Eco-friendly Insecticides Research Articles

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Insecticidal activity of camphene, zerumbone and α-humulene from Cheilocostus speciosus rhizome essential oil against the Old-World bollworm, Helicoverpa armigera

The fast-growing resistance development to several synthetic and microbial insecticides currently marketed highlighted the pressing need to develop novel and eco-friendly pesticides. Among the latter, botanical ones are attracting high research interest due to their multiple mechanisms of action and reduced toxicity on non-target vertebrates. Helicoverpa armigera (Lepidoptera: Noctuidae) is a key polyphagous insect pest showing insecticide resistance to several synthetic molecules used for its control. Therefore, here we focused on the rhizome essential oil extracted from an overlooked Asian plant species, Cheilocostus speciosus (J. Konig) C. Specht (Costaceae), as a source of compounds showing ingestion toxicity against H. armigera third instar larvae, as well as ovicidal toxicity. In acute larvicidal assays conducted after 24h, the C. speciosus essential oil achieved a LC50 value of 207.45µg/ml. GC and GC-MS analyses highlighted the presence of zerumbone (38.6%), α-humulene (14.5%) and camphene (9.3%) as the major compounds of the oil. Ingestion toxicity tests carried out testing these pure molecules showed LC50 values of 10.64, 17.16 and 20.86µg/ml, for camphene, zerumbone and α-humulene, respectively. Moreover, EC50 values calculated on H. armigera eggs were 35.39, 59.51 and 77.10µg/ml for camphene, zerumbone and α-humulene, respectively. Overall, this study represents the first report on the toxicity of C. speciosus essential oil against insect pests of agricultural and medical veterinary importance, highlighting that camphene, zerumbone and α-humulene have a promising potential as eco-friendly botanical insecticides.

The crop-residue of fiber hemp cv. Futura 75: from a waste product to a source of botanical insecticides.

In the attempt to exploit the potential of the monoecious fiber hemp cv. Futura 75 in new fields besides textile, cosmetics and food industry, its crop-residue given by leaves and inflorescences was subjected to hydrodistillation to obtain the essential oils. These are niche products representing an ideal candidate for the development of natural insecticides for the control and management of mosquito vectors, houseflies and moth pests. After GC-MS analysis highlighting a safe and legal chemical profile (THC in the range 0.004-0.012% dw), the leaf and inflorescence essential oils were investigated for the insecticidal potential against three insect targets: the larvae of Culex quinquefasciatus and Spodoptera littoralis and the adults of Musca domestica. The essential oil from inflorescences, showing (E)-caryophyllene (21.4%), myrcene (11.3%), cannabidiol (CBD, 11.1%), α-pinene (7.8%), terpinolene (7.6%), and α-humulene (7.1%) as the main components, was more effective than leaf oil against these insects, with LD50 values of 65.8μg/larva on S. littoralis, 122.1μg/adult on M. domestica, and LC50 of 124.5μl/l on C. quinquefasciatus larvae. The hemp essential oil moderately inhibited the acetylcholinesterase (AChE), which is a target enzyme in pesticide science. Overall, these results shed light on the future application of fiber hemp crop-residue for the development of effective, eco-friendly and sustainable insecticides.

Mosquito-larvicidal efficacy of the extract of Musca domestica maggots against Culex pipiens (Diptera: culidae), an important vector of Filariasis

The intolerably high burdens of mosquito-borne diseases will be reduced sustainably through the development of integral eco-friendly alternative insecticides of natural products origin. The need to broaden the global search for such insecticidal lead-agents, especially , those that will be less vulnerable to resistance, was the reason why this bio-assay study was carried out to test Musca domestica maggots against 4th instar larvae of the mosquito Culex pipiens pipiens. The larvicidal bio-assay followed standard World Health Organisation‟s protocols for testing the susceptibility of mosquitoes to larvicides. Larvicidal tests were carried out in a series of extract concentrations ranging from 0.25-4.50 mg/ml, in distilled and tap water media. The results showed that maggot extract possesses significant (P<0.05) larvicidal activities against the mosquito species, in a way akin to those reported for potent plant extracts. The larvicidal activities of the extract was dose dependent; and extract induced significantly higher larval mortality in tap water bio-assay medium than distilled water, except in the 0.25 mg/ml concentration treatment, where the reverse was the case. While, 100% larval mortality was recorded in extract concentration of 2.50 mg/ml in tap water, it took 4.50 mg/ml to kill all exposed larvae in distilled water bio-assay media. The LC50 values of the extract ranged significantly (P<0.05) from 1.57 mg/ml in tap water to 2.26 mg/ml in distilled water. The LC90 equivalents were 2.14 mg/ml and 3.47 mg/ml, respectively. These results suggest that insects may be at-least as promising as the botanicals in our search for eco-friend alternative insecticides.Key words: Bio-assay media, Insect metabolites, Insecticides, Larval mortality, Lethal Concentration and susceptibility.

Clausena anisata and Dysphania ambrosioides essential oils: from ethno-medicine to modern uses as effective insecticides.

Dysphania ambrosioides (L.) Mosyakin & Clemants (Amaranthaceae) and Clausena anisata (Willd.) Hook. f. ex Benth. (Rutaceae) are two aromatic species traditionally used in Cameroon to repel and kill insects. The present work was carried out to substantiate this traditional use and to evaluate the possible incorporation in commercial botanical insecticides of their essential oils (EOs). The EOs were distilled from leaves of C. anisata and aerial parts of D. ambrosioides and analyzed by gas chromatography-mass spectrometry (GC-MS). The insecticidal activity of both EOs was investigated against the filariasis vector, Culex quinquefasciatus, and the housefly, Musca domestica. As possible mode of action, the inhibition of acetylcholinesterase (AChE) by the two EOs was investigated as well. The D. ambrosioides EO was characterized by the monoterpene peroxide ascaridole (61.4%) and the aromatic p-cymene (29.0%), whereas the C. anisata EO was dominated by the phenylpropanoids (E)-anethole (64.6%) and (E)-methyl isoeugenol (16.1%). The C. anisata EO proved to be very toxic to third instar larvae of C. quinquefasciatus showing LC50 of 29.3μl/l, whereas D. ambrosioides EO was more toxic to adults of M. domestica showing a LD50 of 51.7 μg/adult. The mixture of both EOs showed a significant synergistic effect against mosquito larvae with LC50 estimated as 19.3μl/l, whereas this phenomenon was not observed upon application to M. domestica adults (LD50 = 75.9 μg/adult). Of the two EOs, the D. ambrosioides one provided a good inhibition of AChE (IC50 = 77 μg/ml), whereas C. anisata oil was not effective. These findings provide new evidences supporting the ethno-botanical use of these two Cameroonian plants, and their possible application even in synergistic binary blends, to develop new eco-friendly, safe and effective herbal insecticides.

Ligand-binding characterization of simulated β-adrenergic-like octopamine receptor in Schistocerca gregaria via progressive structure simulation

It is important to design insecticides having both low drug resistance and less undesirable toxicity for desert locust control. Specific GPCRs of Schistocerca gregaria, especially β-adrenergic-like octopamine receptor (SgOctβR), can be considered as its potential effective insecticide targets. However, either the unavailability of SgOctβR’s structure or the inadequate capability of its sequence lead the development of insecticide for Schistocerca gregaria meets its plateau. To relax this difficulty, this paper develops a promising progressive structure simulation from SgOctβR’s sequence, to its predicted structure of SgOctβR in vacuum, to its conformation as well as its complex with endogenous ligand octopamine in a solvent-membrane system. The combined approach of multiple sequence alignment, static structural characterization, and dynamic process of conformational change during binding octopamine reveal three important aspects. The first one is the characterization of SgOctβR’s active pocket, including the attending secondary structure elements, its hydrophobic residues and nonpolar surface. The second one is the interaction with octopamine, especially the involved hydrogen bonds and an aromatic stacking of pi–pi interactions. The third one is the potential binding sites, including six highly conserved residues and one highly variable residue for locust insecticide design. This work is definitely helpful for the further structure-based drug design for efficient and eco-friendly insecticides, as well as site-directed mutagenesis biochemical research of SgOctβR.

The interaction of the bioinsecticide PA1b (Pea Albumin 1 subunit b) with the insect V-ATPase triggers apoptosis

PA1b (Pea Albumin 1, subunit b) peptide is an entomotoxin, extracted from Legume seeds, with a lethal activity towards several insect pests, such as mosquitoes, some aphids and cereal weevils. This toxin acts by binding to the subunits c and e of the plasma membrane H+-ATPase (V-ATPase) in the insect midgut. In this study, two cereal weevils, the sensitive Sitophilus oryzae strain WAA42, the resistance Sitophilus oryzae strain ISOR3 and the insensitive red flour beetle Tribolium castaneum, were used in biochemical and histological experiments to demonstrate that a PA1b/V-ATPase interaction triggers the apoptosis mechanism, resulting in insect death. Upon intoxication with PA1b, apoptotic bodies are formed in the cells of the insect midgut. In addition, caspase-3 enzyme activity occurs in the midgut of sensitive weevils after intoxication with active PA1b, but not in the midgut of resistant weevils. These biochemical data were confirmed by immuno-histochemical detection of the caspase-3 active form in the midgut of sensitive weevils. Immuno-labelling experiments also revealed that the caspase-3 active form and V-ATPase are close-localized in the insect midgut. The results concerning this unique peptidic V-ATPase inhibitor pave the way for the utilization of PA1b as a promising, more selective and eco-friendly insecticide.

Insecticidal Properties of Essential Oils and Some of Their Constituents on the Turkestan Cockroach (Blattodea: Blattidae).

The Turkestan cockroach, Blatta lateralis (Walker), has become the most important peridomestic species in urban areas of the Southwestern United States. The aim of this study was to evaluate the use of botanical compounds to control this urban pest. We tested the acute toxicity and repellency of six botanical constituents and three essential oils on Turkestan cockroach nymphs. Chemical composition of the essential oils was also determined. Topical and fumigant assays with nymphs showed that thymol was the most toxic essential oil constituent, with a LD50 of 0.34 mg/nymph and a LC50 of 27.6 mg/liter air, respectively. Contact toxicity was also observed in assays with trans-Cinnamaldehyde, eugenol, geraniol, methyl eugenol, and p-Cymene. Methyl eugenol and geraniol had limited fumigant toxicity. The essential oils from red thyme, clove bud, and Java citronella exhibited toxicity against nymphs. Cockroaches avoided fresh dry residues of thymol and essential oils. Chemical analysis of the essential oils confirmed high contents of effective essential oil constituents. Our results demonstrated that essential oils and some of their constituents have potential as eco-friendly insecticides for the management of Turkestan cockroaches.

Lepidopteran HMG-CoA reductase is a potential selective target for pest control.

As a consequence of the negative impacts on the environment of some insecticides, discovery of eco-friendly insecticides and target has received global attention in recent years. Sequence alignment and structural comparison of the rate-limiting enzyme HMG-CoA reductase (HMGR) revealed differences between lepidopteran pests and other organisms, which suggested insect HMGR could be a selective insecticide target candidate. Inhibition of JH biosynthesis in vitro confirmed that HMGR inhibitors showed a potent lethal effect on the lepidopteran pest Manduca sexta, whereas there was little effect on JH biosynthesis in Apis mellifera and Diploptera punctata. The pest control application of these inhibitors demonstrated that they can be insecticide candidates with potent ovicidal activity, larvicidal activity and insect growth regulatory effects. The present study has validated that Lepidopteran HMGR can be a potent selective insecticide target, and the HMGR inhibitors (especially type II statins) could be selective insecticide candidates and lead compounds. Furthermore, we demonstrated that sequence alignment, homology modeling and structural comparison may be useful for determining potential enzymes or receptors which can be eco-friendly pesticide targets.

Cyromazine resistance in a field strain of house flies, Musca domestica L.: Resistance risk assessment and bio-chemical mechanism

Developing resistance management strategies for eco-friendly insecticides is essential for the management of insect pests without harming the environment. Cyromazine is a biorational insecticide with very low mammalian toxicity. Resistance to cyromazine has recently been reported in house flies from Punjab, Pakistan. In order to propose a resistance management strategy for cyromazine, experiments were planned to study risk for resistance development, possibility of cross-resistance and bio-chemical mechanisms. A field strain of house flies with 8.78 fold resistance ratio (RR) to cyromazine was re-selected under laboratory conditions. After seven rounds of selection (G1-G7), the RR values rapidly increased from 8.8 to 211 fold. However, these values declined to 81fold when the cyromazine selected (CYR-SEL) strain was reared without selection pressure, suggesting an unstable nature of resistance. The CYR-SEL strain showed lack of cross-resistance to pyriproxyfen, diflubenzuron, and methoxyfenozide. Synergism bioassays using enzyme inhibitors: piperonyl butoxide (PBO) and S,S,S-tributylphosphorotrithioate (DEF), and metabolic enzyme analyses revealed increased activity of carboxylesterase (CarE) and mixed-function oxidase (MFO) in the CYR-SEL strain compared to the laboratory susceptible (Lab-susceptible) strain, suggesting the metabolic resistance mechanism responsible for cyromazine resistance in the CYR-SEL strain. In conclusion, risk of rapid development of cyromazine resistance under consistent selection pressure discourages the sole reliance on cyromazine for controlling house flies in the field. The unstable nature of cyromazine resistance provides window for restoring cyromazine susceptibility by uplifting selection pressure in the field. Moreover, lack of cross-resistance between cyromazine and pyriproxyfen, diflubenzuron, or methoxyfenozide in the CYR-SEL strain suggest that cyromazine could be rotated with these insecticides whenever resistance crisis occur in the field.

Residual Effect of Neem Leaf Extract on The Mortality of Lipaphis erysimi And Its Larvae

The objective was to study the mortality rate of Lipaphis erysimi and its larvae by using neem leaf extract and appropriate dose of concentrations for checking the insect population.For this cultivars were raised with three dates of sowing at an interval of 15 days each in subplots with three replications each and the clones of mustard aphids were maintained. Theeffect of neem leaf extract on different larvae stages of aphids was studied and for that neem leaf extract of different concentrations was prepared, rearing of aphid's larvae was done and then the mortality rate of the aphid larvae (i.e. 1 st , 3 rd and 5 th instars) in presence of neem leaf extract at different time intervals with different concentrations (5%, 10%, 15%, 20%) was studied.From the study it was observed that the aphid, L. erysimi was killed with the neem leaf extract at all concentrations but there was a significant difference among different concentrations, larval stage and period of treatment. Thus the study showed that by using eco-friendly insecticide, neem leaf extract, the spread of L. erysimi can be controlled which in turn will not hamper the yield of the mustard crop.

Original Article. An evaluation of some eco-friendly biopesticides against Bemisia tabaci on two greenhouse tomato varieties in Egypt

Abstract This study has two main approaches. First, it exploits the susceptibility of tomato cultivars as a prophylactic measure to detect auto resistance characters of the tested tomato varieties against Bemisia tabaci (Gennadius) (Homoptera: Aleyrodidae). Secondly, it evaluates the efficacy of different bio-rational insecticides against B. tabaci under greenhouse conditions. The results exhibited a special significance in B. tabaci infestation suitability between the two tomato varieties with a high infestation significance found in the Shifa F1 hybrid tomato variety compared to the Savera F1 hybrid tomato variety in the first plantation period. Subsequently, in the second plantation period, there was a significant difference between the two tomato varieties. Bemisia tabaci showed a preference for the Shifa F1 hybrid over the Savera F1 hybrid tomato variety. These differences occurred during the 1st, 2nd, 4th, 6th, 7th, 8th, and 10th weeks. In the experimental trial for the efficacy of eco-friendly biorational insecticides, spinosad, azadirachtin, Beauveria bassiana and Metarhizium anisopliae, there were significant differences between the treated and untreated plants during the two plantation periods. A high efficacy of spinosad on the B. tabaci population was found. Bemisia tabaci infestation under all the applications was reduced from 50 to 94.61% for the two plantation periods. This obvious decrease in B. tabaci population increase attention to benefits of the different bio-rational insecticides.

Occurrence of Tomato Russet Mites, Aculops lycopersici Massee (Acari: Eriophyidae) in a Greenhouse and Selection of an Eco-friendly Organic Insecticide

Occurrence of Tomato Russet Mites, Aculops lycopersici Massee (Acari: Eriophyidae) in a Greenhouse and Selection of an Eco-friendly Organic Insecticide

Agave sisalana extract induces cell death in Aedes aegypti hemocytes increasing nitric oxide production

ObjectiveTo investigate the effects of Agave sisalana (A. sisalana) extract on Aedes aegypti (Ae. aegypti) primary cell culture. MethodsCells of Ae. aegypti were exposed to different concentrations of A. sisalana crude extract (0.18–6.00 mg/mL) for 24 h. Then, the cells were labeled with propidium iodide and subjected to fluorescence microscopy to verify cell viability. In addition, nitric oxide production was measured. ResultsResults showed that cells exposed to 6 mg/mL of the crude extract presented a greater percentage of death when compared to control (73.8% ± 9.6% vs. 34.6% ± 9.6%). Furthermore, there was an increase in the nitric oxide production in cells exposed to 6 mg/mL of A. sisalana crude extract [(0.81 ± 0.08) μmol/L] compared to control group [(0.41 ± 0.18) μmol/L]. ConclusionsThe results show that A. sisalana is cytotoxic to Ae. aegypti and may be used as raw material for new eco-friendly and inexpensive insecticides, since sisal industry discards the liquid waste for the extraction of plant fiber.

Comparative study on ecofriendly management of chilli thrips,Scirtothrips dorsalishood in mungbean by using different bio- and chemicals pesticides

Effect of certain ecofriendly insecticides against thrips (Scirtothrips dorsalis Hood) was studied at Varansi, Uttar Pradesh on mungbean. Ten different treatments (including control) of microbial and chemical insecticides were taken in different combinations and used at different crop stages. Among various insecticidal treatments, the combination of seed treatment with Pseudomonas fluorescens and spraying of Beuvaria bassiana gave better responses and was found most effective against thrips (Scirtothrips dorsalis) followed by seed treatment of P. florescens was found effective to minimise the infestation of thrips (Scirtothrips dorsalis Hood).

Physiological and biochemical response of Aedes aegypti tolerance to Bacillus thuringiensis

ABSTRACTBacillus thuringiensis subsp. israelensis (Bti) represents the only eco-friendly bio-degradable insecticide for mosquito-borne disease control. Our research aims to identify if mosquito detoxification enzymes play an important role in Bti tolerance mechanisms in the dengue vector, Aedes aegypti. Several enzymes, such as amylase, cytochromes P450, Na+/K+-ATPase, acetylcholinesterase, protease and glutathione S-transferase (GST) were analysed and level of activity determined in Ae. aegypti larvae after Bti treatment. Bti exposure significantly increased the level of amylase (183.2%) as well as the activity of cytochromes P450 (177.5%), and Na+/K+-ATPase (142.9%). On the other hand, there was a decrease of 8.6% and 11.4% in acetylcholinesterase and GST activity, and no significant effect in the total level of protease activity. We suggest that the variation in amylase, cytochromes P450, Na+/K+-ATPase, acetylcholinesterase, protease and GST activity may be associated with the Bti insecticidal mechanism. This study provides the basis of detoxifying enzymes in Bti tolerance.

Eco-Friendly Insecticide Discovery via Peptidomimetics: Design, Synthesis, and Aphicidal Activity of Novel Insect Kinin Analogues

Insect kinin neuropeptides are pleiotropic peptides that are involved in the regulation of hindgut contraction, diuresis, and digestive enzyme release. They share a common C-terminal pentapeptide sequence of Phe(1)-Xaa(2)-Yaa(3)-Trp(4)-Gly(5)-NH2 (where Xaa(2) = His, Asn, Phe, Ser, or Tyr; Yaa(3) = Pro, Ser, or Ala). Recently, the aphicidal activity of insect kinin analogues has attracted the attention of researchers. Our previous work demonstrated that the sequence-simplified insect kinin pentapeptide analogue Phe-Phe-[Aib]-Trp-Gly-NH2 could retain good aphicidal activity and be the lead compound for the further discovery of eco-friendly insecticides which encompassed a broad array of biochemicals derived from micro-organisms and other natural sources. Using the peptidomimetics strategy, we chose Phe-Phe-[Aib]-Trp-Gly-NH2 as the lead compound, and we designed and synthesized three series, including 31 novel insect kinin analogues. The aphicidal activity of the new analogues against soybean aphid was determined. The results showed that all of the analogues exhibited aphicidal activity. Of particular interest was the analogue II-1, which exhibited improved aphicidal activity with an LC50 of 0.019 mmol/L compared with the lead compound (LC50 = 0.045 mmol/L) or the commercial insecticide pymetrozine (LC50 = 0.034 mmol/L). This suggests that the analogue II-1 could be used as a new lead for the discovery of potential eco-friendly insecticides.

Novel phthalamides containing sulfiliminyl moieties and derivatives as potential ryanodine receptor modulators.

To tackle the serious challenge of insect resistance and stricter environmental regulations, innovating a new eco-friendly insecticide is urgently required. A series of new phthalamides containing sulfiliminyl and sulfoximinyl moieties were designed and synthesized. In total, 30 new structures were characterized by 1H NMR spectra and HRMS. The bioassay results indicated that some title compounds exhibited excellent insecticidal activities against oriental armyworm (Pseudaletia separata Walker) and diamondback moth (Plutella xylostella (L.)). 4a showed the same larvicidal level as that of commercial flubendiamide as a control. 7a and 9a exhibited outstanding activity against diamondback moth. The LC50 values of 7a and 9a were 8.33 × 10(−8) and 2.34 × 10(−8) mg L(−1), respectively, lower than that of flubendiamide (1.25 × 10(−7) mg L(−1)). The effects of 4a, 7a and 9a on intracellular calcium of neurons from the beet armyworm (Spodoptera exigua) indicated that these title compounds activate the receptor-operated calcium channel. The calcium ions efflux from the calcium store on endoplasmic reticulum (ER) when treated with novel compounds. The results of CoMFA calculation showed that N-cyanosulfilimines and N-trifluoroacetylsulfoximines might be of importance to the larvicidal activity. The present work demonstrated that structures containing sulfiliminyl and sulfoximinyl moieties can be considered as lead compounds for the development of new insect ryanodine receptor modulators.

Effects of two eco-friendly insecticides (Dennettia tripetala & Piper guineense) against Dermestes maculatus (Degeer) on smoked dried Clarias gariepinus (Pisces: Clariidae)

The efficacy of pulverized and extracts of Dennettia tripetala and Piper gunieense indigenous to Nigeria on larvicidal and adult deterrents of fish beetle Dermestes maculatus on stored dried smoked catfish was investigated. The beetles were reared separately in the laboratory at ambient temperature 30±2 o C and relative humidity of (65±5%). The pulverized plants parts at 0.5, 1.0, 1.5, and 2.0g and 0.100, 0.125 and 0.150ml of extracts were used against 20g of smoked fish. Adults and larvae stages of D. maculatus were introduced into different aerated jars containing smoked catfish treated with pulverized plant parts and extracts. The jars were left in the laboratory for 168hours. Results showed that the two plants had varying degree of insecticidal activities but were both effective against the beetles. It was observed that the extracts were more effective than pulverized powder when the results were compared. The plants materials can therefore serve as alternative to synthetic chemicals because of they were effective. Keyword: black pepper, dermestid beetle, catfish, Pepper fruit, insecticides

Bio-efficacy of Eco-friendly Insecticides against Cabbage Butterfly, <i>Pieris brassicae</i> (L.) on Cabbage in the Mid Altitudes Hills of Meghalaya, North East India

In this study nine eco-friendly insecticides viz., Annonin, Azadirachtin (oil base 300 ppm), Neem Seed Kernel Extract 300 ppm, Garlic Extract (1%), Karanjin, Bacillus thuringiensis (Bt), Beauveria bassiana , Spinosad 45 SC and Endosulfan 35 EC were tested for their bio-efficacy against Pieris brassicae (L.) on cabbage. After fifteen (15) days of spray it was found that endosulfan, annonin and spinosad killed maximum number of larvae with 98.65%, 98.47% and 97.84% mortality respectively. Among the botanicals, annonin was found to be the most effective whereas for microbial, spinosad was found to give maximum control.