Repellent Activity Research Articles

(E)-7-Phenyl-2-heptene-4,6-diyn-1-ol from Bidens pilosa as a repellent against isopods.

The development of repellents as alternatives to insecticides has expanded in recent years. However, their use in isopod pest control is limited. To develop an isopod repellent, a plant extract library from wild plants native to the Kochi Prefecture was screened for repellent activity against pillbugs and 82 samples (87%) exhibited repellent activity. Among them, (E)-7-phenyl-2-heptene-4,6-diyn-1-ol was isolated and identified as a repellent from the root of Bidens pilosa. It had a half-maximal effective concentration of 0.20 µM, with a strong repellency. A study of the structure-activity relationship to (E)-7-phenyl-2-heptene-4,6-diyn-1-ol revealed that the presence of a hydroxyl group and an aromatic at both ends of the length of the seven-carbon chain is important for the expression of repellency. These results can potentially lead to a new repellent of phenylalkyl alcohol.

Development of attractants and repellents for Tuta absoluta based on plant volatiles from tomato and eggplant

IntroductionTuta absoluta is currently considered one of the most devastating invasive pests of solanaceous plants worldwide, causing severe damage to the tomato industry. Insects use volatile organic compounds (VOCs) to locate host plant for feeding and oviposition. Those VOCs could be developed as lures for pest monitoring and control.MethodsIn this study, the differentially accumulated VOCs between the preferred host (tomato) and non-preferred host (eggplant) were analyzed by GC–MS method, and their roles on female T. absoluta host selection and egg laying behaviors were investigated using electroantennography (EAG), olfactometer and cage experiments.ResultsA total of 39 differentially accumulated VOCs were identified in tomato and eggplant. Strong EAG signals were obtained in 9 VOCs, including 5 VOCs highly accumulated in tomato and 4 VOCs highly accumulated in eggplant. Further olfactometer bioassays showed that 4 compounds (1-nonanol, ethyl heptanoate, ethyl octanoate and o-nitrophenol) were attractive to T. absoluta females, while 5 compounds (2-phenylethanol, 2-pentylfuran, trans,trans-2,4-nonadienal, 2-ethyl-5-methylpyrazine and trans-2-nonenal) were repellent, indicating that VOCs from host plants play important roles in host plant preferences. The attractive activities of 1-nonanol and ethyl octanoate, as well as the repellent activities of trans,trans-2,4-nonadienal and trans-2-nonenal, were further confirmed in cage experiments.DiscussionIn this study, two attractants and two repellents for T. absoluta were developed from plant released VOCs. Our results could be useful to enhance the development of eco-friendly and sustainable pest management strategies for T. absoluta.

Valorization of clove (Syzygium aromaticum) by-products as potential stored grain protectants.

Clove (Syzygium aromaticum) being a most valuable spice, produce stems and leaves as by-products during processing. This study aimed to valorize these by-products as potential grain protectants against rice weevils since it is a novel approach to reducing the post-harvest loss of rice and minimizing synthetic insecticide usage. The composition of clove stem and leaf essential oils was analyzed using gas chromatography-mass spectrometry. Accordingly, the contact repellent activity and fumigation mortality of essential oils were tested while computing the mortality percentage and LD50 values. The yield of stem essential oil (5.52%) was significantly higher than leaf essential oil (3.92%). Further, stem essential oil with a 100µL dose showed the highest repellency (100.00 ± 0.00%) and mortality (96.67 ± 3.33%) while 50 and 75µL doses caused similar mortality (83.30 ± 3.33%) after 5days. The lowest LD50 (28.06µL/L) was observed on day 5, indicating the higher toxicity of stem essential oil. Eugenol (73.73 and 82.56%), β-caryophyllene (24.84 and 16.67%), α.-humulene (0.82 and 0.33%), and 1S, CIS-calamenene (0.14 and 0.03%) were detected as the major components responsible for the insecticidal activity of stem and leaf essential oils. Hence, the valorization of clove by-products was successful as potential grain protectants, and clove stem essential oil could be the most effective alternative for rice weevil management.

Wood Vinegar as an Alternative Insecticide in Controlling Rice Weevil, Sitophylus oryzae (Coleoptera: Curculionidae)

Rice production faces many challenges including damages due to pest infestation in storage after harvest. Stored rice grains are often under threat and damage from pests such as rice weevil which resulted in reduction of the quality and quantity. Application of chemical insecticides helps to control this pest, however, it gives negative impacts to the environment and human health. Application of plant-based insecticides including the use of wood vinegar can become an alternative to the conventional method. This work describes the effectiveness of wood vinegar as bioinsecticide to inhibit the rice weevil’s activity by assessing the repellency, mortality and antifeedant activity at different concentration of 50, 100, 150 and 200 rpm. Wood vinegar showed high repellency of 98.3% towards rice weevils at 200 ppm after 5 hours of exposure times. Increased in concentration affects in increased mortality with highest number of 97% recorded at 200 ppm. The lethal concentration (LC) of wood vinegar was calculated to be 77.62 ppm. Antifeedant activity resulted in reduction of weight loss in stored rice with lowest reduction of 2% at 200 ppm. This promising result reflects the ability of wood vinegar as insecticidal agents in management and control of stored-grain pest.

Clinical studies of the repellent effectiveness of the new veterinary drug Okvet

Mosquitoes are one of the most common dipteran insects and are carriers of dangerous vector-borne diseases. An important role of reservoirs of ectoparasites belongs to dogs. The domestic dog is close to the person. The problem of maintaining the health of the dog and reducing the risk of human infection in conditions of high density of blood-sucking insects can be solved by the use of repellent sprays for animals. Recently, synthetic pyrethroids have been used as effective insecticides. We have conducted clinical studies to study the effectiveness of the repellent action of the new veterinary drug "Okvet" insect-acaricidal spray on dogs. The use of the spray was carried out during the period of mosquito activity, depending on the time of day in the Republic of Armenia. The study involved 22 clinically healthy dogs aged 1.5 to 9 years of both sexes. According to the results of clinical studies, it was found that the repellent effect of the veterinary drug "Okvet" applied to dogs individually, once, while preventing bites of dipterous flying insects according to the presented doses, rules and application techniques, the drug "Okvet" showed a high efficiency of the repellent effect in the conditions of farms in Ararat area within 3 days. During the physical examination, no side effects from the use of the drug "Okvet" were revealed.

Lethal and repellent effect of amitraz, eugenol and thymol against Triatoma infestans, the main vector of Trypanosoma cruzi in the southern of America.

The lethal and repellent effect of the synthetic insecticide amitraz and the botanical insecticides eugenol and thymol separately and together in binary mixtures was tested against late-stage nymphs of a susceptible strain of Triatoma infestans, the main vector of Trypanosoma cruzi, the etiological agent of Chagas disease, in the Southern Cone of America. For the lethality study, the LD50 was determined for each insecticide alone and in binary mixture by topical application. The combination index (CI) was established to quantify interactions occurring between the insecticides. The repellent effect was tested using the area preference technique. The lethal effect of amitraz was 11 and 34 times more potent than that of thymol and eugenol, respectively. Only the combination of eugenol and amitraz at high concentrations showed a synergistic effect (CI: 0.3). The repellent activity of monoterpenes after 30 min of exposure was significant at 780 and 78 μg/cm2 for eugenol and thymol, respectively. The residual repellent effect of eugenol lasted for one week at the concentrations of 1170 and 1560 μg/cm2 , whereas thymol managed to retain its repellent effect for two weeks at concentrations of 1560 and 3900 μg/cm2 .

Chemical composition and repellent activity of essential oils of Tithonia diversifolia (Asteraceae) leaves against the bites of Anopheles coluzzii

Tithonia diversifolia is widely used in African traditional medicine for the treatment of a large number of ailments and disorders, including malaria. In the present study, we evaluated the repellent activity of essential oils (EO) of this plant against Anopheles coluzzii, a major vector of malaria in Africa. Fresh leaves of T. diversifolia were used to extract EO, which were used to perform repellency assays in the laboratory and in the field using commercially available N,N-Diethyl-meta-toluamide (DEET) and Cymbopogon (C.) citratus EO as positive controls and vaseline as negative control. The repellency rates and durations of protection of the human volunteers involved were used as measures of repellent activity. Chemical composition of the T. diversifolia EO was established further by gas chromatography coupled with mass spectrometry. The moisture content and oil yield were 81% and 0.02% respectively. A total of 29 compounds in the T. diversifolia EO was identified, with d-limonene (20.1%), α-Copaene (10.3%) and o-Cymene (10.0%) as the most represented. In field studies, the mean time of protection against mosquito bites was significantly lower in T. diversifolia EO-treated volunteers compared to treatments with C. citratus EO (71 min versus 125 min, p = 0.04), but significantly higher when compared with the non-treated volunteers (71 min vs 0.5 min, p = 0.03). The same pattern was found in laboratory repellency assays against A. coluzzii. In contrast, repulsion rates were statistically similar between T. diversifolia EO and positive controls. In conclusion, the study suggests promising repellent potential of leaves of T. diversifolia EO against A. coluzzii.

Study of the toxic effect of insecticides on the honey bee: methodological recommendations

Goal. Improving the methodology for assessing the toxicity and potential safety of insecticides for the honey bee.
 Methods of determining the toxicity of insecticides for bees — laboratory and field. Laboratory experiments determine the toxicity of insecticides for bees, and field experiments determine the degree of danger of drugs at the concentrations used in production, with the establishment of the terms of detoxification in plants and the nature of the danger for insects. To evaluate the gastric and combined toxicity of insecticides, the principle of group feeding of bees with poisoned feed was used. Contact toxicity of insecticides was assessed using the etched screen method.
 Results. A methodology for studying the toxicity of insecticides is proposed. It provides an opportunity to study the contact, gastric and total toxicity of insecticides for the honey bee (Apis mellifera L.). Experiments were conducted to study the toxicity of biological preparations for honey bees. The speed and duration of the toxic effect of insecticides and their repellent activity on bees were established. The method of processing material for toxicological studies has been improved. Methods for calculating the toxicity criteria of insecticides have been developed.
 Conclusions. Improved methods of determining the contact, gastric (oral) and combined poisoning of honey bees with chemical preparations are given, and the method of assessing the level of toxicity of insecticides for insects is improved.

Potential of 3-octanone as a lure and kill agent for control of the Brown garden snail

The brown garden snail (Cornu aspersum) is a major agricultural pest, causing damage to a wide range of economically important crops. Withdrawal or restricted use of pollutant molluscicides like metaldehyde has prompted a search for more benign control products. This study investigated the response of snails to 3-octanone; a volatile organic compound (VOCs) produced by the insect pathogenic fungus Metarhizium brunneum. Concentrations of 1 – 1000 ppm of 3-octanone were first assessed in laboratory choice assays to determine behavioural response. Repellent activity was found at 1000 ppm whereas attractance was found for the lower concentrations of 1, 10 and 100 ppm. These three concentrations of 3-octanone were carried forward in field evaluations to assess potential for use in “lure and kill” strategies. The highest concentration (100 ppm) was the most attractive to the snails but also the most lethal. Even at the lowest concentration this compound proved toxic effects making 3-octanone an excellent candidate for the development as a snail attractant and molluscicide.

Volatile Organic Compounds of Bacillus velezensis GJ-7 against Meloidogyne hapla through Multiple Prevention and Control Modes.

The Bacillus velezensis GJ-7 strain isolated from the rhizosphere soil of Panax notoginseng showed high nematicidal activity and therefore has been considered a biological control agent that could act against the root-knot nematode Meloidogyne hapla. However, little was known about whether the GJ-7 strain could produce volatile organic compounds (VOCs) that were effective in biocontrol against M. hapla. In this study, we evaluated the nematicidal activity of VOCs produced by the fermentation of GJ-7 in three-compartment Petri dishes. The results revealed that the mortality rates of M. hapla J2s were 85% at 24 h and 97.1% at 48 h after treatment with the VOCs produced during GJ-7 fermentation. Subsequently, the VOCs produced by the GJ-7 strain were identified through solid-phase micro-extraction gas chromatography mass spectrometry (SPME-GC/MS). Six characteristic VOCs from the GJ-7 strain fermentation broth were identified, including 3-methyl-1-butanol, 3-methyl-2-pentanone, 5-methyl-2-hexanone, 2-heptanone, 2,5-dimethylpyrazine, and 6-methyl-2-heptanone. The in vitro experimental results from 24-well culture plates showed that the six volatiles had direct-contact nematicidal activity against M. hapla J2s and inhibition activity against egg hatching. In addition, 3-methyl-1-butanol and 2-heptanone showed significant fumigation effects on M. hapla J2s and eggs. Furthermore, all six of the VOCs repelled M. hapla J2 juveniles in 2% water agar Petri plates. The above data suggested that the VOCs of B. velezensis GJ-7 acted against M. hapla through multiple prevention and control modes (including direct-contact nematicidal activity, fumigant activity, and repellent activity), and therefore could be considered as potential biocontrol agents against root-knot nematodes.

Front Cover: Two New Eremophilane‐Type Sesquiterpenoids from Japanese Liverwort Bazzania japonica (Chem. Biodiversity 4/2023)

Front Cover. Two new eremophilane-type sesquiterpenoids, fusumaols A (1) and B (2), were isolated from the stem-leafy liverwort, Bazzania japonica, collected in Mori-Machi, Shizuoka, Japan. Their structures were established using extensive spectroscopic data, and the absolute configuration of 1 was determined using the modified Mosher's method. This is the first report of eremophilanes isolated from the liverwort genus Bazzania. Compounds 1 and 2 were evaluated for their repellent activity against an adult population of the rice weevil Sitophilus zeamais using a modified filter paper impregnation method. Both sesquiterpenoids exhibited moderate repellent activity, as reported by Ryosuke Fukada et al. in their research article at 10.1002/cbdv.202300131.

Acaricidal and Repellent Activity ofZanthoxylum myriacanthum(Rutaceae) Fruit Extracts AgainstTetranychus urticaeandTetranychus truncatus(Acari: Tetranychidae)

AbstractThis work investigated acaricidal and repellent activities of Zanthoxylum myriacanthum Wall. ex Hook. f. (Rutaceae) extracts against Tetranychus urticae Koch and Tetranychus truncatus Ehara (Acari: Tetranychidae). Acaricidal activities were tested by spraying the extracts on adult females and eggs, and repellent activity was assessed in paired-choice tests with filter paper treated with the extracts by using adult female mites. Adult mortality 24 h after application of a 12% (w/v) concentration of the hexane extract was 73.3% for T. urticae and T. truncatus, whereas application of the methylene chloride extract caused 85.8% mortality of T. urticae and 85% mortality of T. truncatus. Lower concentrations (6–12%) of the methanol extract yielded low efficacy against T. urticae but exhibited high efficacy against T. truncatus (73.8–95.8%). In general, egg hatch was reduced <50% by 5 d following application of the extracts. Only the 6–12% concentration of the hexane extract caused higher levels of T. truncatus egg mortality ranging 55.4–68.7%. All extracts repelled adult mites over 64% from 5 to 72 h after exposure. However, the percentage of repellency showed no statistical differences in all treatments. Gas chromatography-mass spectrometry (GC-MS) analysis identified that the major chemical compounds in the hexane extract were DL-limonene (29.75%) and sabinene (9.76%), whereas limonene (40.70%) and sabinene (16.60%) were the principal constituents of the methylene chloride extract. Our results demonstrate that Z. myriacanthum dried fruit extracts have potential for controlling T. urticae and T. truncatus and might be developed as acaricides for integrated pest management programs.

Evaluation of Acaricidal Activity of Cinnamomum camphora (F. Lauraceae) Essential Oil Nanoemulsion Against Cattle Tick Rhipicephalus microplus

The present study aims at preparing nanoemulsions of plant essential oil Cinnamomum camphora as acaricidal agent against cattle tick Rhipicephalus microplus larvae. In the initial step, the phytochemical screening of oil was done through gas chromatography and mass spectrometry depicting major compounds as α-pinene (53.99%) and camphor (20.89%) in C. camphora oil. Different ratios of Cinnamomum camphora oil and surfactant Tween 80 (oil:surfactant- 1:0.25, 1:0.5, 1:1, 1:1.5, 1:2 and 1:2.5) were used for preparing stable nanoemulsion through ultrasonication approach. Thermodynamic stability analysis exhibited that CA3 ratio (1:1) to be the most stable which was further characterized using Dynamic light scattering study through Nano zeta sizer indicating droplet size of 101.60 nm, polydispersity index as 0.50 and zeta potential value measured as -8.59 mV. Spectral analysis through Fourier Transform Infrared spectrometry for functional group interaction and Transmission electron microscopy for morphology of nanoemulsion droplets was also done for CA3 nanoemulsion. Acaricidal activity of stable nanoemulsion was evaluated against R. microplus larvae using larval packet assay and repellency rod test with concentration ranging from 500 ppm to 20000 ppm and 500 ppm to 25000 ppm respectively. Highest concentration (20000 ppm) showed 77% mean mortality with LC₅₀ (3364.46 ppm) after 24 hour. CA3 showed promising repellent activity that ranged from 27% to 87% at various concentrations at different time intervals. These findings proved that Cinnamomum camphor essential oil nanoemulsion could be developed and used against R. microplus larvae as a safer, greener and nanoacaricide product.

Anti-termite Activities of Extracts from Euphorbia tithymaloides and Euphorbia tithymaloide variegatus

The objective of this work was to investigate the anti-termite properties of solvent extracts of two Euphorbia plant species, Euphorbia tithymaloides and Euphorbia tithymaloides “variegatus”. Termiticidal activity of stem barks and leaf extracts were analysed by using anti-termite activity tests. All crude extracts obtained by petroleum ether and ethyl acetate exhibited 100% repellency activities at a concentration of 36 mg mL-1. Average repellency time decreased as the concentration of crude extracts were increased. Contact bioassay tests revealed that crude extracts from stem barks are more potent than extracts from leaves; and non-polar solvents gave crude extracts which are more effective that those extracted by polar solvents. Crude extracts obtained by petroleum ether from stem barks of both E. tithymaloides and E. tithymaloides “variegatus” plants species gave dissimilar peaks in GC-MS chromatograms, except two peaks, which correspond to the compounds: 1-heptadecene and n-hexadecanoic acid. Crude extract from E. tithymaloides gave a prominent peak corresponding to the compound tetracontane as the principal constituent (73.7%) of the extract. Since this peak is absent in crude extracts from E. tithymaloides “variegatus” stem barks, its presence in crude extracts from E. tithymaloides stem barks can be attributed to its high termite lethality assay results. In general, from the results obtained from this work, it could be concluded that the Euphorbia species are potential sources of botanical pesticides against termites.

Bioactivity and chemical composition of forty plant essential oils against the pea aphid Acyrthosiphon pisum revealed peppermint oil as a promising biorepellent

The pea aphid Acyrthosiphon pisum Harris is a major insect pest of Fabaceae crops causing significant damage and economic losses. Its management is a real challenge and the use of plant essential oils (EOs) as biorepellents is a serious alternative to chemical pesticides. Here, we conducted for the first time an in-depth study on the effects of forty plant EOs and their chemical compounds on A. pisum. Using choice bioassays, we reveal the strong repellency of Chinese cinnamon, peppermint, anise, basil, spearmint, and dill oils. Analysis of their chemical composition shows that their respective high contents of trans-cinnamaldehyde, trans-anethole, menthol + menthone, estragole and carvone could be responsible for their high repellency. An additional economic analysis underlines that peppermint EO is the most available and the cheapest. Our data show that peppermint EO with menthol and menthone as major compounds seems to be the most promising EO as biorepellent against the pea aphid. Overall, the repellent activity of peppermint EO may provide a new way to control A. pisum in the future, which may lead to effective strategies for controlling these sucking pests.

Two New Eremophilane-Type Sesquiterpenoids from Japanese Liverwort Bazzania japonica.

Two new eremophilane-type sesquiterpenoids, fusumaols A (1) and B (2), were isolated from the stem-leafy liverwort, Bazzania japonica collected in Mori-Machi, Shizuoka, Japan. Their structures were established using extensive spectroscopic (IR, MS, and 2D NMR) data, and the absolute configuration of 1 was determined by the modified Mosher's method. This is the first time eremophilanes have been discovered in the liverwort genus Bazzania. Compounds 1 and 2 were evaluated for their repellent activity against the adult population of the rice weevil Sitophilus zeamais using the modified filter paper impregnation method. Both sesquiterpenoids showed moderate repellent activities.

Bioactivity of Cinnamomum verum powder and extract against Cryptolestes ferrugineus S., Rhyzopertha dominica F. and Sitophilus granarius L. (Coleoptera)

The world is heading to increase the productivity, quantity and quality, of basic crops, but the stored grain pests destroy all these efforts and reduce its quality. This study aims to assess activity of Cinnamomum verum powder and extract against Cryptolestes ferrugineus, Rhyzopertha dominica, and Sitophilus granarius. Residual film of cinnamon was tested with and without grains (as contact toxicity). Repellent activity was estimated by using choice chamber method and waved filter paper for powder and extract, respectively. There were significant differences among all tested insects. S. granarius was more affected with cinnamon extract than C. ferrugineus followed by R. dominica. LC50 values were 1.01, 1.37 and 3.13% at 24 h. While, C. ferrugineus was more affected with powder than S. granarius followed by R. dominica. For repellent activity, C. ferrugineus was the most affected with the powder and extract followed by R. dominica and S. granarius, where, the mean repellent percentages were 100, 98 and 82% for the powder and 86.94, 62.78 and 29.44% for the extract, respectively. The repellent percentage increased with increasing the concentration and the time of exposure. Cinnamon powder and extract can be used as insecticide against stored grain pests by easy way and safety to human and the environment.

Synthesis of Carvacrol-Loaded Invasomes Nanoparticles Improved Acaricide Efficacy, Cuticle Invasion and Inhibition of Acetylcholinestrase against Hard Ticks.

Carvacrol is a monoterpenoid phenol found in many essential oils that has antibacterial, antifungal and antiparasitic activities. Drug loaded-invasome systems are used to deliver drugs utilizing nanoparticles to improve bioavailability, efficacy, and drug release duration. As a result, the present study developed carvacrol-loaded invasomes and evaluated their acaricidal effect against Rhipicephalus annulatus (cattle tick) and Rhipicephalus sanguineus (dog tick). Carvacrol loaded-invasome (CLI) was prepared and characterized using UV/Vis spectrophotometer, zeta potential measurements, Scanning Transmission Electron Microscopy (STEM), Fourier Transform Infrared (FT-IR) Spectroscopy, and Differential Scanning Calorimetry Analysis. CLI (5%) induced significant mortality (100%) in R. annulatus adult ticks with LC50 of 2.60%, whereas the LC50 of pure carvacrol was 4.30%. Carvacrol and CLI were shown to have a significant larvicidal action on both tick species, with LC50s of 0.24 and 0.21% against R. annulatus and 0.27 and 0.23% against R. sanguineus, respectively. Carvacrol and CLI (5%) induced significant repellent activities for 24 h against R. annulatus and R. sanguineus, as evidenced by the rod method and the petri-dish selective area choice method, respectively. High-performance liquid chromatography (HPLC) demonstrated that the CLI form had 3.86 times the permeability of pure carvacrol. Moreover, carvacrol and CLI inhibited acetylcholinesterase activity and decreased glutathione and malonedealdehyde levels in the treated ticks. In conclusion, invasomes significantly improved adulticidal and repellency activities of carvacrol against both tick species.

Chemical Composition and Repellent Activities of Formulated Creams from Essential Oils of Three Tropical Plants Against Adults of Simulium damnosum Sensu Lato

Chemical Composition and Repellent Activities of Formulated Creams from Essential Oils of Three Tropical Plants Against Adults of Simulium damnosum Sensu Lato

Fumigant Contact and Repellent Actions of Essential Oils of Leaves, Fruits and Stems from Melicope pteleifolia Against Three Pests

Storage pests influence food production and conservation worldwide. The common control measures for these pests involve the use of synthetic pesticides, but these pesticides are harmful to the environment and human health. Thus, biological insecticides can substitute or reduce dependence on synthetic insecticides. This work aimed to study the insecticidal activities of essential oils (EOs) from leaves, fruits and stems of Melicope pteleifolia and their main compound against three kinds of pests, Tribolium castaneum, Lasioderma serricorne and Liposcelis bostrychophila. The Gas Chromatography - Mass Spectrometry (GC-MS) detection showed that β-cis-ocimene was the major compound in EOs from leaves and fruits of M. pteleifolia (26.96, and 65.99%, respectively). The main compound of stems EO is origanene (77.00%). In the fumigation test, EO of fruits and β-cis-ocimene were toxic to L. serricorne, and β-cis-ocimene was toxic to T. castaneum. The EOs and β-cis-ocimene had significant contact toxicity and repellent effect on these three species of pests. The results indicated that M. pteleifolia EOs are potential biological insecticides for controlling storage pests.