LIBRARY TATE PLANT BOARD January 1943 \\ DETRIMENT OF AGRICULTURE BUREAU OF ENTOMOLOGY ANO E-585 w TLANT QUARANTINE J/ LABORATORY TESTS WITH ORGANIC COMPOUNDS /.S LARVICIDES FOR CUL5X QUINQUEFASCIATUS SAY By R. C. Bushland and W. V. King, Division of Insects Affecting Man and Animals One phase of the investigation on new chemicals for mosquito larvi- cides consists in selecting toxic materials for field tests. During the course of this study data have been accumulated on a variety of organic compounds, and the results obtained with 114 of these materials are summa- rized here. Although none of these coirpounds can be recommended at present for use in mosquito control, the data may be of interest to other workers on organic insecticides. The test insect was the southern house mosquito (Culex quinquefas c iatus Say). Eggs were obtained from oviposition tubs exposed on the laboratory grounds at Orlando, Fla. , and the larvae were reared indoors in battery jars. For food they were given one of the proprietary dog biscuits, finely ground, as employed by Crowell (3) in rearing Anop heles larvae. The organic compounds used in these studies were either commercial products of high purity or materials synthesized by chemists of the Division of Insecticide Investigations. The latter were given "E" numbers. Patents have been issued on some of these compounds. To disperse the test materials in distilled water, the compounds were introduced in acetone solution. The few materials insoluble in acetone were finely ground and used as suspen- sions. A maximum concentration of 2.5 ml. of acetone in 250 ml. of water was used, since this concentration, as reported by Fink and coworkers (4) and confirmed by the present writers, was harmless to the test larvae. The testing procedure was a modification of methods described by Camp- bell, Sullivan, and Smith (2); Fink, Smith, Vivian, and Claborn (4); and Phillips and S.vingle (5) . When most of the larvae in a culture had reached the fourth instar (usually 6 days after hatching) ,. they were collected in a wire strainer and gently washed with distilled water. Larvae of uniform size were then placed in groups of 50 in beakers containing 25 ml. of water. A beaker of larvae was selected at random, and the contents were poured into a larger beaker of distilled water, containing the material dispersed in 225 ml. Thus, a test consisted of 50 fourth instars in 250 ml. of distilled water containing the desired quantity of test material. - 2 - The test beakers were immersed in a constant-teirperature water bath at 78° F., and after approximately 16 hours the first mortality readings were taken. Those beakers in which larvae survived were replaced in the water bath, and 24 hours later final readings were taken. A large proportion of larvae killed by most organic insecticides sink to the bottom of a test beaker, where they are easily counted, but sometimes the dead or dying larvae float at the surface and may be difficult to distinguish from those not fatally poisoned. Before mortality readings were taken, the beakers were gently stirred to cause as many of the larvae as possible to sink. Larvae at the bottom of the beaker and incapable of rising to the surface were counted as dead. Sick larvae at the water surface which were so helpless that they could not wriggle off when lifted on the tip of a bent teasing needle were also considered as dead. Thus only larvae capable of vigorous movement were counted as alive. With certain compounds a few of the moribund larvae recovered during the second day. For each culture of larvae used in these tests an untreated check beaker was prepared. In the tests reported herein rarely was a dead larva found in a check beaker. Such mortality could be attributed to injury from washing or counting. Fourth instars can spend 2 days in distilled water without food with negligible natural mortality. Each culture was further tested against a median lethal concentration of a compound of established toxicity, either phenothiazine or 4-(p-bromophenylazo)-m-cresol. The highest concentration used routinely in these studies was 100 parts per million (p.p.m.). Materials lethal at this concentration were retested at successively lower concentrations until approximately the median lethal concentration was attained. With materials of outstanding toxicity several toxic concentrations were tested to obtain indications as to the slope of the concentration-mortality curve. All materials were tested at least twice to arrive at a concentration-mortality figure. For two or more tests at any concentration larvae from different cultures were used. The data on 114 compounds are summarized in tables 1 to 5. The most toxic compounds (table 1) are arranged in the approximate order of toxicity (based on the 40-hour readings), while the others (tables 2 to 5) are listed alphabetically, since the exact order of toxicity within tables could not be established in a few tests. As the primary object of this study was to select very toxic compounds, it was not considered practical to make direct comparisons of the less toxic materials. Because of variation in resistance between lots of larvae, a compound causing high mortality in tests against two lots was not necessarily more toxic than another producing a considerably lower kill at the same concentration against two different lots of larvae. Unless otherwise indicated, all the compounds were soluble in water at the concentrations used in the tests. - 3 - Phenothiazine, which was employed as a standard of comparison, was reported by Fink and coworkers (4) to have caused 100-percent mortality of Culex larvae at 1 p. p.m. In the tests carried out by the present authors a culture was seldom so susceptible that all larvae were killed at this concentration. In a typical series of tests against 56 lots of 100 larvae (in duplicate beakers of 50) each, phenothiazine caused a mean mortality of 70.5 + 2.32 percent in 16 hours and 69.1 + 2.08 percent in 40 hours, some of the larvae previously recorded as dead having re- covered. Only 1 lot showed 100-percent mortality, but the least kill was 40 percent. In these tests the lo.vest concentration giving 100- percent kill (minimum lethal concentration) averaged about 2 p. p.m. while the median lethal concentration was about 0.75 p. p.m. Against another series of 51 lots, 0.75 p. p.m. caused mean mortalities of 52.4 +2.35 and 55.4 + 2.93 percent in 16 and 40 hours, respectively. p-Bromohydrazobenzene was found to be more toxic than phenothiazine. The medium lethal concentration for Culex qu inqu 3 f as hiatus larvae with • this azo compound appears to be slightly more than 1.0 p. p.m., and the median lethal concentration between 0.5 and C.75 p. p.m. The 11 compounds of outstanding toxicity listed in table 1 represent several classes in the aromatic series. Since this report deals with a large variety of compounds with but few representatives of any group, little can be concluded regarding chemical constitution and toxicity. In tests on screwworms (Cochliomyia americana C&P.) Bushland (1) found quinoline, isoquinoline, 6-nitroquinoline, and 8-nitroquinoline to te approximately as toxic as phenothiazine, 2,6-dimethylquinoline and 6-methylquinoline to be somewhat less toxic, and 7-methylquinoline and 8-methylquinoline less effective than the 6-methyl derivative but more toxic than 8-hydroxyquinoline. These nine compounds were tested against Culex larvae, and again all showed larvicidal quantities, but the order of toxicity was very different. As mosquito larvicides 8-methylquino- line ranked first and 7-methylquinoline second, both being outstanding- ly toxic with median lethal concentrations approximately 1 and 2 p. p.m., respectively; 8-hydroxyquinoline was third, 100 p. p.m. killing all the larvae. The remaining six compounds caused only partial kills of mos- quito larvae at 100 p. p.m. The results with quinoline derivatives against these two species of dipterous larvae further illustrate the specificity of toxic action of organic insecticides and add to the instances of unpredictable changes in toxicity brought about by slight changes in the composition of the r.ole:u!e or in the position of substituents. Among the materials of little toxicity the results with phenol and the three cresols deserve notice, since these substances have been used as the chief ingredients of mosquito larvicides. In addition to the tests reported in table 5, mixtures of the cresols were tested in both tap and distilled water and found to be no more effective than the pure isomers. In view of these results the value of these substances in mosquito larvicides is questionable. - 4 - Summar y. — The results are given on 114 organic compounds that were evaluated for toxicity to fourth instars of Culex qui nqu e fas ci atus Say. The tests were conducted in beakers containing 50 laboratory-reared larvae in 250 ml. of distilled water and the desired quantity of test material. Test beakers were held at 78° F. and mortality readings were made at intervals of approximately 16 and 40 hours. Materials found lethal at a maximum concentration of 100 p. p.m. were tested at successively lower concentrations until part of the larvae survived. Minimum lethal and sublethal concentrations were retested against different cultures of larvae. Materials were considered to be of outstanding toxicity if they caused 100-percent mortality at concentrations of 10 p. p.m. or less. Eleven materials in this category were toxic in the following order: p-bromohydrazobenzene, xanthene, p-thiocyanoiodobenzene, dibenzothio- phene, p-thiocyanobromobenzene, 8-methylquinoline, 4-chloro-2-nitrodi- phenylamine, dimethylacridan, thio-2-naphthyl methyl ether, 7-methylquino- line, p-nitrobenzyl bromide. p-Bromohydrazobenzene was more toxic than phenothiazine in these laboratory tests. The order of toxicity to Culex larvae for quinoline and eight of its derivativies was different from that reported for these substances against screwworms. Phenol and the three cresols failed to kill all larvae in 40 hours at 100 p. p.m. LITERATURE CITED (1) Bushland, R. C. 1940. The toxicity of some organic compounds to young screw- worms. Jour. Econ. Ent. 33: 659-676. (2) Campbell, F. L., Sullivan, W. N. , and Smith, C. R. 1933. The relative toxicity of nicotine, anabasine, methyl anabasine, and lupinine for culicine mosquito larvae. Jour. Econ. Ent. 26: 500-509, illus. (3) Crowell, R. L. 1940. Insectary rearing of Ano pheles quadrimac u latus . (A preliminary report.) Amer. Jour. Hyg. 32, Sec. C: 12-20. (4) Fink, D. E., Smith, L. E., Vivian, D. L., and Claborn, H. V. 1938. Toxicity tests with synthetic organic compounds against culicine mosquito larvae. U. S. Bur. Ent. and Plant Quar. E-425, 34 pp. [Processed.] (5) Phillips, A. M., and Swingle, M. C. 1940. Rearing of mosquito larvae and effect of diet on their resistance to rotenone and nicotine. Jour. Econ. Ent. 33: 172-176. - 5 - Table 1. — Compounds of outstanding toxicity (lethal at 10 p.p.m. or less) Compound Concen-: Average mortality ration sTests: After ; After t 16 hours : UO hours P.p.m. No. Percent Percent 1.25 U 99.5 100 1.0 7 93 99 .75 6 88 92 .5 u 25 36 3.0 2 98 100 2.0 u 92 98 1.5 2 77 92 1.0 k 50 80 2.5 k 100 2.0 k 98 9« 1.5 U 86 88 1.0 k 1+6 53 .5 u 6 32 2.5 3 100 2.0 3 99 97 1.5 3 88 81 1.0 3 *9 Ul .5 3 8 12 2.5 U 100 2.0 U 97 96 1.5 u 68 68 1.0 u 29 U5 .5 u 7 3* 5.0 5 100 U.o 5 97 100 3.0 5 96 100 2.5 3 86 97 2.0 5 80 91 1.5 3 59 83 1.0 5 38 60 .5 3 11 22 u.o 3 99 100 3.0 3 93 97 2.0 3 67 69 1.0 3 31 LIBRARY 52 STATE PLANT BOARD p-Bromohydrazobenzene BrCgH^NHNHCgH^ Xanthene C6% CH 2 C 6 H U° p-Thiocyanoiodobenzene ICg%SCN Dibenzothiophene C 6 H U SC 6 H U p-Thiocyanobromobenzene BrC^SCN 8-Methylquinoline CH-jCoHgN 1207 1327 1396 130 1397 Comm. H-Chloro-2-nitrodiphenylamine CgH 5 NHC6B4|(Cl)N0 2 ID. 399 -6- Tahle 1.— (Continued) Compound : B :Concen-: : Average mortality : No. :tration: Tests: After : After : : : : 16 hours: Uo hours P. p.m. Ho. Percent Percent D i me thy lac r i dan CgH^CCCH^CgH^HH Thlo-2-naphthyl methyl ether C 10 H 7 SCH 3 178 1132 5.0 U.O 3.0 2.0 1.0 5.0 U.O 3.0 2.0 3 3 3 3 3 U 2 2 1 95 90 76 59 15 99 92 15 97 95 79 66 31 97 87 13 7-Methylquinoline CH-jC^HgN p-Nitrohenzyl "bromide NOgCgH^CHgBr Comm. Comm. 5.0 U.O 3.0 2.0 1.0 5.0 U.O 3.0 2.0 U 3 3 3 3 U U u 2 9U 88 67 U7 10 92 56 27 U 9U 91 83 61 33 96 70 U2 7 - 7 - Table 2. — Compounds that killed all larvae at 20 p.p.m. but not at 10 p.p.m, E :Concen-: Average mortality Compound : No. :trationi * Tests: • After : 16 hours : After 40 hours P.u.rn. No. Percent Percent p-Aminoaiphenyl NH 2 C 6 H U C 6 H 5 6o6 10 2 21 55 2 , ^-Dibromo-o-cresol Br 2 C 6 H 2 (CH 3 )OH Comm. 10 5 3 3 39 71 6 N-Phenylanthranilic acid C.H NHC.H. COOH b 5 o 4 Comm. 10 2 22 24 Xanthone C 6 H U C(0)C 6 H U Comm. 10 5 2 2 3* 63 12 - 8 - Table 3» — Compounds that killed all larvae at 50 p. p.m. but not at 20 p.p.m. Compound E : Cone en-: ; No. '- tration: Tests; Average mortality After : After 16 hours : Uo hours o-Aminobiphenyl o-Bromophenetole BrC 6 H u 0C 2 H 5 p-Bromonhenetole BrC^OC^ 3-Chloroac enaph thene c io H 5 (c V2 C1 3,^— Bichloronitrobenzene C1 2 C 6 H 3 K0 2 2 , 6-Dichloro-h-nitrophenol Cl 2 CgH 2 (N0 2 )0H 2,U- Dinitrobromobenzene (N0 2 ) 2 C 6 H 3 Br 2, h-Dinitrochlorobenzene (N0 2 ) 2 C 6 H Cl 2,U-Dlnitrophenol acetate CH,C0 2 C 6 H 3 (N0 2 ) 2 Hexachlorethane P.p.m. No, Comm. 20 2 Comm. 20 Comm. 20 2 10 2 1176 20 3 10 5 5 3 . 2.5 1 Comm, 20 3 10 2 130U 20 3 10 2 5 1 Comm, 20 2 10 2 5 2 Comm. 20 2 10 2 1537 20 2 10 1 Comm. 1/20 2 Percent 69 66 9U 39 96 88 65 6 85 21 97 ^3 98 51 9 96 57 15 95 Percent 73 73 Uo 99 92 81 16 91 29 97 U6 99 75 15 99 83 97 CCl CCl 10 5 2 2 39 1+ 1*2 9 p-Nitrophenetole N0 2 C 6 H U 0C 2 H 5 Comm. 20 2 & 72 m-Nitrophenyliodochloride (N0 2 )C 6 H U IC1 2 137^ 20 10 1 2 18 20 1 Phenazine oxide CgH^NONCgH^ t 1 1538 20 10 2 2 67 27 92 65 1/ Formed a colloidal precipitate which disappeared after a few hours. - 9- Tahle k, — Compound* that killed all larvae at 100 p. p.m. "but not at 50 p.p.m. : E : No. : Cone en-: i tratlon: • 1 Tests; Average 1 mortality Compound After 16 hours : After : Uo hours P.p.ra. No. Percent Percent Bis-(l-aminophenyl) disulfide (HH 2 C 6 H U ) 2 S 2 3*5 2/50 20 3 2 97 U3 99 59 o-Bromoanisole BrCg%0CH-j Comm . 50 20 2 2 73 9 69 11 p-Bromoanlsole BrCgH^OCH, Comm. 50 20 3 2 92 32 91 20 2, Ij-Dimethylquinoline (CH 3 ) 2 C 9 H 5 K Comm. 50 2 99 68 o-Dichlorobenzene Cl 2 C 6 H k Comm. 50 20 2 2 99 *5 99 p-Dichlorobenzene Cl 2 CgH u Comm. 50 20 2 2 98 U5 96 4U alpha-Ethyl butyraldehyde semicarbazone ( C 2 He ) 2 CHCHNNHC0NH 2 1523 50 20 2 2 53 2 8-Hydroxylquinollne HOCgHgN Comm. ^50 2 26 33 Me thylpheny lni trosoamine C 6 H 5 N(CH 3 )NO Comm. 50 2 20 33 o-Nltroanisole N0 2 C 6 H U 0CH 3 Comm. 50 2 12 21 p-Nitroanlsole N0 2 C 6 H U OCH 3 Comm. 50 20 3 2 98 2 99 8 p-Nitrobenzonitrlle HOgC^H^CN Comm. 50 20 2 2 89 2 91 U c-Nitrophenetole UOgCgH^OCgHe Comm. 50 20 2 2 96 2 98 19 1,3* 5-^rini trohenzene (H0 2 ) 3 C 6 H 3 Comm. 2/50 2 8 50 1/ Insoluble in water at this concentration 2/ Tests in tap water. - 10 - Table 5« — Compounds that were not completely effective at 100 p.p.m. (nontoxic and slightly toxic materials) Compound E :Concen-: i No. :tration: Tests; Average mortality After : After 16 hours: UO hours P.p.m. No. Percent Percent Acetonyl acetone disemicarbazone (CH 3 C(NNHC0HH 2 ) 2 CH 2 ) 2 1522 i/100 2 Anisalacetone CH,OCgH^CHCHCOCH, Comm. 100 2 6U 85 Anisaldehyde CH^OCgH^CHO Comm. 100 2 59 78 Anisole C 6 H 5 OCH 3 Comm. 100 2 22 23 Benzaldehyde semicarbazone 1U62 i/100 2 CgH_CHNNHC0NH 2 N-Ben zylpyromuc amide (C^H-0)C0HH0HgCgH 5 1335 100 2 18 63 Carvacrylpropionamide C 2 HcC0NHC 6 H,(CH,)(C,H 7 ) 1U69 100 2 Clnchonine c^oH 22 n 2 o Comm. 1/100 2 5 11 Cinnamaldehyde semicarbazone C6H5CHCHCHNNHCONH2 IU63 1/100 2 7 o-Cresol CH,CgH^0H Comm. 200 100 50 k 5 k 100 79 15 86 UO m-Creaol CH,CgH^0H Comm. 200 100 50 k 5 k 100 51 9 61 22 p-Cresol CH,C 6 H^0H Comm. 200 100 50 k 5 k 100 37 8 5* 1U - 11 - Table 5. — (Continued) Compound 35 :Concen-s > No . : trat ion : Teste l Average mortality After : After 16 hours Uo hours Crotonaldehyde semicarbazone CH CHCHCHNNHCONH N-Cyc lohexylTJyr omucamide (C^OCONHCgHjj Di-n-butyl amine (C U H9 ) 2 NH 2, 6-Dimethyl-U-heptanone semicarbazone ( ( CH, ) _CHCH_ ) _CNNHCONH„ 3'2 2'2 2, 6-Dimethylauinoline (CHjJgO^H 2,U-Dinitroanisole CH,0C 6 H,(N0 2 ) 2 1 , U-DiT>henylsemicarbazide ; 6 H 5 CgH-NHNHCONHC^H, Diuhenyl sulfoxide (C 6 H 5 ) 2 S0 Di-o-tolylthiourea CS(NHC 6 H U CH,) 2 2-Furanac ry lami de (C^H 0)CH:CHC0NH 2 2-(D-Gluco-B-glucoheptohexa- hydroxyhexyl) benzlmidazole CH 2 0H ( CHOH ) -CNC gH^NH l-Hydroxy-2-acetonat>hthone C 10 H 6 (OH)COCH,' p-Hydroxyacetophenone semi- carbazone HOC gH^C ( NNHC0NH 2 ) CH P. p.m. No. Percent Percent 1504 100 2 1U02 100 Comm. 100 1505 100 2 Comm. 100 50 2 2 1535 100 50 1+ 2 1106 i/100 2 Comm. 100 50 2 2 Comm. i/100 11 50 2 1 1^79 100 2 1U23 100 3 1318 I/ 100 1 50 y 20 2 1 1 1U61 100 2 36 77 99 58 86 59 28 73 16 79 62 93 go 66 Us so 18 99 80 88 70 52 88 38 9U 95 96 88 78 - 12 Table 5.— (Continued) Compound B : Cone en- s j No. .tration. Tests: Average mortality After : After 16 hours: Uo hours Indoleacetamide C r H,,HHCHCHH0OCH_ Indoleacetic acid C.H,,NHCHCCH o C00H Indolebutyric acid CgHj^NHCHCC-HgCOOH Iodosobenzene C 6 H 5 IO p-Iodosonitrobenzene C 6 H^(N0 2 )IO Isoquinoline CgH^CHNCHCH p-Methylacetophenone semicarbazone CH-CgH^C ( CH, )MHC0NH 2 Methylanthranilic acid CH NHC^H^COOH Methylindole butyrate CgH. NHCHCC H^COOCH 6-Me thy lquino line CH^C^HgN 3-Ni troac enaphthene C 10 H 5 (CH 2 ) 2 N0 2 p-Nitroacetanilide CH,C0NHC^N0 2 p-Nitroiodosobenzene acetate (N0 2 )C 6 H^I-(0C0CH,) 2 Comm. P. p.m. No. Percent Percent 100 2 Comm. 100 2 1 Comm. 100 2 5 163 100 50 2 1 90 85 2 1356 i/ 100 Comb > 100 50 2 2 8U 15 98 33 1507 100 2 U Comm* 100 2 1 k Comm. • 100 2 6H 8h Comm. 100 2 59 75 1177 i/100 2 69 71 1U12 100 2 2 1U2U i/100 U 50 2 2 71 3 73 10 - 13 - Table 5. — (Continued) Compound I : Cone en-: ; No. : tration:Tests: Average mortality After : After 16 hours: kO hours p-Nitrophenyliodochloride (N0 2 )C 6 H U IC1 2 P.p.m. No. Percent Percent 1359 1/lCO 2 7 36 p-Nltrophenylmercaptan N0 2 C 6 H U SH Co mm. A/ 100 2 U6 50 U-Nitrophthalimide NOgCgH^COjgNH 1206 100 2 6-Nitroqulnoline N0 2 C g HgH Comm, 100 50 3 3 99 39 99 83 g-Nitroquinoline N0 2 C q HgN Comm. 100 50 3 3 99 H9 99 71 N-Nitrosodicyclohesylamine (CgH^^O 396 l/lOO 2 33 to m-Phenetidine ° 2 H 5 0C 6\ ra 2 Comm. 100 2 11 U3 p-Phenetidine Og^OCgH^g Comm. 100 2 12 38 Phenetole ° 2 H 5 OC 6 H 5 Comm. 100 2 to U9 Phenol C.H^OH 6 5 Comm. 300 200 100 u h h 99 7 100 9* 22 1-Phenylsemicarbazlde CgH_NHNHC0NHp 1311 100 2 Phthalonitrile C 6 H^(CN) 2 13U2 100 50 h 2 98 15 99- 18 Picric acid (N0 2 ) 3 C 6 H 2 0H Comm. 100 2 1U 21 Table 5.— (Continued) - 14 - Compound ; X :Concen-i t Average mortality : Ho. :tration; Tests: After : After : : : I 16 hours: 40 hours P.u.m. Up, Percent Percent Piperidine-piperidyl 1U21 100 2 28 79 dithiocarbamate (CJ^HWSJSHCC^jH) p-Propi ono t o lul de 1263 100 2 3 Cg^COHHCgiyJHj Qulnoline Coffin, 100 5 91 93 CglLNCHCHCH 50 5 14 44 2,4,2' .U'-Tetrahromodiphenylamine 1U22 1/100 3 3 U Br 2 CgH_NHCgH,Br 2 p-Tolyllac tamide CH^CHOHCONHCgH^CH, N-Xenylac e tamide CBLCONHCgH^CgH,. N-Xeny lb e n z ami d e C 6 H 5 C0NHC 6 H U C 6 H 5 N-Xenylformamide HCOHHCgH^CgKg N-Xenylpropionamide N-Xenylpyromuc amide (CijHjOjCONHCgfyCgHj N-(2.4-Xylyl)benzamide CgH-COHHCgH-CCH-Jg N-( 2 , 6-Xylyl )benzamide H- ( 2 , 4-Xylyl ) f ormamide HCONHC 6 H,(CH^) 2 1U31 100 3 1U65 ^100 2 1H67 l/lOO 2 1438 1/100 3 1U3U 100 21 34 57 1464 i/100 1/ 50 3 2 7« *3 86 56 1U66 1/100 2 42 1468 1/100 2 20 69 1436 1/100 1/ 50 2 2 39 33 1 41 - 15 - Table 5. — (Continued) Conroound S :Concen-: i No. :tration:Te8ts; Average mortality After : After 16 hours: ho hours N-( 2, 5-Xylyl )formamide HC0NHCgH,(CH,) 2 N-( 2, U-Xylyl )T)roT)ionamide C 2 H^C0NHCgH^(CH,) 2 N- ( 2 , 5~Xy lyl ) or opionamide C 2 H CONHCgH (CH ) g . N- ( 2, 6-Xy lyl )nroT)ionamide C 2 H 5 C0ITHCgH,(CH,) 2 N-( 2 , h-Xylyl )t>y romuc amide (C U H OjCONHCgH (CH ) 2 N- ( 2 , 5-Xy ly 1 )pyromucamide (C^H 0)COtfHC 6 H 3 (CH ) 2 N-( 2, 6-Xylyl )pyromucamide (C u H 3 0)CONHCgH 3 (CH_) 2 P. p.m. Hp. Percent Percent 1U35 100 3 1 1U39 100 3 lUUO 100 3 lUUl 100 1UH2 100 lUUU 100 2 IUU3 100 2 25 15 31 1/ Insoluble in water at this concentration. NIVERSITY OF FLORIDA IIIIIIIIIIIIIIIIIII 3 1262 09224 7187