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The toxicity of three pyrethroids to Amblyseius Fallacis (garman) acari. Phytoseiidae and their residues on apple foliage
Agriculture, Ecosystems and Environment, 14 (1985) 243--250
243
Elsevier Science Publishers B.V., Amsterdam -- Printed in The Netherlands
THE TOXICITY OF THREE PYRETHROIDS TO AMBL YSEIUS F A L L A C I S (GARMAN) ACARI. PHYTOSEIIDAE AND THEIR RESIDUES ON APPLE FOLIAGE 1
N.J. BOSTANIAN and A. BELANGER
Research Station, Agriculture Canada, P.O. Box 457, St.-Jean-sur-Richelieu, Qudbec J3B 6Z8 (Canada) Contribution No. J-989 (Accepted for publication 20 June 1985)
ABSTRACT
Bostanian, N.J. and Belanger, A., 1985. The toxicity of three pyrethroids to Amblyseius fallacis (Garman) Acari. Phytoseiidae and their residues on apple foliage. Agric. Ecosystems Environ., 14: 243--250. Permethrin 25WP, cypermethrin 12.5WP, 20WP and fenvalerate 30EC applied at petal fall against plant bugs and several lepidopterous pests leave detectable residues on the foliage for 124 days post-treatment. Residues declined rapidly (by 65--75%) for about 2 weeks post-treatment and then the dissipation rate decreased. Residues on the foliage were highly toxic to Amblyseius fallacis for at least 6 weeks post-treatment, when these phytoseiids were exposed in the laboratory to field-treated leaves.
INTRODUCTION
In Quebec apple orchards, synthetic pyrethroids are applied predominantly pre-bloom at the pink bud stage of development to control lepidopterous pests such as eyespotted bud moth, Spilonota ocellana (Denis & Schiffermiiller), oblique banded leafroller, Choristoneura rosaceana (Harris), speckled green fruitworm Orthosia hibisci Guenee, fruit tree leafroller Archips argyrospilus {Walker), leafminers and plant bugs. A second insecticide treatment is also applied at petal fall to obtain commercially acceptable control of these pests and others, such as the plum curculio Conotrachelus nenuphar (Herbst). Since Hoyt et al. (1978) and Roush and Hoy {1978) reported on the toxic effects of synthetic pyrethroids on phytophagous and predacious arthropods, considerable research has been devoted to explain the toxicity, residues and subtle effects of these insecticides on arthropods. Zwick 'Presented at the XVII International Congress of Entomology, Hamburg, Federal Republic of Germany, 20--26 August 1984.
0167-8809/85/$03.30
© 1985 Elsevier Science Publishers B.V.
244
and Fields (1978), reported that fenvalerate was very toxic to Typhlodromus pyri (Scheuten) and caused resurgences of European red mite, Panonychus ulmi (Koch), in apple orchards. Rock (1979) suggested that permethrin and fenvalerate would be detrimental to integrated mite-control programs. Hall (1979) confirmed the findings of Zwick and Fields (1978) and observed that synthetic pyrethroids appeared to cause behavioral changes in the plum curculio, (Conotrachelus nenuphar (Herbst)). Aliniazee and Cranham (1980) showed that treatments with permethrin, cypermethrin, fenvalerate and deltamethrin applied in apple orchards at "pink b u d " were highly toxic to Typhlodromus pyri (Scheuten) in England. Other investigators who have confirmed or added additional information on the effects of synthetic pyrethroids to predatory arthropods include Wong and Chapman (1979); Riedl and Hoying (1980); Penman and Chapman (1980); Penman et al. (1981); Croft et al. (1982); Hull and Van Starner (1983) and Riedl and Hoying (1983). Studies have also been made to determine the metabolism and residues of these synthetic pyrethroids in plants. Talekar (1977) described a residue methodology for fenvalerate in cabbage; Chiba (1978) studied permethrin isomers in peach leaves. Residues of these insecticides in various food crops have also been reported by Harris et al. (1978); Greenberg (1981); Hill et al. (1982); Shwe Yin Tan (1983) and B~langer et al. (1985). Bostanian et al. (1985) showed that two to three treatments with synthetic pyrethroids to suppress Rhagoletis pomonella (Walsh) activity in July and early August in apple orchards was very toxic to Amblyseius fallacis and resulted in appreciable residues on the foliage. In this study, we measured residues of permethrin, fenvalerate and cypermethrin on apple foliage and determined their effects on Amblyseius fallacis. This predacious mite was exposed in the laboratory to apple foliage treated only once at petal fall with these three insecticides. It was hoped that such an early treatment would allow residues of these insecticides to dissipate before the appearance of large numbers of Amblyseius fallacis on the trees later in the season. MATERIAL AND METHODS
The field work was conducted at the Agriculture Canada Experimental orchard at Frelighsburg, Quebec. A randomized complete block design was used. Each block consisted of 3 standard mature apple trees (cultivar McIntosh) in row and replicated three times. Between each replicate, a row and sometimes two rows of trees were left untreated as buffer. Insecticides were applied with a Swanson air-blast sprayer adjusted at 1200 kPa and delivering 900 1 of spray material per ha. The insecticides applied, rates, formulation and dates of application are reported in Tables I--IV.
245 TABLE I Residues of three synthetic pyrethroids on apple foliage, Frelighsburg, Quebec, 1980 Insecticides and trade designation
Residues in ug cm -2 at different days post-treatment Rate ga.i. ha -1 0 8 50 77 124
Permethrin 200 Ambush 25WP
ug cm -2 1.160 0.360 -+0.141 -+0.010 SD a % (100) (31.0)
Permethrin 100 Ambush 25WP
ug c m SD %
Fenvalerate Belmark 30EC
140
ug cm-2 SD %
Cypermethrin Ripcord 20WP
100
ug cm -2 0.402 0.128 SD -+0.079 -+0.018 % (100) (31.8)
-2
0.062 -+0.013 (5.3)
0.101 -+0.014 (8.7)
0.110 ±0.025 (9.5)
0.450 0.160 0.046 -+0.036 -+0.00 -+0.019 (100) (35.6) (10.2)
0.033 -+0.010 (7.3)
0.035 ±0.010 (7.8)
0.957 0.273 0.125 0.226 0.128 -+0.202 -+0.097 -+0.012 -+0.087 -+0.046 (100) (28.5) (13.1) (23.6) (13.4) 0.018 -+0.00 (4.5)
0.029 -+0.009 (7.2)
0.024 ~0.006 (6)
aSD = standard deviation, mean (-+ SD) of 3 replicates, each replicate the mean of 2 readings.
TABLE II Residues of four synthetic pyrethroids on apple foliage, Frelighsburg, Quebec, 1981 Insecticides and trade designation
Rate Residues in ug cm -2 at different days post-treatment ga.i. ha -1 0 14 26 60 83
Permethrin Ambush25WP
150
ug cm -2 0.650 0.123 0.096 SD a +0.042 -+0.051 -+0.084 % (100) (18.9) (14.8)
Fenvalerate Belmark30EC
140
ug cm -2 0.703 0.175 0.175 0.079 0.085 0.111 SD -+0.159 -+0.061 -+0.066 -+0.030 -+0.032 -+0.030 % (100) (24.9) (24.9) (11.2) (12.1) (15.8)
Cypermethrin 100 Cymbush12.5WP
ug cm -~ 0.290 0.086 0.071 0.042 0.036 0.033 SD -+0.004 -+0.043 +-0.025 +-0.025 -+0.025 -+0.012 % (100) (29.7) (24.5) (14.5) (12.4) (11.4)
Cypermethrin R i p co r d 2 0 WP
~g cm -2 0.605 0.145 0.093 0.074 SD -+0.064 -+0.021 -+0.005 -+0.016 % (100) (24.0) (15.4) (12.2)
100
0.052 +-0.027 (8.0)
124
0.048 0.088 +-0.019 -+0.030 (7.3) (13.5)
0.060 0.079 -+0.003 -+0.013 (9.9) (13.1)
aSD = standard deviation, mean (-+ SD) of 3 replicates, each replicate the mean of 2 readings.
246 TABLE III Percent mortality of Amblyseius fallacis on apple foliage treated with synthetic pyrethroids at Petal Fall a, Quebec, 1980 Insecticides and trade designation
Rate Percent mortality b at different days post-treatment ga.i. ha -1 7 14 21 28 35 42
Permethrin Ambush 25WP
200
Permethrin Ambush 25WP
100
Fenvalerate Belmark 30EC
140
Cypermethrin Ripcord 20WP
100
Control
--
97.9
79.1
89.3
79.5
53.8
57.1 a c
75.0
66.7
53.8
46.21
53.6 a
95.8
84.2
97.2
87.2
71.8
78.5 a
93.8
89.0
80.4
94.9
84.6
53.5 a
0
0
12.5
18.8
18.8
12.5 b
100
aTreatment applied on 28 May 1980. bpercent mortality calculated according to Abbott (1925). (N = 96 adult mites per date). CColumn means not followed by the same letter are significantly different according to Duncan's multiple-range test at P = 0.05.
TABLE IV Percent mortality of Amblyseius fallacis on apple foliage treated with synthetic pyrethroids at Petal Fall a, Frelighsburg, Quebec, 1981 Insecticides and trade designation
Percent mortality b at different days post-treatment Rate ga.i. ha -~ 7 14 21 28 35 42
Permethrin Ambush 25WP
150
93.3
84.6
76.2
78.6
Fenvalerate Belmark 30EC
140
95.6
92.5
100.0
80.9
Cypermethrin Ripcord 20EC
100
93.3
96.2
88.1
35.1
61.5
84.0a
Cypermethrin 100 Cymbush 12.5WP
97.8
89.7
100.0
42.9
48.7
51.0 a
6.3
18.8
12.5
12.5
18.8
6.3 b
Control
--
53.8
62.0a c
100.0 8 4 . 4 a
aTreatment applied on 28 May 1981. bpercent mortality calculated according to Abbott (1925). (N = 96 adult mites per date). CColumn means not followed by the same letter are significantly different according to Duncan's multiple-range test at P = 0.05.
247
Toxicological methods One leaf per replicate was collected at weekly intervals at shoulder height (1.5 m) and brought to the laboratory. Sixteen adult females of Amblyseius fallacis were exposed to the leaves according to a m e t h o d described by Bostanian et al. {1985). Each treatment was replicated 6 times. Percent mortality was calculated 24 h after the mites were exposed to insecticide-treated leaves (Abbott, 1925). The control consisted of untreated apple leaves sprayed with tap water. The mortality data were arcsine transformed for analysis of variance (ANOVA).
Residue analysis Samples of 25 leaves per replicate were collected at shoulder height (1.5 m) around a tree. The surface area of the leaves was measured with a portable Li-Cor area meter (Li-Cor Inc., Lincoln, Nebraska, U.S.A.). The insecticides were extracted three times with glass-distilled acetone. The combined acetone extracts (total volume = 200 ml) were then partitioned between hexane and water and the aqueous layer was extracted two more times with hexane before being discarded. The combined hexane extracts were dried (anhydrous Na2SO4) and concentrated on a rotary evaporator before being quantitatively transferred to a 50-ml volumetric flask and brought to volume. All samples were refrigerated (2--3°C) until analysis. Aliquots of 1 pl were analyzed in duplicate with a Varian gas chromatograph model 3700. The extraction efficiency for the different insecticides was found to be 95% for cypermethrin, 101% for deltamethrin, 98% for fenvalerate and 97% for permethrin. Additional details on the extraction technique and the optimal operating parameters of the gas chromatograph are reported elsewhere (Bostanian et al., 1985). A measure of persistence was obtained by designating the initial residue level for each insecticide just after the spray had been applied and dried as 100% and, thereafter, the residues for each insecticide were expressed at different intervals of time as a percentage of the initial level. The mean and standard deviation (+ SD) were computed from three replicates, each replicate was the mean of two readings. RESULTS AND DISCUSSION
The data in Tables I and II reveal that when we designate the residue level just after a treatment had dried as 100%, then eight and fourteen days post-treatment, all products have dissipated to 1/3 and 1/4 of their original level. Thereafter, dissipation of the products continues, but at a slower rate. One hundred and twenty-four days later, fenvalerate was the most persistent pyrethroid in both years. She Yin Tan (1983) reported
248 fenvalerate to be more persistent than trans-permethrin, which in turn was more persistent than cis-permethrin. The cypermethrin (Ripcord) data for 1980 do not correspond with that of 1981 and we believe that in 1980, the cypermethrin (Ripcord) in the samples was partially degraded in storage because of a breakdown in refrigeration. The percent data in Table II indicate that all synthetic pyrethroids have approximately the same level of persistence. Chiba {1978) reported that on peach leaves, both isomers of permethrin dissipated at about the same rate. However, if actual residue data are examined, slight differences become apparent. Thus, in both years fenvalerate residues were highest (Tables I and II). Harris et al. {1978) reported higher residues of fenvalerate than permethrin 21 days post-treatment on celery. Furthermore, in this study, cypermethrin (Ripcord) residue levels were higher than cypermethrin (Cymbush) residue levels (Table II). The two products contain the same active ingredient and were applied at the same rate. They probably differ in their formulation ingredients, which may influence their persistence. A similar observation was made by Bostanian et al. (1985). The mortality data (Tables III and IV) reflect that these products remained more or less at the same level of toxicity for 6 weeks post-treatment, unlike the residue levels that decreased considerably in the first 2 weeks posttreatment. Thus, even after the rapid dissipation of synthetic pyrethroids in the first 2 weeks post-treatment, enough residues remained on the foliage to be highly toxic to AmbIyseius fallacis for another 4 weeks. The toxicity study was not continued any further as A. fallacis had already made its appearance in non-treated orchards and orchards under an integrated pestmanagement program. Thus, very low doses of these products are sufficient to cause high mortalities. Rock (1979) reported the LCs0 to be 1.4 ga.i. 100 1-1 for permethrin and 0.26 ga.i. 100 1-1 for fenvalerate. On pears in California, fenvalerate applied in spring was toxic to Typhlodromus occidentalis (Nesbitt) until leaf drop (Riedl and Hoying, 1983). CONCLUSIONS Our results indicate that permethrin, fenvalerate and cypermethrin, applied at petal fall against plant bugs and several lepidopterous pests, leave detectable residues on the foliage for 124 days. Although the residues decrease with time, the levels of synthetic pyrethroids remaining on the foliage are highly toxic to A. fallacis for at least 6 weeks post-treatment. Such toxicity would severely disrupt any integrated pest-management program for an apple orchard where A. fallacis is the principal predator of phytophagous mites. To include synthetic pyrethroids in integrated pest management programs, new strategies such as the mass rearing and release of synthetic pyrethroid-resistant strains of predacious mites (WhaIon et al., 1982) and other strategies (Bostanian et al., 1985) should be considered and evaluated.
249 ACKNOWLEDGEMENTS
We extend our appreciation to Mrs. F. Boudreau and D. Pitre for their assistance in collecting and analysing the samples.
REFERENCES Abbott, W.S., 1925. A method of computing the effectiveness of an insecticide. J. Econ. Entomol., 18: 265--267. Aliniazee, M.T. and Cranham, J.E., 1980. Effects of four synthetic pyrethroids on a predatory mite Typhlodromus pyri and its prey, Panonychus ulmi on apples in Southeast England. Environ. Entomol., 9: 436--439. B41anger, A., Bostanian, N.J. and Rivard, I., 1985. Apple maggot {Diptera: Trypetidae) control with insecticides and their residues in and on apples. J. Econ. Entomol., 78: 463--466. Bostanian, N.J., B61anger, A. and Rivard, I., 1985. Residues of four synthetic pyrethroids and azinphos-m6thyl on apple foliage and their toxicity to Amblyseius fallacis: Acari Phytoseiidae. Can Entomol., 117: 143--152. Chiba, M., 1978. A gas chromatographic determination of permethrin isomers on peach foliage. J. Environ. Sci. Health, Part B. Pestic. Food Contam. Agric. Wastes, 13: 261--268. Croft, B.A., Wagner, S.W. and Scott, J.G., 1982. Multiple and cross-resistance to insecticides in pyrethroid-resistant strains of the predatory mite, Amblyseius fallacis. Environ. Entomol., 11 : 161--164. Greenberg, R.S., 1981. Determination of fenvalerate, a synthetic pyrethroid, in grapes, peppers, apples and cottonseed by gas-liquid chromatography. J. Agric. Food Chem., 29: 856--860. Hall, R.F., 1979. Effects of synthetic pyrethroids on major insect and mite pests of apple. J. Econ. Entomol., 72: 441--446. Harris, C.R., Svec, H.J. and Chapman, R.A., 1978. Laboratory and field studies on the effectiveness and persistence of pyrethroid insecticides used for cabbage looper control. J. Econ. Entomol., 71: 642--644. Hill, B.D., Charnetski, W.A., Schaalje, G.B. and Schaber, B.D., 1982. Persistence of fenvalerate in alfalfa: Effects of growth dilution and heat units on residue half-life. J. Agric. Food Chem., 30: 653--657. Hoyt, S.C., Westigard, H. and Burts, E.C., 1978. Effects of two synthetic pyrethroids on the codling moth, pear psylla, and various mite species in Northwest apple and pear orchards. J. Econ. Entomol., 71: 431--434. Hull, L.A. and Starner, V.R., 1983. Impact of four synthetic pyrethroids on major natural enemies and pests of apple in Pennsylvania. J. Econ. Entomol., 76: 122-130. Penman, D.R. and Chapman, R.B., 1980. Woolly apple aphid outbreak following use of fenvalerate in apples in Canterbury, New Zealand. J. Econ. Entomol., 7 3 : 4 9 --51. Penman, D.R., Chapman, R.B. and Jesson, K.E., 1981. Effects of fenvalerate and azinphos-methyl on twospotted spider mite and phytoseiid mites. Entomol. Exp. Appl., 30: 91--97. Riedl, H. and Hoying, S.A., 1980. Impact of fenvalerate and diflubenzuron on target and non-target arthropod species on Bartlett pears in northern California. J. Econ. Entomol., 73: 117--122. Riedl, H. and Hoying, S.A., 1983. Toxicity and residual activity of fenvalerate to Typhlodromus occidentalis (Acari: Phytoseiidae) and its prey Tetranychus urticae (Acari: Tetranychidae) on pear. Can. Entomol., 115 : 807--813.
250 Rock, G.C., 1979. Relative toxicity of two synthetic pyrethroids to a predator Amblyseius fallacis and its prey Tetranychus urticae. J. Econ. Entomol., 72: 293--294. Roush, R.T. and Hoy, M.A., 1978. Relative toxicity of permethrin to a predator Metaseiulus occidentalis and its prey Tetranychus urticae. Environ. Entomol., 7 : 2 8 7 --288. Shwe Yin Tan, C., 1983. Analyses, persistence and degradation of the synthetic pyrethroid insecticides permethrin and fenvalerate. M.Sc. Thesis, Brock Univ., Ontario, Canada, 131 pp. Talekar, N.S., 1977. Gas--liquid chromatographic determination of cyano-3-phenoxylbenzyl -isopropyl-4-chlorophenyl acetate residues in cabbage. Assoc. Off. Anal. Chem., 60: 908--910. Whalon, M.E., Croft, B.A. and Mowry, T.M., 1982. Introduction and survival of susceptible and pyrethroid-resistant strains of Amblyseius fallacis (Acari: Phytoseiidae) in a Michigan apple orchard. Environ. Entomol., 11: 1096--1099. Wong, S.W. and Chapman, R.B., 1979. Toxicity of synthetic pyrethroid insecticides to predacious phytoseiid mites and their prey. Aust. J. Agric. Res., 30: 497--501. Zwick, R.W. and Fields, G.J., 1978. Field and laboratory evaluations of fenvalerate against several insect and mite pests of apple and pear in Oregon. J. Econ. Entomol., 71: 793--796.
243
Elsevier Science Publishers B.V., Amsterdam -- Printed in The Netherlands
THE TOXICITY OF THREE PYRETHROIDS TO AMBL YSEIUS F A L L A C I S (GARMAN) ACARI. PHYTOSEIIDAE AND THEIR RESIDUES ON APPLE FOLIAGE 1
N.J. BOSTANIAN and A. BELANGER
Research Station, Agriculture Canada, P.O. Box 457, St.-Jean-sur-Richelieu, Qudbec J3B 6Z8 (Canada) Contribution No. J-989 (Accepted for publication 20 June 1985)
ABSTRACT
Bostanian, N.J. and Belanger, A., 1985. The toxicity of three pyrethroids to Amblyseius fallacis (Garman) Acari. Phytoseiidae and their residues on apple foliage. Agric. Ecosystems Environ., 14: 243--250. Permethrin 25WP, cypermethrin 12.5WP, 20WP and fenvalerate 30EC applied at petal fall against plant bugs and several lepidopterous pests leave detectable residues on the foliage for 124 days post-treatment. Residues declined rapidly (by 65--75%) for about 2 weeks post-treatment and then the dissipation rate decreased. Residues on the foliage were highly toxic to Amblyseius fallacis for at least 6 weeks post-treatment, when these phytoseiids were exposed in the laboratory to field-treated leaves.
INTRODUCTION
In Quebec apple orchards, synthetic pyrethroids are applied predominantly pre-bloom at the pink bud stage of development to control lepidopterous pests such as eyespotted bud moth, Spilonota ocellana (Denis & Schiffermiiller), oblique banded leafroller, Choristoneura rosaceana (Harris), speckled green fruitworm Orthosia hibisci Guenee, fruit tree leafroller Archips argyrospilus {Walker), leafminers and plant bugs. A second insecticide treatment is also applied at petal fall to obtain commercially acceptable control of these pests and others, such as the plum curculio Conotrachelus nenuphar (Herbst). Since Hoyt et al. (1978) and Roush and Hoy {1978) reported on the toxic effects of synthetic pyrethroids on phytophagous and predacious arthropods, considerable research has been devoted to explain the toxicity, residues and subtle effects of these insecticides on arthropods. Zwick 'Presented at the XVII International Congress of Entomology, Hamburg, Federal Republic of Germany, 20--26 August 1984.
0167-8809/85/$03.30
© 1985 Elsevier Science Publishers B.V.
244
and Fields (1978), reported that fenvalerate was very toxic to Typhlodromus pyri (Scheuten) and caused resurgences of European red mite, Panonychus ulmi (Koch), in apple orchards. Rock (1979) suggested that permethrin and fenvalerate would be detrimental to integrated mite-control programs. Hall (1979) confirmed the findings of Zwick and Fields (1978) and observed that synthetic pyrethroids appeared to cause behavioral changes in the plum curculio, (Conotrachelus nenuphar (Herbst)). Aliniazee and Cranham (1980) showed that treatments with permethrin, cypermethrin, fenvalerate and deltamethrin applied in apple orchards at "pink b u d " were highly toxic to Typhlodromus pyri (Scheuten) in England. Other investigators who have confirmed or added additional information on the effects of synthetic pyrethroids to predatory arthropods include Wong and Chapman (1979); Riedl and Hoying (1980); Penman and Chapman (1980); Penman et al. (1981); Croft et al. (1982); Hull and Van Starner (1983) and Riedl and Hoying (1983). Studies have also been made to determine the metabolism and residues of these synthetic pyrethroids in plants. Talekar (1977) described a residue methodology for fenvalerate in cabbage; Chiba (1978) studied permethrin isomers in peach leaves. Residues of these insecticides in various food crops have also been reported by Harris et al. (1978); Greenberg (1981); Hill et al. (1982); Shwe Yin Tan (1983) and B~langer et al. (1985). Bostanian et al. (1985) showed that two to three treatments with synthetic pyrethroids to suppress Rhagoletis pomonella (Walsh) activity in July and early August in apple orchards was very toxic to Amblyseius fallacis and resulted in appreciable residues on the foliage. In this study, we measured residues of permethrin, fenvalerate and cypermethrin on apple foliage and determined their effects on Amblyseius fallacis. This predacious mite was exposed in the laboratory to apple foliage treated only once at petal fall with these three insecticides. It was hoped that such an early treatment would allow residues of these insecticides to dissipate before the appearance of large numbers of Amblyseius fallacis on the trees later in the season. MATERIAL AND METHODS
The field work was conducted at the Agriculture Canada Experimental orchard at Frelighsburg, Quebec. A randomized complete block design was used. Each block consisted of 3 standard mature apple trees (cultivar McIntosh) in row and replicated three times. Between each replicate, a row and sometimes two rows of trees were left untreated as buffer. Insecticides were applied with a Swanson air-blast sprayer adjusted at 1200 kPa and delivering 900 1 of spray material per ha. The insecticides applied, rates, formulation and dates of application are reported in Tables I--IV.
245 TABLE I Residues of three synthetic pyrethroids on apple foliage, Frelighsburg, Quebec, 1980 Insecticides and trade designation
Residues in ug cm -2 at different days post-treatment Rate ga.i. ha -1 0 8 50 77 124
Permethrin 200 Ambush 25WP
ug cm -2 1.160 0.360 -+0.141 -+0.010 SD a % (100) (31.0)
Permethrin 100 Ambush 25WP
ug c m SD %
Fenvalerate Belmark 30EC
140
ug cm-2 SD %
Cypermethrin Ripcord 20WP
100
ug cm -2 0.402 0.128 SD -+0.079 -+0.018 % (100) (31.8)
-2
0.062 -+0.013 (5.3)
0.101 -+0.014 (8.7)
0.110 ±0.025 (9.5)
0.450 0.160 0.046 -+0.036 -+0.00 -+0.019 (100) (35.6) (10.2)
0.033 -+0.010 (7.3)
0.035 ±0.010 (7.8)
0.957 0.273 0.125 0.226 0.128 -+0.202 -+0.097 -+0.012 -+0.087 -+0.046 (100) (28.5) (13.1) (23.6) (13.4) 0.018 -+0.00 (4.5)
0.029 -+0.009 (7.2)
0.024 ~0.006 (6)
aSD = standard deviation, mean (-+ SD) of 3 replicates, each replicate the mean of 2 readings.
TABLE II Residues of four synthetic pyrethroids on apple foliage, Frelighsburg, Quebec, 1981 Insecticides and trade designation
Rate Residues in ug cm -2 at different days post-treatment ga.i. ha -1 0 14 26 60 83
Permethrin Ambush25WP
150
ug cm -2 0.650 0.123 0.096 SD a +0.042 -+0.051 -+0.084 % (100) (18.9) (14.8)
Fenvalerate Belmark30EC
140
ug cm -2 0.703 0.175 0.175 0.079 0.085 0.111 SD -+0.159 -+0.061 -+0.066 -+0.030 -+0.032 -+0.030 % (100) (24.9) (24.9) (11.2) (12.1) (15.8)
Cypermethrin 100 Cymbush12.5WP
ug cm -~ 0.290 0.086 0.071 0.042 0.036 0.033 SD -+0.004 -+0.043 +-0.025 +-0.025 -+0.025 -+0.012 % (100) (29.7) (24.5) (14.5) (12.4) (11.4)
Cypermethrin R i p co r d 2 0 WP
~g cm -2 0.605 0.145 0.093 0.074 SD -+0.064 -+0.021 -+0.005 -+0.016 % (100) (24.0) (15.4) (12.2)
100
0.052 +-0.027 (8.0)
124
0.048 0.088 +-0.019 -+0.030 (7.3) (13.5)
0.060 0.079 -+0.003 -+0.013 (9.9) (13.1)
aSD = standard deviation, mean (-+ SD) of 3 replicates, each replicate the mean of 2 readings.
246 TABLE III Percent mortality of Amblyseius fallacis on apple foliage treated with synthetic pyrethroids at Petal Fall a, Quebec, 1980 Insecticides and trade designation
Rate Percent mortality b at different days post-treatment ga.i. ha -1 7 14 21 28 35 42
Permethrin Ambush 25WP
200
Permethrin Ambush 25WP
100
Fenvalerate Belmark 30EC
140
Cypermethrin Ripcord 20WP
100
Control
--
97.9
79.1
89.3
79.5
53.8
57.1 a c
75.0
66.7
53.8
46.21
53.6 a
95.8
84.2
97.2
87.2
71.8
78.5 a
93.8
89.0
80.4
94.9
84.6
53.5 a
0
0
12.5
18.8
18.8
12.5 b
100
aTreatment applied on 28 May 1980. bpercent mortality calculated according to Abbott (1925). (N = 96 adult mites per date). CColumn means not followed by the same letter are significantly different according to Duncan's multiple-range test at P = 0.05.
TABLE IV Percent mortality of Amblyseius fallacis on apple foliage treated with synthetic pyrethroids at Petal Fall a, Frelighsburg, Quebec, 1981 Insecticides and trade designation
Percent mortality b at different days post-treatment Rate ga.i. ha -~ 7 14 21 28 35 42
Permethrin Ambush 25WP
150
93.3
84.6
76.2
78.6
Fenvalerate Belmark 30EC
140
95.6
92.5
100.0
80.9
Cypermethrin Ripcord 20EC
100
93.3
96.2
88.1
35.1
61.5
84.0a
Cypermethrin 100 Cymbush 12.5WP
97.8
89.7
100.0
42.9
48.7
51.0 a
6.3
18.8
12.5
12.5
18.8
6.3 b
Control
--
53.8
62.0a c
100.0 8 4 . 4 a
aTreatment applied on 28 May 1981. bpercent mortality calculated according to Abbott (1925). (N = 96 adult mites per date). CColumn means not followed by the same letter are significantly different according to Duncan's multiple-range test at P = 0.05.
247
Toxicological methods One leaf per replicate was collected at weekly intervals at shoulder height (1.5 m) and brought to the laboratory. Sixteen adult females of Amblyseius fallacis were exposed to the leaves according to a m e t h o d described by Bostanian et al. {1985). Each treatment was replicated 6 times. Percent mortality was calculated 24 h after the mites were exposed to insecticide-treated leaves (Abbott, 1925). The control consisted of untreated apple leaves sprayed with tap water. The mortality data were arcsine transformed for analysis of variance (ANOVA).
Residue analysis Samples of 25 leaves per replicate were collected at shoulder height (1.5 m) around a tree. The surface area of the leaves was measured with a portable Li-Cor area meter (Li-Cor Inc., Lincoln, Nebraska, U.S.A.). The insecticides were extracted three times with glass-distilled acetone. The combined acetone extracts (total volume = 200 ml) were then partitioned between hexane and water and the aqueous layer was extracted two more times with hexane before being discarded. The combined hexane extracts were dried (anhydrous Na2SO4) and concentrated on a rotary evaporator before being quantitatively transferred to a 50-ml volumetric flask and brought to volume. All samples were refrigerated (2--3°C) until analysis. Aliquots of 1 pl were analyzed in duplicate with a Varian gas chromatograph model 3700. The extraction efficiency for the different insecticides was found to be 95% for cypermethrin, 101% for deltamethrin, 98% for fenvalerate and 97% for permethrin. Additional details on the extraction technique and the optimal operating parameters of the gas chromatograph are reported elsewhere (Bostanian et al., 1985). A measure of persistence was obtained by designating the initial residue level for each insecticide just after the spray had been applied and dried as 100% and, thereafter, the residues for each insecticide were expressed at different intervals of time as a percentage of the initial level. The mean and standard deviation (+ SD) were computed from three replicates, each replicate was the mean of two readings. RESULTS AND DISCUSSION
The data in Tables I and II reveal that when we designate the residue level just after a treatment had dried as 100%, then eight and fourteen days post-treatment, all products have dissipated to 1/3 and 1/4 of their original level. Thereafter, dissipation of the products continues, but at a slower rate. One hundred and twenty-four days later, fenvalerate was the most persistent pyrethroid in both years. She Yin Tan (1983) reported
248 fenvalerate to be more persistent than trans-permethrin, which in turn was more persistent than cis-permethrin. The cypermethrin (Ripcord) data for 1980 do not correspond with that of 1981 and we believe that in 1980, the cypermethrin (Ripcord) in the samples was partially degraded in storage because of a breakdown in refrigeration. The percent data in Table II indicate that all synthetic pyrethroids have approximately the same level of persistence. Chiba {1978) reported that on peach leaves, both isomers of permethrin dissipated at about the same rate. However, if actual residue data are examined, slight differences become apparent. Thus, in both years fenvalerate residues were highest (Tables I and II). Harris et al. {1978) reported higher residues of fenvalerate than permethrin 21 days post-treatment on celery. Furthermore, in this study, cypermethrin (Ripcord) residue levels were higher than cypermethrin (Cymbush) residue levels (Table II). The two products contain the same active ingredient and were applied at the same rate. They probably differ in their formulation ingredients, which may influence their persistence. A similar observation was made by Bostanian et al. (1985). The mortality data (Tables III and IV) reflect that these products remained more or less at the same level of toxicity for 6 weeks post-treatment, unlike the residue levels that decreased considerably in the first 2 weeks posttreatment. Thus, even after the rapid dissipation of synthetic pyrethroids in the first 2 weeks post-treatment, enough residues remained on the foliage to be highly toxic to AmbIyseius fallacis for another 4 weeks. The toxicity study was not continued any further as A. fallacis had already made its appearance in non-treated orchards and orchards under an integrated pestmanagement program. Thus, very low doses of these products are sufficient to cause high mortalities. Rock (1979) reported the LCs0 to be 1.4 ga.i. 100 1-1 for permethrin and 0.26 ga.i. 100 1-1 for fenvalerate. On pears in California, fenvalerate applied in spring was toxic to Typhlodromus occidentalis (Nesbitt) until leaf drop (Riedl and Hoying, 1983). CONCLUSIONS Our results indicate that permethrin, fenvalerate and cypermethrin, applied at petal fall against plant bugs and several lepidopterous pests, leave detectable residues on the foliage for 124 days. Although the residues decrease with time, the levels of synthetic pyrethroids remaining on the foliage are highly toxic to A. fallacis for at least 6 weeks post-treatment. Such toxicity would severely disrupt any integrated pest-management program for an apple orchard where A. fallacis is the principal predator of phytophagous mites. To include synthetic pyrethroids in integrated pest management programs, new strategies such as the mass rearing and release of synthetic pyrethroid-resistant strains of predacious mites (WhaIon et al., 1982) and other strategies (Bostanian et al., 1985) should be considered and evaluated.
249 ACKNOWLEDGEMENTS
We extend our appreciation to Mrs. F. Boudreau and D. Pitre for their assistance in collecting and analysing the samples.
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