June 1949 E-781 LIBRARY T r pLANT BOAKL'uhited States Department of Agriculture STAl Agricultural Research Administration Bureau of Entomology and Plant Quarantine LABORATORY TESTS ON TOXICITY OF SOME PHEICYLHYDRAZIDES TO THE EUROPEAN CORN BORER By S. I. Gertler, Division of Insecticide Investigations, and D. D. Questel and R. V. Connin, Division of Cereal and Eorage Insect Investigations • Twenty-one organic compounds were tested for toxicity to newly hatched European corn borer larvae ( Pyrausta nubilalis (Hbn.)) at Toledo, Ohio, from 19^*4 through 19^7. These compounds are .all chemically re- lated. They are all derived from phenylhydrazine^/ and most of them are prepared by reacting phenylhydrazine with an acid or acid chloride. They may be represented by the general formula, K ^ ^ -IJR'-MR. In each case R is an acyl group, which is derived from an acid, R 1 is hydrogen except in one compound, where it also is an acyl group. In most cases where there is only one acyl substituent, the compound is named as a phenylhydrazide of the acid. The compound that has an acyl substit- uent on each nitrogen is named as a phenylhydrazine. The ethoxalyl de- rivative, which is derived from an ester, is also named as a phenylhydrazine, The larvae used in the tests were obtained from eggs laid by moths reared in the laboratory from field-collected borers. Usually the borers were retained in cold storage for several months in order to satisfy their diapause requirements and thus provide a continuous supply of moths as needed. Male and female moths were confined in a cylindrical wire (5 meshes to the inch) oviposition cage 1 foot high and 9 inches in diameter. To prevent the escape of the moths from the cage, the side v/all was covered with coarse cheesecloth, which is not a suitable surface for oviposition. The top of the cage was covered with a sheet of waxed paper, and the moths readily oviposited on this surface through the wire mesh. The cage was placed under a bell jar to insure the high humidity that is favorable to oviposition. The paper with the attached egg masses was removed daily and cut into small sections, each containing an egg mass. These masses were then placed in a gallon earthenware jar containing moist blotting paper and allowed to incubate. Erom 20 to 100 egg masses in the "blackhead stage," which just precedes hatching, were required daily when the chemicals were being tested. i,/ Tests with the same group of compqunds against other insects have been reported in processed publication E-769, entitled "Preliminary tests of certain phenylhydrazides as insecticides. G. T. Bottger, A. P. Yerrington and S. I. Gertler. 10 pp. March 19^9. ml 9- -2- The sprays ware prepared "by grinding with a stirring rod 0.25 gram of the compound in a "beaker containing a little water plus all the wetting agent, sodium monosulfonate of butylphenylphenol (Areskap) , required to furnish a dilution at the rate of 1 gram of wetting agent to 2,000 cc. of water in the completed spray. After the material had "been finely ground, enough water was added to "bring the dilution of the compound to the rate desired. This preparation was sprayed thoroughly upon fresh green leaves with a small atomizer connected to an air-pressure tank fitted with an auto- matic air regulator set for 10 pounds' pressure. Cauliflower leaves, which do not decompose readily, and upon which the borer thrives, were used as the feeding medium. As soon as the surface water had evaporated, the leaves were made into small rolls and one role inserted into each test tube containing one or two corn borer egg masses in the "blackhead stage. A cotton-filled cloth stopper was used to plug the mouth of the tube. Observations were made daily. At the end of the test period records were made of the dead and living larvae, the condition of the leaves, and the amount of feeding. The number of larvae used at each application at each concentration ranged from 3^ to 206, and averaged 121. All the larvae were given an opportunity to feed for 48 hours "before mortality readings were taken. The amount of feeding by the larvae varied from none, where mortalities were high, to much, where mortalities were low. In comparable checks with untreated leaves, which were included in all tests, mortalities ranged from 0.4 to 1.0 percent. Compounds that gave high mortalities were retested at lower concentrations. Results of these tests are given in table 1. Of the 21 compounds 13 gave 90 percent or higher mortality when tested at 4 pounds per 100 gallons of water. Eight compounds continued to give this mortality when tested at the 2-pound concentration. Three of these compounds gave kill above 90 percent when tested at 1 pound per 100 gallons of water. Three of the phenylhydrazides shovred no appreci- able mortality when tested at the 4-pound rate. Results of these tests indicate that the phenyl hydra zide group is quite toxic to newly hatched corn borer larvae. Among the compounds most toxic at 1 pound per 100 gallons are the phenylhydrazides of some of the isoaliphatic acids. Of this group the phenylhydrazide of the 4-carbon isobutyric acid is the most toxic. The 5-and 6-carbon derivatives, isovaleric and isocaproic, are somewhat less toxic. Among the phenylhydrazides of the straight-chain aliphatic acids, that of the 5-carbon valeric acid shows the most toxicity, whereas those of the lower acids - butyric, propionic, and acetic - show practically no toxicity at this concentration. The long-chain stearic acid is nontoxic. The phenylhydrazide of benzenesulfonic acid is one of the two most toxic compounds, whereas the derivative of the higher homolog, toluenesulfonic acid, is less toxic and that of sulfonic acid much less. -3- Among the phenylhydrazid.es of the aromatic acids, that of cinnamic acid, which has an unsaturated side chain, is most toxic. Benzoic and p_-chlorobenzoic acid phenylhydrazides are somewhat less toxic and all the other substituted "benzoic acid derivatives have little toxicity. Table 1. — Toxicity of cauliflower leaves sprayed with different phenylhydrazides to newly hatched European corn "borer larvae in laboratory tests. Percent mor tality , at indicated Phenylhydrazide strength per 100 gall ons 4 pounds 2 pounds X pound Benzenesulfonic acid 100 100 99 Isobutyric acid 100 100 99 Isocaproic acid 100 100 91 Isovaleric acid 100 100 80 Cinnamic acid 95 98 65 Toluenesulfonic acid 10C 97 60 Valeric acid 100 100 44 c^-Chlorobenzoic acid 100 66 42 Benzoic acid 94 74 34 Sulfonic acid 100 93 18 Pheny lace tic acid 90 59 10 Butyric acid 95 60 2 Acetic acid 95 21 3 Propionic acid 78 - - 3 t 4- Dichlorobenzoic acid 35 - - Hydrazine, l-ethoxalyl-2-phenyl- 34 - - 2>-Nitrobenzoic acid 23 - - 2,i|— Dichlorobenzoic acid 21 - - m-Nitrobenzoic acid 3 - - p_-Chlorobenzoic acid 2 - - Stearic acid ■• •~ UNIVERSITY OF FLORIDA lllllllllllll 3 1262 09239 2371