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Laboratory studies on toxicity of three carbamate (mexacarbate, carbaryl, and aldicarb) and three organophosphorus (trichlorfon, formothion, and phorate) compounds were made on two species of snails, Lymnaea acuminata Lamarck and Pila globosa Swainson. L. acuminata was more sensitive to the pesticides tested. LC50 values computed for different exposure periods from 24 to 240 h showed a gradual decrease as the exposure time was increased. Although trichlorfon was most toxic to L. acuminata and mexacarbate to P. globosa , the relative LC50s of the six compounds varied at different exposure periods. A possible explanation on the basis of pharmacological evidences and structure-activity of these compounds has been given.

The contact toxlaty of 100 insecticides to last stage larvae of Choristoneura occidentalis Freeman was tested by topical application in a 10-yr series of screening experiments. Pyrethroids were generally the most toxic group of chemicals tested. Compounds more toxic than the standard, mexacarbate, at LD90 were: bioethanomethrin, (+) cis -resmethrin, (+) trans -resmethrin, (+) cis -phenothrin. ENT 29117 (5-benzyl-3-furylmethyl (IR,3S,E) 2,2-dimethyl-3-(2-oxo-3-tetrahydrothiophenylidenmethyl) cyclopropanecarboxylate), resmethrin, and NRDC 143 (3-phenoxybenzyl (±)-3-(2,2-dichlorovinyl-2,2-dimethylcyclo-propanecarboxylate). Mexacarbate spray was tested on the western spruce budworm at selected developmental stages. First instars were least susceptible at both LD50 and LD90; instars 3–5 and 6th instars weighing less than 110 mg were most susceptible. Since long-term laboratory realing of insects did not change their responses to 3 representative chemicals periodically tested during this series of experiments, the results represented a valid estimate of relative toxicity.

Mortality of last instar western spruce bud worm, Choristoneura occidentalis Freeman, exposed to a series of increasing doses (topical application) or concentrations (diet incorporation) of 10 insecticides was analyzed over 7 d by time-dose-mortality regression. Regression based on the complementary log-log model was useful for analyzing time trends for all dose levels simultaneously. Each of the 10 insecticides acted more quickly when applied topically. In both kinds of experiments, speed of lethal action of the insecticides depended on dose or concentration. The statistical methods developed to estimate lethal doses as functions of time and median times of death as functions of dose are more efficient than methods published previously.

The experimental mexacarbate formulation Zectran UCZF19 was effective in controlling spruce budworm, Choristoneura fumiferana (Clemens), in a trial conducted during 1984 in eastern Canada. The formulation was mixed in both water and an oil-based diluent and applied as double applications at 70 g (AI) in 1.5 liters tank mix per ha with an aircraft (Cessna Ag-truck) equipped with four atomizers (Micronair AU3000). The aqueous mix produced significantly greater percentages of

Fifty-five insecticides were tested for their toxicity to larvae of the Douglas-fir tussock moth, Hemercampa pseudotsugata McDunnough. The 10 most active insecticides in descending order of average toxicity at LD90 were: pyrethrins, Dursban® ( O, O -diethyl O -3,5,6-trichloro-2-pyridyl phosphorothioate), Zectran® (4-dimethylamino-3,5-xylyl methylcarbamate), dichlorvos, GC-6506 (dimethyl p-(methythio) phenyl phosphate), aminocarb, tetramethrin, allethrin, Bayer 37298 ( O -ethyl 0-2,4,5-trichlorophenyl ethylphosphonothioate), and DDT. Four of the 10 insecticides–pyrethrins, Dursban, Zectran. And DDT–have been field-tested recently with varying results. Several insecticides were examined in the laboratory in more detail in different formulations for such characteristics as rate of toxic action and residual activity.

Laboratory screening tests showed the following pesticides to have activities equal to or better than carbaryl against young Porthetria dispar (L.) larvae: Dursban® ( O,O -diethyl O -3,5,6-trichloro-2-pyridyl phosphorothioate), diazinon, dimethrin, Shell SD-8530 (3,4,5-trimethylphenyl methylcarbamate), SD-9098 ( O -[2-chloro-1- (2,5-dichloro- phenyl) vinyl] O,O -diethyl phosphorothioate) , Mobil MC -A-600 (benzo [b) thien-4-yl methylcarbamate) , and tetramethrin. Large-acreage aerial spray comparisons of triehlorfon ULV at 1 pound per quart per acre with carbaryl at 1 pound per gallon were very effective. Dead and live larval counts and postspray egg mass counts all indicated good control in the 569-acre trichlorfon spray block. Three similar size blocks sprayed with carbaryl showed generally good control, but in all cases areas with living larvae could still be found. Dursban demonstrated poor control in six 40-acreplots, both when sprayed alone at 2 oz per acre, and in combination with malathion at the rate of 1oz Dursban and 7 oz malathion per acre. Poor control also was shown in a 20-acre plot treated with 4 oz of Zectran® (4-dimethylamino-3,5-xylyl methylcarbamate) per acre.

Zectran® (4-dimethylamino-3,5-xylyl methylcarbamate), and parathion were very toxic, malathion and carbaryl less toxic, and methoxychlor nontoxic when applied topically to Tarentula kochi Keyserling in the laboratory. The penetration, metabolism, and excretion of a 4-μliter/spider dosage of carbaryl were studied and found to be about 1–5%, 0.1–0.7% and 0.01–0.04% of the applied dosage, respectively, for the N -14C methyl label, and 7%, 2% and 0.8%, respectively, of the applied dosage for the 1-14C naphthyl label. The percent penetration was increased to a range of 11–82% when only 0.2 μg/spider were applied. With all dosages the internal recovery ranged from 0.017 to 0.239 μg/spider, of which 1–30% were conjugated metabolites and about 1–20% of the conjugated metabolites were excreted. When the spiders were fed flies treated with 0.5 μg carbaryl, mortality occurred in 15 minutes to 10 hours, and 0.04–0.08 μg was recovered internally. These feeding studies showed that carbaryl was as toxic as Zectran and parathion, but that penetration had limited its toxicity with topical application.

Direct contact toxicity of seven insecticides, propoxur, Zectran® (4-dimethylamino-3,5-xylyl methylcarbamate), Sumithion® ( O, O -dimethyl O -4-nitro- m -tolyl phosphorothioate), amidithion, phosphamidon, dimethoate, and DDT was evaluated against larvae of the jack-pine sawfly, Neodiprion pratti banksianae Rohwer; the Swaine jack-pine sawfly, N. swaineii Middleton; and the larch sawfly, Pristiphora erichsonei (Hartig), in search of an insecticide alternate to DDT and to establish baseline toxicity data of the present populations of these species. A comparison of the relative susceptibility of the 3 species to the insecticides was made. Propoxur was the most effective carbamate and Sumithion was the most toxic oregano phosphate. Both carbamates were superior to the oregano phosphates, and DDT was the least toxic. P. erichsonii was relatively more susceptible to DDT and less susceptible to propoxur and Sumithion than N. p. banksianae and N . swainei. N. swainei was more susceptible than N. p. banksianae to most of the insecticides tested.

A laboratory bioassay with wafers of elder pitch was used to evaluate 28 compounds as feeding deterrents for Hylobius pales (Herbst). Fourteen of the compounds which significantly deterred feeding were then bioassayed by measuring the amount of feeding on pine twigs dipped in the compounds. Carbaryl, Benlate® (methyl 1-(butylcarbamoyl)-2-benzimidazolecarbamate), mexacarbate, and Dexon® (sodium (4-(dimethylamino) phenyl) diazenesulfonate) were sufficiently promising as feeding deterrents to warrant field testing.

Ten insecticides were tested against larvae of Calocalpe undulata (L.). The decreasing order of toxicity at LD50 was: bioethanomethrin, phenothrin, pyrethrins, phoxim, tetrachlorvinfos, mexacarbate, carbaryl, phosmet, DDT, and malathion. At LD90, the decreasing order of toxicity was the same, except that phoxim and tetrachlorvinfos switched positions. Malathion was not toxic at the highest dose level tested (500 μg/g body weight). When the response of C. undulata was compared with that of 4 other forest geometrid species, the data showed that pyrethroids were always the most toxic candidates whereas malathion was always the least toxic.

The apple rust mite, Vasates schlechtendali (Nalepa), was effectively controlled by pre-bloom applications of Thiodan® (6,7,8,9, 10,10-hexachloro-1 ,5,5a,6,9,9a-hcxahydro-6, 9-methano-2,4,3-beuzodioxathicpin-3-oxide), Eradex® (2,3-quinoxalinedithiol cyclic trithiocarbonate), and NIA-9044 (2-(2-butyl)-4,6-dinitrophenyl 3,3-dimethylacrylate). Applications of Thiodan, OW-9 (2 [2-( p-tert butylphenoxy )-isopropoxy] isopropyl 2-chloroethy1 sulfite), and Sevin® (1-naphthyl N -methylcarbamate) during the summer gave control lasting 4 weeks. However, applications o Sevin at n dosage as low as 0.5 pound of .50% wettable powder per 100 gallons of water resulted in an increase in numbers of the McDaniel spider mite, Tetranychus mcdanieli McGregor, over those found on the unsprayed check plot.: Preliminary tests with Bayer 37344 (4-(methylthio)-3,5-xylyl methylearbamate), Bayer 39007 ( o -isopropoxyphenyl methylcarbamate), and Zectran® (4-dimethylamino-3,5-xylyl methylcarbamate) indicated that these carbamates were effective for apple rust mite control.

Large numbers of Argyrotaenia citrana (Fernald) were successfully reared on an artificial wheat-embryo diet. Width of head capsules of 5 larval stages and their rate of development, by sex, were recorded. The response of the 5th-stagc larva to topical application of 4 compounds representing 4 major classes of insecticides showed the following descending order of toxicity at LD50: pyrethrins > Zectran® (4-dimethylamino-3,5-xylyl methylcarbamate) > DDT or malathion.

Twenty chemicals were tested for their toxicity to 4th-instars of Hemerocampa pseudotsugata McDunnough. Eleven were more toxic than the standard, mexacarbate, at both LD50 and LD90. They were, in decreasing order of toxicity at LD50 bioethanomethrin, NIA 26021 ([+] cis stereo isomer of resmethrin), NIA 18739 ([+] trans stereo isomer of resmethrin), resmethrin, methomyl, phoxim, DDTpp′, chlormethylfos, and Phosvel ®([2, 5-dichloro-4-bromophenyl) O-methyl phenyl thiophosphate). The descending order of toxicity at LD90 was: bioethanomethrin, NIA 26021, NIA 18739, resmethrin, methomyl, phoxim, chlorphoxim, pyrethrins, DDTpp′, chlormethylfos, and Phosvel. The cis isomer of resmethrin was significantly more toxic at both LD50 and LD90 than the trans isomer. Data also were obtained on the effect of posttreatment holding conditions and on the effect of dye tracers and stabilizing adjuvants on the insecticidal activity of pyrethrins.

Of 30 insecticidal sprays applied to lima beans infested 1 to 5 days previously by Liriomyza munda Frick, 97–100% eggs and larvae of all ages were killed by azinphosmethyl, chlorpyrophos, Dasanit® ( O,O -diethyl O -[ p -(methylsulfinyl)phenyl] phosphorothioate), demeton, diazinon, dichrotophos, dimethoate, fenthion, lindane, parathion, phorate, and mexacarbate. Of the remaining 18 insecticides, some were less effective vs. eggs or young larvae, others were ineffective vs. both at all ages. When applied in aerosols, parathion was more effective than dichlorvos or sulfotepp. The results support the need for a series of spray or aerosol applications scheduled to destroy the insect as eggs or larvae, the most vulnerable stage.

Resmethrin-selected house flies, Musca domestica L., were cross-resistant to fenvalerate. Fenvalerate was between 30- and 100-fold less toxic to resmethrin-selected flies (R) than to susceptible flies (S). While both DEF (S,S,S-tributyl phosphorotrithionate) and piperonyl butoxide (PB) significantly synergized fenvalerate ( P < 0.05) in R flies, PB was 8-fold more effective than DEF. PB was not a good synergist in S flies. In R flies, PB did not affect the rate of fenvalerate penetration as measured by unpenetrated insecticide. GA4-282, (2,6-dichlorobenzyl-2 propynyl) ether, and PB synergized pyrethrins, resmethrin, and the carbamates Mobam™, propoxur, and mexacarbate; the propynyl ether was more effective than PB with the carbamates, whereas PB was the better synergist for pyrethrins and resmethrin was synergized equally. GA4-282 had no effect on fenvalerate toxicity, although PB was markedly synergistic.

Twenty-one insecticides were tested on adults and 7 of the 21 were tested on 3rd and 4th instars of Chrysomela scripla F. In tests with adults, the decreasing order of toxicity at LD90 was: chlorpyrifos, resmethrin, phoxim, diazinon, mexacarbate, aminocarb, dimethoate, fenitrothion, Dowco 217 (dimethyl 3,5,6-trichloro-2-pyridyl phosphate), trichlorfon, Landrin® (3,4,5-trimethyl-phenyl methylcarbamate 93%; 2,3,5-trimethyl-phenyl methylcarbamate 7%)-carbaryl, lauroyl-trichlorfon (N-dodecanoyltrichlorfon), propoxur, methomyl, pyrethrins, carbofuran, tetrachlorvinphos, naled, malathion, and DDT. Chlorpyrifos and resmethrin were both over 240 times more toxic than DDT. Phoxim and diazinon were over 130 times more toxic than DDT; the other candidate insecticides ranged from 2–61 times more toxic than DDT. In tests with larvae, the decreasing order of toxicity at LD90 was: mexacarbate, resmethrin, chlorpyrifos, phoxim, propoxur, diazinon, and DDT. Toxicity to adults and larvae was generally similar. However, mexacarbate was significantly more toxic to the larvae than to the adults at both LD50 and LD90.

The fall cankerworm, Alsophila pometaria (Harris), defoliates deciduous trees over wide areas of North America (Craighead 1950). Trees generally recover from attack, but some mortality has been reported on 43,000 acres in Pennsylvania (Doerner 1969). Aerial applications of carbaryl at 1 lb/acre have been successful against fall cankerworm in Pennsylvania and in New Jersey (Doerner 1969).