Desmedipham

Toxicity to terrestrial arthropods

Link to relevant study record(s)

Reference

Reference 1

Endpoint:

toxicity to terrestrial arthropods: long-term

Type of information:

experimental study

Adequacy of study:

key study

Study period:

2010-05-25 to 2010-07-26

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 226 (Predatory Mite (Hypoaspis (Geolaelaps) Aculeifer) Reproduction Test in Soil)

Version / remarks:

October 03, 2008

Deviations:

yes

Remarks:

Extraction of soil mites started after 15 days of exposure.

GLP compliance:

yes

Application method:

mixed into soil

Specific details on test material used for the study:

The test material is a white powder.

Analytical monitoring:

no

Details on preparation and application of test substrate:

- Method of mixing into soil: The test item was applied as a test-item-quartz-sand-mixture. The test-item-quartz-sand-mixture was thoroughly mixed into 500 g dry weight artificial soil of each application rate using a laboratory mixer.
- Controls: 8 control replicates of 10 adult female Hypoaspis aculeifer

Test organisms (species):

Hypoaspis aculeifer

Animal group:

Acari (soil-dwelling predatory mite)

Details on test organisms:

TEST ORGANISM
- Common name: Soil mite, Hypoaspis aculeifer
- Age at test initiation: a uniform age not differing more than three days (28 days after start of egg laying)
- Stage at test initiation: fertilized adult female
- Kept according to standard practices: yes
- Feeding: The Hypoaspis aculeifer were fed with Tyrophagus putrescentiae (cheese mite)

Study type:

laboratory study

Total exposure duration:

15 d

Remarks:

The extraction of the soil mites started after a period of 15 days instead of 14 days.

Post exposure observation period:

After an exposure period of 15 days, the surviving adults and the living juveniles per test vessel were extracted, applying a temperature gradient. All Hypoaspis aculeifer (adult, females and juveniles) were counted under a binocular. Missing adults (compared to the number of initially placed test organisms) were considered to be dead, since dead mites cannot be extracted.

Test temperature:

20 ± 2 °C

pH (if soil or dung study):

Test start: 5.51 - 5.58; test end: 5.59 - 5.77

Humidity:

Test start: 19.57% of the maximum water holding capacity; test end: 19.86 - 20.60% of the maximum water holding capacity.

The maximum water holding capacity (WHCmax) of the artificial soil used in this study was determined to be 49.25 g water/100 g dry weight artificial soil.

Photoperiod and lighting:

Photoperiod: 16-hour light to 8-hour darkness
Light intensity: 400 - 800 Lux

Details on test conditions:

TEST SYSTEM
- Test container (material, size): reusable glass vessels (Weck Mini-Sturzglas, volume 140 ml, diameter 5 cm at the bottom, height 7 cm).
- Amount of soil: 20 g dry weight artificial soil
- No. of organisms per container (treatment): 10 adult fertilized female Hypoaspis aculeifer
- No. of replicates per treatment group: 4 replicates

SOURCE AND PROPERTIES OF SUBSTRATE
- Composition (if artificial substrate): 74.8% fine quartz sand (sort F 36, particle size 0.2 – 0.05 mm = 91.50%), 5% Sphagnum peat, air dried and finely ground, 20% Kaolin clay ((content of Kaolinite: Al2Si2O5(OH)4) = 30.2%), approximately 0.2% Calcium carbonate (CaCO3) (for the adjustment to pH to 6.0 ± 0.5).
- Maximum water holding capacity (in % dry weight): 50% of the maximum water holding capacity

Nominal and measured concentrations:

Nominal concentration: 32, 56, 100, 178 and 316 mg/kg artificial soil dry weight alongside a control.

Reference substance (positive control):

yes

Remarks:

dimethoate

Toxic reference:

dimethoate

Key result

Duration:

15 d

Dose descriptor:

NOEC

Effect conc.:

>= 316 mg/kg soil dw

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

reproduction

Remarks on result:

other:

Details on results:

Adult Mortality
The values for adult mortality are shown in Table 1. In the control 1.3 % of the adult Hypoaspis aculeifer died which is below the allowed maximum of = 20% mortality. A LC50 can not be calculated and is considered to be >316 mg test item/kg dry weight artificial soil.

Reproduction
The results of the reproduction performance are shown in Table 2. Concerning the number of juveniles statistical analysis (Dunnett’s test, one-sided smaller, a = 0.05) revealed no significant differences between the control and all treatment concentrations. Therefore the No-Observed-Effect-Concentration (NOEC) for reproduction is =316 mg test item/kg dry weight artificial soil. The Lowest-Observed-Effect-Concentration (LOEC) for reproduction is >316 mg test item/kg dry weight artificial soil. An EC50 could not be calculated and is considered to be >316 mg test item/kg dry weight artificial soil.

Results with reference substance (positive control):

The most recent non-GLP-test with the reference item dimethoate was performed at test concentrations 1.0, 1.8, 3.2, 5.6 and 10.0 mg dimethoate/kg dry weight artificial soil. Dimethoate showed a LC50 of 4.2 mg a.s./kg (95% confidence limits from 3.6 to 5.0 mg a.s./kg dry weight artificial soil) for mortality of the adult mites according Probit analysis using maximum likelihood regression. The NOECreproduction was calculated to be 3.2 mg a. s./kg dry weight artificial soil and accordingly the LOECreproduction is 5.6 mg a.s./kg dry weight artificial soil according Williams-Test multiple t-test procedure, a = 0.05, one-sided. Dimethoate showed a EC50 of 5.7 mg a.s./kg dry weight artificial soil (95% confidence limits from 5.7 to 5.8 mg a.s./kg dry weight artificial soil) for reproduction according Probit analysis using maximum likelihood regression. This is in the recommended range of the guideline of 3.0 – 7.0 mg a.s./kg dry weight artificial soil. This shows that the test organisms are sufficiently sensitive.

See "Attachments" in "Overall remarks, attachments" for the tables and figure.

Validity criteria fulfilled:

yes

Remarks:

The mean adult female mortality =20%, mean number of juveniles per replicate (with 10 adult females) was =50, and Coefficient of variation (mean number of juveniles per replicate) was =30%.

Conclusions:

The study fulfilled the validity criteria for control mortality (¿20 %), for the mean number of juveniles per test vessel in control (=50) and for the coefficient of variance of reproduction in control (¿30%). Also, the physico-chemical parameters measured at the start and at the end of the tests met the guideline requirements. The Hypoaspis aculeifer were collected on Day 15 instead of Day 14. This is not considered to have affected the outcome of the test. The toxic standard showed an LC50 value of 4.2 mg/kg soil d.w. for adult mortality which is within the range required in the guideline (3-7 mg/kg soil d.w.). Hence, the study is considered valid. A NOEC value of = 316 mg a.s./kg dry weight soil was obtained and is used in the risk assessment.

Executive summary:

This study was conducted in order to determine the influence of desmedipham on mortality and reproduction on the soil mite species Hypoaspis aculeifer tested in artificial soil. The test was conducted at the following nominal concentrations of the test substance: 0 (control), 32, 56, 100, 178 and 316 mg/kg artificial soil dry weight. In the control 1.3% of the adult Hypoaspis aculeifer died which is below the allowed maximum of ≤20% mortality. A LC₅₀ could not be calculated and is considered to be >316 mg test item/kg dry weight artificial soil. A NOEC (for reproduction) value of ≥316 mg a.s./kg dry weight soil was obtained and is used in the risk assessment.

Reference 2

Endpoint:

toxicity to terrestrial arthropods: long-term

Type of information:

experimental study

Adequacy of study:

key study

Study period:

2010-02-26 to 2010-07-21

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 232 (Collembolan Reproduction Test in Soil)

Version / remarks:

September 07, 2009

Deviations:

no

GLP compliance:

yes

Application method:

mixed into soil

Specific details on test material used for the study:

The test material is a white powder.

Analytical monitoring:

no

Details on preparation and application of test substrate:

- Method of mixing into soil: The test item was applied as a test-item-quartz-sand-mixture. The test-item-quartz-sand-mixture was thoroughly mixed into 500 g artificial dry weight artificial soil of each application rate using a laboratory mixer.
- Controls: 7 replicates of 10 collembolans

Test organisms (species):

Folsomia candida

Animal group:

Collembola (soil-dwelling springtail)

Details on test organisms:

TEST ORGANISM
- Common name: Springtails (Folsomia candida)
- Age at test initiation: 10 – 12 days
The breeding culture was kept under the following conditions:
Temperature: 22 ± 2°C
Light cycle: permanent dark
Feeding: once a week with dry yeast

Study type:

laboratory study

Total exposure duration:

28 d

Remarks:

After 28 days, the surviving adults and living juveniles were counted, and missing adults (compared to the number of initially placed test organisms) were considered to be dead, since dead collembolans cannot be extracted.

Test temperature:

20 ± 2°C

pH (if soil or dung study):

Test start: 5.51 - 5.66; test end: 5.44 - 5.52

Humidity:

Test start: 19.57% of the maximum water holding capacity; test end: 19.21 - 20.52% of the maximum water holding capacity.

Photoperiod and lighting:

Light intensity: 400 – 800 Lux
Photoperiod: 16h light and 8h dark

Details on test conditions:

TEST SYSTEM
- Test container (material, size): reusable glass vessels (volume 140 ml, diameter 5 cm at the bottom, height 7 cm).
- Amount of soil: 30 g wet weight artificial soil.
- No. of organisms per container (treatment): 10 collembolans
- No. of replicates per treatment group: 4 replicates
- No. of replicates per control: 7 replicates

SOURCE AND PROPERTIES OF SUBSTRATE
- Composition (if artificial substrate): 74.8% fine quartz sand (sort F 36, particle size 0.2 – 0.05 mm = 91.50%); 5% Sphagnum peat, air dried and finely ground; 20% Kaolin clay (content of Kaolinite: Al2Si2O5(OH)4) = 30.2%); approximately 0.15% Calcium carbonate (CaCO3).
- Maximum water holding capacity (in % dry weight): 50% of the maximum water holding capacity

Nominal and measured concentrations:

Nominal concentration: 100, 177, 316, 562 and 1000 mg a.s./kg artificial soil dry weight alongside a control (water treated).

Reference substance (positive control):

yes

Remarks:

Boric acid

Key result

Duration:

28 d

Dose descriptor:

NOEC

Effect conc.:

>= 316 mg/kg soil dw

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

reproduction

Remarks on result:

other:

Details on results:

Adult Mortality
The values for adult mortality are shown in Table 1. In the control group, 8.6% of the adult Folsomia candida died which is below the allowed maximum of = 20% mortality. A LC50 could not be calculated and is considered to be > 1000 mg test item/kg artificial soil dry weight.

Reproduction
The results of the reproduction performance are shown in Table 2. A statistically significant effect (William's-t test, one-sided-smaller, a = 0.05) was found in the treatment groups with 562 and 1000 mg test item/kg artificial soil dry weight. The No-Observed-Effect-Concentration (NOECreproduction) is 316 mg test item/kg artificial soil dry weight. The Lowest-Observed-Effect-Concentration (LOECreproduction) is 562 mg test item/kg artificial soil dry weight. An EC50 could not be calculated and is considered to be >1000 mg test item/kg dry weight artificial soil.

Results with reference substance (positive control):

A most recent non-GLP-test with the reference item Boric acid was performed at test concentrations 44, 67, 100, 150, and 225 mg Boric acid/kg artificial soil dry weight. Boric acid showed an EC50 of 96 mg test item/kg artificial soil dry weight (95% confidence limits from 87 mg to 105 mg Boric acid/kg artificial soil dry weight) for reproduction according to Probit analysis using maximum likelihood regression. The result is in the recommended range of the guideline (about 100 mg Boric acid/kg artificial soil dry weight). The NOECreproduction was calculated to be 44 mg Boric acid/kg artificial soil dry weight and accordingly the LOECreproduction is 67 mg Boric acid/kg artificial soil dry weight according Williams-Test multiple t-test procedure, a = 0.05, one-sided smaller. This shows that the test organisms are sufficiently sensitive.

See "Attachments" in "Overall remarks, attachments" for the tables and figure.

Validity criteria fulfilled:

yes

Remarks:

The study fulfilled the validity criteria for control mortality (<20%), for the mean number of juveniles per test vessel in control (=100) and for the coefficient of variance of reproduction in control (=30%).

Conclusions:

The physico-chemical parameters measured at the start and at the end of the tests met the guideline requirements. In addition, the toxic standard showed an EC50 value which was within the range required in the guideline. Hence, the study is considered valid. The LOEC value for reproduction was 562 mg a.s./kg soil dry weight. A NOEC value of 316 mg a.s./kg dry weight soil was obtained and is used in the risk assessment.

Executive summary:

This study was conducted in order to determine the influence of desmedipham on the reproduction of the collembolan species Folsomia candida tested in artificial soil. The test was conducted at the following nominal concentrations of the test substance: 0 (control), 100, 177, 316, 562 and 1000 mg a.s./kg artificial soil dry weight. In the control group 8.6% of the adult Folsomia candida died which is below the allowed maximum of ≤20% mortality. A LC₅₀ could not be calculated and is considered to be >1000 a.s./kg artificial soil dry weight. The Lowest-Observed-Effect-Concentration (LOEC) for reproduction is 562 mg a.s./kg artificial soil dry weight. An EC₅₀ value could not be calculated and is considered to be >1000 mg a.s./kg soil dry weight. The No-Observed-Effect-Concentration (NOEC) for reproduction is 316 mg a.s./kg artificial soil dry weight.

Description of key information

2 studies of different terrestrial arthropods summaries are documented below.

The purpose of this study is to determine potential effects of different concentrations of Desmedipham on the reproductive output of the collembolans Folsomia candida during a test period of 28 days.  The overall NOEC was determined to be ≥316 mg/kg soil dw.

The purpose of this study was to determine potential effects of Desmedipham on the mortality and the reproductive output of the soil mite species Hypoaspis aculeifer (CANESTRINI) during a test period of 15 days. The NOEC was determined to be ≥316 mg/kg soil dw.

 

In addition, three studies on honey bees are availabe and executive summaries are documented below.

Sekine, 2011

The acute oral toxicity and acute contact toxicity of Desmedipham was assessed in a limit test in Apis mellifera. Under laboratory conditions Apis mellifera 50 worker bees per treatment were exposed for 48 hours to a single dose of 100.0 µg a.s. per bee for topical application (contact limit test) and to a single dose of 100.6 µg a.s. per bee for feeding (oral limit test, value based on the actual intake of the test item).

The results can be considered as valid, as all validity criteria of the test were met: control mortality is <10% in the oral and in the contact test, LD₅₀ (24 h) of the toxic standard in the oral test equals 0.13 mg a.s./bee, the LD₅₀ (24 h) of the toxic standard in the contact test equals 0.17 mg/bee. LD₅₀ oral (solution in acetone and mixed with syrup) >100.6 µg a.s./bee (2% mortality after 48h), no behavioral effects were observed at any time in the oral toxicity test. LD₅₀ contact (solution in acetone) >100.0 µg a.s./bee (0% mortality after 48h).

 

Kling, 2014

The purpose of this study was to determine the chronic effects of the test item Desmedipham formulation on the honey bee, Apis mellifera L., in a 10 days continuous feeding test in the laboratory. Honey bees were exposed to a 50% aqueous sucrose application (feeding) solution containing the nominal concentration level of 120 mg a.s./kg of Desmedipham by continuous and ad libitum feeding over a period of 10 days.

Mortality and sublethal effects were observed every day at about the same time of day. The chronic effects of the test item as well as the NOEC value were evaluated by comparing the results of the test item treatment to those of the control treatment.

The NOEDD was determined at the end of the test period to be 4.8 µg a.s./bee/day (nominal). The LDD₅₀ was determined to be >4.8 µg a.s./bee/day (nominal).

 

Jeker, 2013

This study was designed to assess the effects of Desmedipham formulation to the honey bee brood over a 22 day period.

Behaviour, mortality, colony strength, brood nest, storage and brood termination rate were observed. The results were compared to an untreated control (50% w/v sucrose solution) and to a reference item (fenoxycarb). The mixing ratio was 4.802 mL Desmedipham SE 160 in 1 L sucrose solution (= 0.8 g Desmedipham/L). Also bee brood development (eggs, young and old larvae) were recorded one day before test initiation and after 4, 8, 15 and 22 days.

The exposure of honey colonies to Desmedipham caused no adverse effects on the survival of adult bees, eggs, larvae and pupae, brood development, behaviour, colony strength and colony conditions at the tested rate. A NOEDD value for larvae was determined to be 171.04 μg a.s./larva.

In the table below all available studies are listed. For some studies only the results are presented since they are not considered relevant due to the reasons given under “Assessment”. All available studies have been evaluated within the scope of Plant Protection Regulation in the respective Draft Renewal Assessment Report (DAR) under Regulation (EC) 1107/2009.

Test species	Result	Assessment	Reference
Hypoaspis aculeifer	15-d NOEC ≥316 mg/kg dws	Key study	Kratz (2010)
Folsomia candida	28-d NOEC ≥316 mg/kg dws	Key study	Frommholz (2010)
Apis mellifera L	10-d NOEDD = 4.8 µg/bee/day 10-d LDD50 >4.8 µg/bee/day	Summary	Kling (2014)
Apis mellifera L	22-d NOEDD = 171.04 µg/larval	Summary	Jeker (2013)
Aphidius rhopalosiphi	Desmedipham not harmful to foraging adult wasps at application rates of up to 3 L product/ha	Study was not found in the dRAR.	Baxter (1999)
Aphidius rhopalosiphi	48-h LR50 = 398.8 mL prod./ha	Study with NTAs (Aphidius rhopalosiphi) is not a data requirement.	Jans (2013)
Typhlodromus pyri	It is considered unlikely that desmedipham, applied at rates up to 3 L/ha, will pose a significant risk to mite populations.	Study was not found in the dRAR.	Waltersdorfer (1999)
Typhlodromus pyri	7-d LR50 = 1214 mL prod./ha	Study with NTAs (Typhlodromus pyri) is not a data requirement.	Jans (2013)
Apis mellifera L (Honey bee)	Contact 48-h LD50 >100.6 µg a.s./bee Oral 48-h LD50 >100.6 µg a.s./bee	Summary	Sekine (2011)
Bombus terrestris (Bumble bee)	48 h - LD50 contact = 100 µg a.s./bumble bee	Acute oral and contact bumble bee study is not a data requirement. No validated TG is available.	Kling (2014)

 

Key value for chemical safety assessment

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

316 mg/kg soil dw