- Email: [email protected]
Side effects of selected pesticides on earthworms under laboratory and field conditions
Soil Biol. Biochem. Vol. 24, No. 12, pp. 1711-1714. 1992
Printed in GreatBritain. All rightsreserved
Copyright 0
SIDE EFFECTS OF SELECTED PESTICIDES EARTHWORMS UNDER LABORATORY AND FIELD CONDITIONS
0038-07 I7/92 S5.00 + 0.00 1992 Pcrgamon Press Ltd
ON
HARTMUTKULA’* and CHRISTINEKOKTA~ ‘Zoologisches Institut, TU Braunschweig, Pockelsstrasse IOa, D-3300 Braunschweig and ‘Biologische Bundesanstalt fur Land- und Forstwirtschaft, Fachgruppe fur zoologische Mittelprilfung, Messeweg I l/12, D-3300 Braunschweig, Germany
Sununary-Acute and sublethal toxic effects of the insecticides parathion and propoxur on earthworms were determined in laboratory and field tests. In acute toxicity tests according to OECD Guideline No. 207 Aporrectodea caliginosa SAV. and Aporrectodea longa UDE were more susceptible than Eisenia fetida SAV. In prolonged toxicity tests with E./efida parathion significantly reduced the number of cocoons and surviving juveniles whereas propoxur reduced the number of surviving juveniles only. Results from these laboratory tests were used to explain species-specific effects of the insecticides in a field study.
INTRODUCTION Pesticides used in agroecosystems may cause hazard to non-target organisms, for example soil organisms (Edwards and Thompson, 1973). Within the different taxonomic groups of soil organisms, earthworms play an important role in degradation of organic matter and improving and maintaining soil structure (Edwards and Lofty, 1977). Therefore information about pesticide effects on earthworms is necessary before using these pesticides in agriculture. In order to improve knowledge and methods for routine testing, selected pesticides were studied in the laboratory and in the field. This paper will deal with the effects of two insecticides: “E 605 forte” (active ingredient: parathion) and “Unden fliissig” (active ingredient: propoxur). METHODS
Acute toxicity test
Tests for acute toxicity according to OECD-guideline No. 207 (Anonymous, 1984) were carried out with adult, laboratory bred Eirenia fetida SAV., and adult, field captured Aporrectodea caliginosa SAV., Aporrectodea longa UDE and Alloiobophora chlorotica SAV. Following a preincubation period of 1 day in moist “artificial soil”, consisting of 10% spagnum peat, 69% fine sand, 20% kaolin clay and 1% calcium carbonate, the animals were introduced into artificial soil with different concentrations of the test substance. Test duration was 14 days. Aporrectodea and Allolobophora species were kept at 15°C and Eisenia fetida at 20°C. LC% values were calculated by probit analysis. *Author for correspondence.
Prolonged toxicity test In order to observe effects on live weight and reproduction, test substances were homogeneously sprayed on the soil surface of test boxes containing 2 kg (dry wt) of artificial soil and 20 individuals of E. fetida (soil surface contamination). Parathion was tested with a normal application rate of 210 ml ha-’ and a IO-fold overdose. Propoxur was only tested with a normal application rate of 900 ml ha-‘. In another experimental design the amount of test substance according to the surface of the test box was mixed into the soil homogeneously (total contamination). For practical reasons the amount of water used to apply the test substance was 20 times the normal rate used in agricultural applications. Following the application of the test substance finely ground cattle manure as food source was spread on the surface of the test box and moistened. Test animals were fed once a week. The studies lasted 6-8 weeks. Multiple t-test by Tukey (Weber, 1986) was used to calculate significant differences. Field test
An orchard without pesticide treatments for the last 4 yr was used for field studies. Size of test plots was 14 x 14m with 2 m wide guard rows. Each treatment was replicated four times and compared to untreated control plots. The orchard was mown before application’in late spring. Parathion was applied at a normal rate of 210 ml ha-‘, propoxur at a normal rate of 900ml ha-‘. Earthworms from treated and untreated plots were sampled I,4 and 12 months after treatment with the formalin expellent method (IO litres of 0.2% formaldehyde solution, 2 x 15 min extraction). 1711
1712
HARTMLT KL.LAand
Table 1. LCw, (mg pesticide kg-’ dry substrate) of parathion and propoxur for different earthworm species (test according to OECD guideline No. 207) Parathion
Species Eismio feridu Aporrecrodea caliginosa Aporrecrodea longa Aii~~abap~ora chlororico
460 (400-528)’ 126 (88-181) 119(78-181) 577 (38%.9S9)
Propoxur 291 (180472) 4.5 (3.2-6.4) 3.8 (U-4.9)
ND
CHRSTIS KOKTA Results for parathion were confirmed in another experiment with only soil surface contamination (normal application rate and IO-fold overdose), where similar reductions in juvenile numbers could be observed. Reductions of cocoon production showed the same tendencies, but were not significantly different due to the great variability between test boxes.
*In parentheses: 95% confidence limits.
Field test
At each sampling date, S-10 samples of 0.25 m2 were taken per test plot. Earthworms were stored in 5% formaldehyde solution. For determination of biomass the fixed animals were cleaned, dried on filter paper and weighed. RESULTS
Acute tosicity test
Different mortality was observed between Efetida and Aporrectodea caliginosa, Aporrectodea longa and Allolobophora chlorotica (Table 1). Weight development seemed to be a sensitive parameter considering sublethal effects. At low pesticide concentrations without mortality earthworms lost up to 25% of live weight compared to the beginning of the test, whereas control animals kept their initial live weight. Prolonged toxicity test
During the experiments no adult mortality occurred, not even in a IO-fold overdose treatment with parathion. Concerning propoxur (Table 2) significant differences (P < 0.05) in numbers of juveniles between control and the different treatments were found. In contrast, cocoon production seemed to be equal in all treatment groups (no significant difference, P = 0.05).
Concerning parathion (Table 3), control showed 2.5 and 3.6 times more juveniles than test boxes with soil surface contamination, which had been sprayed with normal rate or a lo-fold overdose respectiveiy. These differences were significant (P < 0.05), whereas the test boxes with total soil contamination did not differ from the control. Regarding the number of cocoons, all treated boxes showed significant (P c 0.05) lower cocoon production compared to control. In both experiments, treatments themselves did not differ significantly from each other.
Mean earthworm abundance in control plots was 420 ind. me2 and mean earthworm biomass was 143 g m-* (formalin expellent method, autumn samples). In the following changes in percent are always related to control plot values of corresponding sampling date. The tested pesticides had different effects on earthworm populations. Parathion test plots showed overall decreases in earthworm abundance and biomass (Table 4). These could still be observed 1 yr after application of the pesticide. Juveniles seemed to be more susceptible to pesticides than adults. Table 5 demonstrates for the anecic L. terrestris and Table 6 for the endogeic Aporrectodea caliginosa, A. rosea and Al~olobopho~a chiorotica that reduction of juveniles was nearly always higher than reduction of adults. For parathion these results could be demonstrated for all three ecological groups (Bouchi, 1977) of earthworms (L. terrestris, L. castanew, Allolobophora chlorotica and Aporrectodea spp.). Propoxur test plots, in contrast, showed a smaller overall short-term reduction 1 month after application, whereas 4 months later in autumn, earthworm abundance and biomass was slightly higher than in control plots (Table 4). Unfortunately no sampling could be done 1 yr after application because of dry weather conditions. In spite of the increase in overall abundance of L. terrestris in treated plots in juveniles showed a higher reduction autumn, (Table 5). Juveniles of Aporrectodea caliginosa, A. rosea and Allolobophora chlorotica, in contrast, were more abundant in treated than in control plots. DISCUSSION
Species specific sensitivity towards pesticides, as described for E. fetida and L. terrestris (Haque and Ebing, 1983; Heimbach, 1985) could also be demonstrated for E. fetida and indigenous species of the genera Aporrectodea and Ailo[obophora. These
Table 2. Protonged toxicity test with propoxur (8 weeks, 20 individuals of E.felidoper replicate. 4 replicates per treatment) Treatment and concentration Control Soil surface contamination Total contamination
lSi&icant
Mortality (Oh)
Number of juveniles
Number of cocoonst
Weight changes: (%)
0
305 k 36
37&6’
+-I9
xI
0
I50 k48’
521 14 NS
+57
xt
0
188 t 29’
3825
+58
NS
difference against control (P c 0.05; multiple t-test by Tukey). t&coons not yet hatched. $Total biomass of adults and juveniles.
Side effects of selected
pesticides
on earthworms
under
laboratory
and field conditions
Table 3. Prolonged toxicity test with parathion (6 weeks, 20 individuals of E./&da per replicate. 4 rtalicates txr treatment) Treatment and concentration
Mortality (%l 0
Control
Soil surface contamination Soil surface contamination Total contamination
Number of iuveniles
Number of
127i27
Weight changesf
COCOOflSt
(%)
s7* IO
+34
xI
0
52 * 30.
35 * 98
+30
x IO
0
35+77’
32 f 7.
+25
xI
0
89 + 42 NS
29+3*
+34
‘Significant difference against control (P c 0.05: multiple f-test by Tukey). tCocoons not yet hatched. :Total biomass of adults and juveniles.
Table 4. Effects of parathion and propoxur on abundance and biomass of earthworms: differences to control plots in % (mean out of 3-l replicates with &IO samples each) I Month (%) Parathion Individuals mm2 g m-r Propoxur Individuals m-* I m-r
4 Months (%) I2 Months (%) Followina atmlication
-42 -38
-13 -a
-30 -23
-26 -25
fl4 +17
ND ND
Table 5. Effects of parathion and propoxur on abundance and biomass of different lifestages of L. rerresrris: differences to control plots in % (mean out of 3-4 replicates with &IO samDIes each) Parathion 4 Months (%)
Individuals g m-c Subadults* Individuals g m-’ Juveniles Individuals g m-r Sum Individuals a m-r
Propoxur
I2 Months 4 Months (%) (“/) Following application
12 Months (%)
m-*
+8 f4
-34 -31
+34 i-26
ND ND
m-r
-16 -31
f13 -8
-4 -8
ND ND
m-*
-II -II
-43 -46
-35 -10
ND ND
m-r
-6 -7
-28 -2s
+2 + 14
ND ND
*Subadults: animal length 24 cm, without clitellum.
Table 6. Effects of parathion and propoxur on abundance and biomass of different lifestages of Apporectoden caliginoso, A. rosecz, and Allolobophoro chlorotico: differences to control plots in % (mean out of 3-4 replicates with S-IO samples each) Parathion 4 Months (%) Adults Individuals m-* g m-r Juveniles Individuals m-r g m-r Sum Individuals m-* g me2
Propoxur
12 Months 4 Months (%) (%) Followinn atmlication
12 Months (%)
-10 -13
-14 -7
f4 +4
ND ND
-21 -24
-44 -26
+I5 +21
ND ND
-18 -20
-35 - I4
fl2 + I4
ND ND
1713
1714
HARTML?
HULA and
differences must be considered when only E. fetida is used as laboratory test species to detect harmful pesticides. Change in live weight appeared to be a sensitive parameter for the determination of sublethal effects. Weight losses were observed at low concentrations of the test substances where mortality did not yet occur. Furthermore these low test concentrations are equivalent to normal field concentrations. More detailed information could be derived from prolonged toxicity tests, because reproduction can be used as additional criterion. As there might exist an inverse relationship between reproduction (i.e. cocoon production) and body weight (‘Van Gestel et al., 1989) both parameters should be tested. The advantage of the described testing procedure is the simulation of a field-like exposure of the pesticide {i.e. soil surface contamination). In soil surface treatments with parathion a threshold concentration for pesticide effects seemed already to be reached at a normal application rate because effects did not rise with a IO-fold concentration increase in the application rate. Parathion may directly affect cocoon production which was significantly lower in all treatments. The lower juvenile numbers in propoxur treatments could not be explained by reduced cocoon production, but may be the consequence of increased juvenile mortality after hatching. Another possibility may be a reduced hatching rate or a reduced number of juveniles per cocoon. These arguments may also hold for parathion treatments. Parathion, which is reported to be moderately toxic (Lee, 1983, caused more severe effects on field populations of earthworms (Tables 4-6) than propoxur, although propoxur showed a higher acute toxicity in laboratory experiments (Table 1). The differences between the pesticides may be explained by differences in pesticide behaviour according to physical and chemical properties when reaching the soil. Application mode and weather conditions can also play an important role for the distribution of pesticides in soil. The higher decrease in juvenile abundance compared to that of adults can be explained by the fact that upper soil layers are the preferred habitat of juveniles (Lee, 1985). Because juveniles are unable to escape into deeper soil Iayers they may be exposed to higher pesticide concentrations. These explanations may especially be valid for species with long juvenile development. For example,
CnaisnNE
KOKTA
it can be assumed for L. terrestris that juveniles were
abundant at the date of application and suffered from direct toxic effects of both pesticides tested. In other species, direct effects on reproduction (i.e. reduction in cocoon production) might be more important as demonstrated in proIonged laboratory experiments. Concerning parathion, cocoon production was significantly lower in all treatments. This corresponds to decreased juvenile abundance in all three ecological groups of earthworms in all parathion plots in the field. For propoxur, which is of lower stability, direct toxicity may have been of more importance. This can be an explanation for a decrease only in L. terrestris juveniles, whereas juveniles of Aporrectodea culiginosa, A. rosea and AIlolobophoru eb~orotic~, which were not abundant in propoxur plots at the date of application could not suffer from direct toxic effects. It can be concluded that acute toxicity tests according to OECD guideline No. 207 are helpful for a first screening of pesticides, but prolonged toxicity tests give more information, especially on sublethal effects (reproduction, weight development). This information about chronic effects may be important to understand data from field tests, which normally show a great variability and therefore are difficult to interpret. REFERENCES Anonymous (1984) OECD Guideline for testing of chemicals No. 207. Earthworm, acute toxicity test. 4 April 1984. Bouche M. B. (1977) Strategies iomb~ciennes. Ecologicaf Bulletin 25, 122-132.
Edwards C. A. and Lofty J. R. (1977)Biohqy of Eurrhworms, 2nd Edn. Chapman & Hall, London. Edwards C. A. and Thompson A. R. (1973) Pesticides and the soil fauna. Residue Reviews 45, 1-79. Haoue A. and Ebing W. (1983) Toxicity determination of pesticides tQ earthworms in the soil substrate. Zeiuchri/l fir Pflunzenkrankheiren und Pflanzenschurz 90. 395-408.
Heimbach F. (1985) Comparison of laboratory methods, using Eifenia foetida and Lumbricus terresiris, for the assessment of the hazard of chemicals to earthworms. Zeitschrifttfir P~anzenkrunkheiren und P$an:enschurz 92, 186193, Lee K. E. (1985) Earthworms, Their Ecology and Relationships with Soil and Land Use. Academic Press, New York.
Van Gestel C. A. M., Van Dis V. A., Van Breemen E. M. and Sparenburg P. M. (1989) Development of a standardized reproduction toxicity test with the earthworm species Eiseni~fetida andrei using copper, pentachlorophenol, and 2,4-dichloroaniline. Ecotoxicology and Encironmental Sufety 18, 305-312.
Weber E. (1986) Grundriss der Biologischen Staristik. VEB Fischer, Jena.
Printed in GreatBritain. All rightsreserved
Copyright 0
SIDE EFFECTS OF SELECTED PESTICIDES EARTHWORMS UNDER LABORATORY AND FIELD CONDITIONS
0038-07 I7/92 S5.00 + 0.00 1992 Pcrgamon Press Ltd
ON
HARTMUTKULA’* and CHRISTINEKOKTA~ ‘Zoologisches Institut, TU Braunschweig, Pockelsstrasse IOa, D-3300 Braunschweig and ‘Biologische Bundesanstalt fur Land- und Forstwirtschaft, Fachgruppe fur zoologische Mittelprilfung, Messeweg I l/12, D-3300 Braunschweig, Germany
Sununary-Acute and sublethal toxic effects of the insecticides parathion and propoxur on earthworms were determined in laboratory and field tests. In acute toxicity tests according to OECD Guideline No. 207 Aporrectodea caliginosa SAV. and Aporrectodea longa UDE were more susceptible than Eisenia fetida SAV. In prolonged toxicity tests with E./efida parathion significantly reduced the number of cocoons and surviving juveniles whereas propoxur reduced the number of surviving juveniles only. Results from these laboratory tests were used to explain species-specific effects of the insecticides in a field study.
INTRODUCTION Pesticides used in agroecosystems may cause hazard to non-target organisms, for example soil organisms (Edwards and Thompson, 1973). Within the different taxonomic groups of soil organisms, earthworms play an important role in degradation of organic matter and improving and maintaining soil structure (Edwards and Lofty, 1977). Therefore information about pesticide effects on earthworms is necessary before using these pesticides in agriculture. In order to improve knowledge and methods for routine testing, selected pesticides were studied in the laboratory and in the field. This paper will deal with the effects of two insecticides: “E 605 forte” (active ingredient: parathion) and “Unden fliissig” (active ingredient: propoxur). METHODS
Acute toxicity test
Tests for acute toxicity according to OECD-guideline No. 207 (Anonymous, 1984) were carried out with adult, laboratory bred Eirenia fetida SAV., and adult, field captured Aporrectodea caliginosa SAV., Aporrectodea longa UDE and Alloiobophora chlorotica SAV. Following a preincubation period of 1 day in moist “artificial soil”, consisting of 10% spagnum peat, 69% fine sand, 20% kaolin clay and 1% calcium carbonate, the animals were introduced into artificial soil with different concentrations of the test substance. Test duration was 14 days. Aporrectodea and Allolobophora species were kept at 15°C and Eisenia fetida at 20°C. LC% values were calculated by probit analysis. *Author for correspondence.
Prolonged toxicity test In order to observe effects on live weight and reproduction, test substances were homogeneously sprayed on the soil surface of test boxes containing 2 kg (dry wt) of artificial soil and 20 individuals of E. fetida (soil surface contamination). Parathion was tested with a normal application rate of 210 ml ha-’ and a IO-fold overdose. Propoxur was only tested with a normal application rate of 900 ml ha-‘. In another experimental design the amount of test substance according to the surface of the test box was mixed into the soil homogeneously (total contamination). For practical reasons the amount of water used to apply the test substance was 20 times the normal rate used in agricultural applications. Following the application of the test substance finely ground cattle manure as food source was spread on the surface of the test box and moistened. Test animals were fed once a week. The studies lasted 6-8 weeks. Multiple t-test by Tukey (Weber, 1986) was used to calculate significant differences. Field test
An orchard without pesticide treatments for the last 4 yr was used for field studies. Size of test plots was 14 x 14m with 2 m wide guard rows. Each treatment was replicated four times and compared to untreated control plots. The orchard was mown before application’in late spring. Parathion was applied at a normal rate of 210 ml ha-‘, propoxur at a normal rate of 900ml ha-‘. Earthworms from treated and untreated plots were sampled I,4 and 12 months after treatment with the formalin expellent method (IO litres of 0.2% formaldehyde solution, 2 x 15 min extraction). 1711
1712
HARTMLT KL.LAand
Table 1. LCw, (mg pesticide kg-’ dry substrate) of parathion and propoxur for different earthworm species (test according to OECD guideline No. 207) Parathion
Species Eismio feridu Aporrecrodea caliginosa Aporrecrodea longa Aii~~abap~ora chlororico
460 (400-528)’ 126 (88-181) 119(78-181) 577 (38%.9S9)
Propoxur 291 (180472) 4.5 (3.2-6.4) 3.8 (U-4.9)
ND
CHRSTIS KOKTA Results for parathion were confirmed in another experiment with only soil surface contamination (normal application rate and IO-fold overdose), where similar reductions in juvenile numbers could be observed. Reductions of cocoon production showed the same tendencies, but were not significantly different due to the great variability between test boxes.
*In parentheses: 95% confidence limits.
Field test
At each sampling date, S-10 samples of 0.25 m2 were taken per test plot. Earthworms were stored in 5% formaldehyde solution. For determination of biomass the fixed animals were cleaned, dried on filter paper and weighed. RESULTS
Acute tosicity test
Different mortality was observed between Efetida and Aporrectodea caliginosa, Aporrectodea longa and Allolobophora chlorotica (Table 1). Weight development seemed to be a sensitive parameter considering sublethal effects. At low pesticide concentrations without mortality earthworms lost up to 25% of live weight compared to the beginning of the test, whereas control animals kept their initial live weight. Prolonged toxicity test
During the experiments no adult mortality occurred, not even in a IO-fold overdose treatment with parathion. Concerning propoxur (Table 2) significant differences (P < 0.05) in numbers of juveniles between control and the different treatments were found. In contrast, cocoon production seemed to be equal in all treatment groups (no significant difference, P = 0.05).
Concerning parathion (Table 3), control showed 2.5 and 3.6 times more juveniles than test boxes with soil surface contamination, which had been sprayed with normal rate or a lo-fold overdose respectiveiy. These differences were significant (P < 0.05), whereas the test boxes with total soil contamination did not differ from the control. Regarding the number of cocoons, all treated boxes showed significant (P c 0.05) lower cocoon production compared to control. In both experiments, treatments themselves did not differ significantly from each other.
Mean earthworm abundance in control plots was 420 ind. me2 and mean earthworm biomass was 143 g m-* (formalin expellent method, autumn samples). In the following changes in percent are always related to control plot values of corresponding sampling date. The tested pesticides had different effects on earthworm populations. Parathion test plots showed overall decreases in earthworm abundance and biomass (Table 4). These could still be observed 1 yr after application of the pesticide. Juveniles seemed to be more susceptible to pesticides than adults. Table 5 demonstrates for the anecic L. terrestris and Table 6 for the endogeic Aporrectodea caliginosa, A. rosea and Al~olobopho~a chiorotica that reduction of juveniles was nearly always higher than reduction of adults. For parathion these results could be demonstrated for all three ecological groups (Bouchi, 1977) of earthworms (L. terrestris, L. castanew, Allolobophora chlorotica and Aporrectodea spp.). Propoxur test plots, in contrast, showed a smaller overall short-term reduction 1 month after application, whereas 4 months later in autumn, earthworm abundance and biomass was slightly higher than in control plots (Table 4). Unfortunately no sampling could be done 1 yr after application because of dry weather conditions. In spite of the increase in overall abundance of L. terrestris in treated plots in juveniles showed a higher reduction autumn, (Table 5). Juveniles of Aporrectodea caliginosa, A. rosea and Allolobophora chlorotica, in contrast, were more abundant in treated than in control plots. DISCUSSION
Species specific sensitivity towards pesticides, as described for E. fetida and L. terrestris (Haque and Ebing, 1983; Heimbach, 1985) could also be demonstrated for E. fetida and indigenous species of the genera Aporrectodea and Ailo[obophora. These
Table 2. Protonged toxicity test with propoxur (8 weeks, 20 individuals of E.felidoper replicate. 4 replicates per treatment) Treatment and concentration Control Soil surface contamination Total contamination
lSi&icant
Mortality (Oh)
Number of juveniles
Number of cocoonst
Weight changes: (%)
0
305 k 36
37&6’
+-I9
xI
0
I50 k48’
521 14 NS
+57
xt
0
188 t 29’
3825
+58
NS
difference against control (P c 0.05; multiple t-test by Tukey). t&coons not yet hatched. $Total biomass of adults and juveniles.
Side effects of selected
pesticides
on earthworms
under
laboratory
and field conditions
Table 3. Prolonged toxicity test with parathion (6 weeks, 20 individuals of E./&da per replicate. 4 rtalicates txr treatment) Treatment and concentration
Mortality (%l 0
Control
Soil surface contamination Soil surface contamination Total contamination
Number of iuveniles
Number of
127i27
Weight changesf
COCOOflSt
(%)
s7* IO
+34
xI
0
52 * 30.
35 * 98
+30
x IO
0
35+77’
32 f 7.
+25
xI
0
89 + 42 NS
29+3*
+34
‘Significant difference against control (P c 0.05: multiple f-test by Tukey). tCocoons not yet hatched. :Total biomass of adults and juveniles.
Table 4. Effects of parathion and propoxur on abundance and biomass of earthworms: differences to control plots in % (mean out of 3-l replicates with &IO samples each) I Month (%) Parathion Individuals mm2 g m-r Propoxur Individuals m-* I m-r
4 Months (%) I2 Months (%) Followina atmlication
-42 -38
-13 -a
-30 -23
-26 -25
fl4 +17
ND ND
Table 5. Effects of parathion and propoxur on abundance and biomass of different lifestages of L. rerresrris: differences to control plots in % (mean out of 3-4 replicates with &IO samDIes each) Parathion 4 Months (%)
Individuals g m-c Subadults* Individuals g m-’ Juveniles Individuals g m-r Sum Individuals a m-r
Propoxur
I2 Months 4 Months (%) (“/) Following application
12 Months (%)
m-*
+8 f4
-34 -31
+34 i-26
ND ND
m-r
-16 -31
f13 -8
-4 -8
ND ND
m-*
-II -II
-43 -46
-35 -10
ND ND
m-r
-6 -7
-28 -2s
+2 + 14
ND ND
*Subadults: animal length 24 cm, without clitellum.
Table 6. Effects of parathion and propoxur on abundance and biomass of different lifestages of Apporectoden caliginoso, A. rosecz, and Allolobophoro chlorotico: differences to control plots in % (mean out of 3-4 replicates with S-IO samples each) Parathion 4 Months (%) Adults Individuals m-* g m-r Juveniles Individuals m-r g m-r Sum Individuals m-* g me2
Propoxur
12 Months 4 Months (%) (%) Followinn atmlication
12 Months (%)
-10 -13
-14 -7
f4 +4
ND ND
-21 -24
-44 -26
+I5 +21
ND ND
-18 -20
-35 - I4
fl2 + I4
ND ND
1713
1714
HARTML?
HULA and
differences must be considered when only E. fetida is used as laboratory test species to detect harmful pesticides. Change in live weight appeared to be a sensitive parameter for the determination of sublethal effects. Weight losses were observed at low concentrations of the test substances where mortality did not yet occur. Furthermore these low test concentrations are equivalent to normal field concentrations. More detailed information could be derived from prolonged toxicity tests, because reproduction can be used as additional criterion. As there might exist an inverse relationship between reproduction (i.e. cocoon production) and body weight (‘Van Gestel et al., 1989) both parameters should be tested. The advantage of the described testing procedure is the simulation of a field-like exposure of the pesticide {i.e. soil surface contamination). In soil surface treatments with parathion a threshold concentration for pesticide effects seemed already to be reached at a normal application rate because effects did not rise with a IO-fold concentration increase in the application rate. Parathion may directly affect cocoon production which was significantly lower in all treatments. The lower juvenile numbers in propoxur treatments could not be explained by reduced cocoon production, but may be the consequence of increased juvenile mortality after hatching. Another possibility may be a reduced hatching rate or a reduced number of juveniles per cocoon. These arguments may also hold for parathion treatments. Parathion, which is reported to be moderately toxic (Lee, 1983, caused more severe effects on field populations of earthworms (Tables 4-6) than propoxur, although propoxur showed a higher acute toxicity in laboratory experiments (Table 1). The differences between the pesticides may be explained by differences in pesticide behaviour according to physical and chemical properties when reaching the soil. Application mode and weather conditions can also play an important role for the distribution of pesticides in soil. The higher decrease in juvenile abundance compared to that of adults can be explained by the fact that upper soil layers are the preferred habitat of juveniles (Lee, 1985). Because juveniles are unable to escape into deeper soil Iayers they may be exposed to higher pesticide concentrations. These explanations may especially be valid for species with long juvenile development. For example,
CnaisnNE
KOKTA
it can be assumed for L. terrestris that juveniles were
abundant at the date of application and suffered from direct toxic effects of both pesticides tested. In other species, direct effects on reproduction (i.e. reduction in cocoon production) might be more important as demonstrated in proIonged laboratory experiments. Concerning parathion, cocoon production was significantly lower in all treatments. This corresponds to decreased juvenile abundance in all three ecological groups of earthworms in all parathion plots in the field. For propoxur, which is of lower stability, direct toxicity may have been of more importance. This can be an explanation for a decrease only in L. terrestris juveniles, whereas juveniles of Aporrectodea culiginosa, A. rosea and AIlolobophoru eb~orotic~, which were not abundant in propoxur plots at the date of application could not suffer from direct toxic effects. It can be concluded that acute toxicity tests according to OECD guideline No. 207 are helpful for a first screening of pesticides, but prolonged toxicity tests give more information, especially on sublethal effects (reproduction, weight development). This information about chronic effects may be important to understand data from field tests, which normally show a great variability and therefore are difficult to interpret. REFERENCES Anonymous (1984) OECD Guideline for testing of chemicals No. 207. Earthworm, acute toxicity test. 4 April 1984. Bouche M. B. (1977) Strategies iomb~ciennes. Ecologicaf Bulletin 25, 122-132.
Edwards C. A. and Lofty J. R. (1977)Biohqy of Eurrhworms, 2nd Edn. Chapman & Hall, London. Edwards C. A. and Thompson A. R. (1973) Pesticides and the soil fauna. Residue Reviews 45, 1-79. Haoue A. and Ebing W. (1983) Toxicity determination of pesticides tQ earthworms in the soil substrate. Zeiuchri/l fir Pflunzenkrankheiren und Pflanzenschurz 90. 395-408.
Heimbach F. (1985) Comparison of laboratory methods, using Eifenia foetida and Lumbricus terresiris, for the assessment of the hazard of chemicals to earthworms. Zeitschrifttfir P~anzenkrunkheiren und P$an:enschurz 92, 186193, Lee K. E. (1985) Earthworms, Their Ecology and Relationships with Soil and Land Use. Academic Press, New York.
Van Gestel C. A. M., Van Dis V. A., Van Breemen E. M. and Sparenburg P. M. (1989) Development of a standardized reproduction toxicity test with the earthworm species Eiseni~fetida andrei using copper, pentachlorophenol, and 2,4-dichloroaniline. Ecotoxicology and Encironmental Sufety 18, 305-312.
Weber E. (1986) Grundriss der Biologischen Staristik. VEB Fischer, Jena.