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Five spray mixes of mexacarbate (4-dimethylamino-3,5-xylyl N-methylcarbamate) were prepared using different inert ingredients. Among the mixes, ZE-DIL was oil-based, ZE-EML-1 14 and ZE-EML-3409 were emulsions, ZE-WP-W was a wettable powder in water, and ZE-FL-W was a flowable in water. The mixes were sprayed over potted balsam fir [Abies balsamea (L.) Mill.] seedlings in a laboratory chamber and foliar residues were analyzed by gas chromatography. The results showed that the ratios of the initial dislodgeable to penetrated residues were low for ZE-DIL, ZE-EML-114 and ZE-EML-3409, but were high for ZE-WP-W and ZE-FL-W. The latter two spray mixes contained mexacarbate in the particulate form, and contributed to greater surface residues than those of the former three spray mixes which contained mexacarbate in the solution or emulsion form. Foliar residues declined rapidly during 0 to 3 d post-spray, with half-lives (DT 50 ) ranging from 0.84 to 1.73 d. The rate of decline was slow from 3 to 20 d post-spray and the DT 50 values ranged from 2.49 to 4.65 d. Mexacarbate volatilized and codistilled appreciably within 24 h. Volatilization occurred more from dislodgeable residues than from penetrated ones, whereas codistillation occurred from both dislodgeable and penetrated residues. The penetrated residues of ZE-WP-W and ZE-FL-W volatilized less than those of ZE-DIL, ZE-EML-114 and ZE-EML-3409. This behaviour was due to the presence of mexacarbate in the particulate form in the former two spray mixes, as opposed to its presence as a solution or as an emulsion in the latter three spray mixes.

Mobility and metabolic fate of 14 C-mexacarbate (4-dimethlyamino-3,5-xylyl N-methylcarbamate) were studied using columns containing sandy and clay loam forest soils. Flooding and subsequent analysis of the soil segments showed the presence of free and bound (nonextractable) residues. The bulk of the 14 C-labelled material was adsorbed onto the litter layers. However, when the columns were saturated with 454 μg of the material, a small part of the radioactivity moved beyond the column length into the leachate. Analysis of the litter segments and the leachate showed carbamate moieties, phenols and other metabolites. Incubation of the soil columns under aerobic (dry) and anaerobic (wet) conditions for 30 d showed the retention of radioactivity in litter layers. The quantities of mexacarbate and its degradation products found were influenced, to some extent, by the soil type and incubation conditions. Except for phenolic and polar metabolites, no intact carbamate moieties were found in the litter after the 30-d incubation period. Mexacarbate seemed to breakdown rapidly in forest soil columns into various degradation products. A metabolic pathway for its degradation in soil is proposed.

The distribution and persistence of aerially applied mexacarbate were studied in a New Brunswick aquatic forest environment after spraying twice at a dosage of 70 g A.l./ha using a fixed‐wing aircraft. Average droplet density (drops/cm2) and ground deposition (g A.1./ha) between the two applications differed considerably. The values for the first and second applications were 1.7 and 0.73, and 5.2 and 2.0, respectively; but the average NMD (20 μm) and VMD (36 μm) for both applications were nearly the same. The maximum 1‐h postspray concentrations of mexacarbate in the stream and pond waters were 0.73 and 18.74 ppb, respectively. Concentrations fell rapidly to below detection limits within 12 h in stream and within 3 d in pond water. Cattails (Typha latifolia), manna grass (Glyceria borealis) and bog moss (Sphagnum sp.) collected from the pond contained peak 1‐h postspray concentrations of 720, 482 and 81 ppb, respectively. The concentration levels decreased rapidly and the average half‐lives of th...

A sensitive and selective high-performance liquid chromatographic method with post-column derivatization, using o-phthalaldehyde and 2-mercaptoethanol, is described for the analysis of aminocarb, mexacarbate and some of their carbamate metabolites. The separation system consisted of an RP-8 OS (10 μm) 20 cm × 4.6 mm I.D. column, an acetonitrile-water mobile system and a reactor for the hydrolysis of analytes from column effluents and fluorophore formation. The fluorophores were detected at 230 nm (excitation) and 418 nm (emission). The recoveries of the carbamates in spiked natural water at 2 and 20 ng/ml fortification levels ranged from 72.0 to 98.4% with relative standard deviations of 5.0 to 11.5%. The recoveries for spiked forest soil at 20 and 200 ng/g fortification levels ranged from 74.1 to 97.6% with relative standard deviations of 5.8 to 10.7%. Limits of detection and quantification for all the analytes were 0.1 and 0.4 ng in water and soil, respectively.

Laboratory dose-response studies were conducted with four species of adult bees, Apis mellifera (workers), Andrena erythronii (females), Megachile rotundata (females), and Bombus terricola (workers), using six insecticides, permethrin, mexacarbate, aminocarb, fenitrothion, carbaryl, and trichlorfon. All insecticides were applied topically to the thorax of the bees as technical grade in an acetone carrier. Mortality was accumulated over 48 h, and probit analyses were conducted separately on data sets expressed in units of μgAI (active ingredient)/g body weight and of μgAI/bee. LD50 values with 95% confidence limits and slopes with standard errors are provided for each bee/insecticide combination in each data set. Relative toxicities, relative susceptibilities, and fresh body weights are also provided. The analysis in units of μgAI/g body weight indicated that the insecticides were typically ranked in order of decreasing toxicity—permethrin, mexacarbate, aminocarb, fenitrothion, carbaryl, and trichlorfon. Likewise, the bees ranked from the most to least susceptible in the order of A. mellifera, A. erythronii, M. rotundata and B. terricola. Trends within the data set for units of μgAI/bee were less consistent. These data are discussed and compared with other published data on the toxicology of insecticides to bees and from the perspective of risk assessment.

Zectran (4-dimethylamino-3,5-xylyl N-methyl-carbamate), a carbamate insecticide (active ingredient [AI] mexacarbate), was aerially applied to two 300 ha plots of coniferous forest at dosage rates of 70 and 140 g AI/ha, respectively. The brains of 288 birds collected from the treated areas and 84 birds from untreated areas were sagittally sectioned into approximately equal halves. Each of the laboratories participating in the study, the Forest Pest Management Institute (FPMI) and the Canadian Wildlife Service, Atlantic Region (CWS), assayed one half of each brain for cholinesterase (ChE) activity and the results were compared. The ChE estimates of the two laboratories on half brains from the same birds were poorly correlated (R = 0.136, P less than 0.05) and differed significantly (P less than 0.00005). The reasons for this are uncertain. Despite the discrepancy in ChE estimates, however, separate statistical analysis of each data set produced the same general conclusion: the ChE response to Zectran exposure was statistically significant but biologically unimportant. In both data sets, statistically significant ChE responses by niche and time since spraying were found. The dosage rate emitted from the airplane was a better predictor of ChE activity in the canopy niches than was volume deposited at ground level, but volume deposited was a more useful predictor for ground birds in most situations. These results are discussed in the context of a proposal to develop a reference file of normal brain ChE activities of common wildlife species.

Mexacarbate (4‐dimethylamino‐3,5‐xylyl N‐methylcarbamate) insecticide has potential for use in spruce budworm (Choristoneura fumiferana Clem.) control operations in Canada. Its persistence and fate in balsam fir (Abies balsamea (L.) Mill.), litter and soil samples were studied by spraying aerially oil‐based and water‐based formulations, each at 70 g A.I./ha over a coniferous forest near Bathurst, New Brunswick. The oil‐based formulation gave the maximum concentration of the chemical in the substrates studied. In fir needles, the highest concentrations observed were 0.51 ppm and 0.19 ppm (fresh weight) for the oil‐based and emulsion formulations respectively, 1 h after application. The residue levels decreased very rapidly with a half‐life of approximately 5 h. Three and eight days after the spray application of the emulsion and oil formulations respectively, the concentrations of mexacarbate in foliage decreased to trace levels ( 0.008 ppm). Only very low levels of residue were detected in litter...

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 nature of a reductive system which actively degrades mexacarbate in the rat intestine and liver was investigated. The system is characterized by its stability against heat and protease treatments and its requirements for a flavin cofactor and an acidic pH for a maximum activity. As a result of purification and spectroscopic identification attempts the system responsible for the above reductive activity was identified to be flavoprotein. Under anerobic conditions such flavoproteinflavin cofactor systems degrade mexacarbate first to 4-N-desmethylmexacarbate and then to polar water-soluble metabolites.

The degradation and metabolism of mexacarbate were studied in two types (sandy loam and clay loam) of sterile and nonsterile forest litters after incubation for 45 days under aerobic and submerged conditions. Degradation of the chemical in non‐autoclaved litters was rapid initially and reached a maximum after 30 d. The rate of formation of 14CO2 and the amount, the extractable metabolites produced and the nonextractable 14C adsorbed onto the litters varied depending on the litter type and experimental conditions. Rate constants and half‐lives (t1/2) of evolution of 14CO2 were very similar for the aerobic and submerged conditions. However, the t1/2 values for the clay loam litter were slightly higher than those for the sandy loam litter. Litter microbes played a major role in the degradation of mexacarbate and formation of 14CO2. Metabolites detected included demethylated carbamates, various xylenols, polar and other unknown products. The principal degradative pathway for the chemical appears to b...

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.

Mexacarbate (Zectran®) is a carbamate insecticide that has been considered for controlling forest insect pests, particularly in northern conifer forests. The effects of different water characteristics (temperature, hardness, and pH) and aging (deactivation) on its toxicity to coho salmon(Oncorhynchus kisutch), Atlantic salmon(Salmo solar), brown trout(Salmo trutta), fathead minnows(Pimephales promelas), bluegills(Lepomis macrochirus), and yellow perch(Perca flavescens), were determined. Identification and toxicity of the breakdown products were also investigated. Mexacarbate was less toxic to eggs than to other life stages of fish. Water temperature and hardness did not affect its biological activity, but pH did—the insecticide was was 38 times more lethal to bluegills at pH 9.5 than at pH 6.5. Solutions of mexacarbate hydrolyzed to more toxic breakdown products during the first 3 weeks of aging; the rate of hydrolysis increased as alkalinity increased. The breakdown product 4-amino-3,5-xylenol was 70 times more lethal to bluegills than mexacarbate in 96-hr bioassay tests at pH 7.5. However, this breakdown product was apparently not present in sufficient concentrations or long enough to cause fish mortality when the insecticide is applied at rates recommended for control of forest insects.

Field samples of freshwater algae were examined to determine the effect of the insecticide Zectran on photosynthesis rate. Concentrations of Zectran between 10 and 10(3) parts per billion (ppb) affected neither O2 production nor NaH14CO3 uptake in any of the seven genera tested. However, Zectran at a concentration of 10(4) ppb after 1 hour effected a reduction in photosynthesis of Chroococcus, Oedogonium and in a mixed sample composed of Zygnema,Mougeotia and Spirogyra. Mougeotia, Spirogyra and Schizogonium were not affected by exposure to 10(4) ppb Zectran after 1 hour, but O2 production was significantly reduced after 24 hours of exposure to this same concentration.

A rapid and sensitive analytical technique to quantify carbamate insecticides at nanogram levels is reported using resin column and sorption, and desorption followed by N-P gas-liquid chromatography (GLC) analysis. The carbamates were extracted from natural water by percolation through a column of Amberlite XAD-2, followed by elution with ethyl acetate. The carbamate residues were directly analyzed by GLC with a Tracor Model 702 N-P detector. The recoveries for several carbamates including aminocarb, mexacarbate, carbaryl, propoxur, carbofuran, pirimicarb and methiocarb were from 86 to 108% at 1.0 and 0.01 ppm levels. Only 41 to 58% was recovered for methomyl. The extraction efficiency of Amberlite XAD-2 was pH-dependent as indicated in the extraction of aminocarb. More than 90% of the added aminocarb was recovered from phosphate buffer by the described method at pH 5.0 to 7.5 at 5.0 and 0.5 ppm levels.

k2, Kd and ki, for 2 organophosphorus (Phorate and Formothion) and 2 carbamate pesticides (Mexacarbate and Carbaryl) using acetylcholinesterase present in homogenates of the nervous tissue of the snail Lymnaea acuminata, were determined. Calculation of zero time velocities demonstrated that even in their P-S form the organophosphate compounds inhibited snail acetylcholinesterase. The kinetic constants of the 2 carbamates have been explained on the basis of their structure. The toxicity of the 4 pesticides has been explained on the basis of their kinetic constants.

The synergistic effects of piperonyl butoxide (PB)2, sulfoxide (SU), and dimethyl amino aniline (DAA) used in conjunction with two organophosphate pesticides (phorate and formothion) and two carbamate pesticides (mexacarbate and carbaryl) were examined in terms of the LC50 and acetylcholinesterase (AChE) inhibition in the snailLymnaea acuminata. The three synergists reduced the LC50 of phorate, formothion, mexacarbate, and carbaryl at exposure periods ranging from 24 to 144 hr. PB and SU had strong synergistic action; DAA had little effect; the highest synergistic ratio (70) was found with carbaryl and PB. The synergists enhanced thein vitro inhibition of cholinesterase caused by the pesticides; the synergistic effect onin vitro inhibition, however, was lower, compared to the change in the LC50.

A simple method was developed to quantify a fluorescent dye tracer [Erio Acid Red (EAR)] in spray deposits of forestry insecticides on balsam fir foliage. Three types of instruments, Beckman DU‐7 Spectrophotometer, Beckman Model 772 Ratio Fluorometer, Turner Model 111 Fluorometer, were investigated for sensitivity and precision during quantification of EAR in aqueous tank‐mix formulations of fenitrothion, ami‐nocarb and mexacarbate. Turner Fluorometer was found to be the most suitable out of the instruments tested, and the minimum detection limit was 0.5 ng/mL. Foliage samples were spiked with variable concentrations of EAR, extracted at different intervals of time after treatment, and cleaned using an Al2O3 column to remove plant pigments. EAR concentrations were quantified using Turner Fluorometer. Recovery was the greatest when extracted 12 to 15 min after spiking, but decreased rapidly as the time lapse between treatment and extraction increased. The minimum quantification limit (MQL) was 10 ...

Mexacarbate was less toxic to juvenile Atlantic salmon ( Salmo salar ) than its formulation, UCZF-19 (96-h LC50 - 19.5 and 3.4 mg/L, respectively). The increased lethality of the formulation is due to its volatile components (largely C3–C5 alkylbenzenes and naphthalene). The hazard indices of mexacarbate and UCZF-19 in forest spraying indicate low risk of direct mortality of juvenile Atlantic salmon.

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.

Volatilization of three forestry insecticides, aminocarb, fenitrothion and mexacarbate, from balsam fir seedlings was investigated after spray application of these chemicals as aqueous emulsions in a laboratory chamber at a dosage rate of 210 g (active ingredient)/ha. Highest airborne residues were found in the spray chamber at 0.25 h after mexacarbate application (21.7 μg/L) and lowest after aminocarb (6.3 μg/L). The treated seedlings were transferred to air‐tight chambers for investigation of volatilization over a 12 h post‐spray period. Mexacarbate was the most volatile, while aminocarb was the least. From the initial amounts of deposits on the seedlings, about 30% of mexacarbate, 15% of fenitrothion and 9% of aminocarb were lost within 12 h by volatilization. Residue levels that remained in the seedlings at 12 h post‐spray were ca. 70% of the initial values for aminocarb and fenitrothion, but were only ca. 9% for mexacarbate. Calculations on the mass‐balance indicated that 60% of the deposite...

The snailLymnaea acuminata, vector of the liver flukesFasciola hepatica andFasciola gigantica, was exposed to 40% and 80% LC50 doses of the pesticides 12/24 mg/L phorate (O,O-diethylS-(ethylthio) methyl phosphorodithioate) and 2.5/5.0 mg/L of mexacarbate (4-dimethylamino)-3,5-dimethylphenyl methyl carbamate) for 24 or 48 hr. These pesticides, although considered to be antiacetylcholinesterase agents, inhibited alkaline phosphatase and enhanced the activity of acid phosphatase in hepatopancreas, mantle, intestine, and foot of the snail. Trypsin activity in the alimentary canal of the snail was also inhibited. Discontinuation of pesticide treatment resulted in partial recovery in mexacarbate-treated animals while in phorate-treated animals the effect of the pesticide was largely irreversible.

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.

A simplified and sensitive method for the analysis of eight carbamate insecticide residues in foliage, forest soil and fish tissue by direct gas-liquid chromatography (GLC) is described. After fortification, the carbamate residues were extracted from the natural substrates by homogenization in ethyl acetate. The interfering co-extratives present in the crude extracts were removed by filtration through Whatman GF/A glass microfibre after coagulation. The carbamate residues were re-extracted into dichloromethane and directly analyzed intact by GLC with a Tracor Model 702 nitrogen-phosphorus detector. The rate of recovery for aminocarb, carbofuran, carbaryl, methomyl, mexacarbate, pirimicarb and propoxur was better than 80% at 5.0-ppm and 0.50-ppm levels. Slightly less than 60% was recovered for methiocarb.

The carbamate insecticide Zectran® (active ingredient [AI] mexacarbate) was applied aerially to two 300 ha blocks of coniferous forest, one at a dosage rate of 70 g AI/ha and the other at 140 g AI/ha. Brain cholinesterase (ChE) activity was determined in 372 exposed and control forest song-birds representing seven species. Brain ChE activity was similar among controls of all species studied. Among exposed birds, ChE activity was lowest in individuals from the high-dose block, although differences were not statistically significant. Warbler ChE activity showed a statistically significant relationship to dosage rates. Spray deposit was four times as great on the high-dosage block as on the low one. Zectran® provides a margin of safety to songbirds exceeding that of the organophosphorus insecticide fenitrothion which is currently used on a widespread operational basis against spruce budworm (Choristoneura fumiferana) in New Brunswick, Canada.

A modified analytical method employed to determine the insecticide Zectran in natural waters frequently has resulted in erroneous data. The errors have been attributed to interferences from particulate matter in these waters. In order to evaluate analytical interferences due to sorption of Zectran on particulates, a series of experiments was performed using bottom sediments and a peat moss in contact with aqueous solutions of zectran at a pH values of 6.0 and 20 degrees C. Isotherm studies confirmed that Zectran sorption occurs in a direct relation to the amount of chemically oxidizable carbon present in the bottom sediments or peat moss. However, the extent of sorption was limited, which suggested that particulates may not be the primary interference in the modified analytical method.

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).