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[The chemical control of disease vectors. Evaluation of new insecticides. Operational insecticides. New insecticides (author's transl)].

The chemical control of disease vectors which has been very successful during about 15 years is now faced with some difficulties due to the resistance of insects to the insecticides, to the decreasing number of candidate insecticides, to the increase of their price and to the legal restrictions concerning their safe use and their environmental inocuity. Since 1960, W.H.O. has carried out an evaluation programme to define the properties of new insecticides and to access their usefulness for public health. Through this programme several alternative insecticides have been selected and are now used in vector control operations. Although research continues on organophosphorous compounds and carbamates, it also includes the promising groups of pyrethroids and insect growth regulators. The present trend of vector control is to integrate various control techniques and to limit the use of insecticides to the control of the epidemiologically dangerous part of the vector population. This approach might prevent or delay the development of resistance.

Animals↗
PubMed1975

[Investigations on the influence of insecticides on autoxidation processes. X. Formation of peroxides from octadecenic acid methylester in the presence of water and chlorinated hydrocarbon insecticides (author's transl)].

According to the range DDT less than DDE less than heptachlor less than heptachlorepoxide, chlorinated hydrocarbon insecticides promote the formation of peroxides from cis- and trans-9-octadecenic acid methylesters within the lipid and the water phase of the investigated model system. Compared with DDT and heptachlor the metabolites DDE and heptachlorepoxide proof as more efficient prooxidants; this may be explained by their higher reactivity. According with these observations the amount of insecticides, especially of heptachlor and heptachlorepoxide, that can be extracted from the model system with petroleumether after 72 hrs of autoxidation is markedly diminished. From that it is concluded, that in the investigated lipid-water-system the insecticides not only have a catalytic effect, but also are in part immediately involved in the formation of peroxides from 9-octadecenic acid methyl ester.

DDT↗
PubMed1975

[Investigations on the influence of insecticides on autoxidation processes. XI. Formation of secondary metabolites from octadecenic acid methyl ester in the presence of water and chlorinated hydrocarbon insecticides (author's transl)].

For determining the influence of chlorinated hydrocarbon insecticides on the formation of secondary metabolites from peroxidized 9-octadecenic acid methylester by autoxidation within 72 hrs, substances reacting with phosphomolybdanic acid have been separated by TLC. Furthermore the increase of metabolites containing carbonyl groups and the variation of the ratio of polar to unpolar OH-groups in the metabolites have been determined by IR-spectrophotometry. All results proved, that the trans-9-octedecenic acid ester is autoxidized more rapidly than the cis-ester. Moreover the insecticides principally favour the formation of secondary metabolites from the lipidperoxide. This effect increases in the range DDT, DDE, heptachlor, heptachlorepoxide. If the increase of metabolites with carbonyl groups is chosen as a measure for the prooxidative effect, the effect appears equally high for the cis- and the trans-ester. But the hydroxyl index is changed depending on the kind of the insecticide added and the steric configuration of the lipid.

Chromatography, Thin Layer↗
PubMed1977

Insecticide solvents: interference with insecticidal action.

Several commercial solvent mixtures commonly used as insecticide carriers in spray formulations increase by more than threefold the microsomal N-demethylation of p-chloro N-methylaniline in midgut preparations of southern army-worm (Spodoptera eridania) larvae exposed orally to the test solvents. Under laboratory conditions, the same solvent mixtures exhibit a protective action against the in vivo toxicity of the insecticide carbaryl to the larvae. The data are discussed with respect to possible solvent-insecticide interactions occurring under field conditions and, more broadly, to potential toxicological hazards of these solvents to humans.

Enzyme Induction↗
PubMed1991

Insecticide-induced inhibition of thyroid activity in the fish Oreochromis mossambicus and recovery in insecticide-free water.

The histological and histochemical state of the thyroid gland of Oreochromis mossambicus was analyzed after 20 days' exposure of the fish to BHC (p less than 0.001 ppm). Histological changes after exposure included acolloidal and atrophied follicles and goitre formation. Follicular and nuclear diameter and the E/T ratio were significantly (p less than 0.001) higher than in the corresponding controls. The above insecticide led to thyroid dysfunction. The histochemical characteristics of the gland also changed after BHC treatment. When exposed fish were transferred to normal, clear, dechlorinated water, the altered follicles displayed remarkable recovery of activity and thyroid function returned to almost the same state as in normal controls. Histological and histochemical evaluation at 10-day intervals revealed healthy functional restitution of the gland, indicating that BHC-induced changes are reversible.

Animals↗
PubMed1991

Differences in the mode of lethality produced through intravenous and oral administration of organophosphorus insecticides in rats.

This study was undertaken to investigate the possibility that mechanisms other than cholinesterase (ChE) inhibition account for the acute toxicity of organophosphorus insecticide. Both the P = O type insecticide (direct ChE inhibitors: chlorfenvinphos and dichlorvos) and the P = S type insecticide (indirect ChE inhibitors: diazinon and fenthion) were employed. Rats treated with lethal doses of intravenous and oral P = O type insecticides and oral P = S type insecticides exhibited typical signs of anti-ChE poisoning along with marked inhibition of brain and erythrocyte ChE activity. In contrast, rats given lethal doses of intravenous P = S type insecticides exhibited tonic convulsions and opisthotonos, with only slight inhibition of ChE activities. When P = O type insecticides were intravenously administered to anesthetized and conscious rats, animals exhibited typical anti-ChE poisoning signs in cardiorespiration: hypertension and apnea which were antagonized by atropine. After administration of lethal doses of P = O type insecticides, breathing disappeared before the cessation of heart beats. Rats receiving lethal doses of intravenous P = S type insecticides did not show hypertension, but exhibited transient cessation of breathing and heart beats. Breathing was observed after the disappearance of heart beats. The electroencephalogram (EEG) was characterized by spike and wave complexes. The EEG and cardiorespiratory changes were not antagonized by atropine. It was concluded that lethality following intravenous P = S type insecticides may be independent of ChE inhibition.

Administration, Oral↗
PubMed1975

Uptake and excretion of organophosphorus and carbamate insecticides by fresh water fish, motsugo, Pseudorasbora parva.

Fresh water fish, Motsugo was reared in aquarium water tank containing about 1 ppm of 3 organophosphorus and 3 carbamate insecticides for about 30 days. The persistence of these insecticides in water and uptake and excretion of insecticides by fish were examined. Among organophosphorus insecticides, malathion is the most unstable in water, and degraded more than 99% for 7 days. Fenitrothion is moderately stable, and degraded 97% for 29 days. Diazinon is the most stable, and degraded 72% for 30 days. Among carbamates, carbaryl is the most unstable in water, and degraded more than 95% for 6 days. BPMC is moderately stable, and degraded 80% for 32 days. XMC is the most stable, and degraded 45% for 34 days. As for the uptake of the pesticides by fish, organophosphorus insecticides were generally higher than carbamate insecticides. The concentration of diazinon in fish reached to 211 ppm of the maximum level after 3 days, and that of fenitrothion reached to 162 ppm of the maximum level after 4 days. Afterwards, the concentration of both the insecticides decreased gradually due to the metabolism and excretion of the insecticides in fish. Uptake of malathion was very low and metabolized rapidly, and its concentration became to less than 0.01 ppm after 7 days. Among carbamate insecticides, the concentration of carbaryl in fish after one day reached to 7.5 ppm which was the maximum level of uptake. On the other hand, the concentration of BPMC in fish after 4 days became to 4.8 ppm, which was the maximum level, and decreased gradually. The concentration of XMC in fish was only 1.4 ppm after one day, but the metabolism rate of XMC in fish was fairly slow. Therefore, 0.55 ppm of XMC in fish remained even after 34 days. Moreover, in the test tank of diazinon, fenitrothion and BPMC, the appearance of deformed fish with spinal curvature of back bone came out at the rate of 10 to 30%.

Animals↗
PubMed2026

Genome-wide identification and expression profiling of CSP and OBP genes in Stictocephala bisonia reveals candidate genes potentially associated with insecticide response.

Stictocephala bisonia is an important invasive agricultural pest. Due to the frequent application of insecticides in its habitat, this species is under intense selection pressure. Chemosensory proteins (CSPs) and odorant-binding proteins (OBPs) are known to play key roles in insecticide resistance, but their specific functions in S. bisonia remain unclear. In this study, we identified a total of 22 SbisCSPs and 16 SbisOBPs based on the S. bisonia genome. To screen for candidate genes potentially linked to insecticide resistance, we adopted a multi-criteria screening strategy that integrated phylogenetic analysis, molecular docking with three insecticides, and tissue-specific expression profiling. Phylogenetic analysis identified several SbisCSPs and SbisOBPs clustering with genes known to be involved in insecticide resistance, serving as an initial evolutionary filter. Molecular docking results indicated that λ-Cyhalothrin exhibited the strong predicted binding affinity with most of SbisCSPs and SbisOBPs. Subsequent qPCR validation of seven prioritized candidates revealed distinct expression patterns: SbisCSP22 was highly expressed in adults and demonstrated strong binding affinity to all three insecticides tested, suggesting a potential role in mediating multi-insecticide response. Conversely, SbisCSP17 was significantly upregulated in larvae, clustered with genes known to mediate imidacloprid resistance, and exhibited strong binding affinity to imidacloprid. Given its larval-specific expression and the soil-dwelling behavior of larvae, we hypothesize that SbisCSP17 is a key candidate gene for larvae coping with soil-treated insecticides.

Animals↗
PubMed1991

Prediction of insecticidal activity of Bacillus thuringiensis strains by polymerase chain reaction product profiles.

A rapid analysis of Bacillus thuringiensis strains predictive of insecticidal activity was established by using polymerase chain reaction (PCR) technology. Primers specific to regions of high homology within genes encoding three major classes of B. thuringiensis crystal proteins were used to generate a PCR product profile characteristic of each insecticidal class. Predictions of insecticidal activity were made on the basis of the electrophoretic patterns of the PCR products. Included in the screen were PCR primers specific for cryI, cryIII, and cryIV genes, which are insecticidal for lepidopterans, coleopterans, and dipterans, respectively. Known B. thuringiensis strains as well as unidentified strains isolated from soil and insect cadavers were analyzed by PCR. Small amounts of crude sample lysates were assayed in a single PCR reaction containing 12 to 20 primers capable of distinguishing between the different insecticidal genes. Insecticidal activity predicted by the PCR screen was found to correspond with the insecticidal activity of insect bioassays. In addition to identifying strains with known insecticidal genes, the PCR screen can identify strains with altered electrophoretic patterns containing potentially novel genes.

Animals↗
PubMed1976

Nonoxidative enzymes in the metabolism of insecticides.

Two major classes of enzymes, i.e., hydrolases and transferases, comprise all the nonoxidative enzymes, and together these enzymes catalyze a wide variety of biotransformations of insecticides. The hydrolytic enzymes involved in insecticide metabolism are carboxylesterase (EC 3.1.1.1), arylesterase alkylamidase, and DFPase (EC 3.8.2.1). Recent experimental evidence suggests that carboxylesterase enzyme(s), formerly known to hydrolyze malathion-type insecticides, can also catalyze hydrolysis of a variety of diversified insecticidal esters such as benzilic acid derivatives, carbanilate compounds, and pyrethroids. These organophosphate-sensitive esterases, with the exception of the enzyme which hydrolyzes malathion, are all present in microsomes. Similarly, the action of amidases now extends to those insecticidal compounds of their intermediates which contain an aminoformyl (N-CHO) moiety. Arylesterase and DFPase catalyze the P-anhydride bond cleavage of the leaving group, a major hydrolytic pathyway for organophosphate insecticides. Transferal enzymes which are presently know to metabolize insecticidal organophosphates are GSH-S-alkyltransferase (EC 2.5.1.12) and GSH-S-aryltransferase (EC 2.5.1.13). These enzymes cleave P-O-R (R = alkyl) or P-0-X (X = aromatic), with subsequent transfer of the R or X group to glutathione. Regarding the other conjugating enzymes, UDP-glucuronyltransferase (EC 2.4.L.17), UDP-glucosyltransferase (EC 2.4.1.35), and arylamine acetyltransferase (EC 2.3.1.5), much work is needed to understand their interactions with insecticidal compounds. There is some evidence that arylsulfotransferase (EC 2.8.2.1) MAY PLAY A PROMINENT ROLE IN THE CONJUGATIVE MECHANISMS OF INSECTS.

Amidohydrolases↗
PubMed1976

Nonoxidative enzymes in the metabolism of insecticides.

Two major classes of enzymes, i.e., hydrolases and transferases, comprise all the nonoxidative enzymes, and together these enzymes catalyze a wide variety of biotransformations of insecticides. The hydrolytic enzymes involved in insecticide metabolism are carboxylesterase (EC 3.1.1.1), arylesterase (EC 3,1.1.2), alkylamidase, and DFPase (EC 3.8.2.1). Recent experimental evidence suggests that carboxylesterase enzymes(s), formerly known to hydrolyze malathion-type insecticides, can also catalyze hydrolysis of a variety of diversified insecticidal esters such as benzilic acid derivatives, carbanilate compounds, and pyrethroids. These organo-phosphate-sensitive esterases, with the exception of the enzyme which hydrolyzes malathion, are all present in microsomes. Similarly, the action of amidases now extends to those insecticidal compounds or their intermediates which contain an aminoformyl (N--CHO) moiety. Arylesterase and DFPase catalyze the P--anhydride bond cleavage of the leaving group, a major hydrolytic pathway for organophosphate insecticides. Transferal enzymes which are presently known to metabolize insecticidal organophosphates are GSH-S-alkyltransferase (EC 2.5.1.12) and GSH-S-aryltransferase (EC 2.5.1.13). These enzymes cleave P--O--R (R = alkyl) or P--O--X (X = aromatic), with subsequent transfer of the R or X group to glutathione. Regarding the other conjugating enzymes, UDP-glucuronyltransferase (EC 2.4.1.17), UDP-glucosyltransferase (EC 2.4.1.35), and arylamine acetyltransferase (EC 2.3.1.5), much work is needed to understand their interactions with insecticidal compounds. There is some evidence that arylsulfotransferase (EC 2.8.2.1) may play a prominent role in the conjugative mechanisms of insects.

Amidohydrolases↗
PubMed1976

Insecticide movement following application to crevices in rooms.

The movement of chlorpyrifos and diazinon from cracks and crevices in empty dormitory rooms with and without forced air movement to houseflies and plates in non-target areas was studied. Aluminum pie plates in rooms with the high concentrations of an insecticide, no forced air movement, and at the earlier sampling interals contained more insecticide. Insecticides were not detectable at 48 hr. Increased housefly movement occurred simultaneously with the initiation of insecticide application in rooms with forced air and 1 min later in rooms with no forced air. Mortality of houseflies exposed during and at 5 hr after insecticide application was greater for males than females in all tests except one; at the high insecticide concentrations; and at successive time intervals through the 24-hr interval after their transfer from the treated rooms to holding rooms. Houseflies in cages near the ceiling, exposed to an insecticide, and forced air movement, exhibited greater mortality than those in cages on the floor, while the reverse was true for houseflies in rooms with no forced air movement.

Air Movements↗
PubMed1992

Susceptibility of house flies (Diptera: Muscidae) and five pupal parasitoids (Hymenoptera: Pteromalidae) to abamectin and seven commercial insecticides.

Assays of five commercial insecticides applied as residual sprays at label rates to plywood indicated the most toxic insecticide overall for pteromalid parasitoids of house flies, Musca domestica L., was Atroban (permethrin), followed by Ciodrin (crotoxyphos), Rabon (tetrachlorvinphos), Ectrin (fenvalerate), and Cygon (dimethoate). Insecticide-susceptible house flies were susceptible to all five insecticides (mortality, 62-100%). Flies that were recently colonized from populations on dairy farms in New York were susceptible only to Rabon. Urolepis rufipes (Ashmead) was the most susceptible parasitoid species overall to these insecticides, followed by Muscidifurax raptor Girault & Sanders, Nasonia vitripennis Walker, Pachycrepoideus vindemmiae (Rondani), and Spalangia cameroni Perkins. Compared with susceptible flies, newly colonized flies showed moderate resistance to avermectin B1a (abamectin). Abamectin was more toxic to all of the parasitoids except N. vitripennis and S. cameroni than to newly colonized house flies when exposed for 90 min to plywood boards treated with 0.001-0.1% abamectin. Space sprays with Vapona (dichlorvos) killed all of the parasitoids and susceptible flies and 64% of the newly colonized flies when insects were placed directly in the path of the spray; mortality was substantially lower among flies and parasitoids protected under 5 cm of wheat straw. Space sprays with Pyrenone (pyrethrins) killed greater than 86% of all insects exposed to the spray path except for the newly colonized flies (1% mortality); mortality of insects protected under straw was low (less than 12%) except for S. cameroni (76%). Because responses of the five parasitoids to the different insecticides varied considerably, general conclusions about parasitoid susceptibility to active ingredients, insecticide class, or method of application were not possible.

Animals↗
PubMed1977

[Neurologic involvement caused by insecticides. Study of chronic manifestations in 13 cases].

The clinical study of 13 patients with chronic neurological manifestation induced by insecticides (organophosphorades and organochlorades compounds) is reported. Twelve patients were male and farmers and one was a saleslady. The authors adopted five conditions for diagnosis: frequent contact with insecticides, synaptomatology directly related to the compounds exposition, clinical and laboratorial exclusion of others pathologies, quickly improvement of the symptoms when the patients were away from their original environment and high levels of insecticides in blood and urine determination. The clinical data was not uniform and the manifestation include pure motor neuropathy, mixed sensory-motor neuropathy, mielopathy and cranial nerves palsies. No relationship could be established between the insecticides (type, frequency of number of exposition) to the clinical picture. The insecticides determination was positive (moderated or elevated levels) in all patients and in 40% of controls (traces). Eletromyographic studies showed a neuropathic pattern in the majority of cases and reduced motor nerve conduction velocities. The authors believe that insecticides determination has a relative value and others criterion must be used in the diagnosis of chronic illness caused by insecticides. They think that others factors can be related with the symptomatology (hypersensibility, malnutrition, previous sensibilization or cumulative effect).

Adult↗
PubMed1992

Cytogenetic effects of pesticides. IV. Cytogenetic effects of the insecticides Gardona and Dursban.

The cytogenetic effects of the insecticides Gardona and Dursban were investigated. The toxicity and ability of both insecticides to induce chromosome aberrations and sister-chromatid exchange in vitro was tested in a primary culture of mouse spleen cells, in order to assess the potential mutagenicity of both insecticides. The concentrations 10(-7)-10(-3) M were used for testing the toxic effects of the insecticides. Both Gardona and Dursban were toxic to spleen cell cultures and the percentage of viable cells decreased as the concentration of the insecticide was increased. It reached 76.8% and 77.8% of control after treatment with the highest concentration tested (10(-3) M) of Gardona and Dursban respectively. Gardona at 0.25, 0.50, 1.0 and 2.0 micrograms/ml, and Dursban at 0.50, 1.0, 2.0 and 4.0 micrograms/ml were tested for the induction of chromosome aberrations and sister-chromatid exchanges. All of the tested concentrations of both insecticides induced a high percentage of metaphases with chromosomal aberrations in cultured mouse spleen cells after 4-h treatment. The frequency of SCEs/cell increased with increasing concentration of the insecticides. It reached 11.92 +/- 0.14/cell and 13.40 +/- 0.20/cell after treatment with Gardona (2 micrograms/ml) and Dursban (4 micrograms/ml), respectively, compared with 8.2 +/- 0.19/cell and 7.6 +/- 0.15/cell in the solvent control. The presented results indicate that both Gardona and Dursban in the tested concentrations are mutagenic in mouse spleen cell cultures.

Animals↗
PubMed2026

Bacillus thuringiensis pathogenicity islands encode regulatory circuits controlling insecticidal Cry toxin expression during vegetative growth.

Bacillus thuringiensis (Bt) produces insecticidal toxins, including Cry and Vip3 proteins, that are widely used for biological pest control. Cry proteins are classically expressed during sporulation under the control of sporulation-specific σ factors, whereas Vip3 is produced during vegetative growth, suggesting distinct regulatory pathways. Notably, many cry and vip3A genes are clustered within pathogenicity islands (PAIs), such as BtPAI-1. However, whether these PAIs also encode regulatory mechanisms coordinating toxin expression remains unclear. Here, we identify VipR, a BtPAI-1-encoded transcriptional regulator, as an activator of insecticidal gene expression during the vegetative phase in Bt strains HD-1 and CT-43. In these strains, VipR promotes the transcription of BtPAI-1 associated insecticidal genes, including vip3A and selected cry genes, resulting in premature Cry protein accumulation and increased insecticidal activity. In addition, VipR contributes to the vegetative-phase expression of the non-BtPAI-1 cry9Aa genes in strain BGSC 4AE1. Phylogenetic analysis revealed that vipR is widely distributed in one-third of Bt strains, and is strongly associated with PAIs. Futhermore, heterologous expression of vipR in BGSC 4J5 and HD-73 was sufficient to activate vegetative-phase transcription of some cry independently of sporulation-specific σ factor cascade. These results support a role for VipR in coordinating vegetative-phase expression of insecticidal genes in the Bt strains examined and suggest that BtPAI-1 can encode both insecticidal determinants and regulatory functions that influence their expression. These findings provide new insights into the regulatory architecture of Bt pathogenicity islands and may facilitate the engineering of strains with enhanced insecticidal activity.

Bacillus thuringiensis↗