Organic Insecticides Research Articles

Efficacy of oils and powders of some medicinal plants in biological control of the pea weevil (Callosobruchus chinensis L.)

Each year, the chickpea suffer’s from significant losses in both quantity and quality. These losses are observed particularly in stocks, which are principally due to attacks by weevils. The most devastating is the Chinese weevil (Callosobruchus chinensis). In the context of biological control as an alternative to chemical control, three plants were tested for their possible role organic insecticide, namely Thymus vulgarus, Santolina chamaecyparissus and Anagyris foetida. The leaf powders and oils of these plants that was extracted by hydro distillation were tested for their effect on the biology of C. chinensis such asfertility, longevity and sex ratio. The results showed that oils and powders of three different plants tested possess insecticidal activity against C. chinensis. By comparing these oils, Thyme oil at a dose of 10 μl exhibited great biocidal power against insects as we experienced 100% mortality after only hours of exposure to treatment, hard tan l 'oil santolina also had 100% mortality but at a dose of 20 μl. Regarding the powder, that of Santoline when compared to other powders at a dose of 1 g significantly reduces longevity (2.9 days), fecundity (3.06) and fertility (3.33). It even has an ovicidal effect. For 10 repetitions, we have recorded a single outbreak. This allows us to move forward so that the oils and powders tested plants can be used as bio insecticide for control of C. chinensis populations of pests of stored foodstuffs. Key words: Callosobruchus chinensis, Cicer arietinum, Thymus vulgarus,Santolina chamaecyparissus, Anagyris foetida and bio-insecticide.

Toxicity, Feeding Preference, and Repellency Associated With Selected Organic Insecticides Against <I>Acrosternum hilare</I> and <I>Euschistus servus</I> (Hemiptera: Pentatomidae)

Experiments were conducted to evaluate the toxicity, feeding preference, repellency, and field efficacy associated with the organic insecticides azadirachtin, pyrethrins, and spinosad against two stink bug species, Acrosternum hilare (Say) and Euschistus servus (Say) (Hemiptera: Pentatomidae). Laboratory toxicity bioassays were conducted using treated green bean pods. The conventional pyrethroid lamda-cyhalothrin was included for comparison. A. hilare adults and nymphs were most susceptible to lamda-cyhalothrin and to tank mixes of pyrethrins + spinosad. E. servus adults were susceptible to lamda-cyhalothrin, spinosad, and all tank mixes, whereas E. servus nymphs were susceptible to lamda-cyhalothrin only. Feeding preference tests were conducted using insecticide-treated tomatoes and counting the number of feeding stylet sheaths on fruit after 24 h. All tomatoes treated with either azadirachtin, pyrethrins, or tank mixes resulted in fewer numbers of stylet sheaths than the untreated control, whereas treatment with spinosad alone did not. In filter paper repellency tests, both E. serous and A. hilare were repelled by pyrethrins and exhibited no response to azadirachtin. E. servus was attracted to spinosad in comparison with a water-treated control; however, A. hilare displayed no response. In field efficacy trials, each of the organic insecticides reduced the number of stink bugs in soybean, Glycine max (L.) Merr., for up to 2 d after treatment; however, none of the insecticides reduced stink bug damage to fruit in tomatoes even after multiple applications. Implications for organic growers and integrated pest management programs are discussed.

Rapid analysis of organic farming insecticides in soil and produce using ultra-performance liquid chromatography/tandem mass spectrometry

A new method for the analysis of three ecological insecticides, namely azadyrachtin, spinosad (sum of spinosyn A and spinosyn D) and rotenone, in produce and soil samples is presented. Investigated compounds are one of the most significant insecticides authorized for organic farming crop protection in many countries. Extraction of the pesticides from plant and soil matrices was performed by using a modified quick, easy, cheap, effective, rugged, and safe (QuEChERS) method. The method entailed a single extraction of the investigated compounds with acidified acetonitrile followed by a dispersive solid-phase extraction cleanup step prior to the final determination by reverse-phase ultra-performance liquid chromatography/tandem quadrupole mass spectrometry (UPLC-MS/MS). Validation studies were carried out on cabbage, tomato and soil samples. Recoveries of the spiked samples were in the range between 67% and 108%, depending on the matrix and the spiking level. Relative standard deviations for all matrix-compound combinations did not exceed 12%. The limits of quantification were < or = 0.01 mg kg(-1) in all cases, except for azadirachtin. The developed method was applied to the analysis of real samples originating from organic farming production.

Non-target effect of organic insecticides: effect of two plant extracts on soil microbial biomass and enzymatic activities in soil

Efficacious botanical derivatives can provide an alternative to synthetic pesticides for organic farming systems. However, there is lack of information regarding the side effects of organic pesticides on key soil ecological processes. In this study, we investigated the effects of aqueous extracts from Urginea maritima and Euphorbia myrsinites exhibiting translaminar and systemic activity against pests on microbial biomass and enzymatic activities in soil. Two grams of plant material was extracted with 100 ml of water and then diluted 1:100, 2:100, and 4:100 with distilled water. Diluted plant extracts were applied around hypocotyl of tomato by soil drench. The effect of both plant extracts on microbial biomass C, amount of total N and organic C, and enzymatic activity in soil was significant. After the last application, the highest microbial biomass C was determined in the lowest U. maritima concentration (U 1:100). Soils treated with the highest concentration of U. maritima (U 4:100) had always lower SMBC content than control soil. All concentrations of E. myrsinites decreased microbial biomass C by 18% to 27% compared to the control. Total nitrogen and organic carbon decreased in soils without (control) and with treated U. maritima extract from first application to last application. Phosphatase, urease, and beta-glucosidase activities were monitored in plant extract-treated soils. Except U. maritima 1:100 treatments of second and fourth applications, the other treatments of plant extracts negatively affected enzymatic activity in soil. U. maritima and E. myrsinites plant extracts exhibited different effects on soil microbial biomass and activity, probably because of their different chemical contents.

Larvaecidal effects of azadirachtin on the pine processionary moth

The effects of azadirachtin, a natural extract of the neem tree Azadirachta indica A. Juss, on larval growth and feeding activity of pine processionary moth (Thaumetopoea pityocampa (Schiff.)) was investigated in laboratory experiments conducted in 2007 - 2008. The organic insecticide NeemAzal-T/S (a commercial neem preparation) was applied as suspension in distilled water at concentration levels of 0.3, 0.5 and 1%. Comparing with the untreated leaves, the effect of the insecticide NeemAzal-T/S was tested on the 10 th day after treatment. The results obtained in conducted experiments indicated that NeemAzal-T/S was effective against T. pityocampa larvae, significantly inhibiting larval growth and reducing feeding activity.

Mortality and Progeny Production of Several Stored Grain Beetle Pests in Shelled Corn Treated with Entrust®

ABSTRACT Use of synthetic chemicals has been the primary method of insect control in stored grain. Concern for insecticide resistance, chemical residues, environmental contamination, and worker exposure has lead to development of biologically based insecticides such as Spintor® 2SC. Spintor has been found to be effective against several stored grain beetle species on wheat and shelled corn in storage. Recently it was re-formulated to conform to OMRI national standards and is now commercially available as an organic insecticide (i.e., Entrust®) registered for use on fruits and vegetables. However, no information regarding the use of Entrust on stored grains has been found. A laboratory study was conducted to determine efficacy of Entrust on maize weevil (Sitophilus zeamais Motsculsky), red flour beetle (Tribolium castaneum (Herbst)), and sawtoothed grain beetle (Oryzaephilus surinamensis (Linnaeus)) infesting stored shelled corn. Shelled corn was treated with 1 ppm or 3 ppm of Entrust or left untreated. Mo...

Aerobic degradation of lindane (γ-hexachlorocyclohexane) in bacteria and its biochemical and molecular basis

gamma-Hexachlorocyclohexane (gamma-HCH, also called gamma-BHC and lindane) is a halogenated organic insecticide that causes serious environmental problems. The aerobic degradation pathway of gamma-HCH was extensively revealed in bacterial strain Sphingobium japonicum (formerly Sphingomonas paucimobilis) UT26. gamma-HCH is transformed to 2,5-dichlorohydroquinone through sequential reactions catalyzed by LinA, LinB, and LinC, and then 2,5-dichlorohydroquinone is further metabolized by LinD, LinE, LinF, LinGH, and LinJ to succinyl-CoA and acetyl-CoA, which are metabolized in the citrate/tricarboxylic acid cycle. In addition to these catalytic enzymes, a putative ABC-type transporter system encoded by linKLMN is also essential for the gamma-HCH utilization in UT26. Preliminary examination of the complete genome sequence of UT26 clearly demonstrated that lin genes for the gamma-HCH utilization are dispersed on three large circular replicons with sizes of 3.5 Mb, 682 kb, and 191 kb. Nearly identical lin genes were also found in other HCH-degrading bacterial strains, and it has been suggested that the distribution of lin genes is mainly mediated by insertion sequence IS6100 and plasmids. Recently, it was revealed that two dehalogenases, LinA and LinB, have variants with small number of amino acid differences, and they showed dramatic functional differences for the degradation of HCH isomers, indicating these enzymes are still evolving at high speed.

DFT Studies on Hydrolyses of Dimethylchlorothiophosphate

Many thiophosphates are widely used as substrate analogues in studies of enzymatic reactions as well as organic insecticides in agricultural pest control. These organophosphorus compounds yield toxic metabolites by several reactions before hydrolysis occurs. Therefore, the rates of hydrolyses of these compounds are important for green chemistry. More sluggish degradations of thiophosphate pesticides are often observed as compared with the corresponding phosphate compound: for example, the hydrolysis rate of diazinon (I, X=S) is slower than that of the diazoxon (I, X=O), where the sulfur atom is replaced by oxygen atom, by about 10 times at pH of 7.4, corresponding to the difference in the free energy of activation by about 1.1 kcal/ mol at 20 °C. However, an inverse thio effect (kS/kO > 1) was found occasionally for the hydrolyses of organophosphorus compounds including parathion (II, X=S) and paraoxon (II, X=O), and it was rationalized by the higher electronegativity of oxygen as compared to sulfur. Although, the differential electronic structure including the bond order and charge localization of P=O and P=S bond are discussed in detail, the relative bond order and charge localization are varied for the phosphorothioates and the origin of differential reactivity of those compounds is not clear.

Processed kaolin as an alternative insecticide against the European pear sucker, Cacopsylla pyri (L.)

Abstract: Application of processed kaolin particle film (Surround® WP; Engelhard Corporation, Iselin, NJ, USA) repels insects without lethal effects; hence side effects on beneficial arthropods are low. Processed kaolin may be an alternative to broad‐spectrum insecticides used against European pear sucker, Cacopsylla pyri (L.), in organic and conventional pear production. A small‐plot field trial was conducted in spring 2003 to assess this hypothesis. Multiple applications of processed kaolin during the first flying period of C. pyri significantly reduced the number of nymphs compared to the untreated control. Processed kaolin protected pear trees at least as good as the standard organic insecticide rotenone. Since the effects on the summer population could not be assessed in this small‐plot trial due to the high mobility of the adult C. pyri, a large‐plot trial was conducted in 2004. Thereby, the processed kaolin showed a very high efficacy and the population of C. pyri was kept under a damaging level over the whole season. At the end of June the population density of C. pyri in the processed kaolin treated area was lower than in the IPM treated plot. In conclusion, kaolin shows promise as an alternative control for C. pyri in organic and IPM orchards.

Comparison of Predator and Pest Communities in Washington Potato Fields Treated with Broad-Spectrum, Selective, or Organic Insecticides

In the northwestern United States, insect pests of potatoes (Solanumtuberosum L.) have typically been controlled using broad-spectrum insecticides. However, the loss or impending loss of many broad-spectrum chemicals is increasing the use of selective insecticides, and organic potato production is growing in the region. In the 2001 and 2002 growing seasons, we intensively sampled the arthropods in 31 (14 in 2001 and 17 in 2002) production potato Þelds under three pest management regimens: conventional Þelds treated with broad-spectrum insecticides (Hard), conventional Þelds treated with selective insecticides (Soft), and organic Þelds treated with insecticides certiÞed for organic production (Organic). All Þelds were within the Columbia Basin of Washington, grown under center-pivot irrigation. We sampled arthropods using three techniques: D-vac suction sampling, pitfall trapping, and visual searching. Geocoris spp. and Nabis spp. bugs (Hemiptera) and spiders (Araneae) were the most abundant predators in plant foliage, together making up 90% of the foliar predator community in both years. Total predator densities and densities of Geocoris, Nabis, and spiders not in the family Linyphiidae were highest in Organic and Soft, and lowest in Hard Þelds. Linyphiid spider densities were marginally elevated in Soft compared with Hard Þelds. On the ground, carabid (Coleoptera: Carabidae) and staphylinid (Coleoptera: Staphylinidae) beetles and a diverse group of spiders dominated the community, together making up 90% of the ground-active predator com- munity in both years. Total predator densities and densities of carabid beetles, staphylinid beetles, and linyphiid spiders were highest in Organic and Soft and lowest in Hard Þelds, whereas densities of these arthropods did not differ between Organic and Soft. Densities of nonlinyphiid spiders were highest in Organic, intermediate in Soft, and lowest in Hard Þelds. While predator densities were generally high in organic Þelds, these Þelds also had the highest densities of the two most injurious insect pests, the green peach aphid (Myzus persicae Sulzer) and the Colorado potato beetle (Leptinotarsa decem- lineata Say). Selective insecticides allowed conventional growers to achieve predator densities similar to those seen in organic Þelds while retaining low pest densities typical of Þelds treated with broad-spectrum insecticides.

Oximes in organophosphorus poisoning

Acute organic insecticide poisoning is a major health problem all over the world, particularly in the developing countries, where organophosphates (OPs) are the most common suicidal poisons with high morbidity and mortality and account for a large proportion of patients admitted to intensive care units. Other insecticides less commonly used are organocarbamates, organochlorides, and pyrethroids, which are less toxic and are associated with less morbidity and mortality. Patients with poisoning present with a wide spectrum of gastrointestinal, neurological, and cardiac manifestations. A strong clinical suspicion is necessary to make an early diagnosis and to start appropriate therapy. Treatment is primarily supportive and includes decontamination, anticholinergics, protection of the airway, and cardiac and respiratory support. The use of oximes has been controversial and may be associated with higher mortality owing to a higher incidence of type-II paralysis. They may have other toxic side effects. This paper reviews the literature on OP poisoning.

Organoclorados: um problema de saúde pública

A descoberta do poder inseticida do DDT, primeiro inseticida orgânico sintético, além de render a Paul Mueller o prêmio Nobel de Fisiologia e Medicina, em 1948, deu início à era dos pesticidas organoclorados. A partir do DDT, foram surgindo números cada vez maiores de pesticidas. Apesar dos benefícios, o uso indiscriminado desta classe de substâncias gerou graves problemas ecológicos. Hoje, estima-se que a porcentagem de seres vivos, vegetais e animais, não contaminados, seja relativamente baixa. Este artigo de revisão focaliza os graves problemas de contaminação e saúde gerados pelos organoclorados, bem como a busca de soluções para minimizar tais problemas.

Effects of Two Plant Extracts on Larval Leafminer &lt;I&gt;Liriomyza trifolii&lt;/I&gt; (Diptera: Agromyzidae) in Tomatoes

Aqueous extracts from two plants, Urginea maritima L. (Liliaceae) and Euphorbia myrsinites L. (Euphorbiaceae), were tested for their insecticidal activity against the leafminer Liriomyza trifolii (Burgess) on infested tomato, Lycopersicon esculentum Mill., plants in the laboratory and field. Two grams of plant material was extracted with 100 ml of water and then diluted 1:100, 1:50, and 1:25 with distilled water. Diluted plant extract was either applied to the infested tomato leaves or by soil drench and was compared with foliar application of cyromazine. All dilutions of both plant extracts caused significant control of the leafminer larvae and maintained populations below those of the nontreated control plants in all trials. Only at the most concentrated dilutions (1:25) were the plant extracts statistically similar to the cyromazine treatment. Furthermore, greenhouse yields from all of the foliar treatments were statistically similar to the cyromazine treatment and significantly better than the nontreated control. Four species of leafminer parasitoids were found in the greenhouse; however, the percentage of parasitism was significantly less in all treated replicates than in the nontreated control replicates. Aqueous extracts from these two plant extracts exhibited both translaminar and systemic activity and are potential candidates as new organic insecticides.

Compatibility of a natural enemy, Coleomegilla maculata lengi (Col., Coccinellidae) and four insecticides used against the Colorado potato beetle (Col., Chrysomelidae)

Abstract: The toxicity of four insecticides used to control the Colorado potato beetle, Leptinotarsa decemlineata (Say) (Coleoptera: Chrysomelidae), imidacloprid (Admire®), cryolite (Kryocide®), cyromazine (Trigard®), and Bacillus thuringiensis var. tenebrionis (Novodor®), to one of its natural enemies, the 12‐spotted lady beetle, Coleomegilla maculata lengi Timberlake (Coleoptera: Coccinellidae) was determined in the laboratory. Toxicity assays against C. maculata adults and larvae consisted of (1) topical applications and (2) exposures to treated foliage and prey, using concentrations up to 10 times the manufacturer's recommendations. Over a 6‐day period, cyromazine (insect growth regulator) and B. t. var. tenebrionis (microbial insecticide) had no lethal effects on first and third instars C. maculata. For both larval and adult stages, cryolite (inorganic insecticide) caused very low predator mortality when topically applied and moderate mortality when ingested through contaminated eggs of Colorado potato beetles. Imidacloprid (systemic organic insecticide) was highly toxic to adult and larval C. maculata. Its estimated LD50 at 6 days following treatment, corresponded to 0.02–0.09 times the recommended field concentration, depending on the developmental stage and mode of contamination. These results indicate that integrated pest management programmes for Colorado potato beetles using imidacloprid or, to a lesser degree, cryolite, would be detrimental to C. maculata. Cyromazine and B. t. var. tenebrionis seem to present a better compatibility with the protection of C. maculata populations.

A Reassessment of Topical Organic Phosphorus Insecticide Exposures and Permanent Paralysis

A Reassessment of Topical Organic Phosphorus Insecticide Exposures and Permanent Paralysis

Boric Acid Dust as a Component of an Integrated Cockroach Management Program in Confined Swine Production

Boric acid dust treatments were evaluated as a tool for the integrated management of the German cockroach, Blattella germanica (L.), in commercial confined swine production. The efficacy of boric acid dust was comparable to that of an organic residual insecticide, cyfluthrin, which is commonly used to control cockroaches in this environment. Fall treatments suppressed the cockroach population for longer durations than treatments in the Spring. Boric acid dust is an effective, inexpensive, and low risk (to animal and human health, and the environment) alternative for the management of cockroaches in livestock production systems.

A comparative study of bioassays based on enzyme biosynthesis in Escherichia coli and Bacillus subtilis exposed to heavy metals and organic pesticides

Two enzyme assays, namely β-galactosidase in Escherichia coli (E.C.3.2.1.23) and α-amylase in Bacillus subtilis (E.C.3.2.1.1), were compared following exposure to various concentrations of heavy metals and organic pesticides. It was shown that α-amylase biosynthesis in the Gram-positive bacteria was more sensitive to heavy metals, particularly to mercury as low as 0.1 ppm, compared to β-galactosidase in the Gram-negative bacteria. The results of organic pesticide treatment were more clear-cut, when comparing both assays. Alpha-amylase test system can detect the inhibition by the organometallic fungicides Maneb and Mancozeb at as low as 0.1 ppm, while no inhibition with β-galactosidase system up to as high as 100 ppm. The effect of organic insecticide endosulfan on α-amylase was also seen at very low concentrations (0.048 ppm). The electrophoretic analysis also revealed the inhibition of enzyme biosynthesis at the tested toxicant concentrations.

Use of Paramecium Species in Bioassays for Environmental Risk Management: Determination of IC50 Values for Water Pollutants

Effect of chemical water pollutants on the growth of two Paramecium species (Paramecium caudatum and Paramecium trichium) were examined. The chemicals used as model chemical pollutants include organic solvents, potential carcinogens, mutagens, metabolic modulators, herbicides, insecticides, fungicides, antimicrobials, heavy metals, and heavy metal-containing chemicals. In this study, the IC50 values indicating the concentration of substances inhibiting the proliferation of Paramecium cells by 50% were used instead of the LD50 value, which indicates the dose of substances killing half the population of organisms, since the former is a more sensitive parameter for assessing the toxicity of substances at lower concentrations. Among 25 chemicals examined, di-(2-ethylhexyl)phthalate, potassium dichromate, 2,4-dichlorophenoxy acetic acid, and paraquat stimulated the growth of paramecia depending on the concentrations used. Dimethyl sulfoxide and formaldehyde were shown to be inert to paramecia in the range of concentrations (up to 1%, v/v) used here. Other chemicals were shown to inhibit the growth of the paramecia and thus the IC50 values for those chemicals were determined. Our data presented here may be a useful reference for assessing the impact of water pollutants on aqueous microecosystems consisting of various microorganisms including protozoa.

High-performance liquid chromatographic assay of dichlorvos, isocarbophos and methyl parathion from plant leaves using chemiluminescence detection

A high-performance liquid chromatographic (HPLC) method has been developed for the detection of organic phosphorous insecticides (dichlorvos(DDVP), isocarbophos and methyl parathion). In addition to a traditional method using UV detection, we developed an alternative method based on chemiluminescent reaction of organic phosphorous insecticides with luminol and hydrogen peroxide. The sample containing organic phosphorous insecticides was injected into a Hypersil ODS column (5 μm 4.6×100 mm) and eluted with methanol:water (60:40 (v/v)). The chemiluminescence (CL) response is linear to the concentration of DDVP, isocarbophos and methyl parathion, respectively. Most metal ions and organic compounds tested do not interfere with the determination.

Effect of Fertilizer, Pesticide Treatment, and Plant Variety on the Realized Fecundity and Survival Rates of Brown Planthopper, Nilaparvata lugens (Stål) (Homoptera: Delphacidae) — Generating Outbreaks in Cambodia

Uneven farm practices between farmers cause the patchy pest distribution, especially in the brown planthopper (BPH: Nilaparvata lugens (Stål)) in Cambodia. Since 1994 BPH have attacked Cambodian rice fields in patchy form. More BPH attacked in field where farmers have more opportunity to use fertilizer and insecticides. Rice production in Cambodia will probably face more problems with BPH outbreaks as rice production intensifies. The birth and/or survival rate of BPH that leads to population outbreaks are related to fertilizer, plant variety and insecticide treatments. The experiments were conducted in the field and laboratory in Cambodia in 1999 to test the hypothesis above. A traditional variety (Eath Chhmoush), low and high fertilizer rates, and an organic phosphate insecticide (Diazinon) were used in the field experiment and two varieties (susceptible and tolerant to BPH) and three rates of NPK fertilizer were used in the laboratory study. BPH population and others arthropods were collected weekly from the field experiment by a D-vac machine. Two kinds of net cages (temporary and permanent) were covered the rice plants to determine the birth and survival rate of BPH population with and without natural enemies. Number of oöcytes was counted from BPH females, which reared in plant-cages. Birth and survival rates of BPH were higher in susceptible plants with high fertilizer rate used. The experiment indicated that natural enemies have played the important role to control the BPH population. The realized fecundity and survival of BPH was higher in susceptible host plant variety with high rate of NPK fertilizer used. The immediate response of fertilizer application to the BPH offspring production was not shown and will be tested in wet season 2000.