dinotefuran (ISO); 1-methyl-2-nitro-3-(tetrahydro-3-furylmethyl)guanidine

Toxicity to terrestrial plants

Link to relevant study record(s)

Reference

Endpoint:

toxicity to terrestrial plants: short-term (with study design considered suitable for long-term assessment)

Type of information:

experimental study

Adequacy of study:

key study

Study period:

27 April 2016 to 10 June 2016

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 208 (Terrestrial Plants Test: Seedling Emergence and Seedling Growth Test)

Deviations:

no

GLP compliance:

yes

Specific details on test material used for the study:

Batch number: K123D150
Purity: 99.86%
Description: solid/white
Expiration date: 01 July 2016
Stability: Verified by analytical determination of the highest test item concentration tested for all species

Analytical monitoring:

yes

Details on sampling:

- Concentrations: 953.81 mg dinotefuran/kg fresh soil and the untreated control soil were taken at the day of application.
- Sample storage conditions before analysis: The samples were stored deep frozen (≤-20 °C) until analysis was performed.

Vehicle:

no

Details on preparation and application of test substrate:

- Method of mixing into soil (if used): using an analytical balance. The test item was mixed with fine quartz sand by means of a blender for around 10 minutes. The test item treated fine quartz sand was mixed with the soil by using a laboratory mixer for approximately 10 minutes. The amount of quartz sand depended on the water content of the used soil and was identical in all test item treatment groups (48.4 g quartz sand per kg soil (dw)).
- Controls: For the control the same amount of untreated quartz sand was added to the soil. The soil for one treatment group was prepared in one to two batches and then split into the replicates.

Species:

Brassica napus

Plant group:

Dicotyledonae (dicots)

Details on test organisms:

- Common name: Oilseed rape
- Plant family: Brassicaceae
- Variety: Smart
- Source of seed: Syngenta Seeds

Species:

Glycine max (G. soja)

Plant group:

Dicotyledonae (dicots)

Details on test organisms:

- Common name: Soybean
- Plant family: Fabaceae
- Variety: Cardiff
- Source of seed: Saatzucht Donau

Species:

Helianthus annuus

Plant group:

Dicotyledonae (dicots)

Details on test organisms:

- Common name: Sunflower
- Plant family: Asteraceae
- Variety: Zohar F1
- Source of seed: Hild Samen GmbH

Species:

other: Solanum lycopersicum

Plant group:

Dicotyledonae (dicots)

Details on test organisms:

- Common name: Tomato
- Plant family: Solanaceae
- Variety: Diplom F1
- Source of seed: Hild Samen GmbH

Species:

Avena sativa

Plant group:

Monocotyledonae (monocots)

Details on test organisms:

- Common name: Oat
- Plant family: Poaceae
- Variety: IVORY
- Source of seed: NORDSAAT Saatzucht GmbH

Species:

Allium cepa

Plant group:

Monocotyledonae (monocots)

Details on test organisms:

- Common name: Garden onion
- Plant family: Amaryllidaceae (Liliaceae)
- Variety: Sturon
- Source of seed: Bingenheimer Saatgut AG

Test type:

seedling emergence and seedling growth test

Study type:

laboratory study

Substrate type:

natural soil

Limit test:

no

Total exposure duration:

21 d

Post exposure observation period:

The exposure time was 14 to 21 days after 50% germination in the control depending on the growth of the seedlings.

Justification for exposure duration:

Dependent on the growth of the seedlings.

Test temperature:

Exposure period 27 April 2016 to 28 April 2016: Mean 21.8 °C (16.3 °C to 25.3 °C)
Exposure period 28 April 2016 to 24 May 2016: Mean 21.5 °C (14.0 – 26.0 °C)

pH:

5.7 ± 0.6

Moisture:

A spot check on soil moisture was carried out daily. Bottom watering (through saucers) was done where necessary. Water was given in order to assure optimal water supply of the plants.

Details on test conditions:

TEST SYSTEM
- Testing facility: ibacon
- Test container (type, material, size): Commercial plastic flower pots (12 cm or 14 cm diameter)
- Amount of soil: 900 or 1200 g soil, respectively
- Method of seeding: manual introduction to soil
- No. of seeds per container: 5
- No. of replicates per treatment group: 6
- No. of replicates per control: 6

SOURCE AND PROPERTIES OF SUBSTRATE (if soil)
- Geographic location:
- Pesticide use history at the collection site: No pesticide treatments were performed in the year of sampling and for at least the two previous years.
- Soil Type: LUFA 2.3 (USDA: sandy loam) Particle Size: all particles ≤ 0.2 cm Corg: 0.67 ± 0.03% pH: 5.7 ± 0.6
- Soil taxonomic classification: sandy loam
- Soil classification system:
- Pretreatment of soil: The soil was steam sterilized.

GROWTH CONDITIONS
- Photoperiod: 16 h light : 8 h dark
- Light intensity and quality:
Exposure period 27 April 2016 to 28 April 2016 : Mean 200 µE/m²/s (131 – 294 µE/m²/s)
Exposure period 28 April 2016 to 24 May 2016 : Mean 265 µE/m²/s (170 – 369 µE/m²/s)
- Relative humidity (%):
Exposure period 27 April 2016 to 28 April 2016 : Mean 55 (47 – 85)
Exposure period 28 April 2016 to 24 May 2016 : Mean 71 (51 – 100)
- Watering regime and schedules: A spot check on soil moisture was carried out daily. Bottom watering (through saucers) was done where necessary. Water was given in order to assure optimal water supply of the plants.
- Method of application:
- Any fertilization: After development of the first true leaves, Ferty® 9 “Hydro” (Planta-Düngemittel GmbH) at 3 g/L and Terraflor®-AZ (Terraflor GmbH) at 0.4 g/L were added to the water up to three times a week, depending on the development of the plants.

ACCLIMATION PERIOD:

EFFECT PARAMETERS MEASURED (with observation intervals if applicable) :

- Phytotoxicity rating system (if used): Visual phytotoxicity (e.g. chlorosis, necrosis, abnormal growth) was recorded weekly according to EPPO Standard PP 1/135 (3) after 50% seedling emergence in the control.


TEST CONCENTRATIONS
- Spacing factor for test concentrations: 3
Range finding study
- Test concentrations: 1000, 100, 10, 1.0 and 0.1 mg dinotefuran/kg soil (dw).
- Results used to determine the conditions for the definitive study: Based on the results of the range finder the definitive concentrations were set to be 3000, 1000, 333, 111, 37.0, 12.3 and 4.12 mg dinotefuran/kg soil (dw).

Nominal and measured concentrations:

Nominal: 3000, 1000, 333, 111, 37.0, 12.3, 4.12 mg dinotefuran/kg dry soil

Reference substance (positive control):

no

Species:

Brassica napus

Duration:

14 d

Dose descriptor:

NOEC

Effect conc.:

111 mg/kg soil dw

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

other: fresh weight

Species:

Brassica napus

Duration:

14 d

Dose descriptor:

EC50

Effect conc.:

650 mg/kg soil dw

Nominal / measured:

estimated

Conc. based on:

test mat.

Basis for effect:

other: fresh weight

Key result

Species:

Glycine max (G. soja)

Duration:

14 d

Dose descriptor:

NOEC

Effect conc.:

< 37 mg/kg soil dw

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

other: fresh weight

Species:

Glycine max (G. soja)

Duration:

14 d

Dose descriptor:

EC50

Effect conc.:

1 734 mg/kg soil dw

Nominal / measured:

estimated

Conc. based on:

test mat.

Basis for effect:

other: fresh weight

Species:

Helianthus annuus

Duration:

14 d

Dose descriptor:

NOEC

Effect conc.:

>= 3 000 mg/kg soil dw

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

other: fresh weight

Species:

other: Solanum lycopersicum

Duration:

14 d

Dose descriptor:

NOEC

Effect conc.:

111 mg/kg soil dw

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

other: fresh weight

Species:

Avena sativa

Duration:

14 d

Dose descriptor:

NOEC

Effect conc.:

>= 3 000 mg/kg soil dw

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

other: fresh weight

Species:

Allium cepa

Duration:

21 d

Dose descriptor:

NOEC

Effect conc.:

333 mg/kg soil dw

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

other: fresh weight

Details on results:

Brassica napus
Fresh Weight (14 days):
The fresh weight of Brassica napus in the 1000, 333, 111, 37.0 and 12.3 mg dinotefuran/kg soil (dw) treatment was reduced (-5.8% to -58.9%). The reduction in the 333 mg and 1000 mg dinotefuran/kg soil (dw) was statistically significant compared to the control.
Plant development in the 333 mg and 1000 mg dinotefuran/kg soil (dw) treatment groups was delayed.
Germination:
The germination rate ranged between 80% and 93% (control: 97%). There was no statistically significant compared to the control.
Mortality (14 days):
None
Phytotoxicity (14 days):
Phytotoxic effects observed were growth reduction and chlorosis. Sporadically deformation of leaves and discolouration occurred. Clear effects were observed in the 333 and 1000 mg dinotefuran/kg soil (dw) treatments groups.

Glycine max
Fresh Weight (14 days):
The fresh weight of Glycine max was statistically significantly reduced compared to the control at all tested concentrations (-13.3% to -65.7%). Plant development in the 333, 1000 and 3000 mg dinotefuran/kg soil (dw) treatment groups was delayed.
Germination:
The germination rate ranged between 80% and 100% (control: 100%). There was no statistically significant difference compared to the control.
Mortality (14 days):
None
Phytotoxicity (14 days):
Phytotoxic effects observed were growth reduction, chlorosis and deformation of leaves and stems. Clear effects were observed in the 1000 and 3000 mg dinotefuran/kg soil (dw) treatment groups.

Helianthus annuus
Fresh Weight (14 days):
The fresh weight of Helianthus annuus was reduced in the 37.0, 333 and 3000 mg dinotefuran/kg soil (dw) treatment groups.(-0.6% to -7.6%) This reduction was not statistically significant compared to the control.
Plant development was delayed in the 333 mg and 3000 mg dinotefuran/kg soil (dw) treatment groups.
Germination:
The germination rate ranged between 87% and 97% (control: 90%). There was no statistically significant difference compared to the control.
Mortality:
None
Phytotoxicity (14 days):
Phytotoxic effects observed were growth reduction, chlorosis and deformation of leaves. Clear effects were observed in the 3000 mg dinotefuran/kg soil (dw) treatment group.

Solanum lycopersicum
Fresh Weight (14 days):
The fresh weight of Solanum lycopersicum was reduced in all test item treatment groups (-11.2% to -88.5%). The reduction was statistically significant compared to the control in the 37.0, 333, 1000 and 3000 mg dinotefuran/kg soil (dw) treatment groups. The effect at 37.0 mg dinotefuran/kg soil (dw) is considered not to be test item related, as there was no concentration response.
The plant development was delayed compared to the control at 333, 1000 and 3000 mg dinotefuran/kg soil (dw).
Germination:
The germination rate ranged between 73% and 97% (control: 90%). Differences to the control were not statistically significant.
Mortality (14 days):
In the test item treatment groups, no statistically significant mortality compared to the control occurred.
Phytotoxicity (14 days):
Phytotoxic effects were growth reduction and chlorosis. Clear effects were observed at 1000 and 3000 mg dinotefuran/kg soil (17% and 71%).

Avena sativa
Fresh Weight (14 days):
The fresh weight of Avena sativa was reduced in all test item treatment groups (-10.7% to -26.6%). The reduction was not statistically significant compared to the control.
The plant development was delayed compared to the control in 111, 333, 1000 and 3000 mg dinotefuran/kg soil (dw) treatment groups.
Germination:
The germination rate ranged between 77% and 97% (control: 97%). Differences compared to the control were not statistically significant.
Mortality (14 days):
None
Phytotoxicity (14 days):
Phytotoxic effects observed were growth reduction, chlorosis and sporadical deformation of leaves. There were no clear effects.

Allium cepa
Fresh Weight (21 days):
The fresh weight of Allium cepa was reduced in all test item treatment groups (-20.9% to -60.1%). The reduction was statistically significant compared to the control at 37.0, 1000 mg and 3000 mg dinotefuran/kg soil (dw). The effect at 37.0 mg dinotefuran/kg soil (dw) is considered not to be test item related, as there was no concentration response. The plant development was not delayed compared to the control.
The germination rate ranged between 72% and 93% (control: 93%). Differences compared to the control were not statistically significant.
Mortality (21 days):
None
Phytotoxicity (21 days):
Phytotoxic effects observed were sporadic chlorosis and growth reduction. There were no clear effects.

Results with reference substance (positive control):

Not applicable

Reported statistics and error estimates:

Fresh weight data were tested for normal distribution and homogeneity of variance using the Shapiro-Wilk’s test (α = 0.05) and the Levene’s test (α = 0.05).If the data were normally distributed and homogeneous the Dunnett’s t-test (multiple comparison, one-sided smaller, α = 0.05) was used for comparing treatment groups and control. If the data were not normally distributed the Bonferroni-Holm U-test (multiple comparison, one-sided smaller, α = 0.05) was used.
In order to determine the EC10, EC20 and EC50values, a regression analysis was performed (Probit-analysis).
For the mortality and germination data Fisher’s Exact Binomial Test (with Bonferroni Correction, multiple comparison, one-sided greater, α = 0.05) was used.
The software used to perform the statistical analysis was ToxRat Professional, Version 2.10.05, ®ToxRat Solutions GmbH.

Summarised results of fresh weight, germination, mortality, phytotoxicity and plant growth

	Treatment group (mg test item/kg dry soil)	Germination¹ [%]	Mortality¹ [%]	Fresh Weight [g]	Standard Deviation	Effect* [%]	Fresh Weight Statistics	Phytotoxicity [%]			Growth Stage (BBCH)
Time of Evaluation ** Species			final check	final check				Day 7	Day 14	Day 21	final check
Brassica napus	Control	97	0	10.94	± 4.19	-	-	0	0	-	13-14
	4.12	87	0	13.79	± 1.06	26.1	n.s.^2	0	0	-	13-14
	12.3	90	0	8.99	± 1.87	-17.8	n.s.^2	1	4	-	13-14
	37.0	80	0	9.40	± 5.58	-14.1	n.s.^2	0	1	-	13-14
	111	93	0	10.31	± 3.12	-5.8	n.s.^2	0	0	-	13-14
	333	83	0	6.20	± 3.16	-43.4	s.^2	14	23	-	12-13
	1000	83	0	4.50	± 2.24	-58.9	s.^2	21	59	-	11-13
Glycine max	Control	100	0	20.69	± 1.39	-	-	0	0	-	13-14
	37.0	100	0	17.93	± 1.15	-13.4	s.^2	0	0	-	13-14
	111	100	0	17.94	± 1.42	-13.3	s.^2	0	0	-	13-14
	333	100	0	16.34	± 1.35	-21.0	s.^2	3	3	-	12-14
	1000	100	0	13.82	± 2.11	-33.2	s.^2	32	31	-	11-13
	3000	80	0	7.09	± 2.91	-65.7	s.^2	71	73	-	10-13
Helianthus annuus	Control	90	0	19.79	± 2.97	-	-	0	0	-	12-16
	37.0	87	0	18.49	± 2.39	-6.5	n.s.^2	0	5	-	12-16
	111	93	0	19.86	± 2.61	0.4	n.s.^2	0	0	-	12-16
	333	90	0	19.67	± 3.69	-0.6	n.s.^2	0	4	-	10-14
	1000	93	0	21.33	± 2.22	7.8	n.s.^2	0	2	-	12-14
	3000	97	0	18.28	± 3.90	-7.6	n.s.^2	0	16	-	10-14
Solanum lycopersicum	Control	90	0	4.09	± 0.78	-	-	0	0	-	10-13
	37.0	90	0	3.05	± 0.79	-25.3	s.^2	0	0	-	11-13
	111	97	0	3.63	± 0.74	-11.2	n.s.^2	0	0	-	10-13
	333	90	0	2.85	± 1.00	-30.2	s.^2	0	1	-	10-12
	1000	93	0	2.41	± 0.64	-41.0	s.^2	0	17	-	10-12
	3000	73	5	0.47	± 0.40	-88.5	s.^2	1	71	-	09-12
Avena sativa	Control	97	0	9.22	± 1.02	-	-	0	0	-	12-14
	37.0	97	0	8.23	± 1.15	-10.7	n.s.^3	0	0	-	12-14
	111	77	0	7.43	± 2.88	-19.5	n.s.^3	0	3	-	11-13
	333	90	0	7.28	± 2.44	-21.1	n.s.^3	2	4	-	11-13
	1000	83	0	6.77	± 3.20	-26.6	n.s.^3	3	7	-	12-13
	3000	97	0	8.04	± 0.85	-12.8	n.s.^3	4	7	-	12-13
Allium cepa	Control	93	0	3.31	± 0.54	-	-	0	0	0	12-13
	37.0	87	0	2.16	± 0.70	-34.8	s.^2	0	2	6	12-13
	111	93	0	2.42	± 1.01	-26.9	n.s.^2	0	0	11	12-13
	333	93	0	2.62	± 0.37	-20.9	n.s.^2	0	0	2	12-13
	1000	72	0	1.32	± 0.78	-60.1	s.^2	0	0	34	12-13
	3000	83	0	2.02	± 1.10	-39.1	s.^2	0	2	23	12-13

the results represent rounded values calculated on the exact raw data

* : negative values indicate reduction compared to the control

**:day after 50% seedling emergence in the control

-:not evaluated

s.: significant

n.s.: not significant

¹ nomortality or no statistically significance at all tested concentrations on all six plant species, pair-wise comparison Fisher's Exact Binomial Test, α = 0.05

² multiple comparison Dunnett's t-test, α=0.05

³ multiple comparison Bonferroni-Holm U-test, α=0.05

Validity criteria fulfilled:

yes

Conclusions:

Dinotefuran was tested for effects on seedling emergence and seedling growth of six different plant families.
The analytical recovery in soil treated with 1000 mg dinotefuran/kg soil dry weight (dw) was 97% and 101% of the two batches used.
The most sensitive species in terms of fresh weight were Brassica napus and Glycine max, the EC50 was 650 mg and 1734 mg dinotefuran/kg soil (dw), respectively. For Solanum lycopersicum and Allium cepa calculation of an ECx was not possible due to absence of a meaningful concentration response. The NOEC for Solanum lycopersicum and Allium cepa was determined to be 111 mg and 333 mg dinotefuran/kg soil (dw), respectively. Avena sativa and Helianthus annuus showed no test item related effects (NOEC ≥ 3000 mg dinotefuran/kg soil (dw)).
There was no statistically significantly reduced germination rate compared to the control for any species tested.
Phytotoxic effects observed were growth reduction and chlorosis (all species). For Brassica napus, Glycine max, Avena sativa and Helianthus annuus abnormal growth of the leaves was observed, Glycine max showed in addition abnormal growth of the stems. Additionally Brassica napus showed discolouration of the leaves (effects were only sporadic). The effects for Brasscia napus, Glycine max, Helianthus annuus and Solanum lycopersicum showed concentration response.

Executive summary:

The purpose of the study was to determine a dose depending effect of dinotefuran on seedling emergence and seedling growth of six non-target plant species representing six plant families. Parameters assessed were plant fresh weight, phytotoxicity, germination and mortality. Six pots each containing five seeds were tested for each treatment group for 14 to 21 days after 50 % germination in the control depending on the growth of the seedlings. Based on the results of a range finding test the test concentrations were set to be 3000, 1000, 333, 111, 37.0, 12.3 and 4.12 mg dinotefuran/kg soil dry weight (dw). The most sensitive species in terms of fresh weight were Brassica napus and Glycine max, the EC₅₀was 650 mg and 1734 mg dinotefuran/kg soil (dw), respectively. For Solanum lycopersicum and Allium cepa calculation of an EC_x was not possible due to absence of a meaningful concentration response. The NOEC for Solanum lycopersicum and Allium cepa was determined to be 111 mg and 333 mg dinotefuran/kg soil (dw), respectively. Avena sativa and Helianthus annuus showed no test item related effects (NOEC ≥ 3000 mg dinotefuran/kg soil (dw)). There was no statistically significantly reduced germination rate compared to the control for any species tested.

Description of key information

The most sensitive species in terms of fresh weight were Brassica napus and Glycine max, the EC50 was 650 mg and 1734 mg dinotefuran/kg soil (dw), respectively. For Solanum lycopersicum and Allium cepa calculation of an ECx was not possible due to absence of a meaningful concentration response. The NOEC for Solanum lycopersicum and Allium cepa was determined to be 111 mg and 333 mg dinotefuran/kg soil (dw), respectively. Avena sativa and Helianthus annuus showed no test item related effects (NOEC ≥ 3000 mg dinotefuran/kg soil (dw)).

There was no statistically significantly reduced germination rate compared to the control for any species tested.

Phytotoxic effects observed were growth reduction and chlorosis (all species). For Brassica napus, Glycine max, Avena sativa and Helianthus annuus abnormal growth of the leaves was observed, Glycine max showed in addition abnormal growth of the stems. Additionally Brassica napus showed discolouration of the leaves (effects were only sporadic). The effects for Brasscia napus, Glycine max, Helianthus annuus and Solanum lycopersicum showed concentration response.

Key value for chemical safety assessment

Long-term EC10, LC10 or NOEC for terrestrial plants:

111 mg/kg soil dw