Toxicity of Spray Residue of Fresh and Processed Fruits and Vegetables


Two species of mosquito larvae were used, the yellow fever mosquito (Aedes aegypti L.) and the southern house mosquito (Culex quinquefasciatus. Say)...
0 downloads 0 Views 354KB Size


Toxicity of Spray Residue of Fresh and Processed Fruits and Vegetables ALBERT HARTZELL

Downloaded by UNIV OF MICHIGAN ANN ARBOR on May 12, 2018 | https://pubs.acs.org Publication Date: January 1, 1950 | doi: 10.1021/ba-1950-0001.ch020

Boyce Thompson Institute for Plant Research, Inc., Yonkers 3, Ν. Y.

Bioassay with mosquito larvae for the detection of insecticide residues in fresh and processed fruits and vegetables is feasible, subject to the limitation that the untreated natural product is in itself nontoxic to the larvae at the dilutions tested.

T h e purpose of this work was to determine the toxicity to mosquito larvae of insecticide spray residues. T h a t certain insecticides are translocated i n plants (4, 5) adds impetus to this study. Fresh orchard fruit sprayed or dusted w ith preparations containing parathion (0,0-diethyl O-p-nitrophenyl thiophosphate), tetraethyl pyrophosphate ( T E P P , H E P P ) , D D D [2,2-bis(p-chlorophenyl)-l,l-dichloroethane], D D T [2,2-bis(pchlorophenyl)-l,l,l-trichloroethane], chlorinated camphene, and basic lead arsenate were shipped from California to Yonkers, Ν. Y . , by air express for bioassay. r

Materials and Methods As mosquito larvae are relatively easy to kill with insecticides, any toxic spray residue is likely to be detected. T w o species of mosquito larvae were used, the yellow fever mosquito (Aedes aegypti L.) and the southern house mosquito (Culex quinquefasciatus Say). Tests with the southern house mosquito were made essentially according to the method of Campbell, Sullivan, and Smith (1), except for the kind of food supplied and size of containers used. The eggs (furnished through the courtesy of C. H . Bradley) were shipped weekly from Orlando, F l a . , to Yonkers, Ν. Y . , via air mail, and as soon as received, they were placed in tap water i n 4-liter beakers at room temperature. The eggs hatched within 24 hours. When the larvae had hatched, powdered dog biscuit was added at the rate of 100 mg. per liter. The following day 125 mg. of blood albumen were dissolved i n 150 m l . of water, and added at the rate of 125 mg. per liter to beakers containing larvae. Thereafter powdered dog biscuit and blood albumen were fed on alternate days in amounts specified above. Larvae 5 days old were used for testing. Test tubes (25-ml. capacity) containing ten larvae each i n the solution to be tested and the controls i n tap water alone were placed in an oven at 30° =±= 1 ° C. overnight (20 hours). The solutions containing larvae were poured into porcelain dishes and living and dead larvae were counted. Tests were run i n duplicate—i.e., two tubes containing 10 larvae each. If any dead larvae were found i n a check, the tests were repeated. Tests were made at four or more concentrations. Each series of tests was repeated on a different day. Larvae of the yellow fever mosquito, which are shallow feeders, were reared at room temperature by methods similar to those used i n culturing Anopheles mosquito larvae (2, 6). Filter papers containing the eggs (furnished through the courtesy of R . E . Heal, Merck & Co., Inc., Rahway, N . J.) were placed i n tap water i n shallow porcelain pans (12 X 7 inches, and 2 inches deep). The eggs hatched within 24 hours. When the larvae had hatched, powdered dog biscuit was added daily at the rate of 100 mg. per liter of water. 99

AGRICULTURAL CONTROL CHEMICALS Advances in Chemistry; American Chemical Society: Washington, DC, 1950.

ADVANCES IN CHEMISTRY SERIES

100

Larvae 3 days old were used in testing. Tests were conducted in the same manner as with the southern house mosquito. The fresh fruit was ground in a meat chopper, and the juice was pressed out and diluted with tap water at ratios of 1 to 7.5, 1 to 15, and 1 to 30. The processed baby food was also diluted with tap water at the same ratios as the ground fresh fruit.

Downloaded by UNIV OF MICHIGAN ANN ARBOR on May 12, 2018 | https://pubs.acs.org Publication Date: January 1, 1950 | doi: 10.1021/ba-1950-0001.ch020

Results Apricots, prunes, and peaches from sprayed trees were tested on the larvae of Aedes aegypti for the toxicity due to spray residues. The apricots were sprayed on April 1 and May 6 and the fruit was harvested on or about August 9. The samples were tested during the month of August at dilutions of 1 to 7.5, 1 to 15, and 1 to 30. Apricot samples from trees sprayed with D D T (50% wettable) at the rate of 1.5 pounds per 100 gallons of water were toxic at all three dilutions tested. Samples from trees sprayed with D D D (50% wettable) at the rate of 2 pounds per 100 gallons of water were toxic at dilutions of 1 to 7.5 and 1 to 15. Apricot samples from trees sprayed with parathion (25% wettable) at the rate of 2 to 3 pounds per 100 gallons of water were also toxic at dilutions of 1 to 7.5 and 1 to 15. The peach trees (cling) were sprayed on June 16 with a single application of tetraethyl pyrophosphate, and the fruit was harvested on or about July 2. Tests were made during the month of July. Both treated and check peaches were unripe when tested. It was found that unripe unsprayed peaches were toxic to mosquito larvae at dilutions of 1 to 7.5 and 1 to 15, but at the dilution of 1 to 30 neither the treated nor the the check peaches showed toxicity. It was not possible to distinguish between the toxicity of treated and check at dilutions of 1 to 7.5 and 1 to 15 by the method of ranking described by Wilcoxon (7).

AGE OF SOLUTION IN DAYS

Figure 1.

Stability of Parathion

In addition to the tests made on peaches and apricots, samples of prunes from trees that had been sprayed with parathion, D D T , D D D , basic lead arsenate, and toxaphene at the rate of from 1 to 2 pounds of these insecticides per 100 gallons of water were tested on larvae of Aedes aegypti. The trees had been sprayed on April 20 and June 16, 1948. The fruit was harvested on or about September 10. Prunes from trees that had been treated with 1 quart of tetraethyl pyrophosphate and 12 pounds of sulfur dust per acre on June 15, and harvested about July 6, were tested on larvae of the above named species. None of the prune samples tested in this study exhibited any significant toxicity to mosquito larvae as compared with the unsprayed check. AGRICULTURAL CONTROL CHEMICALS Advances in Chemistry; American Chemical Society: Washington, DC, 1950.

HARTZELL—TOXICITY OF SPRAY RESIDUE

101

Strained processed peas and peaches containing known quantities of parathion ranging i n concentrations from 0.25 to 10 p.p.m. were diluted with tap water at ratios of 1 to 7.5, 1 to 15, and 1 to 30, and tested on larvae of Aedes aegypti. K i l l s of 100% were obtained at all concentrations tested. The average L D o of aqueous parathion solutions was 0.003 p.p.m. [a value comparable to that obtained by Gleissner (8)], as compared with 0.055 p.p.m. for processed peas and 0.0053 p.p.m. for processed peaches. Strained processed peas containing known quantities of gamma isomer of benzene hexachloride (τ-hexachlorocyclohexane) were nontoxic, whereas strained processed peaches gave kills of 100% at the same dilutions. The p H values of the processed peas and peaches used i n these tests were 6.0 and 3.7, respectively, indicating that the toxin is not destroyed i n an acid medium. The L D of an aqueous solution of the gamma isomer of benzene hexachloride was approximately 0.1 p.p.m. A n aqueous solution containing 1 part i n 200,000,000 of parathion gave 5 0 % k i l l to southern house mosquito larvae (Culex quinquefasciatus Say). Parathion solutions did not lose any toxicity on standing for a month at room temperature (Figure 1). A t the end of 2 months, however, the solutions lost their toxicity to mosquito larvae. 5

Downloaded by UNIV OF MICHIGAN ANN ARBOR on May 12, 2018 | https://pubs.acs.org Publication Date: January 1, 1950 | doi: 10.1021/ba-1950-0001.ch020

5 0

Table I.

Toxicity to Aedes aegypti Larvae of Processed Baby Food" (Known quantities of insecticides added before processing)

Insecticide TEPP BHC Methoxychlor Check

Concn. before Dilution, P.P.M. 10 5 2 10 5 2 10 5 2

Dilution Ratio 1:15 1:30 1:7.5 1:30 1:7.5 1:15 Peaches, Strained, % Dead Peas, Strained, % Dead 4 6 0 0 0 0 56 5 0 0

0 6 0 0 0 7 15 0 0 0

9 5 0 0 0 0 0 0 0 0

0 4 20 100 100 100 14 10 5 6

0 0 0 100 100 100 0

4 0 0

6 0 0 100 100 100 0 0 0 0

% moisture in strained ° % moisture in strained peas ranged from 83.7 to 87.5; total solids, 12.6 to 16.3. peaches ranged from 63.3 to 73.5; total solids, 26.5 to 39.7. Moisture and total solids determinations by Theo Svolos.

Literature Cited (1) Campbell, F . L . , Sullivan, W. N . , and Smith, C. R., J. Econ. Entomol., 26, 500-8 (1933). (2) Deonier, C. C., Hinchey, E., and Incho, H . H . , U . S. Dept. Agr., Bur. Entomol. Plant Quarantine E-733, Part III, 7-9 (1947). (3) Gleissner, B. D., private communication. (4) Grainger, M . M . , "Absorption of Parathion through the Root System of Plants and Its Effect upon Insects Infesting Them," thesis, Cornell University, February 1948. (5) Grainger, M . M . , and Lieby, R. W., Agr. Chemicals, 4 (2), 34-5, 79-81, 83, 85 (1949). (6) Granett, P., and Haynes, H . L., Proc. New Jersey Mosquito Exterm. Assoc., 31, 161-8 (1944). (7) Wilcoxon, Frank, Insecticide and Fungicide Section, Stamford Research Labs., American Cyan­ amid Co., Stamford, Conn., "Some Rapid Approximate Statistical Procedures," 1948.

AGRICULTURAL CONTROL CHEMICALS Advances in Chemistry; American Chemical Society: Washington, DC, 1950.