LIBRARY STATE PLANT BOARD March 19^5 E-639 United States Department of Agriculture Agricultural Research Administration Bureau of Entomology and Plant Quarantine PRELIMINARY TESTS WITH NEW COMPOUNDS AGAINST LARVAE OF THE TOBACCO AND TOMATO HORNWORMS By C. F. Stahl, W. A. Shands, F. S. Chamberlin, and L. B. Scott, Division of Truck Crop and Garden Insect Investigations Summary Laboratory tests of nearly 300 materials, mostly synthetic organic compounds, against larvae of the tohacco hornvorm (Protoparce sexta (JohanO) and the tomato hornworm (P. quinquemaculata (Haw.) )~"have been conducted at Oxford, N. C, Quincy, Fla., and Clarksville, Tenn. Lead arsenate, cryolite, and paris green were included for comparison. The highest mortalities were obtained with the various arsenicals and cryolite. Of the other materials tested, the 20 that appeared to he the most toxic are listed in alphabetical order as follows: 2 -Acetamidof luorene p-Aminoazobenzene p-Aminoazobenzene hydrochloride Antimony trisulf ide Copper cyanamide Cuprous cyanide DDT Diazoaminobenzene p, p ' -Dif luorobiphenyl kf 6-Dinitro-o-cresol U,6-Dinitro-o-creeyl acetate 1, it--Diphenylsemicarbazide 2 -Fluorylamine N-Nitrosodiphenylamine Phenothiazine Phthalonitrile Xanthydrol Xenylamine Zinc cyanamide Zinc mercury thiocyanate Of these materials, ky 6-dinitro-o-cresol, ^,6,dinitro-o-oresyl acetate, xanthydrol, and xenylamine caused injury to the plants under the conditions of the laboratory tests. Some of the more promising materials were tested against the tomato hornworm, which appeared to be easier to kill than the tobacco hornworm. Introduction Exploratory tests on the toxicity of new compounds, particularly organic compounds, were made on the tobacco hornworm (Protoparce sexta (Johan.)) and the tomato hornworm (P. qulnquemaculata (Haw.;) at three laboratories of the Bureau, and the results are given by the laboratory leaders in the following sections of this circular. The tests at Oxford, N. C, are presented by C. F. Stahl and W. A. Shands; those at Quincy, Fla., by F. S. Chamberlin; and those at Clarksville, Tenn., by L. B. Scott. APR 2 1 ms - 2 - Some of these tests were not sufficiently replicated to warrant definite conclusions regarding the possible value of the materials. TESTS AT OXFORD, H. C, 1936-^3 ^ Since the Oxford, N. C, laboratory was established in 1935, tests of new compounds have "been conducted there almost continuously for the purpose of determining their toxicity to the hornworms in- festing tobacco. The majority of the new materials considered were organic compounds obtained from the Division of Insecticide Investi- gations. Many had previously been found by other investigators to be toxic to certain insects other than hornworms. Most of them were first tried against hornworms in unreplicated tests, or screening tests, designed to select for more thorough study those that were toxic to some extent to these insects. Yery few, however, appeared to warrant further investigation. The technique was varied slightly as the studies pro- gressed. The work was carried on under the direction of W. A. Shands during the period 1936-39 and was continued by C. F. Stahl through 19^3. The tobacco hornworm is the most prevalent and injurious species in the flue-cured tobacco area. It was used exclusively in the screen- ing tests, but the tomato hornworm was included in most of the others. Both species are available in satisfactory numbers, but since their periods of development do not coincide, it was seldom possible to have an adequate supply of larvae of both species on hand at the same time. Some materials were applied as dusts, others as sprays. The dust- ing was accomplished by means of a precision dusting apparatus, which was developed at Oxford 2/ The dusts were allowed to settle on small tobacco plants set in 10-inch flowerpots or on fresh tobacco suckers placed in small bottles of water. After the -dusting the plants were infested with 10 third-instar hornworms. In most cases the sprays were applied to circular disks of tobacco leaves by means of a paint- gun sprayer until the deposit reached the drip stage. After the plants had dried, 5 second instars were placed on each leaf disk. The plants were kept in cages, either outside or in the insectary, and the disks were kept in Petri dishes. The mortality was recorded at the end of U- days. Prior to 1939 the larvae were reared in Petri dishes, but after that they were reared on growing tobacco plants in the insectary. The settling time for the dusts in the dusting chamber ranged from 1 to 2 minutes. There were deviations from the above procedure, however, as will be indicated. 1/ J. P. Vinzant conducted the tests with third instars in 1936 and all the laboratory tests in 1937; T. F. Henderson conducted the laboratory tests in 1938-40; and C. Levin assisted with these tests during 19^1-^3. 2/ Vinzant, J. P. An apparatus for dusting individual plants. U. S. Bur. Ent. and Plant Quar. ET-105, 1 p., illus. 1937. [Processed.] - 3 - Among the first test was a series conducted for the purpose of comparing the toxicities of certain homologs of paris gresn to third instars when dusted on potted plants. Lime was used as che diluent. The results are presented in table 1. Table 1. — Toxicity of certain homologs of paris green when applied as dusts to third-instar tobacco hornworms on potted plants. Oxford, N. C, 1936 Materials .* Dilution : with lime Larvae used Mortality: Feeding Cottonseed-oil green Soybean- oil green Copper stearoarsenite Paris green Number Percent None 1:2 1:6 1:10 20 . 180 y 100 60 100 97 78 62 Slight do do Moderate None 1:2 1:6 1:10 10 1/ 180 y 100 60 100 9* 75 53 Very slight Slight do Moderate 1:2 1:6 300 1/ 60 71 90 Slight do 1:2 1:5 1:6 1:10 60 / 120 1/ 100 60 100 92 100 92 Very slight do do do zJ Replicated tests, 60 larvae in each replicate. During the 1936, 1937, and 1938 seasons 150 organic compounds were tested as sprays. The results of tests with materials that gave at least 20 percent mortality are listed in table 2 in the order of the toxicity demonstrated . - k Table 2. — Toxicity of sprays containing organic compounds to second- lnstar tobacco hornvorms on leaf disks. Oxford, N. C, 1936-38. Tests not replicated Materials Dilution by weight ■with water Larvae used Mortality: Feeding Number Percent Lead arsenate Paris green and lime (1:6) 1+,6-Dinitro-o-cresol l/ p, p ' -Dif luorobiphenyl p -Iodosonitr obenzene 2 -Thiocoumar in 2-Fluorylamlne 2 -Acetamidof luorene Zinc mercury thiocyanate Xenylamine 3-Chlorodibenzofuran N-Nitrosodiphenylamine Xanthydrol p -Iodonitrobenzene p-Iodoxynitr obenzene Copper isoamylxanthate and diisoamyl xanthogen (equi- molecular mixture) Bis(o- aminophenyl) disulfide Zinc cyanamide p -Nitropbenyliodochloride 1+,6-Dinitro-o-cresyl acetate beta-Aminoanthraquinone Phenyl disulfide . 2,6-Dibromo-l+- nitrophenol 1/ 2, 6, 7-Trinitrof luorenone Copper cyanamide 9, 9 -Dichlorof luorene beta-Iodonaphthalene 2 - ( 2 -Hydr oxy-6 -ke to -k, 1+- dlmethyl -delta' -cyclohexenyl- methyl) -5, 5 -dimethyl -1, 3- cyc lohexanedi one 2>l+-Dinitrophenol V 3 -Nitrodibenzof uran 9 -F luorenone 9-Chlorof luorene 1:1+00 50 96 Very slight 1:200 50 100 do 1:200 50 100 None 1:1+00 50 100 do 1:1+00 50 100 do 1:1+00 50 100 Slight 1:200 25 100 Yery slight 1:1+00 25 86 do 1:200 25 81+ do 1:1+00 25 100 do 1:200 25 100 do 1:200 75 100 do 1:1+00 25 96 do 1:1+00 50 96 do 1:1+00 50 94 do 1:200 25 92 Slight 1:1+00 25 90 do 1:1+00 50 90 Very slight 1:1+00 50 86 Slight 1:1+00 50 86 do 1:200 75 69 do 1:1+00 50 82 Very slight 1:200 50 82 Slight 1:200 50 80 do 1:200 50 80 Very slight 1:200 25 80 Slight 1:1+00 50 7^ do 1:200 25 72 Very slight 1:200 25 72 Slight 1:200 • 75 60 Moderate 1:1+00 25 32 do 1:200 25 68 Slight 1:1+00 50 61+ Very slight 1:200 25 61+ Normal 1:200 25 60 Moderate 1:1+00 50 58 Very slight 1:200 25 56 Normal 1:200 25 56 Moderate 1:1+00 25 52 do Table 2— (Continued) - 5 - Materials Dilution "by weight with water Larvae used Mortality: Feeding Sodium euif oleate p -Br omoh iphenyl 9-Acetylcarbazole 2, 3-Diaminophenazine p -Phenylene -b is (ammonium- 2-benzothiazolyl) sulfide 1+,6-Dinitro-o-oresol methyl1 ether 5, 6*, 7, 8-Tetrahydro-l- naphthy 1 thi ourea Copper hutylxanthate and dihutylxanthogen 1 -Phenylhenzoxazole 1-Benzothiazolyl-p- nitrobenzyl sulfide p -Aminoacetanil ide 9-Fluorenol 1-Benzothiazolyl-p- "bromohenzyl sulfide Number Percent 1:200 1:1+00 1:1+00 1:200 25 50 50 25 % 52 1+6 1+1+ Normal Slight do do 1:200 25 1+0 Moderate 1:1+00 50 38 Slight 1:200 25 36 Normal 1:200 1:1+00 25 50 36 32 do Slight 1:200 1:1+00 1:200 25 50 25 28 22 20 Moderate do Normal 1:200 25 20 Normal V Caused severe "burning of the foliage, - 6 - The following materials were comparatively nontoxic at the dilutions tested, and in most cases permitted moderate to normal feeding: Diluted l:l<-00 p -Ace totoluide p-Aminophenol o«Aminophenylmethyl sulfide Anthranilic acid Anthraquinone 2, 2 * -Azobis (thioanisole ) k, k ■ -Azobis ( o-anisidine ) Benzanilide Benzidine l-Berizothiazolyl-cyclohexylammonium sulfide S-Benzoyl-1-mercaptobenzothiazole N- ( 1 -Benzoxazolyl ) cyclohexylamine Benzyl disulfide 2-Bromo-5-phenyl-l, 3-cyclohexanedione Carbazole beta-Chloroanthraquinone 2 -Chlorof luorene 2 -Chlor o -2 -nitr o -diphenylamine N-Cyclohexylacetamide N-Cyclohexylbenzamide Dib enzothiophene k, k » -Dibromob iphenyl k-(2, 5-Dichlorophenylazo) -o-cresol k, k • -Diiodob iphenyl 2, 2 • -Dinitrob iphenyl 2-Fluorenol p -Hydr oxyb iphenyl o-Iodoaniline p -Iodob iphenyl Methy-o-nitrophenyl sulfide p-(2-Naphthylazo) - dimethylaniline p-Nitrobenzyl mercaptan p-Nitr ob iphenyl U-(p-Nitrophenylazo) - resorcinol Phenacetin Phenothiazine-S-oiido k -Pheny lazo -m-cre sol ^•-Phenylazo-o-cresol k -Pheny lazore sore inol 1 - ( p -Toluenemthylmer capt o ) - benzothiazole Tri-(thiovanillin benzoate) Xanthone Diluted 1:200 2-Acetoxyfluorenone Allantoin 2 -Amino-9 -f luorenol 2 -Aminof luorenone p -Andnophenylammonium-1 - benzothiazolyl sulfide Anthracene Anthrone Barium sulf oleate 9 -Benzalf luorene 1 -Benzothlazolhydroxymethyl sulfide alpha -Benzoyl -beta- (m-nitrophenyl) ethylene oxide alpha -Benzoyl -beta-phenylethylene oxide Bis(l-benzothiazolyl) disulfide 9,9-Bi8(l-hydroxy-2-naphthyl) - f luorene anhydride 2-Bromo-5,5-dimethyl-l, 3- cyc lohexanedi one Calcium sulfoleate alpha- (p-Chlorobenzoyl) -beta- (m-nitrophenyl) ethylene oxide alpha- (p-Chlorobenzoyl) -beta- phenylethylene oxide p -Chi or ob iphenyl Chrysene Chrysylamine Copper ethylxanthate and diethylxanthogen Copper methylxanthate and dime thy lxanthogen Copper propylxanthate and dipropy lxanthogen Coumarin 1, 2, 3, k- Dibenzophenazlne 9, 10-Dibromoanthracene 2, 7-Dibromo-9-benzalf luorene 2, 7-Dibromof luorene 2, 7-Dibromo-9- ( o-ohlorobenzal ) — fluorene - 7 - Diluted 1:200 (continued) 2, 7 -Dibromo-9 -furalf luorene 9, 9-Di (p-hydroxyphenyl )f luorene 5, 5 -Dimethyl -1, 3-cyolohexanedlone 1, 2-Dlnltrobezene Dlphenylamine, sulfur, and oleio aold 2, 3-Diphenylquinoxaline 2-Fluorene acetate 9-Fluorenol acetate 9-Fluorenone oilme 9-Fluorenone oilme acetate 9-Fluorenone oilme benzoyl ester 9-Fluorenone phenylhydrazone 9-Furalf luorene 9-Furylf luorene 2,2' -HydrazoMe(thloanlsole) Isonl trosoaoetanlllde 10-Nltroanthrone m-Nltrobenzaldehyde Nltroohrysene 6-Nitro-2, 3-dlphenyl^-omega-trichlorocetophenone, and p-omega-dichloroacetophenone, and severe burning by phenazine. Tests were also made with powdered roots of mayapple (Podophyllum peltatum) and pokeberry, each applied as a dust and as a spray, but neither material was even slightly effective. UNIVERSITY OF FLORIDA I 3 1262 09230 3808