S T/ ^T BOAKLJ April 1950 E-797 United States Department of Agriculture Agricultural Research Administration Bureau of Entomology and Plant Quarantine EFFECTIVENESS OF METHOXYCHLOR AGAINST THE JAPANESE BEETLE By Walter E. Fleming and Warren W. Maines Division of Fruit Insect Investigations Tests were made in 19^6 to determine the effectiveness of methoxy- chlor in protecting fruit and foliage from attack by adult Japanese bee- tles ( Popillia japonica Newm. ), and in 1947 this insecticide was tested against the grubs of this beetle in the soil. In these tests methoxy- chlor was compared with DDT. Control of Adult Beetles A peach orchard near Cranbury, N. J,, containing the varieties Triogem, Sunhigh, Goldeneast, Elberta, J. H. Hale, Summercrest, Red- rose, Goldenglobe, Cumberland, and Raritan Rose was selected for one of the tests in 19^6. This orchard had been damaged severely by adult Japanese beetles each year for several years. On July 10, just as the beetles were beginning to invade the orchard, the trees were sprayed with methoxychlor or DDT, or with each of these materials in combination with hydroxypentamethylflavan. The sprays contained 2 pounds of 50- percent methoxychlor or DDT wettable powder in 100 gallons, and when hy- droxypentamethylflavan was added U pounds of a 30-percent wettable powder was used. Thfi hydroxypentamethylflavan was added to control the European red mite I Paratetranycnus pllosus ^C. and T.)) t which sometimes increases rapidly after applications of DDT. Each spray was applied to 59 trees, which included all the varieties in the orchard. Many Japanese beetles were killed by the contact action of these sprays. The infestation was destroyed, and only an occasional beetle was observed on the trees during the remainder of the summer. Methoxychlor proved to be as effective as DDT in protecting the fruit and foliage from attack. The average numbers of adult mites per leaf on the varieties Summercrest and Cumberland, as estimated at different intervals after the spraying, were as follows: 20 days 27 days 33 days Methoxychlor 103 123 1*3 Methoxychlor-hydroxypentamethylflavan 69 97 lU2 DDT 258 *5 213 DDT-hydroxypentamethylflavan 3« 23 75 Unsprayed 65 Bk 180 - 2 - The result* Indicate that the 2uropean red mite ter.is to build up ■ere rapidly on foliage ■prayed with aethoxychlor or DDT tr^ax on *.:.• uieprayed foliage. The gpraya containing hyiroxypentametr.ylf lavan : -ire ■atiafactory control of the mltea. In another test in 1946 methoxychlor fro* two aourcee was compared with DDT in a block near Bridgeton, N. J., containing a variety of peach designated as N. J. 135« Before the spray applications many beetles were feeding on the fruit and foliage on the trees. Sach spray contained 2 pounds of a 50-percent wettable powder in 100 gallons of water and was applied to 21 trees, Many beetles were killed by both sprays. Two days after the spraying many dead beetles were found on the ground beneetn the trees and only an occasional beetle was observed on the fruit or foliage. There aeemed to be more dead beetles under the trees sprayed with DDT than under those sprayed with methoxychlor. The beetles caused no fur- ther injury during the remainder of the summer. Methoxychlor fro* both sources was as effective as DDT in protecting the fruit and foliage from Japanese beetle injury. On June 2^, 19^6, about a week before the beetles began to invade the orchard, blocks of large Williams Early Red apple trees were sprayed with methoxychlor or DDT. The trees were sprayed at this time because it was anticipated that the apples would be picked during the first week in July and it was desirable that 10 to li, days elapse between spraying and harrest to avoid the possibility of objectionable residues on tne fruit. However, market conditions were such that the crop was not har- vested. Sach material was applied to 2o trees at the rates and 2 pounds of a 50-parcent wettable powder per 100 gallons of wa* On July 17 some beetle injury was observed on * ?s of the twigs on trees sprayed with 2 pounds of 50-percent DDT, but few live beetles were seen on the trees, and many dead or moribund beetles were around. The situation was almost the same with the trees sprayed with 1 pound of 50-percent DDT, but there had been al more feeding on the tips of the twigs and fewer dead or moribund beetles were on the ground. The trees sprayed wi * unds of 50-perc :hlor showed evidence of more : g than those sprayed with 1 pound of -percent DDT; more beetles were seen In the trees and fewer dead and moribund beetles were on the ground, ^"urther observations on this test were not possible after July 17, because a few days later practically all the beetles left both the sprayed and the unsprayed trees. Control of Grubs In laboratory tests against Japanese beetle grubs in the soil, methorychlor from two sources (samples A and B in table 1) was Inti- mately mixed with 1-cublc-foot lots of Sassafras sandy loa» at the rates , 1.0/,, 2.08, and 8. -mis per cubic foot, which was valent to lncoi-poratlng 10, . ■■ , % , , ■ I -0G pOOBdl of the - 3 - insecticide with the upper 3 inches of an acre of soil. Sassafras sandy loam was treated with DDT in a similar manner at rates equivalent to 10, 25, and 5° pounds per acre. Ten-percent dusts were used to facilitate mixing the materials with the soil. Each cubic foot of treated soil was divided among five trays, each 18 inches square and 3-3/4 inches deep, and the trays were then put into a chamber maintained at a temperature of 80° P. Immediately after the soil had reached this temperature and again 7 weeks later, 250 third-instar larvae, 50 per tray, were introduced for each treat- ment. The trays were examined at weekly intervals, and the dead and living individuals counted. The living larvae were returned to the tray and the dead individuals were discarded. As approximately the same results were obtained with larvae introduced immediately and 7 weeks after the soil reached 80°, the data were combined. The mortality of 500 grubs receiving each treatment is given in table 1. Table 1. — Comparative effectiveness of methoxychlor and DDT against Japanese beetle grubs in the soil : Pounds : Percent mortality of 500 grubs Material : per acre : Second : Third : Fourth week : week : week Methoxychlor: Sample A 10 10.8 14.8 21.4 25 20.2 30.6 35.6 50 57.6 79.2 89.6 100 85.8 98.0 100.0 200 93.*+ 99.6 100.0 Sample B 10 8.0 9.6 16.2 25 19.6 25.6 32. 4 50 57.S 70.8 75.S 100 87.8 95.4 98.4 200 96.1+ 97.6 99.0 DDT 10 85.6 97.4 99.6 25 97.2 99.S 100.0 50 98.8 100.0 100.0 Untreated check — 9.H 12.2 16.8 The data obtained the first week were not tabulated, because many of the grubs were moribund and the mortality could not be determined accurately. Approximately the same results were obtained with methoxychlor from both sources, but this material was much less toxic to grubs than DDT. The in- sect! cidal action with 100 pounds of methoxychlor per acre was about the same as that with 10 pounds of DDT per acre. In view of the relatively low toxicity of methoxychlor to beetle grubs, plans for further tests with this material in the field were abandoned. 3 121 Summary In limited teats methoxycr.lor was as effectiTe ae DDT in ag t and foliage of peaches from attack by the a J -.panese beetle Llla J aponlca Newo.), but slW-htly less effectire than --.- •arly-rl nples from injury. Methoxychlor was only one- tenth as toxic as DDT to Japanese bMt] • -oil. In riew of this low toxicity, L1 . • • .*«- for DDT in controlling grubl in turf :r in nuraery and -~arden soils.