Repellent effectiveness of seven plant essential oils, sunflower oil and natural insecticides against horn flies on pastured dairy cows and heifers

Insecticidal, Repellent and Antifeedant Activity of Essential Oils from Blepharocalyx cruckshanksii (Hook. & Arn.) Nied. Leaves and Pilgerodendron uviferum (D. Don) Florin Heartwood against Horn Flies, Haematobia irritans (Diptera: Muscidae)

Haematobia irritans is a cosmopolitan obligate blood-feeding ectoparasite of cattle and is the major global pest of livestock production. Currently, H. irritans management is largely dependent on broad-spectrum pesticides, which has led to the development of insecticide resistance. Thus, alternative control methods are needed. Essential oils have been studied as an alternative due to their wide spectrum of biological activities against insects. Thus, the main aim of this study was to evaluate the insecticidal, repellent and antifeedant activity of the essential oils from Blepharocalyx cruckshanksii leaves and Pilgerodendron uviferum heartwood against horn flies in laboratory conditions. The composition of the essential oils was analyzed using gas chromatography coupled to mass spectrometry. Accordingly, α-pinene (36.50%) and limonene (20.50%) were the principal components of the B. cruckchanksii essential oil, and δ-cadinol (24.16%), cubenol (22.64%), 15-copaenol (15.46%) and δ-cadinene (10.81%) were the most abundant compounds in the P. uviferum essential oil. Mortality of flies and feeding behavior were evaluated by non-choice tests, and olfactory response was evaluated using a Y-tube olfactometer. Both essential oils were toxic to horn flies, with LC50 values for B. cruckchanksii essential oil of 3.58 µL L-1 air at 4 h, and for P. uviferum essential oil of 9.41 µL L-1 air and 1.02 µL L-1 air at 1 and 4 h, respectively. Moreover, the essential oils exhibited spatial repellency in the olfactometer using only 10 µg of each oil, and these significantly reduced the horn fly feeding at all doses evaluated. Although further laboratory and field studies related to the insectistatic and insecticide properties of these essential oils against H. irritans are necessary, B. cruckshanksii leaves and P. uviferum heartwood essential oils are promising candidates for horn fly management.

Nutritional Aspects of Ecologically Relevant Phytochemicals in Ruminant Production

This review provides an update of ecologically relevant phytochemicals for ruminant production, focusing on their contribution to advancing nutrition. Phytochemicals embody a broad spectrum of chemical components that influence resource competence and biological advantage in determining plant species' distribution and density in different ecosystems. These natural compounds also often act as plant defensive chemicals against predatorial microbes, insects, and herbivores. They may modulate or exacerbate microbial transactions in the gastrointestinal tract and physiological responses in ruminant microbiomes. To harness their production-enhancing characteristics, phytochemicals have been actively researched as feed additives to manipulate ruminal fermentation and establish other phytochemoprophylactic (prevent animal diseases) and phytochemotherapeutic (treat animal diseases) roles. However, phytochemical-host interactions, the exact mechanism of action, and their effects require more profound elucidation to provide definitive recommendations for ruminant production. The majority of phytochemicals of nutritional and pharmacological interest are typically classified as flavonoids (9%), terpenoids (55%), and alkaloids (36%). Within flavonoids, polyphenolics (e.g., hydrolyzable and condensed tannins) have many benefits to ruminants, including reducing methane (CH4) emission, gastrointestinal nematode parasitism, and ruminal proteolysis. Within terpenoids, saponins and essential oils also mitigate CH4 emission, but triterpenoid saponins have rich biochemical structures with many clinical benefits in humans. The anti-methanogenic property in ruminants is variable because of the simultaneous targeting of several physiological pathways. This may explain saponin-containing forages' relative safety for long-term use and describe associated molecular interactions on all ruminant metabolism phases. Alkaloids are N-containing compounds with vast pharmacological properties currently used to treat humans, but their phytochemical usage as feed additives in ruminants has yet to be exploited as they may act as ghost compounds alongside other phytochemicals of known importance. We discussed strategic recommendations for phytochemicals to support sustainable ruminant production, such as replacements for antibiotics and anthelmintics. Topics that merit further examination are discussed and include the role of fresh forages vis-à-vis processed feeds in confined ruminant operations. Applications and benefits of phytochemicals to humankind are yet to be fully understood or utilized. Scientific explorations have provided promising results, pending thorough vetting before primetime use, such that academic and commercial interests in the technology are fully adopted.

Antifeedant Effects and Repellent Activity of Loline Alkaloids from Endophyte-Infected Tall Fescue against Horn Flies, Haematobia irritans (Diptera: Muscidae)

Haematobia irritans is an obligate bloodsucking ectoparasite of cattle and is the global major pest of livestock production. Currently, H. irritans management is largely dependent upon broad-spectrum pesticides, which lately has led to the development of insecticide resistance. Thus, alternative control methods are necessary. Endophyte-infected grasses have been studied as an alternative due to their capability to biosynthesize alkaloids associated with anti-insect activities. Thus, the main aim of this study was to evaluate the antifeedant and repellent activity of lolines obtained from endophyte-infected tall fescue against H. irritans adults in laboratory conditions. The alkaloid extract (ALKE) was obtained by acid–base extraction. N-formyl loline (NFL) and N-acetyl loline (NAL) were isolated by preparative thin layer chromatography (pTLC) and column chromatography (CC), and the loline was prepared by acid hydrolysis of a NFL/NAL mixture. Loline identification was performed by gas chromatography coupled to mass spectrometry (GC/MS). Feeding behavior was evaluated by a non-choice test, and olfactory response was evaluated using a Y-tube olfactometer. Accordingly, all samples showed antifeedant activities. NFL was the most antifeedant compound at 0.5 µg/µL and 1.0 µg/µL, and it was statistically equal to NAL but different to loline; however, NAL was not statistically different to loline. NFL and NAL at 0.25 µg/µL were more active than loline. All samples except loline exhibited spatial repellency in the olfactometer. Thus, the little or non-adverse effects for cattle and beneficial activities of those lolines make them suitable candidates for horn fly management.

Efficacy of Broilers as a Method of Face Fly (Musca autumnalis De Geer) Larva Control for Organic Dairy Production

The objective of this study was to evaluate Freedom-Ranger broiler chickens as a method to control face fly (Musca autumnalis De Geer) larvae in cow dung pats on pasture. Ninety-nine pats in three replicates were inoculated with first-instar larvae and exposed to one of four treatment conditions for 3 to 4 days: (1) an environment-controlled greenhouse (GH); (2) pasture without broilers (NEG); (3) pasture with 25 broilers stocked at a low density of 2.5 m2 of outdoor area per broiler (LOW); and (4) pasture with 25 broilers stocked at a high density of 0.5 m2 of outdoor area per broiler (HIGH). Broiler behaviors and weather conditions were recorded twice daily. Survival rates of larvae (mean, 95% CI) were similar for pats in the NEG (4.4%, 2-9%), LOW (5.6%, 3-11%), and HIGH (3.2%, 2-7%) groups, and was greatest for larvae reared in the GH (54.4%, 36-72%) group compared to all other groups. The proportion of broilers observed pasture ranging was 14.0% (6-28%) but was negatively related to solar radiation. Broilers were never observed foraging in pats. Results indicate that use of broilers may not be an effective method for controlling larvae of dung pat breeding flies.

Establishing a Method to Evaluate the Efficacy of Compounds Aimed at Repelling Horn Fly (Diptera: Muscidae) Infestations on Cattle in a Laboratory Setting

Use of nonpesticidal chemicals to minimize or eliminate horn fly (Haematobia irritans) populations on cattle could be helpful in combating insecticide resistance. One recent approach is the use of natural products with repellent properties against the target pest. A rapid on-animal evaluation system that accounts for both host and pest interactions and bypasses the need for costly multiyear field assessments is needed. The objective of this study was to develop a system to quantify product repellency of horn flies on cattle in a laboratory setting. Animal pair treatment groups were utilized to assess product efficacy and carrier effects across three experimental trials. A treatment solution consisting of 3% geraniol in mineral oil was the natural product repellent. Horn fly populations on animal pairs receiving the geraniol treatment were significantly reduced when compared with untreated animal pairs. However, animal pairs receiving a mineral oil-only treatment showed reduced horn fly populations similar to animals treated with mineral oil plus geraniol. Thus, there was a strong carrier effect that could be difficult to distinguish in the field but was easily observed using laboratory methods.

Chemosensory-Related Gene Family Members of the Horn Fly, Haematobia irritans irritans (Diptera: Muscidae), Identified by Transcriptome Analysis

Horn flies are one of the most significant economic pests of cattle in the United States and worldwide. Chemical control methods have been routinely utilized to reduce populations of this pest, but the steady development of insecticide resistance has prompted evaluation of alternative control strategies. Behavior modifying compounds from natural products have shown some success in impacting horn fly populations, and a more thorough understanding of the horn fly chemosensory system would enable improvements in the development of species-specific compounds. Using an RNA-seq approach, we assembled a transcriptome representing genes expressed in adult female and male horn fly head appendages (antennae, maxillary palps, and proboscides) and adult fly bodies from which heads were removed. Differential gene expression analysis identified chemosensory gene family members that were enriched in head appendage tissues compared with headless bodies. Candidate members included 43 odorant binding proteins (OBP) and 5 chemosensory binding proteins (CSP), as well as 44 odorant receptors (OR), 27 gustatory receptors (GR), and 34 ionotropic receptors (IR). Sex-biased expression of these genes was not observed. These findings provide a resource to enable future studies targeting horn fly chemosensation as part of an integrated strategy to control this blood-feeding pest.

Using Visual and Digital Imagery to Quantify Horn Fly (Diptera: Muscidae) Densities

The horn fly, Haematobia irritans L. (Diptera: Muscidae), is a persistent pest of cattle globally. A threshold of 200 flies per animal is considered the standard management goal; however, determining when that threshold has been exceeded is difficult using visual estimates that tend to overestimate the actual fly densities and are, at best, subjective. As a result, a more reliable and durable method of determining horn fly densities is needed. Here, we describe the methods commonly used to quantify horn fly densities including visual estimates and digital photography, and provide examples of quantification software and the prospect for computer automation methods.

Essential oil based controlled-release non-toxic evaporating tablet provides effective repellency against Musca domestica

Housefly, Musca (M) domestica L. (Diptera: Muscidae) is a pervasive insect that transmits a variety of pathogens to humans and livestock. Although numerous synthetic pesticides are available to combat houseflies, their ecological and toxicological concerns have led to the exploration of natural products as safer alternatives. The present work was designed to develop an essential oil based controlled-release evaporating tablet (EO-CRT) and investigate its repellency against M. domestica. This study assesses the toxicological impacts of the EO-CRT following its sub-chronic inhalation exposure. Briefly, repellent activity of fourteen essential oils viz. lemon grass, bergamot, mentha, basil, camphor, lavender, clove, patchouli, rosemary, cinnamon, eucalyptus, citronella, jasmine and wild turmeric against M. domestica were screened using the 'Y'-tube olfactometer. The synergistic activity of the best four oils, under preliminary screening, were further evaluated by double and triple blending. The best combination of three oils were finalized for optimization with 17-run, 3-factor, 3-level Box-Behnken design. This was then employed to construct polynomial models and predict the best optimized formulation EO-CRT. EO-CRT was characterized by Differential Scanning Calorimetry (DSC) and Gas Chromatography-Mass Spectroscopy (GC-MS). The efficacy of the EO-CRT against M. domestica was assessed by attraction and repellent assay. Chest X-ray, histopathology and scanning electron microscopy of the exposed lung was performed to study EO-CRT's sub-chronic toxicity on Wistar rats. The EO-CRT showed slow release up to a period of 10 days at room temperature, exhibited 100% repellency (%Error=1.237) against M. domestica and was found to possess all the characteristics of an ideal formulation. Sub-chronic toxicity study further revealed the non-toxic nature of the EO-CRT. Thus, our study provides an assurance that the formulated EO-CRT could be effective not only in repelling the nuisance pest, M. domestica, in human dwellings, but also in minimizing the mechanical transmission of pathogens by it.

Peppermint Essential Oil Toxicity to the Pear Psylla (Hemiptera: Psyllidae) and Potential Applications in the Field

Chinese pear psylla (Cacopsylla chinensis Yang et Li) is a serious orchard pest that causes declines in fruit quality through feeding damage and the spread of pathogens. The rapid development of chemical pesticide resistance has become a severe problem in controlling pear psylla. Thus, the development of natural pesticides to replace conventional chemical pesticides is urgently needed. Here, we found that the essential oil of peppermint (Mentha haplocalyx Briq. [Lamiales: Labiatae]) is an ideal agent for controlling pear psylla based on experiments in the laboratory and the field. The major constituents of peppermint essential oil were found including menthol (49.73%), menthone (30.52%), α-pinene (3.60%), and α-terpineol (3.81%). This oil and chemicals in it performed serious contact toxicity against the winter-form adults and nymphs of pear psylla, yielding LD50 values of 2.54, 10.71, 2.77, 5.85, and 12.58 μg/adult and 1.91, 9.56, 2.18, 4.98, and 12.07 μg/nymph, respectively. Furthermore, the essential oil strongly repelled the adults of pear psylla with 78% repellence at the highest concentration tested in a Y-tube olfactometer in the laboratory. The combined effect of the two factors made peppermint essential oil a natural pesticide, which achieved a maximum reduction of round to 80.9% in winter-form adult population and round to 67.0% in nymph population at the concentration of 4.0 ml/L in the field. Additionally, it had no effect on the natural enemies of pear psylla in the field. Therefore, peppermint essential oil has potential as an alternative to chemical pesticides for pest control in integrated pest management programs in pear orchards.

Agrobiological Interactions of Essential Oils of Two Menthol Mints: Mentha piperita and Mentha arvensis

This review article discusses the active constituents and potential of two menthol mint oils, Mentha piperita (MPEO) and Mentha arvensis (MAEO), as natural sources for botanical pesticides. The biological activities of these menthol mint oils, which can be useful in agriculture, have been broadly researched, especially toward phytotoxic microorganisms. To a lesser extent, the insecticidal and herbicidal activities of mint EOs have also been studied. It is apparent that the prospect of using menthol mint oils in agriculture is increasing in popularity. A number of investigations showed that the in vitro efficacy of MPEO and MAEO, as well as that of their main constituent, menthol, is pronounced. The results of in vitro research are useful for choosing EOs for further investigations. However, it is clear that in situ experiments are crucial and should be more extensively developed. At the same time, known techniques are to be applied to this area and new methods should be worked out, aiming at the improvement of EOs’ pesticidal efficacy and cost-effectiveness, for future implementation in agricultural pest control.

Effect of essential oils on cattle gastrointestinal nematodes assessed by egg hatch, larval migration and mortality testing

The efficacy of eight essential oils (EOs) (Solidago canadensis, Eucalyptus globulus, Pelargonium asperum, Ocimum basilicum, Thymus vulgaris, Mentha piperita, Cymbopogon citratus and Cymbopogon martinii) against gastrointestinal nematodes (GINs) was evaluated using eggs collected from naturally infected cattle and cultured infective larvae (L3). The larvae species cultured from the faecal samples and subjected to two in vitro tests were Haemonchus spp. (55.5%), Trichostrongylus spp. (28.0%), Cooperia spp. (15.0%) and Oesophagostomum spp. (1.5%). The genus of EO Cymbopogon (C. citratus and C. martinii) showed the highest anthelmintic activity at the dose of 8.75 mg/ml, for the egg hatch, the larval migration and mortality assays. All of the EOs tested reduced egg hatching to rates <19.0%, compared to the controls (water and water + Tween 20) that had rates >92.0%. Cymbopogon citratus and C. martinii treatments resulted in 11.6 and 8.1% egg hatch, had the lowest migration of larvae through sieves, 60.5 and 54.9%, and the highest mortality rates, 63.3 and 56.3%, respectively. Dose-response tests showed that EO from C. citratus had the lowest larval LC50 and migration inhibition concentration (IC50) values of 3.89 and 7.19 mg/ml, respectively, compared to two other EOs (C. martinii and O. basilicum). The results suggest that EOs from the genus Cymbopogon can be interesting candidates for nematode control in cattle, although it may prove challenging to deliver concentrations to the gastrointestinal tract sufficient to effectively manage GINs.

Effects of Laboratory Grade Limonene and a Commercial Limonene-Based Insecticide on Haematobia irritans irritans (Muscidae: Diptera): Deterrence, Mortality, and Reproduction

The horn fly, Haematobia irritans irritans (L.) (Diptera: Muscidae), is an important and cosmopolitan blood feeding ectoparasite of cattle. Resistance to conventional insecticides is increasingly problematic and alternative pesticides, including natural products, are being investigated. Limonene is a cyclic monoterpene repellent to some insects that occurs in citrus fruit rinds and in other plants. We assessed laboratory grade limonene and a commercial product, Orange Guard (5.8% AI limonene), against H. irritans irritans in terms of their contact effects upon contact on egg mortality, adults, and larval and pupal development; adult repellency as well as sublethal and fumigation effects. Egg viability declined when they were exposed to Orange Guard at concentrations of 1.45%, 2.9%, and 5.8% whereas laboratory grade limonene at 5.8% and 11.6% was ovicidal. Contact exposure of adult H. irritans irritans to 5.8% laboratory grade limonene and 2.9% Orange Guard caused up to 100 and 88% knockdown (immobilization), respectively. At higher concentrations, laboratory grade limonene and Orange Guard resulted in less, and often shorter periods of knockdown. Although direct contact of 2.9 and 5.8% laboratory grade limonene caused mortality it was negligible when flies were sprayed directly with undiluted Orange Guard. Female H. irritans irritans exposed to sublethal concentrations of Orange Guard did not reduce the numbers of eggs produced, but the undiluted product reduced egg hatchability. Interestingly, limonene and Orange Guard attracted adult H. irritans irritans at concentrations <0.1%. We suggest that the attractancy of unformulated pure limonene might be useful for trapping H. irritans irritans adults.

Biorational substitution of piperonyl butoxide in organic production: effectiveness of vegetable oils as synergists for pyrethrums

Piperonyl butoxide is a semi-synthetic synergist for natural pyrethrum and synthetic pyrethroid insecticides in phytochemicals and biocides. As such it is used in large quantities for crop treatments, stored grain protection, disinfestation of grain storage facilities and indoor uses. Piperonyl butoxide is consequently a regular contaminant in stored grains, and subsequently in corresponding cereal food products and meat via feed uses. Therefore it is regularly monitored and its MRL is ongoing a reassessment. It is also considered as a possible human carcinogen and a suspected endocrine disruptor. For all these reasons and considerations most of the countries have already banned its use in Organic Farming as France in 2017. Thus, ecological substitution of with biorational and sustainable solutions is required. Vegetable oils have been described as exhibiting similar potency and synergistic effects. We have reviewed the literature and have proceeded to ecotoxicological efficacy tests in order to determine the best and most durable substitution candidates. Sesame and rape seed oil were determined to be the most efficient.

Essential oils: effects of application rate and modality on potential for combating northern fowl mite infestations

The northern fowl mite (NFM), Ornithonyssus sylviarum (Mesostigmata: Macronyssidae), is the primary blood-feeding ectoparasite found on poultry in the U.S.A. Three experiments were conducted in vitro to test the acaricidal properties of cade, garlic, lavender, lemongrass, pine and thyme essential oils against NFM, and to evaluate whether these effects are altered by adjusting oil application rates and application modality (direct vs. vapour contact). Applied at the rate of 0.21 mg/cm² , the essential oils of cade, thyme, lemongrass and garlic resulted in higher NFM mortality at 24 h post-application than lavender and pine oils, and the untreated and ethanol-treated controls. Cade and thyme were the most consistent and fast-acting of the essential oils in terms of toxicity to NFM. Cade applied at 0.21 mg/cm² and 0.11 mg/cm² and thyme applied at 0.21 mg/cm² were effective in eliminating NFM within 2 h through direct contact. The modality of application did not affect the efficacy of cade and thyme essential oils. The results suggest that essential oils may be utilized as alternatives to chemical pesticides and could be used as fumigants for the control of NFM.

Sex Ratios and Mating Status of the Horn Fly on Pastured Cattle as a Function of Repellent-Oil Treatments

Haematobia irritans (L.) (Diptera: Muscidae) were netted from pastured cattle in California over two summers, with the goal of documenting on-host sex ratios and mating success as they might vary with repellent applications. Sex ratios were calculated from 100 adults per herd per date, and mating status of females (n = 30 per herd per date) was assessed by dissection of spermathecae. Flies were collected before, during, and after 2-wk treatment periods with each of two repellent-oil mixtures: a 15% mixture of fatty acids (C8, C9, C10) in mineral oil or a 2% solution of geraniol in mineral oil. During the treatment period, flies were collected 3-4 d after the prior treatment and immediately before the next treatment. A separate herd used in the second year was untreated. Overall, the proportion female was 0.65 ± 0.01 (mean ± SE) (range 0.28-0.81). Sex ratios were not altered over time by treatments with either repellent. Overall, proportion of females mated was 0.744 ± 0.018 (range 0.40-1.00). Mating status was significantly affected by the two repellent treatments, which did not differ from each other. For treatment herds, proportion mated before treatment was 0.789 ± 0.039, dropping significantly to 0.659 ± 0.038 during the treatment period, and rebounding to 0.750 ± 0.035 after treatments ceased. Treatments probably killed or repelled the existing heterogeneous fly population, and during treatment relatively more flies were unmated recent arrivals.

Effects of Fatty Acid and Geraniol Repellent-Oil Mixtures Applied to Cattle on Blood Feeding and Reproductive Parameters in Field Populations of Haematobia irritans (Diptera: Muscidae)

California pastured cattle were treated with 250 ml of a 15% mixture of fatty acids (C8-C9-C10) or 125 ml of 2% geraniol in a mineral oil carrier to assess impacts on horn flies, Haematobia irritans (L.) (Diptera: Muscidae) over two summers. Horn flies were netted from cattle every 3-4 d for 2 wk before treatment, 2 wk during treatment (four treatments, with flies collected before each treatment), and 2 wk after treatments ceased. Blood meal weights were estimated by hemoglobin assay of excised abdomens. Other females were dissected to determine the number of active ovarioles and the stage of primary follicle development. Depending on year and herd, pretreatment males contained an average of 0.6-1.0 mg of blood, while females contained 1.7-2.7 mg. Pretreatment egg development (least developed oocytes were stage 1 and fully developed eggs were stage 5) averaged 3.7-4.3, and number of active ovarioles averaged 18.1 to 19.6/female. During treatment periods, significant reductions in blood weight were noted for females, but usually not for males, and females also often exhibited reduced mean oocyte stage and number of active ovarioles. Peaks in proportions of young nulliparous females (oocyte stages 1 or 2) were seen during some repellent application periods. This suggested older females had been killed or driven off from the local population by the treatments, and flies on cattle included more young flies that likely were recent arrivals. The repellent-oil mixture thus impacted blood feeding, reproductive fitness, and probably age structure in the field.

Field trials of fatty acids and geraniol applied to cattle for suppression of horn flies, Haematobia irritans (Diptera: Muscidae), with observations on fly defensive behaviors

Adult horn fly populations were tracked on cattle for 2-week periods before, during and after multiple treatments (every 3-4days) with two repellents in a mineral oil carrier. Cattle were sprayed four times in a two-week period either with 2% geraniol (125ml/cow) or a 15% mixture of short chain fatty acids (C8-C9-C10)(250ml/cow), and there were untreated control cattle. Trials were conducted in California and North Carolina for 3 summers. Short-term fly counts (same day) on treated cattle were reduced by 61-99%, depending on material and trial, and the fatty acid mixture provided better control than geraniol. Horn fly counts were suppressed for 1-3 d and rebounded somewhat after both treatments. Consecutive treatments showed evidence of persistent impact in California where herds were more isolated. Rebounds to pre-treatment levels 3-4 d after treatment occurred more often in North Carolina, where other infested cattle were closer to treated herds. By 3-4 d post-treatment, horn flies were reduced by 29-61% in California and 0-83% in North Carolina, relative to pre-treatment. Background behavior frequencies were assessed from hundreds of counts on untreated, infested California cattle, where horn flies were the only abundant biting fly. Behavior averages were 16.5 tail flicks, 7.6 skin twitches, 1.2 head throws, or 0.2 leg stamps per 2min observation period. At horn fly densities from about 200 to more than 1000 flies per animal (moderate to high numbers), fly defensive behaviors on control cattle were poorly related (or unrelated) to fly numbers. Immediately after repellent application, however, flies were almost absent and behavior frequencies dropped distinctly. Cattle fly defensive behaviors therefore seem to be quite sensitive to low (less than 100 flies/animal) horn fly densities, and behaviors would be a poor quantitative tool to track fly stress at moderate densities and above. Both geraniol and the fatty acids show promise for horn fly control, especially in organic agriculture. Treatments at 1-2 d intervals probably would keep infestations below the economic threshold (200 flies/cow).

Aromatic Medicinal Plants from Tajikistan (Central Asia)

Tajikistan is a small country located in Central Asia. The mostly mountainous terrain with a continental, subtropical, and semiarid climate, is characterized by diverse flora. Many people in Tajikistan rely on medicinal plants as their traditional form of medicine to prevent and cure health disorders. Aromatic medicinal plants, in particular, have played an important role for the local people. In this review, we present a summary of the uses of 18 aromatic medicinal plants from Tajikistan and their compositions of secondary metabolites.