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

Behavioral responses of field-collected German cockroaches to pyrethroids and pyrethroid-formulated insecticides

BACKGROUND

Pyrethroids are synthetic insecticides with low mammalian toxicity and broad-spectrum activity across insects. One major challenge with pyrethroids is their perceived repellency. This perception can influence decisions made by pest control operators, especially when insecticides are used to reduce insect entry into or movement within structures. One major indoor pest that has been repeatedly shown to be repelled by some pyrethroids is the German cockroach, Blattella germanica. However, most experiments evaluating pyrethroid repellency in the German cockroach have used end-point assays, which do not provide information on the movement that led to the final position. Therefore, we evaluated the kinetic behavioral response of field-collected German cockroaches to five pyrethroid-based products and their active ingredients (A.I.) in open behavioral arenas using advanced video tracking software. In addition, in an effort to compare our free-moving experiments with end-point assays, we evaluated sheltering behavior using two-choice harborage arrestment assays where German cockroaches were provided a choice between pyrethroid-treated and untreated shelters.

RESULTS

All pyrethroid-formulated products and their respective A.I.'s failed to affect field-collected German cockroach movement behavior in free-moving assays, while positive controls (DEET, corn mint oil) resulted in reduced time spent by German cockroaches in treated areas. However, despite their willingness to move over pyrethroids-treated surfaces, field-collected German cockroaches displayed a reduced propensity to arrest on pyrethroids treated tents.

CONCLUSION

While most pyrethroids/pyrethroid-formulated products affected German cockroach arrestment, pyrethroids and pyrethroid-formulated products failed to change German cockroach movement behavior in free-moving assays. These results indicate the pyrethroids tested act as contact irritants rather than true-spatial repellents on field-collected German cockroaches. This distinction is critical to refining pest management strategies involving pyrethroids. © 2023 Society of Chemical Industry.

Coconut fatty acids exhibit strong repellency and week-long efficacy against several urban pest arthropods of the southwestern United States

BACKGROUND

The southwestern United States is home to a variety of arthropods including Turkestan cockroaches, Blatta lateralis (Walker); hematophagous kissing bugs, Tritoma rubida (Uhler); and Arizona bark scorpions, Centruroides sculpturatus Ewing. These arthropods cause medical concern when they become established around homes and/or invade indoors. Traditionally, the management of these pests has relied primarily on the use of chemical insecticides; however, they offer poor prospects for control owing to their lack of efficacy as well as the effects of insecticides on humans and the environment. Botanical repellents are an option that has not been fully investigated for the management of these pests. Here, we investigated the behavioral responses of common urban pests of the southwestern USA to recently discovered coconut fatty acids (CFAs), to establish the potential use of these compounds as repellents.

RESULTS

Fresh residues of CFA mixture (CFAm) and their constituents caprylic acid, capric acid, capric acid methyl ester, lauric acid, and lauric acid methyl ester, tested at a concentration of 1 mg cm-2 , strongly repelled all arthropods. The repellent activity of CFAm lasted for at least 7 days, and the addition of lavender oil, used as an odor-masking agent, did not decrease this effect. Concentrations of CFAm ten times lower (0.1 mg cm-2 ) still repelled Turkestan cockroaches, and concentrations 100 times lower (0.01 mg cm-2 ) repelled T. rubida and scorpions.

CONCLUSIONS

CFAm and some of their constituents are efficacious, economical, and logistically feasible for inclusion in integrated pest management programs for these important urban pests of the southwestern USA. © 2023 Society of Chemical Industry.

Essential Oils in Urban Insect Management-A Review

The allures of city life have culminated in the rise of urban populations resulting in conditions that promote the establishment of certain insect pests. Globally, the public health significance of these urban insect pests is enormous, ranging from billions of dollars to loss of lives. Most chemical insecticides no longer provide the anticipated level of control, and significant insecticide resistance has been reported. Therefore, there has been a spike in interest for alternatives to conventional insecticides. Among them, natural products from plants such as essential oils (EOs) and essential oil components (EOCs) have enjoyed the most attention owing to widespread reports of efficacy and toxicity even against insecticide-resistant urban insects. Yet, there is no comprehensive synthesis on the extent and impact of the management of urban insects using EOs or EOCs. Such a review is highly relevant since it provides a means to assess the extent of progress made, shortfalls, limitations, and prospects. More so, we hope it can be used to make informed decisions and develop relevant policies reliably. We present the ranges of insecticidal effects of EOs, EOCs, and commercially available EO-based products from laboratory and field studies. Finally, we discuss the gaps in our knowledge and prospects for the sustainable use of EOs.

Exploration of Clove Bud (Syzygium aromaticum) Essential Oil as a Novel Attractant against Bactrocera dorsalis (Hendel) and Its Safety Evaluation

The oriental fruit fly Bactrocera dorsalis (Hendel) is a destructive polyphagous species that targets many economically important fruits and vegetables. The primary control of B. dorsalis relies mainly on the use of synthetic chemicals, and excessive use of these chemicals has adverse effects on both the environment and human health. Environmentally friendly management of pests involving plant essential oils is useful for controlling the populations of pests responsible for decreasing the yields and quality of crops. In the present study, we demonstrate that clove bud essential oil (CBEO) is strongly attractive to sexually mature males. Mature males responded to the CBEO differently throughout the day; the strongest response was elicited during the day and decreased at dusk. Virgin and mated mature males did not respond differently to CBEO. No obvious response behaviour to the CBEO was observed in two species of beneficial natural predator ladybirds. In addition, a cytotoxicity assessment demonstrated that CBEO is nontoxic to normal human and mouse cells. Based on our laboratory experiments, CBEO may serve as a promising, sustainable, and environmentally friendly attractant for B. dorsalis males; however, field experiments are needed to confirm this hypothesis.

Utilization of Pomelo (Citrus maxima) Peel Waste into Bioactive Essential Oils: Chemical Composition and Insecticidal Properties

Simple Summary

The disposal of agricultural waste products is an emerging concern and an alternative to this is the development of value-added products from these wastes. Here we extracted the essential oil from Citrus maxima (CMEO) and examined its larvicidal and pest control potentials. Results pointed out that CMEO can be effective biopesticides against two major insect pests of stored grains. Furthermore, CMEO had a significant larvicidal action against different mosquito species. This study provided useful information on the compositional aspects and insecticidal properties of CMEO.

Abstract

The wastes generated during the post-harvest handling of various agricultural commodities is rather under-utlilized. The peels of citrus fruits are often discarded as waste. Citrus peels are rich in essential oils and exhibit toxicity towards various insect species. The essential oils are also an eco-friendly option for insect pest management. The Citrus maxima peel essential oil (CMEO), a waste product, characterized it, and evaluated its potential for insect pest management. The major terpenoids present in CMEO are Limonene and α-Pinene. The CMEO displayed potentials in controlling the insect pests via contact and fumigant toxicity. Moreover, CMEO showed significant larvicidal activities against Culex tritaeniorhynchus and Aedes aegypti species of mosquitoes; however, Armigeres subalbatus was more resistant. The biological safety of the essential oil was also tested against the stored seeds, where no significant inhibition of seed germination was noticed compared to the control. Utilizing a waste product such as citrus peel for pest management can achieve the dual objective of waste utilization and eco-friendly pest management. Overall, the CMEO is therefore found to be a bioactive essential oil extracted from the wastes of pomelo (C. maxima).

Synthetic and Natural Insecticides: Gas, Liquid, Gel and Solid Formulations for Stored-Product and Food-Industry Pest Control

The selective application of insecticides is one of the cornerstones of integrated pest management (IPM) and management strategies for pest resistance to insecticides. The present work provides a comprehensive overview of the traditional and new methods for the application of gas, liquid, gel, and solid physical insecticide formulations to control stored-product and food industry urban pests from the taxa Acarina, Blattodea, Coleoptera, Diptera, Hymenoptera, Lepidoptera, Psocoptera, and Zygentoma. Various definitions and concepts historically and currently used for various pesticide application formulations and methods are also described. This review demonstrates that new technological advances have sparked renewed research interest in the optimization of conventional methods such as insecticide aerosols, sprays, fumigants, and inert gases. Insect growth regulators/disruptors (IGRs/IGDs) are increasingly employed in baits, aerosols, residual treatments, and as spray-residual protectants for long-term stored-grain protection. Insecticide-impregnated hypoxic multilayer bags have been proven to be one of the most promising low-cost and safe methods for hermetic grain storage in developing countries. Insecticide-impregnated netting and food baits were originally developed for the control of urban/medical pests and have been recognized as an innovative technology for the protection of stored commodities. New biodegradable acaricide gel coatings and nets have been suggested for the protection of ham meat. Tablets and satchels represent a new approach for the application of botanicals. Many emerging technologies can be found in the form of impregnated protective packaging (insect growth regulators/disruptors (IGRs/IGDs), natural repellents), pheromone-based attracticides, electrostatic dust or sprays, nanoparticles, edible artificial sweeteners, hydrogels, inert baits with synthetic attractants, biodegradable encapsulations of active ingredients, and cyanogenic protective grain coatings. Smart pest control technologies based on RNA-based gene silencing compounds incorporated into food baits stand at the forefront of current strategic research. Inert gases and dust (diatomaceous earth) are positive examples of alternatives to synthetic pesticide products, for which methods of application and their integration with other methods have been proposed and implemented in practice. Although many promising laboratory studies have been conducted on the biological activity of natural botanical insecticides, published studies demonstrating their effective industrial field usage in grain stores and food production facilities are scarce. This review shows that the current problems associated with the application of some natural botanical insecticides (e.g., sorption, stability, field efficacy, and smell) to some extent echo problems that were frequently encountered and addressed almost 100 years ago during the transition from ancient to modern classical chemical pest control methods.

A Review of Alternative Management Tactics Employed for the Control of Various Cockroach Species (Order: Blattodea) in the USA

Simple Summary

Some cockroaches that live within and around human environments are considered pests of public health importance because they can carry and transfer human pathogenic microorganisms to food and food handling surfaces; infestations could result in cockroach allergen-induced allergic sensitization and asthma in sensitized individuals. In addition, cockroaches can cause psychological stress and stigma in people living in infested locations. Historically, cockroach control has been based on the use of insecticide sprays. However, in certain situations, sole dependence on insecticides for cockroach control can lead to issues such as pesticide resistance evolution and raises public concern due to the impact on the environment and human health. To overcome these problems, the use of reduced risk insecticide options (e.g., baits) and their combined use with alternative tactics is recommended. This review aims to examine alternative tactics used for cockroach control, with emphasis on those that are proven to be efficacious, and/or have potential for their incorporation in management programs of important domestic and peridomestic cockroaches in the USA. Remarkable examples of successful cockroach control programs are those that educate the public, promote cleanliness and hygiene, use traps to monitor infestation levels and utilize insecticide baits.

Abstract

Effective control of domestic and peridomestic cockroaches requires integrated approaches that emphasize concurrent use of chemicals with alternative control tactics. An integrated pest management (IPM) approach is particularly justified in environments where satisfactory cockroach control cannot be achieved due to multiple factors including development of insecticide aversion and resistance in some cockroach species, and poor sanitation or structural issues that foster infestations. While a flurry of research effort has been devoted to study alternative tactics for cockroach control, only a few of them have been evaluated in the context of IPM programs. This review focuses on examining studies on alternative tactics that are proven efficacious, economical, and logistically feasible for their inclusion in IPM programs for important domestic and peridomestic cockroaches in the USA. Management programs that educate the public on cockroach biology, behavior, and the importance of sanitation; use of traps to monitor infestation levels; apply targeted low impact insecticides such as baits, have demonstrated a greater success for effective and sustainable control of cockroaches when compared to an insecticide-only approach. Incorporation of other alternative control methods to IPM programs will require more applied research that validates their use in real-world scenarios and demonstrates their cost-effectiveness.

Behavioral Responses of the Common Bed Bug to Essential Oil Constituents

Simple Summary

Bed bugs (Cimex lectularius L.) are blood-sucking insects that have emerged worldwide in the last two decades causing serious public health and economic impact. Today, control of bed bug infestations relies on the use of synthetic insecticides, but their frequent use has led to the development of resistance in bed bug populations. Therefore, there is a growing demand for the development of safer, green, and more effective tools for bed bug control. Plant-derived pesticides are part of the proposed “green” methods for bed bug control. We evaluated behavioral responses of bed bugs to essential oil constituents (EOCs) and detected that bed bugs did not rest on areas treated with geraniol, eugenol, citronellic acid, and carvacrol. Barriers of these constituents did not deter bed bugs from reaching warmed blood meal and feeding. Our results show that novel formulations of natural product insecticides that include geraniol, eugenol, carvacrol, or citronellic acid have potential to repel bed bugs. However, little benefit of protection against bed bug bites can be expected when EOC-based products are applied to items present in close proximity to a sleeping host such as mattress covers, liners, or around the bed.

Abstract

Botanical-derived pesticides have arisen as an attractive alternative to synthetic insecticides to effectively manage infestations of bed bugs (Cimex lectularius L.). While information on contact, residual, and fumigant toxicity of plant-essential oils against bed bugs have been recently published, there is a gap of information regarding the repellent activity of these products and their constituents. Identification of essential oil constituents (EOCs) with repellent activity will help develop potentially efficacious essential oil-based formulations for use in bed bug management programs. In this study, we first screened fresh and 24 h-aged residues of geraniol, eugenol, carvacrol, thymol, citronellic acid, linalool, menthone, trans-cinnamaldehyde, α-pinene, β-pinene, and limonene for avoidance behavior from individual bed bugs with a video-tracking system. Six EOCs, geraniol, eugenol, citronellic acid, thymol, carvacrol, and linalool were further evaluated overnight in choice tests to determine whether 24-h aged residues were still avoided by groups of bed bugs. While bed bugs avoided resting on filter papers treated with 24-h aged residues of geraniol, eugenol, citronellic acid, and carvacrol, bed bugs aggregated in areas treated with linalool-aged residues. Barriers of EOCs did not prevent bed bugs from reaching a warmed blood source and acquiring blood meals. Our results show that novel formulations of natural product insecticides that include geraniol, eugenol, carvacrol, or citronellic acid have potential to repel bed bugs. The presence of host-associated cues might interfere with these responses.

Bed bugs, Cimex lectularius L., exhibiting metabolic and target site deltamethrin resistance are susceptible to plant essential oils

Pyrethroid resistance has been a major hurdle limiting the effective control of bed bugs (Cimex lectularius L.). Alternative approaches that include the use of plant essential oils (EOs) have been proposed for effective management of bed bugs. However, EO resistance level comparisons between pyrethroid susceptible and resistant bed bug populations have not been previously conducted. The goal of this study was twofold: (i) determine deltamethrin resistance levels and associated resistance mechanisms in the field-collected Knoxville strain and (ii) quantify resistance levels of the Knoxville strain to five EOs (thyme, oregano, clove, geranium and coriander), their major insecticidal constituents (thymol, carvacrol, eugenol, geraniol and linalool) and an EO-based product (EcoRaider®). First, we found that the Knoxville strain was 72,893 and 291,626 fold more resistant to topically applied deltamethrin in comparison to the susceptible Harlan strain at the LD₂₅ and LD₅₀ lethal dose levels, respectively. Synergist bioassays and detoxification enzyme assays revealed significantly higher activity of cytochrome P450 and esterase enzymes in the resistant Knoxville strain. Further, Sanger sequencing revealed the presence of the L925I mutation in the voltage-sensitive sodium channel α subunit gene. The Knoxville strain that possesses both enzymatic and target site deltamethrin resistance, however, did not show any resistance to EOs, their major insecticidal constituents and EcoRaider® in topical bioassays (resistance ratio of ~1). In conclusion, this study demonstrated that a deltamethrin-resistant strain of bed bugs is susceptible to EOs and their insecticidal constituents.

Hepatoprotective Essential Oils: A Review

Objectives

Several toxins and molecules are able to damage the liver, causing the hepato-toxicity. This disorder can be protected naturally, by some essential oils obtained from different plants. In this review we are cited some of these compounds that have been tested by their hepatoprotective effect.

Methods

We reviewed 83 articles published between 1981 and 2018 in English via three databases Sciencedirect, Springer and PubMed. So, we have used the keywords Hepatoprotective effect, liver disease, plants and essential oils.

Results and conclusion

In this work, we classified the plants; contain the essential oils, in alphabetical order as a table containing the scientific, family names, information plants, the experimental assay and the results obtained from the hepatoprotective studies. We have described 27 species belonging to 12 families Lamiaceae (7 species), Asteraceae (6 species), Umbellifereae (3 species), Apiaceae (3 species) are the main families which enclose the species that was studied. The study also includes the major compounds isolated from some of these essential oils. The most of those compounds belong to terpene class essentially cineol, carvacrol and thymol. Thus, the different essential oils that have been cited in this review were shown that have an antioxidant activity.

Comparative Efficacy of Residual Insecticides against the Turkestan Cockroach, Blatta lateralis, (Blattodea: Blattidae) on Different Substrates

The Turkestan cockroach, Blatta lateralis (Walker) is an invasive urban pest prevalent throughout the Southwestern United States. Despite the presence of this cockroach in peridomestic areas, there is limited information on strategies that can be utilized by pest management professionals (PMPs) to effectively manage populations of this pest. We evaluated the efficacy of dry residues of liquid insecticides commonly used for household and structural insect pest control: Tandem (0.10% thiamethoxam, 0.03% lambda-cyhalothrin), Transport GHP (0.05% acetamiprid, 0.06% bifenthrin), Temprid SC (0.10% imidacloprid, 0.05% beta-cyfluthrin), Demand CS (0.06% lambda-cyhalothrin), Talstar P (0.06% bifenthrin), and Phantom (0.5% chlorfenapyr) on three different substrates against Turkestan cockroach nymphs. Except for Phantom and Talstar P, all insecticide formulations killed 100% of the cockroaches on concrete, 89–100% on tile, and 77–100% on wood within 4 days. The rate of cockroach mortality varied according to the substrates to which they were exposed. Temprid SC and Transport GHP killed cockroaches faster on tile than wood. Tandem provided a faster mortality rate than Transport GHP and Temprid SC on concrete. Demand CS and Tandem killed cockroaches at similar rates on the three substrates. This study provides information to guide PMPs in their selection of insecticide formulations for the management of Turkestan cockroach infestations.

Synergistic Toxicity Interactions between Plant Essential Oil Components Against the Common Bed Bug (Cimex lectularius L.)

Management of the common bed bug (Cimex lectularius L.) necessitates the use of multiple control techniques. In addition to synthetic pesticides and mechanical interventions, plant-derived essential oils represent one of the control options. Mixtures of two or more essential oil components (monoterpenoids) exhibit synergistic toxicity effects against insects due to increased cuticular penetration. Monoterpenoids, such as carvacrol, eugenol and thymol, are neurologically active and inhibit the nerve firing activity of C. lectularius. However, the effects of mixtures of these monoterpenoids on their toxicity and neuroinhibitory potential against C. lectularius are not known. In this study, the toxicity levels of a tertiary mixture of carvacrol, eugenol and thymol (1:1:1 ratio) and a binary mixture of synthetic insecticides, bifenthrin and imidacloprid (1:1 ratio) were evaluated against C. lectularius through topical bioassays and electrophysiology experiments. Both a mixture of monoterpenoids and the mixture of synthetic insecticides exhibited synergistic effects in topical bioassays. In electrophysiology experiments, the monoterpenoid mixture led to greater neuroinhibitory effects, whereas a mixture of synthetic insecticides caused higher neuroexcitatory effects in comparison to single compounds. This study shows evidence for neurological mechanisms of synergistic interactions between monoterpenoids and provides information regarding the utilization of natural compound mixtures for C. lectularius management.

Toxicity and neurophysiological impacts of plant essential oil components on bed bugs (Cimicidae: Hemiptera)

Bed bugs (Cimex lectularius L.) are globally important human parasites. Integrated pest management (IPM) approaches, which include the use of essential oil-based insecticidal compounds, have been proposed for their control. This study aimed to define insecticidal activity and neurophysiological impacts of plant essential oil constituents. The topical and fumigant toxicity of 15 compounds was evaluated against adult male bed bugs. Neurological effects of the 6 most toxicologically active compounds were also determined. In both topical and fumigant bioassays, carvacrol and thymol were the most active compounds. The potency of bifenthrin (a pyrethroid insecticide) in topical bioassays was 72,000 times higher than carvacrol, while vapors of dichlorvos (an organophosphate insecticide) were 445 times more potent than thymol. Spontaneous electrical activity measurements of the bed bug nervous system demonstrated neuroinhibitory effects of carvacrol, thymol and eugenol, whereas linalool produced an excitatory effect. Although citronellic acid and (±)-camphor increased baseline activity of the nervous system their effects were not statistically significant. Bifenthrin also caused neuroexcitation, which is consistent with its known mode of action. These comparative toxicity and neurological impact findings provide new information for formulating effective essential oil-based insecticides for bed bug IPM and conducting mode-of-action studies on individual essential oil components.

Acaricidal Activity and Synergistic Effect of Thyme Oil Constituents against Carmine Spider Mite (Tetranychus Cinnabarinus (Boisduval))

Studies examining the use of essential oils as replacements for synthetic insecticides require an understanding of the contribution of each constituent present, interactions among these components, and how they relate to overall toxicity. In the present study, the chemical composition of commercial thyme oil was identified by gas chromatography-mass spectrometry. Thyme oil and blends of its major constituents were tested for their acaricidal activitities against carmine spider mites (Tetranychus cinnabarinus (Boisduval)) using a slide-dip bioassay. Natural thyme oil showed greater toxicity than any single constituent or blend of constituents. Thymol was the most abundant component (34.4%), and also possessed the strongest acaricidal activity compared with other single constituents. When tested individually, four constituents (linalool, terpinene, p-cymene and carvacrol) also had activity, while α-pinene, benzoic acid and ethyl gallate had almost no activity. The toxicity of blends of selected constituents indicated a synergistic effect among the putatively active and inactive constituents, with the presence of all constituents necessary to reach the highest toxicity. The results indicated that thyme oil and some of its major constituents have the potential to be developed into botanical acaricides.