests at the higher dose rates. An antifeedant effect was also observed at oral dose rates of 0.12 mg as/bee and above and contact dose rates of 1.00 mg as/bee and above.

Reference 3

Endpoint:

toxicity to terrestrial arthropods: short-term

Type of information:

experimental study

Adequacy of study:

supporting study

Study period:

22 Sep 1992 to 24 Sep 1992

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

other: Laboratory Testing for Toxicity to Honey Bees. Working Document 7/3; MAFF, UK - Data Requirements for Approval under the Control of Pesticides Regulations

Version / remarks:

Oct. 1986.

Deviations:

no

GLP compliance:

yes

Test organisms (species):

Apis mellifera

Animal group:

Hymenoptera (honeybees)

Study type:

laboratory study

Duration:

48 h

Dose descriptor:

LD50

Effect conc.:

> 200 µg per animal

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

mortality

Remarks on result:

other: contact toxicity

Duration:

48 h

Dose descriptor:

LD50

Effect conc.:

> 117 µg per animal

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

mortality

Remarks on result:

other: oral toxicity

Behavioural Records:

Inter-group comparison of bees after contact application did not reveal any changes in behaviour. At 1 hour after the beginning of oral dosing, the findings of uncoordinated movements and/or lateral/dorsal position were observed in treated bees at each dose level. These findings were only transient, as all bees were free from behavioural abnormalities by 24 hours after the beginning of dosing.

 

Mortality:

There was only one bee which died at 1 hour after application start and this was from the 117- μg/bee oral dose group.

 

As there was no mortality above 20% at any dose level, the legit estimation was unnecessary. Based on these observations, the LD50 values of the test item to honey bees were > 200 μg/bee for contact toxicity and > 117 μg/bee for oral toxicity.

Validity criteria fulfilled:

yes

Conclusions:

As there was no mortality above 20% at any dose level, the legit estimation was unnecessary. Based on these observations, the LD50 values of the test substance to honey bees were > 200 μg/bee for contact toxicity and > 117 μg/bee for oral toxicity.

Executive summary:

In this GLP-compliant laboratory study the acute contact and oral toxicities of the test item to worker honey bees were examined. For contact toxicity testing, 1 µL of the assigned test article dilution was placed onto the ventral thorax of each bee, using acetone as a vehicle. For oral toxicity testing, the test item was diluted in acetone and then diluted further at 1:20 (w/v) with undiluted “Apiinvert” syrup. Groups of 10 bees were fed with the assigned test article dilution from 2-mL disposable plastic syringes for 2 hours. Each syringe was initially filled with 250 µL of the assigned test article dilution (i.e. 25 µL/bee) and the amount of uptake of treated food determined by re-weighing the syringes after use. Control bees were always treated accordingly using the vehicle only. The dosing was 0, 5, 10, 50, 100, 200 (µg test item / bee) (contact test – 20 bees per group) and 0, 4, 9, 55, 54, 117 (µg test item / bee) (oral test – 10 bees per group). Per dose level 20 naive worker bees were anaesthetized with carbon dioxide before applying the test chemical. The anaesthetized bees were laid, ventral surface up, on filter-paper in a petri dish and 1.0µLdrops of the test article dilution placed on the ventral thorax using a micro-applicator. The treated bees were returned to the cages and kept for 48 hours. Control bees were treated accordingly using the vehicle (acetone) only. Groups of 10 naive worker bees were deprived of their usual food and fed with the assigned test article dilution. A disposable 2-mL plastic syringe containing 250µLtest article dilution was weighed and then inserted into each bee cage through the top cork. The amount of uptake of test article dilution was determined by re-weighing the syringes, when the bees had taken most of the material (i.e. after 2 hours). Control treatments, given the solvent/ “Apiinvert” mixture only, were included. The 10 bees per group shared the test material preparation between themselves and so received similar doses. After dosing, i.e. after about 2 hours, they were given unlimited “Apiinver” syrup as in the contact toxicity tests.

Behavioural Records: Inter-group comparison of bees after contact application did not reveal any changes in behaviour. At 1 hour after the beginning of oral dosing, the findings of uncoordinated movements and/or lateral/dorsal position were observed in treated bees at each dose level. These findings were only transient, as all bees were free from behavioural abnormalities by 24 hours after the beginning of dosing. Mortality: There was only one bee which died at 1 hour after application start and this was from the 117- μg/bee oral dose group. As there was no mortality above 20% at any dose level, the legit estimation was unnecessary. Based on these observations, the LD50 values of the test item to honey bees were > 200 μg/bee for contact toxicity and > 117 μg/bee for oral toxicity.

Description of key information

The toxicity to honeybees were determined in several studies:

The 96-h contact and oral LD50 values for the test substance are >100 μg as/bee and >62.71 μg as/bee, respectively. Sublethal effects were observed. EPPO Guideline No. 170, Kling 2001

The 48-h contact and oral LD50 values for the test substance are both >100 μg as/bee. EPA Subdivision L, Hadhazy 1990

The 48-h contact and oral LD50 values for the test substance are > 200 μg/bee and > 117 μg/bee, respectively. WO 7/3, MAFF UK guideline, Decker 1993.

Information on this endpoint is not part of Annex VIII data requirements; all included studies are marked as supporting information and considered in the CSA.