Low Insecticidal Activity Research Articles

온실가루이와 담배가루이에 대한 pyrifluquinazon의 살충 및 행동장애

Pyrifluquinazon is known to act as a feeding inhibitor in several insect species. In this study, we investigated the effect of pyrifluquinazon on the whiteflies, Trialeurodes vaporariorum and Bemisia tabaci. Pyrifluquinazon showed high insecticidal activity (> 90%) against adult T. vaporariorum and B. tabaci at 12.5 ppm to 50 ppm. However, there was no effect on eggs and nymphs of both species. Pyrifluquinazon showed low insecticidal activity in root and foliar uptake. Control efficacy of pyrifluquinazon was above 90% at 5 days after treatment. In order to investigate the behavioral response of the whiteflies initiated by application of pyrifluquinazon, we tested the contact toxicity and ingestion toxicity. After 1 h of contact, whitefly drop, wing convulsion, and paralysis were observed. Similar phenomenon of whitefly population was observed in test of ingestion toxicity after 3 h. In the choice test, pyrifluquinazon showed repellent activity against both species. These results suggest that pyrifluquinazon cause behavioral disorder rather than direct inhibition of feeding.

Influence of Permethrin and Cypermethrin on Behavior in the Mouse

Permethrin and Cypermethrin are synthetic pyrethroids, belonging to a group of insecticides with low mammalian toxicity and high insecticidal activity. The present study evaluated sub-acute toxicity of dermally administrated permethrin and cypermethrin in mice. Behavioral examination included assessments of lethality, weight gain, grooming, analgesymetry, anxiety, grasping, motor activity, and despair in response to inescapable swim stress. The study was conducted on 70 adult male mice, which were exposed dermally via the whole tail zone for 10 s once daily for 28 consecutive days at concentrations of 0%, 0.1%, 1% and 10% of each compound. No significant changes were observed in body weight gain, grooming behavior or pain sensation among the treated and control groups. However, the following effects were observed in the experimental groups: a tendency towards increased motor activity compared to controls (47% in P0.1% group, P = 0.025), a tendency to lose grasping faster than controls (48% and 40% decreased in P10% and C1% groups, respectively, (P < 0.05), shorter stay in the long arms and longer stay in the short arms on the elevated plus maze task compared to controls (up to 84% difference , P < 0.05), and failure in terms of floating on the inescapable swim stress task (500% and 900% increase in interruption times in the P10% and C10% groups, respectively, P < 0.05). In conclusion, upon long-term dermal exposure, synthetic pyrethroids may lead to increased motor activity, decreased grasping tendency and/or ability, increased apathy, and increased despair in the mouse animal model.

Insecticidal, brine shrimp cytotoxicity, antifungal and nitric oxide free radical scavenging activities of the aerial parts of Myrsine africana L.

The crude methanolic extract and various fractions derived from the aerial parts of Myrsine africana were screened in vitro for possible insecticidal, antifungal, brine shrimp lethality and nitric oxide free radical scavenging activities. Low insecticidal activity (20 %) was shown by chloroform (CHCl 3 ) and aqueous fractions against Tribolium castaneum and Rhizopertha dominic a, respectively. Good cytotoxic activity (66.66 %) was shown by the n-hexane fraction of the plant at 1000 μg/ml. The rest of the fractions showed low lethality at higher doses. No antifungal activity was observed for the crude extract and fractions screened against various fungal strains. The plant crude extract and fractions showed a concentration dependent nitric oxide free radical scavenging activity. Key words: Myrsine africana, insecticidal, brine shrimp lethality, antifungal and nitric oxide free radical scavenging assay.

Comunicação científica eficiência de inseticidas à base de nim no controle de Grapholita molesta (Busck, 1916) (Lepidoptera: Tortricidae)

O objetivo foi avaliar a eficiência de inseticidas à base de nim no controle da mariposa-oriental G. molesta em laboratório. A dieta artificial foi cortada em cubos e imersa nas caldas dos respectivos tratamentos; em seguida, lagartas recém-eclodidas foram transferidas para tubos de vidro, contendo os cubos de dieta tratados. Os produtos testados foram: NeemAzal-T/S®, Dalneem emulsionável®, Organic Neem® e Natuneem Agrícola® na concentração de 0,5% do produto comercial (p.c.) em comparação com o inseticida químico fenitrotion (Sumithion 500 CE®) a 0,15% p.c. e uma testemunha (água). Os inseticidas NeemAzal-T/S® e Dalneem emulsionável® apresentaram a mortalidade de 100% das lagartas, sendo eficientes no controle do inseto em condições de laboratório. Organic Neem® e Natuneem Agrícola® demonstraram menor atividade inseticida, ocasionando mortalidade de 73,5% e 22,5%, respectivamente; no entanto, afetaram significativamente a viabilidade larval.

Comparative genomic sequence analysis of novel Helicoverpa armigera nucleopolyhedrovirus (NPV) isolated from Kenya and three other previously sequenced Helicoverpa spp. NPVs

A newly cloned Helicoverpa armigera nucleopolyhedrovirus (HearNPV) from Kenya, HearNPV-NNg1, has a higher insecticidal activity than HearNPV-G4, which also exhibits lower insecticidal activity than HearNPV-C1. In the search for genes and/or nucleotide sequences that might be involved in the observed virulence differences among Helicoverpa spp. NPVs, the entire genome of NNg1 was sequenced and compared with previously sequenced genomes of G4, C1 and Helicoverpa zea single-nucleocapsid NPV (Hz). The NNg1 genome was 132,425 bp in length, with a total of 143 putative open reading frames (ORFs), and shared high levels of overall amino acid and nucleotide sequence identities with G4, C1 and Hz. Three NNg1 ORFs, ORF5, ORF100 and ORF124, which were shared with C1, were absent in G4 and Hz, while NNg1 and C1 were missing a homologue of G4/Hz ORF5. Another three ORFs, ORF60 (bro-b), ORF119 and ORF120, and one direct repeat sequence (dr) were unique to NNg1. Relative to the overall nucleotide sequence identity, lower sequence identities were observed between NNg1 hrs and the homologous hrs in the other three Helicoverpa spp. NPVs, despite containing the same number of hrs located at essentially the same positions on the genomes. Differences were also observed between NNg1 and each of the other three Helicoverpa spp. NPVs in the diversity of bro genes encoded on the genomes. These results indicate several putative genes and nucleotide sequences that may be responsible for the virulence differences observed among Helicoverpa spp., yet the specific genes and/or nucleotide sequences responsible have not been identified.

Antibacterial, antifungal, insecticidal, cytotoxicity and phytotoxicity studies on Indigofera gerardiana

The antibacterial, antifungal, acute cytotoxicity, phytotoxicity and insecticidal profile of the crude extract and various fractions of Indigofera gerardiana have been studied. Six bacterial and fungal strains were used, of which Samonella typhi and Microsporum canis were the most susceptible strains with MICs 0.37 mg/mL and 0.09 mg/mL, respectively. The crude extract and the fractions showed low insecticidal activity against Sitophilus oryzae, Rhyzopertha dominica and Callosbruchus analis but no activity against Tribolium castaneum. The brine shrimp lethality assay showed absence of any measurable cytotoxicity of the crude extract and fractions, showing a good safety profile at a preliminary level. All the fractions except crude extract revealed profound and highly significant herbicidal activity against Lemna minor at the concentration of 1000 μg/mL. Indigofera gerardiana was shown by in-vitro assays to be a potential source for natural antifungal, antibacterial and herbicidal agents.

DEVELOPMENT AND PATHOGENICITY OF INFECTIVE JUVENILES ORIGINATING VIA ENDOTOKIA MATRICIDA IN AXENIC STEINERNEMATID NEMATODES

Development and insecticidal activity of axenic infective juveniles (IJs) originating from endotokia matricida in maternal bodies of Steinernema glaseri and S. carpocapsae were investigated with a comparison to IJs developed in monoxenic culture. In comparison with the monoxenic steinernematids, the axenic ones grew slower and produced fewer IJs when they were cultured in a sterile chicken liver extract medium supplement with an autoclaved nematode infected Galleria mellonella larva. The phenomena of endotokia matricida, an intra-uterine development of hatched juvenile, occurred in an axenic culture as did the monoxenic ones. Although it occurred faster in monoxenic culture, the ratio of females bearing endotokia matricida was more numerous in axenic ones. These axenic females also produced IJs through the endotokia matricida phenomenon. Compared to the normal IJs develop in monoxenic culture, the IJs originated via endotokia matricida of axenic nematodes showed lower insecticidal activity and it could not reproduce in G. mellonella cadaver.

An Insecticidal GroEL Protein with Chitin Binding Activity from Xenorhabdus nematophila

Xenorhabdus nematophila secretes insecticidal proteins to kill its larval prey. We have isolated an approximately 58-kDa GroEL homolog, secreted in the culture medium through outer membrane vesicles. The protein was orally insecticidal to the major crop pest Helicoverpa armigera with an LC50 of approximately 3.6 microg/g diet. For optimal insecticidal activity all three domains of the protein, apical, intermediate, and equatorial, were necessary. The apical domain alone was able to bind to the larval gut membranes and manifest low level insecticidal activity. At equimolar concentrations, the apical domain contained approximately one-third and the apical-intermediate domain approximately one-half bioactivity of that of the full-length protein. Interaction of the protein with the larval gut membrane was specifically inhibited by N-acetylglucosamine and chito-oligosaccharides. Treatment of the larval gut membranes with chitinase abolished protein binding. Based on the three-dimensional structural model, mutational analysis demonstrated that surface-exposed residues Thr-347 and Ser-356 in the apical domain were crucial for both binding to the gut epithelium and insecticidal activity. Double mutant T347A,S356A was 80% less toxic (p < 0.001) than the wild type protein. The GroEL homolog showed alpha-chitin binding activity with Kd approximately 0.64 microm and Bmax approximately 4.68 micromol/g chitin. The variation in chitin binding activity of the mutant proteins was in good agreement with membrane binding characteristics and insecticidal activity. The less toxic double mutant XnGroEL showed an approximately 8-fold increase of Kd in chitin binding assay. Our results demonstrate that X. nematophila secretes an insecticidal GroEL protein with chitin binding activity.

A fusion protein containing a lepidopteran-specific toxin from the South Indian red scorpion (Mesobuthus tamulus) and snowdrop lectin shows oral toxicity to target insects

BackgroundDespite evidence suggesting a role in plant defence, the use of plant lectins in crop protection has been hindered by their low and species-specific insecticidal activity. Snowdrop lectin (Galanthus nivalis agglutinin; GNA) is transported to the haemolymph of insects after oral ingestion, and can be used as a basis for novel insecticides. Recombinant proteins containing GNA expressed as a fusion with a peptide or protein, normally only toxic when injected into the insect haemolymph, have the potential to show oral toxicity as a result of GNA-mediated uptake.ResultsA gene encoding a toxin, ButaIT, from the red scorpion (Mesobuthus tamulus) was synthesised and assembled into expression constructs. One construct contained ButaIT alone, whereas the other contained ButaIT fused N-terminally to a GNA polypeptide (ButaIT/GNA). Both recombinant proteins were produced using the yeast Pichia pastoris as an expression host, and purified. Recombinant ButaIT and ButaIT/GNA were acutely toxic when injected into larvae of tomato moth (Lacanobia oleracea), causing slow paralysis, leading to mortality or decreased growth. ButaIT/GNA was chronically toxic when fed to L. oleracea larvae, causing decreased survival and weight gain under conditions where GNA alone was effectively non-toxic. Intact ButaIT/GNA was detected in larval haemolymph from insects fed the fusion protein orally, demonstrating transport of the linked polypeptide across the gut. Proteolysis of the fusion protein was also observed. ButaIT/GNA was significantly more toxic that GNA alone when fed to the homopteran Nilaparvata lugens (rice brown planthopper) in liquid artificial diet.ConclusionThe ButaIT/GNA recombinant fusion protein is toxic to lepidopteran larvae both when injected and when fed orally, showing the utility of GNA as a carrier to transport potentially toxic peptides and proteins across the insect gut. Although ButaIT has been claimed to be lepidopteran-specific, the fusion protein has more wide-ranging insecticidal activity. Fusion proteins based on plant lectins have potential applications in crop protection, both as exogenously applied treatments and as endogenous products in transgenic plants.

Studies on the bioactivity and elementology of marine algae from the coast of Karachi, Pakistan

Some species of marine benthic algae belonging to the Chlorophyta, Phaeophyta and Rhodophyta collected from different coastal areas of Karachi (Pakistan) were investigated for their antibacterial, antifungal, phytotoxic and insecticidal activities. Brown seaweeds showed greater antibacterial activity than the green and red ones. Botryocladia leptopoda (J. Ag.) Kylin exhibited the greatest antifungal activity and Codium shameelii Nizam. the least. The highest phytotoxic activity (95%) was displayed by Enteromorpha intestinalis (L.) Nees at 100 microg/mL concentration, while Osmundea pinnatifida (Huds.) Stack. showed the low insecticidal activity as compared to the other investigated species. Many elements e.g. Ca, Cd, Co, Cr, Cu, Fe, K, Mg, Na, Pb, Zn were determined quantitatively. Among them Ca, Cr and Pb were found to occur in largest amount in green seaweeds, Co, Cu, Fe and Zn in greatest quantity in brown seaweeds, while Cd, K, Mg and Na in highest proportion in the investigated red seaweeds.

EFFECT OF CYPERMETHRIN ON ISOLATED MALE AND FEMALE RAT HEPATOCYTES

Cypermethrin is a synthetic pyrethroid that belongs to a group of insecticides with low mammalian toxicity but high insecticidal activity. The present study was designed to investigate the toxicity of cypermethrin on freshly isolated hepatocytes from male and female rats. Hepatocytes were harvested by a collagenase perfusion technique and were exposed to different concentrations of cypermethrin (100, 200, 400, or 800 ng/2×106 cells) for up to 2 h. Cell viability and the leakage of aspartate transaminase (AST) and alanine transaminase (ALT) were determined throughout the incubation period. The cell viability of the hepatocytes from male and female rats exposed to 400 ng and 800 ng was significantly reduced after 60 and 30 min of incubation, respectively. With cells from female rats, viability was also reduced upon exposure to 200 ng cypermethrin for 2 h. The decrease in cell viability was dose and time dependent. The leakage of ALT and AST was significantly increased with 400 and 800 ng concentrations at 60 and 30 min, respectively. ALT leakage from female hepatocytes was significantly increased at 60 min of incubation with the 200-ng dose, whereas 2 h of incubation was required for the leakage of ALT from the cells of male rats. The present data indicate that cypermethrin has toxic effects on male and female rat hepatocytes in a dose- and time-dependent manner. The data suggest that female rat hepatocytes may be more sensitive to the toxic effects of cypermethrin than male cells.

EFFECT OF CYPERMETHRIN ON ISOLATED MALE AND FEMALE RAT HEPATOCYTES

Abstract Cypermethrin is a synthetic pyrethroid that belongs to a group of insecticides with low mammalian toxicity but high insecticidal activity. The present study was designed to investigate the toxicity of cypermethrin on freshly isolated hepatocytes from male and female rats. Hepatocytes were harvested by a collagenase perfusion technique and were exposed to different concentrations of cypermethrin (100, 200, 400, or 800 ng/2×106 cells) for up to 2 h. Cell viability and the leakage of aspartate transaminase (AST) and alanine transaminase (ALT) were determined throughout the incubation period. The cell viability of the hepatocytes from male and female rats exposed to 400 ng and 800 ng was significantly reduced after 60 and 30 min of incubation, respectively. With cells from female rats, viability was also reduced upon exposure to 200 ng cypermethrin for 2 h. The decrease in cell viability was dose and time dependent. The leakage of ALT and AST was significantly increased with 400 and 800 ng concentrations at 60 and 30 min, respectively. ALT leakage from female hepatocytes was significantly increased at 60 min of incubation with the 200-ng dose, whereas 2 h of incubation was required for the leakage of ALT from the cells of male rats. The present data indicate that cypermethrin has toxic effects on male and female rat hepatocytes in a dose- and time-dependent manner. The data suggest that female rat hepatocytes may be more sensitive to the toxic effects of cypermethrin than male cells.

Triazolines VII. Results of screening l,5‐diaryl‐Δ2‐l,2,3‐triazolines for pesticidal properties

AbstractTwenty‐one l,5‐diaryl‐δ2‐l,2,3‐triazolines were screened for the first time for pesticidal properties—insecticidal, fungicidal, bactericidal and virucidal. Five of the compounds showed some fungicidal activity, and 13 exhibited low level insecticidal activity, mostly toward the Mexican bean beetle.

N-Acylation of N-methylcarbamate insecticides and its effect on biological activity.

AbstractN‐Acylated N‐methylcarbamates have been prepared and tested for contact/stomach poison and systemic insecticidal activities, mammalian toxicity and in vitro anticholinesterase activity. The N‐acyl derivatives in general have lower mammalian toxicities and somewhat lower insecticidal activities than the corresponding unacylated N‐methylcarbamates and are relatively poor inhibitors of bee cholinesterase. Tentative reasons are given for these effects.

Isolation and Structure of an N-isoButyldienediynamide from Pellitory (Anacyclus pyrethrum DC.)

THE roots of the North African plant Anacyclus pyrethrum DC. (pellitory) have been used in medicine since the time of Dioscorides, and mention of the drug is made in the B.P.C. 1934 (Pyrethri radix). It induces copious salivation when chewed and gives rise to an intense burning taste. In a recent investigation it has been found1 that the crystalline sialogogue isolated by Gulland and Hopton2 from this material, and named pellitorine (melting point 72°), is in fact a mixture of isobutylamides3,4 of the general type Hydrogenation and acidic hydrolysis yield a mixture of decanoic, dodecanoic and tetradecanoic acids which can be separated by reversed-phase partition chromatography. Its nature will be discussed more fully elsewhere. During the isolation of pellitorine, a new crystalline substance of melting point 121° has been obtained, which crystallizes from chloroform–petrol in white needles. Unlike pellitorine, it is but sparingly soluble in petrol, has no sialogogue effect and only low insecticidal activity towards the grain insect Tenebrio molitor L.