Natural Pyrethrins Research Articles

Sulfoxaflor and Natural Pyrethrin with Piperonyl Butoxide Are Effective Alternatives to Neonicotinoids against Juveniles of Philaenus spumarius, the European Vector of Xylella fastidiosa.

The threat imposed by the bacterial pathogen Xylella fastidiosa to crops of utter importance to European agriculture such as olive, stone fruit and grapevine calls for immediate research against the meadow spittlebug, Philaenus spumarius (L.), the main European vector. Management tools should consider reducing juveniles of vector populations growing on weeds or cover crops during spring as nymphs have limited movement and do not contribute to disease spread. We examined a wide range of insecticides with different modes of action against P. spumarius nymphs in laboratory and semi-field glasshouse conditions. Pyrethroids (delthamethrin and λ-cyhalothrin) and natural pyrethrin (Pirecris®) + piperonyl butoxide (PBO) efficacy surpassed 86% after 24 h of exposure, without significant differences in the PBO amount tested. The inclusion of PBO caused a 3-fold increase in the mortality of P. spumarius nymphs compared to pyrethrin alone. Sulfoxaflor (Closer®) exhibited similar efficacy at 48 and 72 h but it was slow acting and mortality only reached 60% at 24 h. The LC90 was 34 ppm at 72 h. Pymetrozine, spirotetramat, azadirachtin and kaolin were not effective against nymphs (mortality <33%) although in azadirachtin-treated plants, mortality had a 3-fold increase from 24 to 72 h. Our results will help decision-making policy bodies to set up a sustainable integrated pest management of P. spumarius in areas where X. fastidiosa becomes a problem.

Plant essential oils synergize various pyrethroid insecticides and antagonize malathion in Aedes aegypti.

.Pyrethroid resistance is a significant threat to agricultural, urban and public health pest control activities. Because economic incentives for the production of novel active ingredients for the control of public health pests are lacking, this field is particularly affected by the potential failure of pyrethroid‐based insecticides brought about by increasing pyrethroid resistance. As a result, innovative approaches are desperately needed to overcome insecticide resistance, particularly in mosquitoes that transmit deadly and debilitating pathogens. Numerous studies have demonstrated the potential of plant essential oils to enhance the efficacy of pyrethroids. The toxicity of pyrethroids combined with plant oils is significantly greater than the baseline toxicity of either oils or pyrethroids applied alone, which suggests there are synergistic interactions between components of these mixtures. The present study examined the potential of eight plant essential oils applied in one of two concentrations (1% and 5%) to enhance the toxicity of various pyrethroids (permethrin, natural pyrethrins, deltamethrin and β‐cyfluthrin). The various plant essential oils enhanced the pyrethroids to differing degrees. The levels of enhancement provided by combinations of plant essential oils and pyrethroids in comparison with pyrethroids alone were calculated and synergistic outcomes characterized. Numerous plant essential oils significantly synergized a variety of pyrethroids; type I pyrethroids were synergized to a greater degree than type II pyrethroids. Eight plant essential oils significantly enhanced 24‐h mortality rates provided by permethrin and six plant essential oils enhanced 24‐h mortality rates obtained with natural pyrethrins. By contrast, only three plant essential plants significantly enhanced the toxicity of deltamethrin and β‐cyfluthrin. Of the plant essential oils that enhanced the toxicity of these pyrethroids, some produced varying levels of synergism and antagonism. Geranium, patchouli and Texas cedarwood oils produced the highest levels of synergism, displaying co‐toxicity factors of > 100 in some combinations. To assess the levels of enhancement and synergism of other classes of insecticide, malathion was also applied in combination with the plant oils. Significant antagonism was provided by a majority of the plant essential oils applied in combination with this insecticide, which suggests that plant essential oils may act to inhibit the oxidative activation processes within exposed adult mosquitoes.

Вивчення історії синтезу та хімічної будови піретринів і синтетичних піретроїдів та мутагенна активність піретроїдів у тесті на індукцію мікроядер in vivo (огляд літератури та дані власних досліджень)

Introduction. Pyrethroids are analogues of natural pyrethrins, primarily isolated from plants of the genus Pymthrum, a family of Asteraceae known for their insecticidal properties. Objective. To study literature data on the history of synthesis, peculiarities of the chemical structure of pyrethrins, pyrethroids and their most common isomers, a combination of synthetic pyrethroids (SPs) with other chemical substances and insecticidal activity of SPs. Also, to perform an experimental assessment of SP mutagenicity. Materials and Мethods. For the literature review, data of international organizations, electronic databases and articles of the authors from different countries were used. To study SP mutagenicity, in vivo test for micronucleus (MN) induction in polychromatophilic erythrocytes (PCE) in mice bone marrow was used. Five active substances of SPs were studied: Cypermethrin 94.0 % at the doses of 46.0, 9.2,1.84 mg/kg body weight, 2 samples of Alpha-cypermethrin — 94.0 and 94.7 % at the doses of 20.0,2.0, 0.2 mg/kg, and 2 samples of Lambda-cyhalothrin — 95.2 and 97.1 % at the doses of 5.0,1.0, 0.2 mg/kg. Results and Discussion. The history of SP synthesis dates back about 70 years. Currently, a significant number of SPs were synthesised that differ in chemical structure, have different strength of insecticidal action, as well as may be used in combination with other compounds. Results of experimental studies suggest that Cypermethrin at the doses from 46.0 to 1.84 mg/kg body weight, 2 samples of Alpha-cypermethrin at the doses from 20.0 to 0.2 mg/kg body weight, as well as 2 samples of Lambda-cyhalothrin at the doses 1.0 and 0.2 mg/kg did not show significant increase in MNPCE level in PCs. However, both samples of Lambda-cyhalothrin at the doses: 5.0 mg/kg body weight induced statistically significant exceeding of the spontaneous rate of MNPCE (р &lt; 0.05). Conclusion. Cypermethrin at the doses from 46.0 to 1.84 mg/kg body weight did not show a significant increase in MNPCE level. Samples of Alpha-cypermethrin at the doses from 20.0 to 0.2 mg/kg body weight did not show a significant increase in MN level. Samples of Lambda-cyhalothrin at the doses from 1.0 to 0.2 mg/kg did not show a significant increase in MN level. Samples of Lambda-cyhalothrin at the doses: 5.0 mg/kg body weight induced statistically significant exceeding of the spontaneous rate of MNPCE in comparison with the data of negative and historical controls.

Biomarkers of pyrethroid toxicity in fish

Pesticides contribute to human welfare by reducing vector-borne diseases and protecting crops against pests. Insecticides are the most widely employed pesticides for agricultural, domestic, and industrial pest control. However, some insecticides such as synthetic pyrethroids, analogs of the natural pyrethrin, persist in the environment and result in different hostile effects on nontarget organisms. Due to a continuous increase in the use of pyrethroids and their widespread application, different generations and types of pyrethroids have been frequently reported from environmental media, biota, and residential areas. Synthetic pyrethroids are observed to be less toxic to mammal and birds, relatively toxic to amphibians, and highly toxic to aquatic organisms including fish. Here, we review the occurrence, fate, biotransformation, and bioavailability of pyrethroids in waters. We also present biomarkers used to evidence toxicological effects of pyrethroids on fish. Toxic effects include oxidative stress and damage such as production of reactive oxygen species and lipid peroxidation; neurological behavioral inconsistencies; developmental effects such as delayed development and signaling; biochemical alterations of protein, glucose, and enzymes; hematological changes in white blood cells, red blood cells, and hemoglobin; physiological effects on metabolism and heart function; histopathological changes in the brain, liver, and gills; molecular toxicity including DNA damage, micronuclei induction, and altered gene or mRNA expression; and reproductive or endocrine disruption, e.g., disrupted pathways and signaling. Mechanisms of toxicity and control measures are also discussed.

Lethal and behavioral effects of synthetic and organic insecticides on Spodoptera exigua and its predator Podisus maculiventris.

BackgroundThe beet armyworm, Spodoptera exigua (Lepidoptera: Noctuidae), is a key insect pest of edible vegetables around the world and it is resistant to insecticide of different classes. Insecticides that are effective to this pest and selective to predator stinkbugs are required for the integrated management of S. exigua.MethodsThe toxicity of four commercial insecticide formulations azadirachtin + pyrethrin, spinosad, pyrethrin and chlorantraniliprole was tested on the target pest and their side effect were evaluated on the spined soldier bug, Podisus maculiventris (Heteroptera: Pentatomidae) through different bioassays.ResultsSpinosad and chlorantraniliprole were more toxic to S. exigua than to the predator P. maculiventris but opposite results were obtained for pyrethrin and azadirachtin + pyrethrin in contact toxicity bioassay. Chlorantraniliprole was the most toxic to S. exigua in oral toxicity bioassay, followed by spinosad, pyrethrin and azadirachtin + pyrethrin. Spinosad in oral toxicity bioassay was the most toxic to P. maculiventris, followed by pyrethrin, azadirachtin + pyrethrin and chlorantraniliprole. Spinosad caused irritability to the predator while pyrethrin to the pest. The insecticide repellency was not observed over the tested insect species. The synthetic insecticide chlorantraniliprole was less toxic than the natural pyrethrin, azadirachtin + pyrethrin and spinosad to the predator.ConclusionsThis work provides useful information on the combination of commercial insecticides with the predator P. maculiventris to controlling S. exigua in integrated pest management (IPM) programs.

Self-assembled mixed micelle loaded with natural pyrethrins as an intelligent nano-insecticide with a novel temperature-responsive release mode

Nanotechnology has recently attracted growing interest in the encapsulation of botanical insecticides for sustainable pest control. Biocompatible, biodegradable, and stimuli-responsive devices, however, were scarcely reported in the field of intelligent formulations of botanical insecticides. In the present study, a temperature-responsive mixed micelle (MMs–Pys–7) was developed for controlled release of pyrethrins by cooperative assembly of poly[2-(2-Methoxyethoxy) ethyl methacrylate-co-Octadecyl methacrylate] (P(MEO2MA94–co–ODA6)), monomethoxy (polyethylene glycol)13-poly(D, L-Lactide-co-glycolide) (mPEG13–b–PLGA5–3) and monomethoxy (polyethylene glycol)45-poly(D, L-Lactide) (mPEG45–b–PLA28) in water. This nanodevice could protect the encapsulated pyrethrins from ultraviolet degradation at 26 °C effectively. It also underwent a phase transition process in water from solution state to turbid state with temperature rising from 13 to 26 °C. By inducing this structural change, MMs–Pys–7 could regulate the pyrethrin release amounts to adapt to the larval mosquito population variations along with the ambient temperature changes. Therefore, MMs–Pys–7 exhibited a higher larvicidal activity against Culex pipiens pallens at 26 °C than that at 14 °C or 18 °C. Compared with a commercial pyrethrin formulation (EW–Pys), MMs–Pys–7 was more toxic to C. p. pallens larvae at 26 °C after 24-h exposure but less toxic at 14 °C. Moreover, MMs–Pys–7 also exhibited a longer-lasting larvicidal activity under natural conditions as compared to EW–Pys. These results suggest that MMs–Pys–7 has great potential to be developed as an intelligent nano-insecticide for mosquito control and that the controlled release mode established in this study can be applied to develop more smart formulations of botanical insecticides of application potential.

Current Research on the Safety of Pyrethroids Used as Insecticides.

Pyrethroids are synthetic derivatives of natural pyrethrins extracted from Chrysanthemum cinerariaefolium. They are 2250 times more toxic to insects than to vertebrates due to insects’ smaller size, lower body temperature and more sensitive sodium channels. In particular, three pyrethroid compounds, namely deltamethrin, permethrin, and alpha-cypermethrin, are commonly used as insecticides and are recommended for in-home insect control because they are considered to be relatively non-toxic to humans in all stages of life. However, recent data show that they are not completely harmless to human health as they may enter the body through skin contact, by inhalation and food or water, and absorption level depending on the type of food. Permethrin seems to have an adverse effect on fertility, the immune system, cardiovascular and hepatic metabolism as well as enzymatic activity. Deltamethrin induces inflammation, nephro- and hepatotoxicity and influences the activity of antioxidant enzymes in tissues. Alpha-cypermethrin may impair immunity and act to increase glucose and lipid levels in blood. The aim of the review is to provide comprehensive information on potential hazards associated to human exposure to deltamethrin, permethrin and alpha-cypermethrin. The results of presented studies prove that the insecticides must be used with great caution.

Efficacy of Selected Insecticides and Natural Preparations Against Leptinotarsa decemlineata

A field experiment was carried out to evaluate the effectiveness of synthetic and natural preparations in protecting potato against Leptinotarsa decemlineata (Colorado Potato Beetle). Seven substances and microorganisms with proved or potential toxic effect on the pest were used: Neem extract (Azadirachta indica), suspensions of Beauveria bassiana Balsamo (Vuillemin) (Hypocreales: Cordycipitaceae) and Isaria fumosorosea Wize (Hypocreales: Cordycipitaceae) entomopathogenic fungal spores, natural pyrethrin and three chemical insecticides (lambda-cyhalothrin, thiamethoxam and imidacloprid). Plots where no protection measures were applied served as control. Chemical insecticides were more effective in controlling L. decemlineata larvae than natural preparations. It was found that chemical insecticides protected potato yield more effectively than the preparations containing natural pyrethrin or spores of entomopathogenic fungi. Tuber yield from the plots protected with entomopathogenic fungi and Neem extract was significantly higher than that on unprotected plots but still lower than the yield obtained from the plots protected with a chemical preparation.

Toxicological Effects of Pyrethroids Insecticide on the Spleen and Bone Marrow of Adult Albino Rats

Pyrethroids are synthetic compounds chemically derived from the natural pyrethrins which are the insecticidal components of the pyrethrum extracts of chrysanthemum flower. The aim of this study was to investigate the toxicological effects of pyrethroid insecticide “Mortein” (M) on the bone marrow and spleen of adult Wistar rats. Twenty five adult rats (150-200g) were purchased from the animal facility of the College of Health Sciences, Delta State University, Abraka and assigned into five groups (n = 5). Groups I, II and III were treated orally with 2250mg/kg of Mortein insecticide suspended in olive oil once daily for 7, 21 and 40 days respectively. Groups IV and V were administered tap water and olive oil respectively, once daily throughout the duration of experiment. At the end of each respective durational treatment, the rats were euthanized. The spleen and bones were harvested and processed for histological analysis using standard techniques. The resultant sections were stained with Haematoxylin and Eosin (H&amp;E) and analyzed with the aid of a light microscope for histological changes. Histological examination of the bone marrow of the treated rats revealed extensive congestion that was time dependent as well as hypo cellularity when compared to the oil and normal control groups. The rats‟ spleens were markedly congested and there were intra-parenchyma hemorrhages of varying degrees compared to the rats of control groups. M insecticide at the dosage considered, was highly toxic to both spleen and bone marrows of rats for the different durations considered and the effects observed were time-dependent.Key words: Toxicology, Mortein, Pyrethroids, Spleen, Bone Marrow, Insecticide, Rats

Natural pyrethrins induce autophagy of HepG2 cells through the activation of AMPK/mTOR pathway

Natural pyrethrins, one kind of insects’ neural toxin, have been used worldwide for the control of pests of crops, livestock, and human beings. However, their specific mechanisms of action are incompletely understood and hence further investigation is required. Here we used a series of experiments including colony formation, fluorescent staining, western blotting, enzyme activity detection, immunofluorescence analysis, and real-time quantitative PCR (QPCR) to investigate whether natural pyrethrins (0–40 μg/mL) are able to modulate autophagy process through AMPK/mTOR signaling pathway, in order to reveal their cytotoxic mechanisms. The results showed that natural pyrethrins markedly inhibited the proliferation of HepG2 cells in both concentration- and time-dependent manners. Particularly, natural pyrethrins could induce the resulting autophagosome, and the intensification of LC3-II formation and translocation, the accumulation of Beclin-1 and the reduction of p62 and thus autophagy. We clarified that natural pyrethrins induced the abnormal level of oxidation reduction metabolism, leading to mitochondrial permeability transition pore (mPTP) opening, ATP depletion and mitochondria eliminating by autophagy. Moreover, the phosphorylation levels of AMPK were significantly enhanced, and the mTOR and p70s6k phosphorylation were drastically decreased. These results showed that natural pyrethrins induced autophagy of HepG2 cells and activation of the AMPK/mTOR signaling pathway might have potential risk to human health.

The different effects of natural pyrethrins and beta-cypermethrin on human hepatocyte QSG7701 cells by ROS-mediated oxidative damage

With the widespread use of natural pyrethrins and pyrethroids to defend pest insects, people had the sustained interest in the potential risk to environment and human health. However, the research about natural pyrethrins and beta-cypermethrin induction of cytotoxicity is still seldom. This study is about the cytotoxic effects of these on human non-target cells in vitro. The cytotoxic effect of natural pyrethrins and beta-cypermethrin on QSG7701 cells were researched by using various bioassays in vitro. The results suggested that with the natural pyrethrin concentration increased, the viability of QSG7701 cells were inhibited increasingly, and the IC50 value as calculated was approximately 42.54 and 18.68μg/mL after the cells were treated 24 and 48h. The proliferative potential of QSG7701 cells treated with 40μg/mL natural pyrethrins 6 and 12h was decreased by 67.44 and 94.74%, dramatic enhancement ROS, collapse of mitochondrial membrane potential, DNA exhibit severity of impairment, and chromatin DNA condensation. However, beta-cypermethrin has lower toxicity than natural pyrethrins. The IC50 values of beta-cypermethrin were all > 80μg/mL, and the colony formation expression was decreased by 15.26 and 19.09%, which implied that natural pyrethrins are more significantly cytotoxic and potentially genotoxic to human hepatocyte cells.

Action of six pyrethrins purified from the botanical insecticide pyrethrum on cockroach sodium channels expressed in Xenopus oocytes

Pyrethrin I, pyrethrin II, cinerin I, cinerin II, jasmolin I and jasmolin II are six closely related insecticidal active esters, known as pyrethrins, found in the pyrethrum extract from the dry flowers of Tanacetum cinerariifolium. The chemical structures of the six compounds differ only in the terminal moieties at the acid and alcohol ends, but the compounds' in vivo toxicities are substantially different. Pyrethrins are lead compounds for pyrethroids, a large family of synthetic insecticides that alter nerve functions by prolonging the opening of voltage-gated sodium channels. However, data on the mechanism of action of natural pyrethrins are very limited. In this study, we examined the actions of all six pyrethrins on cockroach sodium channels expressed in Xenopus oocytes. Although the six compounds showed comparable potencies in inhibiting the inactivation of sodium channels, they had greatly variable potencies in inhibiting channel deactivation. Furthermore, unlike pyrethroids, the action of pyrethrins neither depend on nor were enhanced by repeated channel activation. We created a NavMs-based model of the cockroach sodium channel, in which pyrethrin II was docked at the pyrethroid receptor site 1 (PyR1), and proposed a rationale for the observed structure-activity relationship of the six pyrethrins. Our study sheds light on the molecular mechanism of pyrethrum action on sodium channels and reveled differences in the modes of action of the six bioactive constitutes of pyrethrum.

Syntheses of epoxides, and structural analysis of (E)[sbnd]N-hexyl-3-(trans-3-methyloxiran-2-yl)prop-2-enamide by spectroscopic techniques and DFT calculations

Pyrethroids are three membered ring compounds similar to the natural pyrethrins produced by the flowers of Chrysanthemum cinerariaefolium and C. coccineum. Pyrethroids are insecticides and may also have insect repellent properties and are generally harmless to humans. Due to our interest in compounds with insecticidal activity, we have synthesized seven epoxides (2a-g), which are structurally similar to pyrethroids. The epoxides were prepared by stereospecific and regioselective epoxidation of seven dienamides (1a-g) with meta-chloroperbenzoic acid. The energies for two attainable epoxides (2g and 2g′) at their respective equilibrium geometries were calculated, and we have shown that the title epoxide (2g) is more stable than the candidate epoxide (2g′) (trans)N-hexyl-3-((E)-prop-1-en-1-yl)oxirane-2-carboxamide by 13.37 kJ mol−1. Experimental and calculated nuclear magnetic resonance chemical shifts were compared for both candidate epoxides (2g and 2g′), and a better match was achieved for the title compound (2g). The complementarity of Raman and infrared (IR) spectroscopies is a feature that can be explored for the characterization of this class of compound. This is shown by the bands around 3092 cm−1 in the Raman and absent in the IR spectra. On the other hand a strong peak at 1625 cm−1 in the IR is tiny in the Raman. Therefore the title compound was completely identified by NMR, IR, and Raman spectroscopies, and this protocol can be extended to the herein prepared epoxide analogues.

Acute Toxicity and Sublethal Effects of Terpenoids and Essential Oils on the Predator Chrysoperla externa (Neuroptera: Chrysopidae).

The search for new safer insecticides has increased in recent agriculture. Botanical compounds such as terpenoids and plant essential oils with insecticidal activity could represent important tools in pest management, and their risk assessment against non-target organisms is necessary since they may serve as a precursor for the synthesis of new insecticide active ingredients. For this study, the acute toxicity and sublethal effects of seven terpenoids and three essential oils with recognized insecticidal activity were evaluated on the predator Chrysoperla externa (Hagen) (Neuroptera: Chrysopidae) in laboratory bioassays. Results indicate that these compounds feature relative selectivity to the predator C. externa; however, sublethal effects on reproduction were recorded for some compounds. The phenolic monoterpenoids carvacrol and thymol were more acutely toxic than other terpenoids screened, with LD50 <20,000μg/g; however, they were less toxic than natural pyrethrins (toxicity standard) in these bioassays. Sublethal effects on fecundity and fertility were observed for R-(+)-limonene, while oregano oil only affected fecundity. The compounds evaluated here have potential to be used as insecticides and can serve as backbone for future synthesis of selective active ingredients; however, a complete risk assessment to C. externa and other non-target organisms is necessary for their incorporation in future crop protection paradigms.

Introduction of pyrethrum flowers (130 years in Japan)

Pyrethrum, Chrysanthemum tanacetum subsp. cinerariaefolium, is native to the Dalmatian region of former Yugoslavia. It was introduced to Japan in 1885. Eiichiro Ueyama, the founder of Dainihon Jochugiku Co., Ltd., obtained seeds of pyrethrum in 1886 from H.E. Amoore, a British plant trader, for industrial purposes. After starting its cultivation in Wakayama prefecture, he promoted its plantation throughout the country and popularized it for overseas exportation. Similar to the Dalmatian region, pyrethrum was initially utilized as a powder in Japan. Mosquito incense, developed by Eiichiro Ueyama in 1890, was in the shape of a stick and had a burning time of approximately 40 min. The mosquito stick was subsequently improved and developed into a coil type with a burning time of 7-8 h, equivalent to the sleeping time of humans. Eiichiro Ueyama also improved the method of growing pyrethrum flowers and had his methods published in a book. Pyrethrum consequently became the main source of household insecticides such as mosquito coils, and Japanese pyrethrum reached its peak production of 13,000 tons of dried flowers per annum in 1935. The structural elucidation of natural pyrethrins contained in pyrethrum has led to the development of a number of useful synthetic pyrethroids. Continuing with this success, aerosol products effective for various kinds of insects are now available. Other products such as mosquito killer mats, liquid-type mosquito killers, and battery-powered devices have also been developed in Japan. Although the active ingredients in mosquito coils have mostly shifted from pyrethrum to the synthetic pyrethroid allethrin, they have retained the original shape developed by Eiichiro Ueyama and have been used worldwide for more than 110 years. Thus, the technology of the mosquito incense stick has been registered at the National Museum of Nature and Science as one of the scientific technologies developed in Japan.

Comparison of green sample preparation techniques in the analysis of pyrethrins and pyrethroids in baby food by liquid chromatography–tandem mass spectrometry

A new selective and sensitive liquid chromatography triple quadrupole mass spectrometry method was developed for simultaneous analysis of natural pyrethrins and synthetic pyrethroids residues in baby food. In this study, two sample preparation methods based on ultrasound-assisted dispersive liquid–liquid microextraction (UA-DLLME) and salting-out assisted liquid–liquid extraction (SALLE) were optimized, and then, compared regarding the performance criteria. Appropriate linearity in solvent and matrix-based calibrations, and suitable recoveries (75–120%) and precision (RSD values≤16%) were achieved for selected analytes by any of the sample preparation procedures. Both methods provided the analytical selectivity required for the monitoring of the insecticides in fruit-, cereal- and milk-based baby foods. SALLE, recognized by cost-effectiveness, and simple and fast execution, provided a lower enrichment factor, consequently, higher limits of quantification (LOQs) were obtained. Some of them too high to meet the strict legislation regarding baby food. Nonetheless, the combination of ultrasound and DLLME also resulted in a high sample throughput and environmental-friendly method, whose LOQs were lower than the default maximum residue limit (MRL) of 10μgkg−1 set by European Community for baby foods. In the commercial baby foods analyzed, cyhalothrin and etofenprox were detected in different samples, demonstrating the suitability of proposed method for baby food control.

Nano-formulation enhances insecticidal activity of natural pyrethrins against Aphis gossypii (Hemiptera: Aphididae) and retains their harmless effect to non-target predators.

The insecticidal activity of a new nano-formulated natural pyrethrin was examined on the cotton aphid, Aphis gossypii Glover (Hemiptera: Aphididae), and the predators Coccinella septempunctata L. (Coleoptera: Coccinellidae) and Macrolophus pygmaeus Rambur (Hemiptera: Miridae), in respect with the nano-scale potential to create more effective and environmentally responsible pesticides. Pyrethrin was nano-formulated in two water-in-oil micro-emulsions based on safe biocompatible materials, i.e., lemon oil terpenes as dispersant, polysorbates as stabilizers, and mixtures of water with glycerol as the dispersed aqueous phase. Laboratory bioassays showed a superior insecticidal effect of the pyrethrin micro-emulsions compared to two commercial suspension concentrates of natural pyrethrins against the aphid. The nano-formulated pyrethrins were harmless, in terms of caused mortality and survival time, to L3 larvae and four-instar nymphs of the predators C. septempunctata and M. pygmaeus, respectively. We expect that these results can contribute to the application of nano-technology in optimization of pesticide formulation, with further opportunities in the development of effective plant protection products compatible with integrated pest management practices.

Comparative transcriptome analysis reveals candidate genes for the biosynthesis of natural insecticide in Tanacetum cinerariifolium

BackgroundPyrethrins are monoterpenoids and consist of either a chrysanthemic acid or pyrethric acid with a rethrolone moiety. Natural pyrethrins are safe and eco-friendly while possessing strong insecticidal properties. Despite such advantages of commercial value coming with the eco-friendly tag, most enzymes/genes involved in the pyrethrin biosynthesis pathway remain unidentified and uncharacterized. Since the flowers of Tanacetum cinerariifolium are rich in major pyrethrins, next generation transcriptome sequencing was undertaken to compare the flowers and the leaves of the plant de novo to identify differentially expressed transcripts and ascertain which among them might be involved in and responsible for the differential accumulation of pyrethrins in T. cinerariifolium flowers.ResultsIn this first tissue specific transcriptome analysis of the non-model plant T. cinerariifolium, a total of 23,200,000 and 28,500,110 high quality Illumina next generation sequence reads, with a length of 101 bp, were generated for the flower and leaf tissue respectively. After functional enrichment analysis and GO based annotation using public protein databases such as UniRef, PFAM, SMART, KEGG and NR, 4443 and 8901 unigenes were identified in the flower and leaf tissue respectively. These could be assigned to 13344 KEGG pathways and the pyrethrin biosynthesis contextualized. The 2-C-methyl-D-erythritol 4-phosphate (MEP) pathway was involved in the biosynthesis of acid moiety of pyrethrin and this pathway predominated in the flowers as compared to the leaves. However, enzymes related to oxylipin biosynthesis were found predominantly in the leaf tissue, which suggested that major steps of pyrethrin biosynthesis occurred in the flowers.ConclusionsTranscriptome comparison between the flower and leaf tissue of T. cinerariifolium provided an elaborate list of tissue specific transcripts that was useful in elucidating the differences in the expression of the biosynthetic pathways leading to differential presence of pyrethrin in the flowers. The information generated on genes, pathways and markers related to pyrethrin biosynthesis in this study will be helpful in enhancing the production of these useful compounds for value added breeding programs. Related proteome comparison to overlay our transcriptome comparison can generate more relevant information to better understand flower specific accumulation of secondary metabolites in general and pyrethrin accumulation in particular.

Efficient, Baseline Separation of Pyrethrins by Centrifugal Partition Chromatography

Pyrethrins are natural pesticides present in the oil extracted from the flowers of Chrysanthemum cinerariaefolium. They are potent ion-channel neurotoxins which have higher selective toxicity for insects compared to mammals. These phytochemicals have an exceptionally safe environmental profile and are an attractive natural alternative to organophosphate insecticides currently used in agriculture. The oil extract contains six pyrethrins compounds, which are structurally related esters. Isolation of reference standards for pyrethrins and their derivatives in multi-gram quantities is a prerequisite for studying toxicity and soil degradation for these natural pyrethrins. Chromatography is difficult because of the high hydrophobicity and close structural similarity. The isolated pyrethrin compounds also have poor stability because they are photosensitive. To facilitate these studies, we have developed a twostep purification process, in which the two groups were first separated by normal phase liquid chromatography on silica gel. The separation of pyrethrin, cinerin, and jasmolin within each group was achieved by centrifugal partition chromatography (CPC). We explored and successfully optimized solvent systems that were subsequently applied to achieve multi-gram scale separation. The pyrethrins I group compounds were separated using a solvent system containing heptane-methanol-acetonitrile (6:1:2, v/v) in ascending mode. The pyrethrins II group compounds were separated using a solvent system containing heptane-terbutylmethyl ether-acetonitrile-water (8:1:5:1.5, v/v) also in ascending mode. In both cases, gram quantities of individual pyrethrins with purity exceeding 99% were produced.

Laboratory Bioassays with Three Different Substrates to Test the Efficacy of Insecticides against Various Stages of Drosophila suzukii (Diptera: Drosophilidae).

Rapid worldwide spread and polyphagous nature of the spotted wing Drosophila Drosophila suzukii Matsumura (Diptera: Drosophilidae) calls for efficient and selective control strategies to prevent severe economic losses in various fruit crops. The use of insecticides is one option for management of this invasive pest insect. Efficacy of insecticides is usually assessed first in laboratory bioassays, which are compounded by the cryptic nature of D. suzukii larvae and the fact that fruits used in bioassays often start to rot and dissolve before larvae have reached the adult stage. Here, we report on laboratory bioassays using three different types of substrates allowing a thorough screening of insecticides for their potential effects against D. suzukii eggs, larvae and adults. Suitability of our bioassays was validated in an assessment of the efficacy of four bioinsecticides and one synthetic insecticide against various developmental stages of D. suzukii. Water-apple juice agar used as a bioassay substrate allowed egg counting and observation of larval development due to its transparency, while apple-nutrition medium allowed complete metamorphosis. Use of grape berries in bioassays made it possible to assess effects of an insecticide present on a fruit’s surface on oviposition and larval hatch from eggs. Insecticides tested in these three different bioassays with acetamiprid, spinosad or natural pyrethrins as active ingredients achieved a significant D. suzukii control if they were applied before egg deposition. Number of adult flies was significantly reduced if the bioassay medium was treated with an azadirachtin A containing insecticide both before or after egg deposition.