November 1%7 7j ~' : United States Department of Agriculture Agricultural Research Administration Bureau of Entomology and Plant Quarantine INSECTICIDAL ACTIOM OF HELIOPSIS LONGIPLS AND EKLGkROft SPP. By E. R. McGovran,i/G. T. Bottger, W. A. Gersdorff, and J. H. Falee Division of Control Investigations Among the various wild plants tested by the Bureau of Entomology and Plant Quarantine in the search for new insecticides during the war was an herbaceous plant, Heliopsis longjpes (A. Gray) Blake, the roots of which were employed in Mexico in making an insecticide for local use. Because of the confusion of this species with a species of Erigeron f the following members of this genus were tested as well: E. belli- diastrum Nutt., canadensis L., cp,npj,xt"f- Greene, divaricatus Michx., divergens T. end G., flagellaris A. Gray, linifolius Willd., modestus (DC) A. Gray, reoens A. Gray, and two unidentified species. Tests were made on both plant material and extractives of the plants. The extractives of &. longjpes were tested before and after various treat- ments • The materials were tested both as sprays and as dusts, except £. commixtus f which was tested as a spray only. The sprays were prepared by dissolving the extractive, or one of its fractions, in deodorized kerosene to the desired strength, and the dusts by dispersing the powdered plant material or its extractive in talc. The spray tests were conducted at the Beltsville, Md., laboratory against house flies and mosquitoes, end the dusts at Sanford, Fla., against various lepidopterous larvae and the squash bug. The toxicity of the materials to house flies and mosquitoes was determined from the percentage of insects knocked down in 25 and 15 minutes, respec- tively, and the mortality in 1 day. Mortality of the leaf-feeding insects v.as determined after 3 days. The samples tested were prepared by F. Acree, Jr., and M. Jacobson of the Division of Insecticide Investigations. The chemical phases of work on Heliopsis longjpes (reported as Erigeron af finis DC.) have been discussed by Acree, Jacobson, and Haller QJ. In the course of this work they isolated from the root an active principle which they named "affinin." Tests on House Flies In the tests on house flies ( Musca domestica L.), 5-ml. doses of spray containing the various extractives of the plantewere applied by JL/Now with the Office of Experiment Stations. - 2 - the turntable method to adult flies in screen-covered 6-inch petri dishes. After 10 minutes in the settling spray the flies were transferred to clean recovery cages and supplied with liquid food. Two to four repli- cations were made with each material. The results with sprays made from Heliopsi s jLpnfiipes are shown in table 1. They are not precisely comparable because of the use of dif- ferent populations of flies, but they show that the roots of this plant contain a material highly toxic to house flies. Table 1. — Toxicity to house flies of extractives of Helioft Sjs_ longjpes roots in deodorized kerosene Material ' ' Knock-down ' ' Mortality (123 mg. of root per ml, unless ' 1 in ' 1 in otherwise indicated) ' [ 25 minutes ' 1 1 day Percent Percent Petroleum ether extractives: 25 mg. per ml. 100 100 Extractive basis < 10 100 100 2 100 49 Root basis 100 80 Ether-chloroform-cthanol extractives of residue, extractive basis, 10 mg. per ml* 20 1 Fractions of petroleum ether extract; Lves: Soluble in nitromethane 80 A5 Charcoal-treated, soluble in nitromethane 100 a Nonsaponifiable 97 22 Saponifiable 2 Insoluble in nitromethane 10 9 First oily separation 100 9 Petroleum ether extractives of first oily separation 100 22 Second oily separation 100 20 Petroleum ether extractives of second I oily separation 86 Distillate of nitromethane-soluble fraction 100 60 Distillate of roots 100 34 Residue from distillation of roots 1 1 Charcoal-adsorbed extractives 7 1 Pyrethrins 1/ (check), extractive bag sis Jl mg. per ml. 12 100 51 100 75 l/Averages of a number of tests. - 3 - Two sprays from each species of Erige ron were tested, one containing the petroleum ether extractives at 123 nig. of plant material per milli- liter of kerosene and the other the combined ether-chloroform-ethanol extractives of the residues at 25 mg. per milliliter. None of these sprays killed more than 2 percent of the flies, whereas pyrethrum extract (1 to 2 mg. of pyrethrins per milliliter) killed at least half of the flies in check cages. Tests on Mosquitoes Sprays containing extractives of Heliopsis longipes and various fractions of these extractives were tested for toxicity to adult yellow- fever mosquitoes ( Aedes aegyptj. (L.)) in a Peet-Grady chamber. One or two tests, each with 2 ml. of spray applied to approximately 100 mosqui- toes, were made with each material. The results, which are summarized in table 2, show that the petroleum ether extractives are highly toxic to mosquitoes. Table 2, : — Toxicity to yellow-fever mosquitoes of extractives of Heliopsis lpngipes roots in deodorized kerosene Material (123 mg. of root per ml. unless otherwise indicated) Knock-down in 1$ minutes Mortality in 1 day Males | Females Percent Percent 97 100 79 57 31 9A 50 56 A3 10 79 31 33 6 Petroleum ether extractives: Extractive basis, 25 mg. per ml. Root basis Fractions of petroleum ether extractives: Soluble in nitrome thane Charcoal-treated, soluble in nitromethane Nonsaponifiable portion Insoluble in nitromethane Petroleum ether extractives: First oily separation Second oily separation Pyrethrins (check), extractive basis, 0.1 mg. per ml. High High Medium Medium High Low Medium Medium High 91 61 Tests on Leopidopterous Larvae and Squash Bugs In tests on lepidopterous larvae dusts made from Helio psis longjpes extractives and the various species of Erigeron or their - 4 - extractives were applied to leaf sections in the laboratory. The sections were then infested with fourth instars of the raelonworm L ( Diaphania hyalinata (L.)), the southern beet webworm ( Pachvzancla biounctalis (F.)), and the southern armyworm, (Prodenia eridania (Cram,)) The results of these tests are given in table 3. Against the melonwonn the petroleum ether extractives of Hellopsjs longjpes were the most toxic, but the combined ether-chloroform-ethanol extractives of the residue were not toxic, Erigeron repens was the only species of plant which showed no toxicity to this insect. When the dusts were applied to the southern beet webworm, Erigeron bellidiastrum and Helionsis longjpes were the most toxic. The southern armyworm was resistant to the samples of Heliopsis longjpes tested, and only four species of Erigeron showed any toxicity to this insect and that only moderate. A contact treatment with petroleum ether extractives of Heliopsis longjpes against fourth-ins tar nymphs of the squash bug ( Anasa tristis (Deg.)) resulted in 79 percent mortality. The insects were exposed to dust deposits of 170 micrograms per square centimeter. Literature Cited (1) Acree, F. , Jr., Jacobson, M. , and Haller, H. L. 1945. An amide possessing insecticidal properties from the roots of Erigeron af finis DC, Jour. 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