Toxicity of pyrethroids and effect of synergists to larval and adult Helicoverpa zea, Spodoptera frugiperda, and Agrotis ipsilon (Lepidoptera: Noctuidae).

Based on 48 h LD50 estimates from topical bioassays, cypermethrin was more toxic than permethrin to Helicoverpa zea (Boddie) larvae and adults; however, the two pyrethroids did not differ significantly in their relative toxicities to Spodoptera frugiperda (J. E. Smith) and Agrotis ipsilon (Hufnagle). Larvae of each species generally were more susceptible to cypermethrin and permethrin than respective adults. The only exception to this generalization occurred with H. zea where slight overlap of the 95% confidence intervals with larvae and adult males was observed with cypermethrin. Respective males and females of the three species usually did not differ significantly in their susceptibility to either cypermethrin or to permethrin; however, with A. ipsilon, females were more susceptible to permethrin than to cypermethrin. Several instances of greater than additive toxicity were noted when insects were treated with piperonyl butoxide, S,S,S-tri-n-butyl phosphorotrithioate (DEF), or amitraz 30 min before cypermethrin. DEF exhibited the broadest spectrum of synergistic activity.

Pharmacokinetic mechanisms associated with synergism by DEF of cypermethrin toxicity in larval and adult Helicoverpa zea, Spodoptera frugiperda, and Agrotis ipsilon (Lepidoptera: Noctuidae).

Penetration, metabolism, and excretion of radiocarbon were observed after topical treatment of Helicoverpa zea (Boddie), Spodoptera frugiperda (J. E. Smith), and Agrotis ipsilon (Hufnagle) larvae and adults with cypermethrin-14C. These pharmacokinetic events usually were higher with trans-cypermethrin-14C than with cis-cypermethrin-14C. They also were generally higher with H. zea and S. frugiperda than with A. ipsilon, and they were higher in larvae than in adults. No marked sex differences in the degradation of trans-cypermethrin were apparent. Pretreatment of H. zea, S. frugiperda, and A. ipsilon larvae and adults with S,S,S-tri-n-butyl phosphorotrithioate (DEF) 30 min before application of cypermethrin resulted in a perturbation of trans-cypermethrin pharmacokinetics manifested primarily by a lower rate of pyrethroid metabolism as compared with that in the absence of DEF. Appreciably higher internal levels of the toxic parent pyrethroid were often observed in the presence of DEF than in the absence of DEF in most cases. Suppression of cypermethrin penetration and elimination also was usually detected. Inhibition by DEF of the enzymatic degradation of cypermethrin may account for the synergy observed between these two compounds.

DEF sensitive esterases in homogenates of larval and adult Helicoverpa zea, Spodoptera frugiperda, and Agrotis ipsilon (Lepidoptera: Noctuidae).

Homogenates of Helicoverpa zea (Boddie), Agrotis ipsilon (Hufnagle), and Spodoptera frugiperda (J. E. Smith) third instars and adults contained S,S,S-tri-n-butyl phosphorotrithioate (DEF)-sensitive enzymes that hydrolyzed trans-cypermethrin and two known esterase substrates, alpha-naphthyl acetate and beta-naphthyl acetate. Except for H. zea with alpha-naphthyl acetate, larval preparations were more active than those of adults, and no marked sex differences were apparent. The hydrolysis of trans-cypermethrin in noctuid preparations were inhibited by DEF, with pI50 values ranging from 4.5 to 6.7. DEF was a potent inhibitor of the degradation of general carboxylesterase substrates alpha-naphthyl acetate and beta-naphthyl acetate in some cases. Electrophoretic studies confirmed the presence in noctuid gut homogenates of one or more DEF-sensitive esterases that hydrolyzed alpha-naphthyl acetate and beta-naphthyl acetate and that were completely inhibited by dichtorvos.

Inhibition of ATP dephosphorylation by acaricides with emphasis on the anti-ATPase activity of the carbodiimide metabolite of diafenthiuron.

3-(2,6-Diisopropyl-4-phenoxyphenyl)-1-tert-butylcarbodiimide (DFCD), a toxic metabolite and photodegradation product of the propesticide diafenthiuron, and dicyclohexylcarbodiimide (DCCD), a commonly used biochemical inhibitory probe, inhibited Mg(2+)-, Na+K(+)-, and Ca2+Mg(2+)-ATPase activities in preparations from bulb mites (Rhizoglyphus echinopus (Fumouze and Robin)), twospotted spider mites (Tetranychus urticae Koch), and bluegill (Lepomis macrochirus Rafinesque) brain. DCCD was more active than DFCD, but neither carbodiimide was very potent. A possible exception occurred with DCCD, which caused 100% inhibition of bulb mite oligomycin-sensitive Mg(2+)-ATPase activity at a concentration of 0.1 mM. Using house fly, Musca domestica L., thorax mitochondrial Mg(2+)-ATPase, we showed that the binding domain for both carbodiimides was in the F0 portion of the enzyme, probably the transmembrane proton channel which is the known site of DCCD binding in proton-translocating ATPases. Certain other specific acaricides were inhibitors (greater than 50% at 0.1 mM) of ATPase preparations from bulb mites. These acaricides included chloropropylate, bromopropylate, oxythioquinox, cyhexatin, and flubenzimine (Mg2+ and Na+K(+)-ATPase), and ovex, chlorbenside, and propargite (Mg(2+)-ATPase). The role of ATPase inhibition in the modes of acaricidal and insecticidal actions of diafenthiuron, the two carbodiimides, and the other compounds is discussed.

Dopamine and octopamine in whole body extracts of the bulb mite.

Using high performance liquid chromatography with electrochemical detection, whole body extracts of the bulb mite, Rhizoglyphus echinopus (Fumouze and Robin), were found to contain the biogenic amines dopamine and octopamine at concentrations of 4.3 +/- 0.6 and 2.3 +/- 1.4 ng g-1 wet weight, respectively. Adrenaline, noradrenaline, tyramine, N-methyldopamine, N-acetyldopamine, and 5-hydroxytryptamine, if present, were below the limits of detectability. This is the initial demonstration of the presence of octopamine in a mite species.

Effects of aluminum on the biochemical composition of Atlantic salmon.

Biomolecule content, dry weight, and wet weight of Atlantic salmon, Salmo salar L., were monitored during 60-day exposure to aluminum, which began before hatch and extended to about the end of the alevin stage. The Atlantic salmon exposed to aluminum concentrations of 0, 33, 71, 124, or 264 micrograms/L at pH 5.5 for 60 days were evaluated for growth, survival, and biochemical effects on days 15, 30, and 60. Growth and survival were significantly reduced at the two highest aluminum concentrations by day 60. RNA and DNA were the most sensitive biomolecules monitored and were significantly reduced at the three highest aluminum concentrations by day 60. RNA:protein and RNA:DNA ratios were no more responsive than growth and survival. The lipid content of salmon was not significantly affected by exposure to aluminum. It was concluded that biomolecule content or ratios were not particularly sensitive indicators of growth effects in Atlantic salmon exposed to aluminum.

Temporal and spatial variation of RNA content in nymphs of the mayfly, Stenonema femoratum (Say).

Temporal variation of RNA: weight, RNA: protein, RNA: DNA, and protein: DNA ratios in Stenonema femoratum (Say) was assessed by monitoring at the same site in a small midwestern stream over a two-year period. Variation components were estimated using a two-way mixed model analysis of variance with weight class and collection date as main effects. About 30% of the variation in RNA concentration was within-cell variation associated with differences among individuals and analytical error. Temporal variation accounted for about 50% of the total variability in RNA concentration data. RNA: weight had 11% and RNA: protein had 17% variation attributed to weight class effects indicating that these ratios were dependent on the size of the mayfly. RNA: DNA ratios were not influenced by mayfly weight, suggesting that this ratio would be the most appropriate for comparing populations based on means of mixed individual sizes. Comparison of mean RNA: DNA ratios among collection dates yielded significant increases in the ratio during late fall in two consecutive years. Spatial variations in RNA: DNA ratios of S. femoratum collected from sites of similar habitats were not significantly different. These data encourage the future development of RNA concentration as an in situ biochemical indicator of growth rate and possibly of stress related effects on growth rate.

Protein and nucleic acid content in Daphnia magna during chronic exposure to cadmium.

Daphnia magna Straus were exposed to cadmium concentrations of 0, 0.4, 0.8, 2.1, 4.3, and 7.2 micrograms/liter for 21 days. Protein, RNA, DNA, glycogen and lipid content were measured after 4, 7, and 21 days of exposure, and the results were related to survival and reproduction. The no observed effect concentration (NOEC) for survival, protein growth, and reproduction at Day 21 was 2.1, 0.8, and 0.8 microgram/liter cadmium, respectively. Protein growth was most sensitive to cadmium exposure following the rapid growth phase which occurred between Days 4 and 6 of growth and development. All concentrations of cadmium produced significant reductions in protein growth at Day 7 indicating that the NOEC was less than 0.4 micrograms/liter. RNA:protein and protein:RNA:DNA ratios, which are related to the growth rate of daphnids, were most appropriately monitored at Day 4 which was prior to the rapid growth phase. Protein:RNA:DNA ratio at Day 4 identified the same NOEC as identified by protein growth and reproduction after 21 days of exposure.

Effects of fenvalerate on biochemical parameters, survival, and reproduction of Daphnia magna.

Daphnia magna were exposed to fenvalerate at nominal concentrations of 0.5, 0.25, 0.13, 0.06, and 0.03 micrograms/liter for 21 days. On Days 7 and 21 of exposure, levels of ribonucleic acid (RNA), deoxyribonucleic acid (DNA), adenosine diphosphate (ADP), adenosine triphosphate (ATP), glycogen, and lipid were measured, and the results were related to survival and reproduction during the 21-day test period. Survival was not significantly (alpha = 0.05) affected by the 21-day exposure; however, reproduction was reduced at fenvalerate concentrations of 0.25 and 0.5 micrograms/liter. On Day 7, protein, RNA, ADP, caloric equivalents, and glycogen were also significantly reduced at fenvalerate concentrations of 0.25 and 0.5 micrograms/liter. Thus, these biochemical parameters identified the same no observable effect concentration (NOEC) as did reproduction. Variables derived from biochemical parameters were related to reduced protein growth and reproduction. Decreases in protein/RNA and glycogen/lipid ratios and increases in ADP/DNA, ADP/ATP, protein/RNA/DNA, and lipid/DNA ratios were observed at Day 7 for those daphnia exposed to 0.5 micrograms/liter of fenvalerate. The only derived variable that reflected the reduced protein growth at Day 7 in daphnia exposed to 0.25 micrograms/liter of fenvalerate was the glycogen/lipid ratio. Biochemical determinations at Day 21 indicated that the organisms exposed to 0.25 micrograms/liter of fenvalerate were not different from controls, whereas those exposed to 0.5 micrograms/liter were still affected.

Influence of organotins on rat platelet aggregation mechanisms.

The effects of ten organotins on rat platelet aggregation mechanisms were examined. Bis(tri-n-butyltin)oxide was the most potent inhibitor of both ADP- and collagen-induced aggregation, and it was the only organotin that directly induced aggregation. It also increased the latent period for induction of aggregation by collagen. Triphenyltin hydroxide was a weak inhibitor of both ADP- and collagen-induced aggregation. However, in contrast to bis(tri-n-butyltin)oxide, it decreased the latent period for collagen-induced aggregation. A similar effect also was observed with diphenyltin dichloride, phenyltin trichloride, and cyhexatin. Tri-n-butyltin chloride and tetra-n-butyltin demonstrated specificity in their action since aggregation induced by ADP but not collagen was inhibited. Tri-n-propyltin chloride, trimethyltin chloride, and fenbutatin oxide were without discernible effect on rat platelet aggregation.

Biogenic amine uptake by nerve cords from the American cockroach and the influence of amidines on amine uptake and release.

Uptake of 5-hydroxytryptamine (5-HT) by isolated whole nerve cords of the American cockroach, Periplaneta americana (L.), involved a dual component system, with one component consisting of rapid active uptake and the other of passive diffusion. Using high performance liquid chromatography with electrochemical detection, it was shown that nerve cords contained 5-HT levels of about 350 ng/g and an equivalent amount of 5-hydroxyindoleacetic acid (5-HIAA), a 5-HT metabolite not previously reported in cockroach nerve cords. Amidines had no discernable effect on uptake of 5-HT or octopamine by nerve cords or on endogenous levels of 5-HT and 5-HIAA in cords.

Formamidine-mediated inhibition of rat platelet aggregation.

The formamidine pesticide chlordimeform (CDF) was a strong inhibitor of aggregation of rat platelets induced by collagen and arachidonic acid and was a weak inhibitor of that induced by ADP. With the exception of 4-chloro-o-formotoluidide which was an inhibitor of arachidonic acid-induced aggregation only, the CDF metabolites were without discernible effect on aggregation induced by these agents. Amitraz, another formamidine pesticide, inhibited arachidonic acid-induced aggregation but was without effect on that induced by collagen or ADP. Inhibition of collagen- and/or arachidonic acid-induced aggregation by formamidines was concentration-dependent. Although platelets underwent shape change, primary aggregation was markedly inhibited, and secondary aggregation was abolished in some cases. CDF, its two N-desmethyl metabolites, and octopamine, but not amitraz, caused significantly elevated levels of cyclic AMP in platelet rich plasma as compared to controls; however, this effect did not fully account for the action of formamidines on aggregation.

Effect of formamidines on 5-hydroxytryptamine uptake and biogenic amine levels in rat platelets.

Uptake of radioactive 5-hydroxytryptamine (5-HT) by platelets from rats treated intraperitoneally with the insecticide/acaricide chlordimeform (CDF) at 25 mg/kg was not significantly influenced at 1 h; however, uptake of this amine by platelets from rats treated with its N- monodemethyl metabolite (DMC) at the same dosage was significantly inhibited (37%). Two reversed phase high performance liquid chromatographic systems with electrochemical detection were developed with a capacity to separate 11 biogenic amines and related compounds. Only 5-HT, norepinephrine (NE), dopamine (DA), and 3,4-dihydroxyphenylacetic acid (DOPAC) were consistently detected in platelets and plasma samples. At 1 h and/or 24 h postinjection, CDF effected significant decreases in platelet levels of 5-HT, NE, and DA and plasma levels of 5-HT, whereas platelet and plasma levels of DOPAC were significantly increased. DMC effected significant decreases in both platelet and plasma levels of 5-HT. These in vivo studies confirmed previous in vitro experiments which demonstrated that formamidines inhibited uptake of 5-HT by platelets and released endogenous stores of amines from platelets.

Effects of organotins on rat platelets.

Incubation of rat platelets with organotins inhibited their capacity to take up 5-hydroxytryptamine-14C (5-HT-14C) and stimulated the release of preloaded 5-HT-14C as well as endogenous 5-HT. Similar but less pronounced effects also were observed when platelets from rats treated intraperitoneally with organotins were examined. The relationships of organotin structure to 5-HT uptake inhibition and 5-HT release were similar, with the most active compounds being the trisubstituted derivatives bis(tri-n-butyltin) oxide, tri-n-butyltin chloride, tricyclohexyltin hydroxide, tri-n-propyltin chloride, and triphenyltin hydroxide. Scanning electron micrographs revealed increased platelet aggregation and shape change in organotin treated samples as compared to vehicle treated controls. It was suggested that the action of organotins on rat platelets was due, at least in part, to their known ability to interfere with ATPase mediated systems.

Influence of formamidines on biogenic amine levels in rat brain and plasma.

Biogenic amine levels in samples of whole brain and plasma following treatment of rats with chlordimeform (CDF), its two N-demethyl metabolites (DMC and DDC), p-chloroamphetamine (PCA), and harmaline were separated by high performance liquid chromatography equipped with fluorescence or electrochemical detection systems. At 1 hr following s.c. injection, CDF (200 mg/kg) caused a reduction in levels of norepinephrine (NE), 5-hydroxytryptamine (5-HT), and tyramine (TRM), an increase in dopamine (DA), and no change in levels of beta-phenethylamine (PEA) in samples of whole rat brain, whereas DMC (100 mg/kg) and DDC (25 mg/kg) effected reductions of brain levels of NE, 5-HT, TRM, and PEA with no change in DA. The effect of DMC (100 mg/kg) on NE and DA levels in brain was followed periodically for 24 hr. Following a significant decrease at 1 hr, NE levels increased to a maximum at 12 hr and remained higher than controls throughout the remainder of the 24 hr test period. DA levels increased during the initial 12 hr and remained significantly higher than controls for the remaining 12 hr. The influence of s.c. vs i.p. administration of DMC (100 mg/kg) on brain amine levels was examined. Intraperitoneal treatment generally resulted in lower amine levels in DMC and vehicle treated animals. Differences in treatment effects were similar for all amines except for 5-HT in which s.c. injection produced a slight reduction, while i.p. injection resulted in a two-fold increase.(ABSTRACT TRUNCATED AT 250 WORDS)

Interaction of formamidines with the platelet 5-hydroxytryptamine uptake system.

1. The activity of the insecticide/acaricide N'-(4-chloro-o-tolyl)-N,N-dimethylformamidine (chlordimeform), its two formamidine metabolites, N'-(4-chloro-o-tolyl)-N-methylformamidine (demethylchlordimeform) and N'(4-chloro-o-tolyl) formamidine (didemethylchlordimeform), and 116 other formamidines and related compounds as inhibitors of rat platelet 5-hydroxytryptamine (5-HT) uptake was studied. Though several formamidines were more active than chlordimeform (pI50 3.9), none was as potent as imipramine. Didemethylchlordimeform (pI50 4.4) was the most potent formamidine examined. 2. Inhibition of 5-HT uptake by chlordimeform was mixed. Moreover, chlordimeform inhibition of 5-HT uptake by reserpinized platelets was not significantly different from uptake by non-reserpinized platelets. 3. Chlordimeform and its two formamidine metabolites caused release of platelet 5-HT, and their potency as releasers paralleled their activity as uptake inhibitors. 4. Electron microscopy indicated that chlordimeform treatment changed platelet shape and size but apparently did not alter physical integrity of the membrane. 5. It was suggested that platelet 5-HT storage vesicles were the most probable site of formamidine action.

Microbial degradation of thidiazuron and its photoproduct.

Degradation of the cotton defoliant thidiazuron and its photoproduct photothidiazuron by soil and thirteen species of microorganisms was examined. Aspergillus versicolor, Torula rosea, and Flavobacter sp. were most active in degrading thidiazuron. Unknown water-soluble metabolites and phenylurea were the major products. A. versicolor and Penicillium cyclopium were most active in degrading photothidiazuron. 4-Hydroxyphenylphotothidiazuron was the major organosoluble product formed by A. versicolor; phenylurea and an unidentified metabolite constituted the major organosoluble products from P. cyclopium. Both microbes also formed appreciable water-soluble metabolites. Radioactive carbon dioxide was formed from thidiazuron-aniline-14C by Oscillatoria sp. but not by Chlorella sp., suggesting that the former algal species utilized the defoliant as an energy source.

Inhibition of rat platelet 5-hydroxytryptamine uptake by chlordimeform.

Chlordimeform, a formamidine insecticide and acaricide, and two of its toxic N-demethyl metabolites inhibited rat blood platelet 5-hydroxytryptamine (5-HT) uptake. A direct relationship existed between formamidine uptake inhibitory potency and N-demethylation. Didemethylchlordimeform, the most potent formamidine inhibitor of 5-HT uptake examined, had a pI50 of 4.2. However, it was appreciably less active than the classical inhibitor imipramine, which yielded 86.4% inhibition of 5-HT uptake at a concentration of 1.10(-5) M.