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PubMed2001

Effects of insecticide treatments on insect density and diversity in vegetable open fields.

Vegetable open field areas increased for 15 years in Wallonia, mainly in Hesbaye. To be in accordance with quality standards, especially in terms of agro-chimical residues (R.M.L.), biological pest control was developed and allowed to reduce the insecticide use, leading to have safer fresh products. Among cultivated species in Wallonia, leguminous crops represent more than 85% of the vegetable production. To assess the impact of insecticide treatment on both pests (mainly aphids) and beneficial insects (predators and parasitoïds), broad bean (Vicia faba L.) fields were investigated during all the production duration. Twelve fields between Waremme and Hannut were visited weakly from May to July. In each field, control untreated and treated plots were investigated. Insects were caught using yellow traps and determined until the family level. Approximately 90.000 insects belonging to 59 major families (99% of captures) and 64 minor families were identified. These results showed that biodiversity in terms of family numbers was significantly higher in unsprayed plots. In addition, biodiversity and biomass (insect density) increased gradually during the season. Evaluation of pest and beneficial diversity and density was discussed in relation to aphicid (lambda-cyhalothrin, pirimicarb) treatments and the development of I.P.M. program in vegetable crops.

Animals↗
PubMed2002

A new assembly and technique for testing insecticides.

A new design of insecticide testing assembly has been devised that is highly versatile in testing the efficacy, potency and interaction of insecticides and other test chemicals. The merits of the assembly and technique have been explained.

Insecticides↗
PubMed2002

Insecticide activity of surfactins and iturins from a biopesticide Bacillus subtilis Cohn (S499 strain).

Surfactin C14, surfactin C15, and iturin C15 are lipopeptides purified from Bacillus subtilis (S499 strain). They were incorporated to artificial diet of the fruit fly Drosophila melanogaster (Meigen) (Diptera, Drosophilidae) to assess their potential insecticide activity. Surfactins with long fatty acid chain (C14 and C15) showed insecticide effect on the fruit fly, D. melanogaster. On the contrary, iturin was not toxic to fruit fly D. melanogaster. At 100 ppm, surfactin C14 and C15 showed respectively 85.4 and 92.6% adults mortality after one-day exposure. F1 progeny fly emergence inhibition by C14 and C15 were respectively 79.8% and 91.3%. To check whether the biocide activity of lipopeptides was due to their surface-active properties, detergent Triton X100, SDS, CTAB and Tween 80 were tested. No adult mortality was recorded with the detergents but Triton X100 and SDS showed F1 progeny emergence inhibition similar to that of surfactins. We showed that there was a dose-response activity with surfactin C15.

Animals↗
PubMed2002

Insecticidal activity of a nonsteroidal moulting hormone agonist on mosquito larvae and effects on ecdysteroid amounts.

The secondary effects of conventional insecticides on the environment, vertebrates and beneficial organisms have caused a move to the use of more target-specific chemicals such as insect growth regulators. Halofenozide (RH-0345) is a novel nonsteroidal ecdysteroid agonist that induces a precocious and incomplete moult in several insect orders. In the present study, the insecticidal activity of a commercial formulation of halofenozide (23% EC) was evaluated at different concentrations ranging between 8 and 32 micrograms/l. Treatment was made on newly moulted fourth-instar larvae of the mosquito, Culex pipiens (Diptera: Culicidae), and mortality was scored until adult emergence. Results showed that death in the larval stage was relatively important. Moreover, treatment caused a significant reduction in the length of the larval and pupal stage. In a second series of experiments, halofenozide was tested at two doses (LC50 = 12.58 micrograms/l and LC90 = 28.58 micrograms/l) and the ecdysteroid amounts during the fourth instar were evaluated in an enzyme immunoassay. We noted that halofenozide did not shifted the moment of the single larval ecdysteroid peak, but it caused an increase of the titre values. Finally, the compound at the highest concentration was found to increase significantly the cuticle thickness recorded at day 4 following treatment.

Animals↗
PubMed2002

Effect of some insecticides on acetylcholinesterase from beneficial insects: Coccinella septempunctata, Chrysoperla carnea and Forficula auricularia.

In vitro enzyme activity of head homogenates from adults of Coccinella septempunctata, Chrysoperla carnea and Forficula auricularia originated from different habitats in Belgium (wheat, barley, rye, set-aside fields and experimental orchard, uncultivated area) were investigated in presence of insecticide active ingredients. Using the procedure of Ellman, I50 (M) and Ki (M-1 min-1) values were established. The beneficial insects showed the least susceptibility to diazinon and the differences between their measured values were not remarkable. Paraoxon was extremely toxic to the AChE of F. auricularia but Ch. carnea and C. septempunctata were similarly more tolerant to this organophosphate. In the case of malaoxon earwig and green lacewing AChEs were much more sensitive than AChE of the ladybird beetle. Measuring the carbaryl inhibition, F. auricularia was the least tolerant. The susceptibility of ladybird AChE differed highly from that of both species. According to the measured values, the green lacewing was less tolerant than the ladybird beetle but more tolerant compared with the common earwig. Summarizing our biochemical results, the order of susceptibility of beneficial insects to insecticides investigated was the following F. auricularia > Ch. carnea > C. septempunctata.

Acetylcholinesterase↗
PubMed2002

Biological effects of two insecticides on earthworms (Lumbricus terrestris L.) under laboratory conditions.

Earthworms (Lumbricus terrestris L.) were exposed to endosulfan and aldicarb for 2, 7, and 15 days and lethal concentrations were determined. Worms were then exposed to these concentrations (LC10, LC25, and LC50) of endosulfan and (LC10 and LC25) of aldicarb. Growth rate, total protein content, and insecticide residues were determined. Aldicarb was more toxic than endosulfan and both insecticides caused a significant reduction of growth rate and total protein content of earthworms. Residues remaining in the soil after 2 to 15 days ranged between 37.75% and 68.54% of applied concentration for endosulfan and between 10.13% and 67.71% of applied concentration for aldicarb. Less than 1% of soil concentration was detected in worms and accumulation was more important in the case of endosulfan. This study proposes the use of growth rate and total protein content as biomarkers for contamination by endosulfan and aldicarb.

Aldicarb↗
PubMed1992

Slow voltage-dependent block of sodium channels in crayfish nerve by dihydropyrazole insecticides.

Previous current-clamp work has shown that dihydropyrazole insecticides block sodium channels in tonic sensory receptors and in axons depolarized by high K+ external solutions and that hyperpolarization removes the block [Pestic. Sci. 28:389-411 (1990)]. Voltage-clamp studies on internally perfused crayfish giant axons were done to confirm and extend these observations. At -100 mV dihydropyrazoles had little effect on the sodium current, but at more depolarized potentials they blocked it from either face of the membrane. The onset of block following a holding potential change or during wash-in of a dihydropyrazole was very slow, with a time constant of several minutes, and, although block could be removed with a similar time course by hyperpolarization, the effects of the insecticides could not be reversed by prolonged washing. Dihydropyrazoles did not affect delayed rectifier potassium currents in the axon. The voltage-dependent block could be described as a uniform shift of the steady state (slow) sodium inactivation (S infinity) curve in the direction of hyperpolarization, indicative of selective binding to inactivated states of the channel. Using hyperpolarizing prepulses to remove slow inactivation, block of sodium channels by dihydropyrazoles could be measured directly at holding potentials as positive as -50 mV, and it could be demonstrated that block saturated near -70 mV, consistent with a dependence on slow inactivation. The data were fit to a model tha assumes the dihydropyrazole binds to the slow-inactivated state of the channel on a one to one basis. Dissociation constants obtained from this analysis were similar to those obtained from analysis of inhibition of the binding of [benzoyl-2,5-3H]-batrachotoxinin A 20-alpha-benzoate by the same dihydropyrazoles. In axons whose fast or slow inactivation gates had been removed by N-bromoacetamide or trypsin, respectively, dihydropyrazoles still blocked sodium current, indicating that dihydropyrazoles can block the channel as well as enhance the normal slow inactivation process.

Animals↗
PubMed1990

Construction of chimeric insecticidal proteins between the 130-kDa and 135-kDa proteins of Bacillus thuringiensis subsp. aizawai for analysis of structure-function relationship.

Eight chimeric insecticidal protein (IP) genes were constructed between the 130-kDa and 135-kDa IP genes of Bacillus thuringiensis subsp. aizawai, and expressed in Escherichia coli JM103 cells. The characterization of the produced chimeric IPs indicated that the variable region (VR1) in the amino-terminal half of the IPs is responsible for the insecticidal activity against larvae of Spodoptera litura and Plutella xylostella. The carboxy-terminal half of VR1 was important for the formation of the 60-kDa active fragment in the gut juice of S. litura larvae. Also, combination of the other two variable regions (VR2 and VR3), which were in the central and carboxy-terminal portions of the IPs, appeared to be related to the solubility of the IPs in the gut juice.

Animals↗
PubMed1992

Acute pancreatitis in children with anticholinesterase insecticide intoxication.

Gastrointestinal symptoms are commonly seen in anticholinesterase insecticide intoxication. A few studies in adults have demonstrated some evidence for pancreatic damage in this poisoning. To see whether this association exists also in children, we conducted a prospective study in 17 consecutive children with typical organophosphate and carbamate poisoning. On admission and following recovery, serum amylase, immunoreactive trypsin, glucose, calcium, urea, creatinine, and arterial blood gas values were determined and compared with those of age-matched control subjects. Acute pancreatitis was diagnosed in 5 subjects. They demonstrated significantly elevated (greater than mean + 2 SD) serum levels of both immunoreactive trypsin (914.0 +/- 317.4 ng/mL, 159.9 +/- 36.4 ng/mL, and 169.7 +/- 41.2 ng/mL, respectively; P less than .01) and amylase (448.0 +/- 264.4 U/L, 152.8 +/- 90.9 U/L, and 56.8 +/- 26.3 U/L, respectively; P less than .001; n = 4), compared with other patients and control subjects. Gastrointestinal symptoms were noted in all 5 subjects, with severe abdominal pain in 2. Such symptoms were evident in only 41% of the other 12 patients. Serum glucose levels were significantly elevated in these subjects compared with others (389.0 +/- 66.2 mg/100 mL vs 180.4 +/- 72.3 mg/100 mL; P less than .01). None had hypocalcemia, renal dysfunction, or acidosis. All had complete recovery. It is concluded that acute pancreatitis is probably not rare in children with anticholinesterase insecticide poisoning. This may contribute to the development of gastrointestinal symptoms and hyperglycemia often observed in these patients.

Abdominal Pain↗
PubMedDate not supplied

[Seasonal variability in the insecticide resistance and irritability of Anopheles superpictus].

The resistance and irritability to malathion, fenitrothion, propoxur and DDT (WHO insecticide impregnated papers) in Anopheles superpictus from Dangara District were determined three times in season. Complete susceptibility to malathion, fenitrothion and DDT and low resistance to propoxur probably based on knockdown mechanism were noticed. DDT and malathion irritability levels were high, and those for fenitrothion and propoxur were lower. During the season irritability to malathion and fenitrothion (organophosphorous compounds) was slightly decreasing, and in contrast was increasing to propoxur (carbamate). Irritability to DDT (organochloride) considerably fell down in August and achieved the initial level in September again. None of the tested insecticides can be recommended for residual spraying in Dangara District because of high irritability levels in mosquitos or danger of its rapid increase after onset of spraying.

Animals↗
PubMed1964

SEASONAL VARIATIONS IN SUSCEPTIBILITY TO INSECTICIDES OF WILD-CAUGHT EAST AFRICAN ANOPHELES GAMBIAE.

Monthly tests of the susceptibility to insecticides of wild-caught Anopheles gambiae were made at two places in Tanganyika to see what seasonal variations might be revealed. Over a period of three years the susceptibilities were found to vary over a range of two to three times at different visits. The impression was at first gained that the susceptibilities to chlorinated hydrocarbon insecticides were in some way connected with the rainfall, but later work made this seem unlikely. Of all the factors considered which might affect the susceptibility only the temperature at the time of exposure could be found to have had an effect and it was concluded that this was largely responsible for the variations.

Animals↗
PubMed1964

THE COMPARATIVE TOXICITY OF PHOSPHORAMIDOTHIONATES AND PHOSPHORAMIDATES TO SUSCEPTIBLE AND INSECTICIDE-RESISTANT HOUSEFLIES AND MOSQUITOS.

Studies of the comparative toxicity of a number of homologous X-chlorophenyl phosphoramidothionates and phosphoramidates and related analogues to susceptible and insecticide-resistant houseflies (Musca domestica L.) and mosquitos (Culex pipiens quinquefasciatus Say and Anopheles albimanus Wied.) have shown that the 2,4,5-trichlorophenyl series is the most active and the 4-chlorophenyl series the least active. Toxicity decreases in general with increasing chain length of the alkoxy and alkylamido moieties, maximum toxicity residing in methoxy, ethoxy, amido, methylamido, and ethylamido homologues. Toxicity is greatest to the susceptible strain but the alkylamido and X-chlorophenyl structures confer toxicological advantages from the standpoint of relative effectiveness against organophosphorus-resistance and organophosphorus vigour-tolerance. Many of the phosphoramidates are less toxic than their phosphoramidothionate analogues, probably due to less favourable physical properties.Certain of these compounds show promise against both susceptible and insecticide-resistant housefly adults and it is suggested that they be further evaluated in broad-spectrum field trials. Although some show promise as mosquito larvicides, in general the introduction of an alkyl-amido group markedly decreases residual toxicity from a filter-paper residue to mosquito adults in comparison with the corresponding dialkoxy analogues.

Amides↗
PubMed1964

THE USE OF GAS CHROMATOGRAPHY FOR THE QUANTITATIVE DETERMINATION OF MICRO-AMOUNTS OF INSECTICIDE PICKED UP BY MOSQUITOS.

The test method recommended by the WHO Expert Committee on Insecticides for determining the susceptibility or resistance of adult mosquitos to insecticides has been evaluated quantitatively by the use of gas chromatography to measure the amount of dieldrin picked up by adult Culex quinquefasciatus Say (= C. pipiens fatigans Wiedemann). A strain homozygous for dieldrin-resistance was used to determine the pick-up as a function of time and concentration of dieldrin. The results of experiments using electron-capture detection with gas chromatography suggest that the pick-up is a linear function of the concentration on the paper and also of the time of exposure, even of the 24-hour exposure to the 4.0% dieldrin paper.

Animals↗
PubMed1964

OBSERVATIONS ON THE EFFECT OF RESIDUAL INSECTICIDES IN EXPERIMENTAL HUTS IN MASAKA DISTRICT, UGANDA.

Observations made in Kigezi District, Uganda, had shown a great reduction in the number of Anopheles gambiae entering an experimental hut treated with DDT. The work reported in this paper confirms the phenomenon of reduced entry by A. gambiae and A. funestus in two experiments carried out in Masaka, another district of Uganda, using mud-walled huts, roofed with thatch or corrugated-iron sheets and sprayed with DDT and dieldrin. The fact that no similar reduction was observed with Mansonia (mansonioides) uniformis, a common species in the area, indicates the need to determine and take into account any reduction in the number of entering mosquitos when assessing the effect of residual insecticides. Of interest in these experiments was the finding that DDT and dieldrin produced satisfactory kills with all the local anopheline species in spite of their rapid sorption by the mud walls, an indication of the importance of thatch or metal roofs as a source of active insecticide.

Animals↗
PubMed1955

Resistance to insecticides in the larvae of Culex fatigans in Malaya.

After two years' use of hexachlorocyclohexane (BHC) as a larvicide in Georgetown, on Penang Island, control of Culex fatigans breeding became unsatisfactory. Two laboratory colonies of fatigans were established, one from Georgetown, and one from Kuala Lumpur where no insecticides had been used; tests were then made to determine the median lethal concentrations (MLC) of BHC, dieldrin, and DDT for the larvae of the two strains. The Georgetown strain was found to have acquired a tenfold resistance to BHC, and also to dieldrin to which it had not been exposed, but it showed no significant increase of resistance to DDT, to which it had also not been exposed. A year later, when both strains had passed through some ten generations in the laboratory without exposure to insecticides, the Georgetown strain was found to have lost much of its resistance to BHC, although the MLC was still twice that of the non-resistant Kuala Lumpur strain.

Animals↗
PubMed1959

A new phosphoric ester residual insecticide with a low order of toxicity.

The chlorinated hydrocarbon insecticides, DDT and dieldrin, are currently the most effective residual insecticides available, owing in part to their stability and to the fact that their effect is relatively independent of the materials to which they are applied. Recently two compounds of the group of organic phosphorus esters have been developed which are resistant to alkalies and approach the chlorinated hydrocarbons in residual effect. One of these (S 1752) is reported on in detail here; results are given of tests which show that this compound has a residual effect lasting several months.

Insecticides↗
PubMed1992

[The setting of hygienic standards for the insecticide sonet in potatoes].

A study of the toxic properties of sonet in chronic experiment on white rats established the threshold and non-acting dose of the insecticide. The accumulation of the insecticide in the potato tubers during the entire vegetation period as well as its effect on the potato quality were investigated. The author recommends 0.05 mg/g of sonet per 1 g of potato as a maximum permissible level.

Animals↗
PubMed1992

[Residues of organochlorine insecticides in foods in the years 1986-1990].

During 1986-1990 4625 samples of food commodities were examined for residues of organochlorine (OC) insecticides in 10 provinces in Poland. This monitoring included analysis of total DDT (DDT+DDE+DDD), alpha, beta and gamma-HCH, HCB and Methoxychlor (DMDT) in milk and milk products, fruits, vegetables, vegetable oils and baby foods. The median values for DDT in milk and milk products varied from undetectable to 0.23 mg/kg on fat basis, and the draft national tolerance (1.0 mg/kg) was exceeded in 2-5% of samples in 1986 only. In fruits and vegetables the median concentrations of the total DDT usually were below the limit of determination. Generally, during the five years period the downward tendency in DDT complex concentration was observed, but not in case of the total HCH. The residues of OC insecticides in baby foods were generally very low due to establishing of special "low-pesticide" areas for growing raw materials for these products.

DDT↗