C SOUTH ank Range FOREST SERVICE U. S.DEPARTWIENT OF AGRICULTURE P. 0. BOX 245, BERKELEY, CALIFORNIA 94701

CONTACT TO Robert L. Lyon

Ips paraconfiasus Lanier, formerly known as Ips confusus (LeConte),l is one of the most aggressive bark beetles in California. It does the most damage to ponderosa pine (Pinus ponderosa Laws.) from sapling size to 24 inches d.b.h., but attacks all pine species wi"ln its range.2 I. paraconfusus also attacks the limbs and tops of larger trees. An infestation is soon USDA Forest Service followed by the tree-killing western pine beetle Research Note PSW-249 (Den&octonus bvevicomis keC onte), the most de- 1971 structive insect to ponderosa pine.2 The toxicity of lindane to bark beetles has been well e~tablished.~This insecticide, either pure or as the active ingredient of benzene hexachloride (BHG), is now used in California and elsewhere as a bark spray for suppression of bark beetles or for protec- tion againsMheir attack. Nationwide, ethylene di- bromide is the only other insecticide which is also used for bark beetle suppressi~n.~ The dependence on such a small arsenal for bark beetle suppression poses risks which are compounded by the current disfavor expressed toward chlorinated hydrocarbons, such as lindane. As part of a large-scale study to find alternatives to Absaaet: Thbteen insecticides were tested against Ips paracoafisus Lanier, and six agahst the western pine chlorinated hydrocarbons, we tested 13 insecticides beetle (Dencks~~f~nu~brevicomis Lec.). The rankhg of against Ips paraconfusus Lanier and 6 against the toxikity at LDQO by topical appGcation to I. pam- weskrn pine beetle. The results sugges"chat five of coY1Jusus was: SD 3450 > endosulfm > malathion > the chemicals tested-Zectran, Dursban, malathion, hndane phorate carbayl caPzbophenothion = > > > dichlorvos, pyrethrins-show promise as possible al- Ilmidin > crotoxyphos > dimethoate > DDT >~ilan > trichlorfon. The rankkg of toxicity to D. bbrevi- ternatives to lindane. Further research and field eomis was: Zectran = dichlonros > Dursban > testing would be necessary before the most suitable malathion > pyrethins = Endane. Five compounds- candidate insecticide is decided on. Zectran, Dursban, malathion, dichlomos, pyrethrhs- show promise for study as possible alternatives Lo hdane, which is now commonly used for bark beetle MATERIAU AND METHODS supp1ession. Oxford: 145.7~19.92Ips pa~'ldcoa~sus:Lg53-414.12+ The insecticides tested were formulated in acetone 145.7x19.92 Dendroctonus brevicomis: 453-414.12. on the basis of the active ingredient in the technical Reh.ievaE Terms: Ips pabraconfusus; Deadroctonus grade product. Fresh solutions were made on each brev ico m is; toxicity tests; Zectran; Dursban; day of testing. Common and proprietary names and malathion; dichlomos; pyrelhrins; lhdane. chemical definitions used in this report are those given by the Committee on Insecticide Terminology, Entomological Society of Ameri~a.~The insecticide lindane able 2). On the basis of average insect SD 3450 is not cited. Its chemical name is: mortalities, tlre ranking of toxicity was Zectran = 5 ,$,7,8,9,9-hexachloro-l,4,4a,5,8,8a-hexahydro-dichlowos > Dursban > malathion >- pyrethrins = 1,4:S,8-dimethanophthalazine. lindane. Testing procedures were similar to those described by L~yon.~~~Acetone solutions were applied topically Table 2-Mort~lity of westerr2 pine beetle adults treated with to the venter of the adult beetle at the rate of I 6-11/10 six insectkides at three dosage levels mg. body weigl-ft. The insects were held after treat- I ~o&a~t~lat dosage of ment singly in size No. 000 gelatin capsules. Dead Insecticide insects were counted 3 days later. The insecticides were tested on 6. pavaconfusus at Percent - four to six different concenkrations and replicated Zectran 110 100 100 100 usually two to five times. Full dosage-mortality Dichlorvos 60 100 aoo - regression curves were obtained for tlvs insect by Dursban 110 9 6 100 31 00 Malathion 110 85 100 100 using a computer program of probit analy~is.~Addi- hrethrins 110 5 3 100 100 "conal candidate insecticides were tested at three Lindane 180 6 2 95 100 concentration levels agkst the western pine beetle. l~orrected for natural moaality by Abbott's formula; natural mortaEi;y from treatment with acetone alone was 14 RESULTS percent.

At ED,, , three insecticides-SD 3450, endosulfan, The five compounds-Zectran, , Dursban, and malathon-were more toxic "clan lindane to I. malatl~on,dichlorvos, and pyrethrhs-appear to be paraconfusus, though the differences were not large the most promising candidates for further study, (tabk I; fig. I). Malathion was less toxic at the LD,, 'Ifl~ey are at least as toxic as lindane and, unlike level. chlorinated hydrocarbons, do not have the "eouble- All six insecticides tested on the western pine some quality of persistence in the environment. They beetle were as toxic as or sEghtly more toxic than may, however, have insufficient persistence in bark. Residual action in bark is of considerable importance Table 1- abxicihy of 13 insecticides applied topkdly to Ips in bark beetle suppression, as it tends to increase the ~amconfususadults effectiveness of sprays and their flexibility of use. Residual life of these five compounds, when applied to bark, is not now known. Laboratory and field tests with deposits in bark are needed "I assess fully their potential for use agakst bark beetles. I Number &. /g body weight SD 3450 Endosulfan Mdathion NOTES Llindane (standard) 'kanier, 6. N. Biosystematics of North Arrzerican Ips Phorate (Coleoptera: Scolytid@ Hoppirzg9sgfoup IX. Can. Entomol. Cabsyl 102(9): 1139-1163, 1970. Cabopheno- thion 2~truble,George R., and Hall, Ralph C. The California Imihn five-spined engraver-its biology avzd eo~ztml.U.S. Dep. Agr. Crotoxyphos Ckc. 964, 21 p., illus. 1955. Dimethoate 3~yon,Robert L. Structure and toxicity of insecticide DDT deposits for contml of bark beetles. U.S. Dep. Agr. Tech. Di?lan Bull. 1343, 59 p. 1965. 'Ifrichlorfon on, Robert L. Formulation and s2.Yucture of residual ~LD~~= dose lethal to 50 percent of sample; LDgO= dose lethal insecticides for bark beetle cont'rol. In, Advances in Chemis- to 9 percent of sample. try Ser. 86: 192-206. R. B;. Gould, ed., Washington, D.C.: 2~oxicityrelative to findane: Amer. Chem. Soc.1949. LDS0 lindane = toxicity index. '~illings, Samuel C. Consolidated list of approwd conzmorz LD50 (,, candidate names of insecticides and cert~inother pesticL"des. Bull. Dosage (p.g.4. body weight)

Figure 1-Dosage-mortality curves fir 13 insecticides upplied topical& to Ips pamconfusus adults.

Entomol. Soc. Amer. 1143): 204-213, 1945; 1243): 356-35'7, he assistance of Burton B. Combs and Peter Letchworth in 1966; 1344): 342, 1967; 14(4): 289, 1968; 1564): 380, 1969. the bioassay is gratefully acknowledged. ?Ly on, Robert L. Toxicity of severa.rak residual-type insect; cides is selected western bark beetles. J. Econ. Entomol. 8&ovided by Gerald S. Walkon, U.S. Forest Service, Upper 5262): 323-327, 1959. Daby, Pa.

The Author ROBERT L, LYON, a research entomologist, is responsible for insect culture and bioassay in the Station's studies in the evaluation of chemical insecticides. He attended New Y ark State University College of Forestry, where he earned B.S. (1953) and M.S. (1954) degrees. He received a doctorate in entomology (1961) from the University of CaEfornia, Berkeley.

This pUbGciltion reports $esearch involving psticides. It does not cont~n recommendations for their use, nos; does it imply that the uses discussed here have been regjstered, uses of pesticides must be ne@stered by appropiate State andlor Federal agencies before they can be recommended.

CAWION: Pesticides cm be injurious to Zlumkuas, domestic animals, deskable plants, and fish or other wildl8e-if they ase not handled or applied properly. Use :I a11 pesticides selectively and ca~enTuiHy, Follow recommended practices for the $ispod of surplus pesticides and pesticide containers.

GPO 981-314 The Forest Semice of the U.S, Dep ent of Agdcdme

. . . Conducts forest and range research at more than 75 ' locations from Puerto Rim to Alaska and Hawaii. . . . ParGcipates with all State forestny agencies in cooperative programs to protect and h- prove the Nation's 395 maion acres of State, Bocd, arad private forest lands. . . ; Maages and protects the 187-million-acre National Forest System for sustained yield sf its mmy prohcts and services.

The Pacific Southwest Forest and Rmge Experiment StaGon represents the research brrmch of the Forest Service in Cdifomia and Hawaii.