spirodiclofen (ISO);3-(2,4-dichlorophenyl)-2-oxo-1-oxaspiro[4.5]dec-3-en-4-yl 2,2-dimethylbutyrate

Toxicity to terrestrial arthropods

Link to relevant study record(s)

Reference

Endpoint:

toxicity to terrestrial arthropods: long-term

Type of information:

experimental study

Adequacy of study:

key study

Study period:

2004-04-20 to 2004-05-24

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

test procedure in accordance with generally accepted scientific standards and described in sufficient detail

Qualifier:

according to guideline

Guideline:

other: Guidance document on regulatory testing procedures for pesticides with nontarget arthropods (Barrett et al. 1994).

Version / remarks:

1994

Deviations:

no

Qualifier:

according to guideline

Guideline:

other: SECOFASE- Final Report, improvement and standardisation of test systems forassessing sub-lethal effects of chemicals on fauna in the soil ecosystem (Lokke & van Gestel 1996)

Version / remarks:

1996

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Details on preparation and application of test substrate:

- Preparation of the test item stock solution. The test item was dissolved in a sufficient amount of deionised water to prepare a stock solution. This stock solution was diluted with deionised water to obtain one test item solution (= dosage solution) for each test item concentration. An appropriate amount of these aqueous test item solutions were mixed in the LUFA 2.1 soil. This amount of water/test item-mixture served also to adjust the final soil moisture of 40 - 60% of WHCmax.

- Mixing of the LUFA 2.1 soil until the test item solutions were homogeneously distributed. For each concentration an appropriate amount of soil was separated and 5.1 - 5.3 g fw (fresh weight) was filled into each test unit. The height of the soil column in the test units was approx. 3 mm. After the soil substrate was inserted, it was slightly compressed to equalise the surface.

Test organisms (species):

Hypoaspis aculeifer

Animal group:

Acari (soil-dwelling predatory mite)

Details on test organisms:

The culture of Hypoaspis aculeifer CANESTRINI (Acari: Laelapidae) used in this test is kept at
ECT Oekotoxikologie GmbH since February 2002. The organisms were originally delivered by
MITOX Laboratories (Amsterdam, The Netherlands).
The mites were in the protonymphal stage (with an maximum age of 2 days); i.e. they were
taken from a synchronised culture.

Study type:

laboratory study

Total exposure duration:

14 d

Test temperature:

25 ± 2°C

pH (if soil or dung study):

4.7

Details on test conditions:

Mortality (exposure) period: The mites were exposed to the test item in LUFA 2.1, a standard soil obtained from Landwirtschaftliche Untersuchungs-und Forschungsanstalt Speyer, Germany.

Mating and reproduction period: Following the mortality period mites were tested on an uncontaminated layer of plaster of Paris (approximately 1.5 cm) darkened with activated carbon.

During mortality period the soil moisture was adjusted to 40 - 60% of the WHC max. The plaster of Paris was moistened with deionised water until the plaster was almost saturated. The units were passively ventilated.

During the mortality and mating period the water content of the LUFA 2.1 soil and the plaster of Paris was checked twice per week by reweighing the test units. Losses of water were compensated.

For all test periods the following conditions were observed:
Temperature: 25 ± 2 °C
Light cycle: permanent dark

The mites were fed with prey mites (e.g.Tyrophagus putrescentiae) or enchytraeids (e.g.Enchytraeus vavoulidou). Food was checked twice per week and was added on demand.

Nominal and measured concentrations:

Control: 10.0, 31.6, 100.0, 316.0 and 1000.0 mg test item/kg soil (dw)

Reference substance (positive control):

yes

Remarks:

Reference item 5 mg dimeothate/kg soil (dw)

Key result

Duration:

14 d

Dose descriptor:

NOEC

Effect conc.:

>= 1 000 mg/kg soil dw

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

reproduction

Key result

Duration:

14 d

Dose descriptor:

NOEC

Effect conc.:

>= 1 000 mg/kg soil dw

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

mortality

Details on results:

Eight percent of adult mites died in the control. At all concentrations of the test item tested 6.3-15.0% mortality respectively was observed (corresponding to a corrected mortality according to Abbott (1925) between1.9 and 7.6%). Since the mortality observed with the test item was not higher than 15.0% the LR50 value could not be calculated.

At all tested concentrations of the test item, the highest mortality rate occurred at a concentration of 100.0mg test item/kg soil (dw) and was 7.6% higher than at the control but remained below the maximum recommended control mortality of 25.0% which is set as validity criterion. Thus no statistical analysis was performed and the NOEC Mortality was regarded to be >1000.0 mg test item/kg soil (dw).

Results with reference substance (positive control):

After 14 days of exposure, 83.7% Abbott's (1925) corrected mortality of the adult mites was observed with the reference item group which was within the recommended range (50 -99.5%). Therefore, the observed effects of the reference item assures a high sensitivity of the test system.

Table one

Mortality of the adult mites after 14 days

Concentration [mg/kg soil (dw)]	Average Mortality (%)	Corrected mortality (%)	Mean cummulative number of juveniles / females after 7 days [mean ± sd]	Reduction of Juveniles (%)
Control	8.0	0.0	18.1 ± 4.8	0.0
Reference	85.0	83.7	-         -	-
10.0	6.3	-1.9	-         -	-
31.6	6.3	-1.9	-         -	-
100.0	15.0	7.6	-         -	-
316.0	13.8	6.3	17.3 ± 4.4	4.4
1000.0	8.8	0.8	17.4 ± 2.9	3.9
	Adult Mortality		Reproduction
LR50 [mg test item/ kg soil (dw)]	---		---
LOEC [mg test item / kg soil (dw)]	---		---
NOEC [mg test item/kg soil (dw)]	≥ 1000.0		≥1000.0

Table two

Reproduction after a 7-day period 

Concentration [mg test item/ kg soil (dw)]	Mean cummulative Number of Juveniles / Female after 7 days	Reduction of Juveniles [%]
control	18.1 ± 4.8	0.0
316.0	17.3 ± 4.4	4.4
1000.0	17.4 ± 2.9	3.9

Validity criteria fulfilled:

yes

Conclusions:

The LR50value could not be calculated.

The NOEC Mortality was >= 1000.0 mg test item/kg soil (dw).
The NOEC Reproduction was >= 1000.0 mg test item/kg soil (dw).

Executive summary:

Eight percent of adult mites died in the control. At all concentrations of the test item tested 6.3-15.0% mortality respectively was observed (corresponding to a corrected mortality according to Abbott (1925) from -1.9 to 7.6%).

Since the mortality observed with the test item was not higher than 15.0% the LR₅₀ value could not be calculated.

At all tested concentrations of the test item, the highest mortality rate occured at a concentration of 100.0 mg test item/kg soil (dw) and was 7.6% higher than at the control but remained below the maximum recommended control mortality of 25.0% which is set as validity criterion.

 

Therefore, the NOEC Mortaility was regarded to be ≥ 1000.0 mg test item/kg soil (dw). Reproduction was examined only for the two highest concentrations of the test item which caused less than 50% mortality (i.e. 316.0 and 1000.0 mg test item/kg soil (dw)). Statisticalanalysis (Welch-t test for inhomogeneous variances; 1-sided smaller, p ≤ 0.05) showed no significant difference concerning the cumulative number of juveniles per female after 7 days between the control and this two concentrations of the test item tested.

Therefore, the NOEC reproduction was regarded to be ≥ 1000.0 mg test item/kg soil (dw)

Description of key information

In a 14-day tox study, Hypoaspis aculeifer, were exposed to concentrations of 10.0, 31.6,100.0, 316.0 and 1000.0 mg test item/kg soil dry weight (dw). As a formulation of Spirodiclofen was used in this study, the NOEC_Mortality and NOEC_Reproduction of >= 1000 mg/kg soil (dw) had to be coverted to >= 244 mg/kg soil (dw) to reflect the content of Spirodiclofen in the test item.

 

Key value for chemical safety assessment

Long-term EC10, LC10 or NOEC for soil dwelling arthropods:

244 mg/kg soil dw