Chemical composition and acaricidal properties of Deverra scoparia essential oil (Araliales: Apiaceae) and blends of its major constituents against Tetranychus urticae (Acari: Tetranychidae)

Management potentiality of emulsions based on essential oil of Piper macedoi and Piper arboreum for spider mite: a possible alternative for agroecological control

Tetranychus urticae, popularly known as spider mite, is a pest that causes several economic losses to crops. Thus, this work evaluated the effect of essential oils from the leaves of Piper macedoi and Piper arboreum on managing T. urticae. The chemical compounds present in essential oils were identified by gas chromatography. Tests were carried out to evaluate the acaricidal activity by fumigation effect and direct contact with T. urticae. The results showed that LC50 values for the essential oils of P. macedoi and P. arboreum in the fumigation effect were 16.15 and 50.53 µL L-1 air, respectively. Using the contact application route, the LC50 values for the essential oil of P. macedoi was 17.16 µL mL-1, and for P arboreum, it was 15.17 µL mL-1. So, this work showed that essential oils of Piper macedoi and Piper arboreum could be used as possible alternative to managing T. urticae.

Current Situation of Tetranychus urticae (Acari: Tetranychidae) in Northern Africa: The Sustainable Control Methods and Priorities for Future Research

In North Africa, Tetranychus urticae Koch, 1836 represents one of the most destructive generalists among mite herbivores. Unfortunately, it is a source of important annual casualties in crop production. It is a phytophagous mite that can feed on hundreds of host plants and produces significant damage. The control of T. urticae in North Africa has been principally based on acaricide sprays. However, new alternative methods have shown effective results, such as artificial ultraviolet-B, natural enemies, and the introduction of new genetic methods. This review aims to present a synthesis of information surrounding control methods of T. urticae in North Africa. We highlight the principal findings of previous studies. Then, we discuss current control methods and propose new innovative research and sustainable approaches to controlling this pest. The control method can potentially extrapolate in North African regions due to its positive ecological results. Further, studies proved the use of natural enemies, myco-metabolites, bacteria metabolites, and the introduction of a genetic method in an integrated long-term sustainable program that can successfully defeat the populations of T. urticae. We also discuss high-priority research guidelines to investigate new sustainable management strategies. Setting up an integrated long-term ecological monitoring program in different Northwest African countries and incorporating new technologies into monitoring programs is an urgent need to fight this devastating pest.

Acaricidal, Insecticidal, and Nematicidal Efficiency of Essential Oils Isolated from the Satureja Genus

The overuse of synthetic pesticides in plant protection strategies has resulted in numerous side effects, including environmental contamination, food staff residues, and a threat to non-target organisms. Several studies have been performed to assess the pesticidal effects of plant-derived essential oils and their components, as partially safe and effective agents, on economically important pests. The essential oils isolated from Satureja species are being used in medicinal, cosmetic, and food industries. Their great potential in pest management is promising, which is related to high amounts of terpenes presented in this genus. This review is focused on the acute and chronic acaricidal, insecticidal, and nematicidal effects of Satureja essential oil and their main components. The effects of eighteen Satureja species are documented, considering lethality, repellency, developmental inhibitory, and adverse effects on the feeding, life cycle, oviposition, and egg hatching. Further, the biochemical impairment, including impairments in esterases, acetylcholinesterase, and cytochrome P450 monooxygenases functions, are also considered. Finally, encapsulation and emulsification methods, based on controlled-release techniques, are suggested to overcome the low persistence and water solubility restrictions of these biopesticides. The present review offers Satureja essential oils and their major components as valuable alternatives to synthetic pesticides in the future of pest management.

Essential Oil of Deverra tortuosa Aerial Parts: Detailed Chemical Profile, Allelopathic, Antimicrobial, and Antioxidant Activities

Essential oils (EOs) are a promising group of natural products of the aromatic plants due to their various biological effects such as allelopathic, antioxidant, antimicrobial activities. The present study aimed to construct the detailed chemical profile of the EO derived from Deverra tortuosa aerial parts along with assessing its allelopathic, antimicrobial, and antioxidant potentialities. The EO was extracted by hydrodistillation and analyzed via gas chromatography-mass spectrometry (GC/MS). The allelopathic activity of the EO was assessed against the germination and seedling growth of the weed Chenopodium murale. Also, the EO was tested against five microbes. The antioxidant activity was determined using the free radical 2,2-diphenyl-1-picrylhydrazyl (DPPH) and 2,2'-azinobis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS). The GC/MS analysis of EO revealed the presence of 86 compounds with a preponderance of oxygenated sesquiterpenes and monoterpene hydrocarbons. Widdrol, β-phellandrene, piperitol, cubedol, α-terpinene, (E)-10-heptadecen-8-ynoic acid methyl ester, citronellyl tiglate, and m-cymene were the major compounds. A comparative profile was established between the EOs constituents of our study with the documented EOs of D. tortuosa and the other Deverra species around the world via agglomerative hierarchical clustering (AHC) and principal components analysis (PCA). The EO showed a substantial allelopathic activity against C. murale, as well as it showed considerable antimicrobial and antioxidant activities. Thereby, the EO of D. tortuosa could be considered as a promising environmental-friendly bioherbicide against weeds. Also, it could be integrated into food preservation due to its potent antimicrobial and antioxidant activities. However, further study is recommended for more characterization of the major compounds and evaluation of their activities, either singular or synergistic, and assess their efficiency and biosafety.

Antimicrobial Spectrum of Titroleane™: A New Potent Anti-Infective Agent

Tea Tree oil (TTO) is well known for its numerous good properties but might be also irritating or toxic when used topically or ingested, thus limiting the number of possible applications in Humans. The aim of the study was to characterize the antimicrobial spectrum as well as the toxicity of Titroleane™, a new anti-infective agent obtained from TTO but cleared of its toxic monoterpenes part. The susceptibility to Titroleane™ of various pathogens (bacteria and fungi) encountered in animal and human health was studied in comparison with that of TTO. Antimicrobial screening was carried out using the broth microdilution method. Activities against aerobic, anaerobic, fastidious and non-fastidious microorganisms were performed. For all microorganisms tested, the MIC values for Titroleane™ ranged from 0.08% to 2.5%, except for Campylobacter jejuni, and Aspergillus niger. In particular, Titroleane™ showed good efficacy against skin and soft tissue infection pathogens, such as methicillin resistant Staphylococcus aureus (MRSA), intra-abdominal infections and oral pathogens, as well as fish farming pathogens. Toxicity testing showed little and similar cytotoxicities between TTO and Titroleane™ of 37% and 23%, respectively at a concentration of 0.025% (v/v). Finally, we demonstrated that the antimicrobial activity of Titroleane™ is similar to that of TTO.

Acaricidal activity of binary blends of essential oils and selected constituents against Tetranychus urticae in laboratory/greenhouse experiments and the impact on Neoseiulus californicus

The aim of this study was to test the effectiveness of essential oils form Piper aduncum, Melaleuca leucadendra and Schinus terebinthifolius and their blends by fumigation and residual contact on Tetranychus urticae and its natural enemy, Neoseiulus californicus. Bioassays were performed in a greenhouse with the best blend of the oils and compared to the individual oils and Vertimec® (positive control). The main constituents identified by GC-MS were dillapiole, (E)-nerolidol and limonene in the oils from P. aduncum (76.5%), M. leucadendra (87.3%) and S. terebinthifolius (unripe/ripe fruits, 42.5/34.1%). The P. aduncum and M. leucadendra oils were the most toxic to the pest. Among the blends, the greatest toxicity to T. urticae occurred by residual contact with the M. leucadendra + S. terebinthifolius ripe fruit blend (50/50). The evaluation of the effects on N. californicus showed the compatibility of the oils and blends with the predator mite for use in the integrated management of T. urticae. β-Caryophyllene was the most toxic, independent of the method used. Based on toxicities of 11 oil constituents, the structure-activity relationship of these compounds is also discussed. This study showed that the acaricidal effect of the Piper, Melaleuca and Schinus oils can easily be increased by the binary combination of these oils. The binary blend between the oils of the Melaleuca leaves and ripe Schinus fruit in the greenhouse was effective at controlling the mite after 72 h, exhibiting the same level of toxicity as that found for the positive control (Vertimec 18 EC).

Botanicals Against Tetranychus urticae Koch Under Laboratory Conditions: A Survey of Alternatives for Controlling Pest Mites

Tetranychus urticae Koch is a phytophagous mite capable of altering the physiological processes of plants, causing damages estimated at USD$ 4500 per hectare, corresponding to approximately 30% of the total cost of pesticides used in some important crops. Several tools are used in the management of this pest, with chemical control being the most frequently exploited. Nevertheless, the use of chemically synthesized acaricides brings a number of disadvantages, such as the development of resistance by the pest, hormolygosis, incompatibility with natural predators, phytotoxicity, environmental pollution, and risks to human health. In that sense, the continuous search for botanical pesticides arises as a complementary alternative in the control of T. urticae Koch. Although a lot of information is unknown about its mechanisms of action and composition, there are multiple experiments in lab conditions that have been performed to determine the toxic effects of botanicals on this mite. Among the most studied botanical families for this purpose are plants from the Lamiaceae, the Asteraceae, the Myrtaceae, and the Apiaceae taxons. These are particularly abundant and exhibit several results at different levels; therefore, many of them can be considered as promising elements to be included into integrated pest management for controlling T. urticae.

Identification of Insecticidal Constituents from the Essential Oil from the Aerial Parts Stachys riederi var. japonica

The essential oil of Stachys riederi var. japonica (Family: Lamiaceae) was extracted by hydrodistillation and determined by GC and GC-MS. A total of 40 components were identified, representing 96.01% of the total oil composition. The major compounds in the essential oil were acetanisole (15.43%), anisole (9.43%), 1,8-cineole (8.07%), geraniol (7.89%), eugenol (4.54%), caryophyllene oxide (4.47%), caryophyllene (4.21%) and linalool (4.07%). Five active constituents (acetanisole, anisole, 1,8-cineole, eugenol and geraniol) were identified by bioactivity-directed fractionation. The essential oil possessed fumigant toxicity against maize weevils (Sitophilus zeamais) and booklice (Liposcelis bostrychophila), with LC₅₀ values of 15.0 mg/L and 0.7 mg/L, respectively. Eugenol and anisole exhibited stronger fumigant toxicity than the oil against booklice. 1,8-Cineole showed stronger toxicity, and anisole as well as eugenol exhibited the same level of fumigant toxicity as the essential oil against maize weevils. The essential oil also exhibited contact toxicity against S. zeamais adults and L. bostrychophila, with LC₅₀ values of 21.8 µg/adult and 287.0 µg/cm², respectively. The results indicated that the essential oil of S. riederi var. japonica and its isolates show potential as fumigants, and for their contact toxicity against grain storage insects.

Efficacy of Nanoencapsulated Thymus eriocalyx and Thymus kotschyanus Essential Oils by a Mesoporous Material MCM-41 Against Tetranychus urticae (Acari: Tetranychidae)

Inspite of well-established potentiality of plant essential oils as biopesticides, their environmentally low persistence is considered as a hindering obstacle for its commercialization. In the present study, chemical composition and toxicity of essential oils isolated from leaves of Thymus eriocalyx and Thymus kotschyanus were evaluated against two-spotted spider mite, Tetranychus urticae. The chemicals present in the crude oil were found to be thymol (28.83%), oleic acid (11.51%), palmitic acid (8.60%), borneol (5.72%), ρ-cymene (3.60%), and 1,8-cineole (3.57%) in the essential oil of T. eriocalyx, and camphene (35.59%), linalyl acetate (20.47%), linalool (14.75%), α-terpineol (13.87%), and geranyl acetate (3.07%) in the essential oil of T. kotschyanus. The essential oils had strong fumigant toxicity on the adult females of Te. urticae and their fumigation persistence was prolonged until 6 and 5 d, respectively, for T. eriocalyx and T. kotschyanus. Loading of essential oils in MCM-41 increased their stability and persistence was extended up to 20 and 18 d for T. eriocalyx and T. kotschyanus. Further, mite mortality increased from 80 to 203 mites by T. eriocalyx and from 58 to 186 mites by T. kotschyanus nanoencapsulated essential oils. Based on these results, nanoencapsulation of T. eriocalyx and T. kotschyanus essential oils in MCM-41 may be a useful method for their application in the management of Te. urticae.

Acaricidal and sublethal effects of a Chenopodium-based biopesticide on the two-spotted spider mite (Acari: Tetranychidae)

Acaricidal and sublethal effects of the biopesticide Requiem^®EC (containing an essential oil extract of Chenopodium ambrosioides near ambrosioides) on the two-spotted spider mite, Tetranychus urticae Koch, were evaluated in laboratory bioassays. The biopesticide was applied to bean leaves or leaf discs using a Potter spray tower. Acaricidal activity against eggs and immatures was evaluated in successive acute toxicity bioassays. Concentration-mortality data were subjected to probit analysis and the following LC₅₀ values (ml/l) were calculated: 2.47 (eggs), 0.71 (larvae), 1.13 (protonymphs), 2.23 (female deutonymphs), and 6.02 (female teleiochrysalises). In adult bioassay, in which pre-ovipositional females were treated with a series of concentrations (0.31-10 ml/l), a run-off effect ranging 4-80% (after 24 h) and 8-93% (after 72 h) was observed. In two-choice bioassay, T. urticae females preferred the untreated halves of leaves over the halves treated with 1.25-10 ml/l biopesticide and they laid significantly more eggs on the untreated halves in the first 24 h and summed over 72 h. The indices of repellency and oviposition deterence ranged 11.2-77.3 and 14.8-87.9%, respectively. In age-stage two-sex life table bioassay, the females that hatched from eggs treated with 2.5 ml/l biopesticide and reached adulthood on treated leaf surface showed a significantly reduced the intrinsic rate of increase (r = 0.222), compared to the control (r = 0.317). The reduction of population growth was mainly due to a reduced preadult survival rate (0.42 ± 0.04) and extended juvenile developmental time (9.27 ± 0.11 days), compared to the control (0.93 ± 0.03 and 7.70 ± 0.06 days, respectively).

Acaricidal activities of Santolina africana and Hertia cheirifolia essential oils against the two-spotted spider mite (Tetranychus urticae)

BACKGROUND

Many plant essential oils show a broad spectrum of activity against pests. This study investigated the effects of two essential oils on Tetranychus urticae, one of the most serious pests in the world.

RESULTS

The chemical composition of the two oils was characterised by GC-MS. The most abundant component in the Santolina africana (Jord. & Fourr) oil was terpinen-4-ol (54.96%), while thymol (61%) was prevalent in the Hertia cheirifolia (L.) oil. Mortality and fecundity were measured upon treatment with oil concentrations ranging from 0.07 to 6.75 mg L(-1) with a Potter spray tower. Mite mortality increased with oil concentration, with LC(50) values of 2.35 mg L(-1) for S. africana and 3.43 mg L(-1) for H. cheirifolia respectively. For both oils, a reduction in fecundity was observed at concentrations of 0.07, 0.09 and 0.29 mg L(-1) . Artificial blends of constituents of oils were also prepared and tested with individual constituents missing from the mixture. The results showed that the presence of all constituents was necessary to equal the toxicity of the two natural oils.

CONCLUSION

S. africana and H. cheirifolia oils can provide valuable acaricide activity with significantly lower LC(50) values. Thus, these oils cause important mortality and reduce the number of eggs laid by females.

Acaricidal activity and repellency of essential oil from Piper aduncum and its components against Tetranychus urticae

The chemical composition of essential oil of leaves of Piper aduncum L., growing wild in a fragment of the Atlantic Rainforest biome in northeastern Brazil, was determined through gas chromatography-mass spectrometry. The acaricidal activity and repellency of the essential oil and its components [dillapiole (0.28 g/ml), α-humulene (0.016 g/ml), (E)-nerolidol (0.0007 g/ml) and β-caryophyllene (0.0021 g/ml)] were evaluated in the laboratory against adults of Tetranychus urticae Koch. The mites were more susceptible to the oil in fumigation tests (LC(50) = 0.01 μl/l of air) than in contact test with closed Petri dish (LC(50) = 7.17 μl/ml); mortality was reduced by approximately 50 % in the latter test. The repellent action of the oil and toxicity by fumigation and contact did not differ significantly from the positive control (eugenol). The repellent activity was attributed to the components (E)-nerolidol, α-humulene and β-caryophyllene, whereas toxicity by fumigation and contact was attributed to β-caryophyllene. The effect of Piper oil and the role of its components regarding host plant preference with a two-choice leaf disk test are also discussed.