Fabrication of Carum copticum essential oil-loaded chitosan nanoparticles and evaluation its insecticidal activity for controlling Rhyzopertha dominica and Tribolium confusum

Introduction

Plant essential oils (EOs) can be used as a feasible tool for insect pest control. Nanoparticle formulations of plant EOs can improve the efficiency and stability of EOs, as well as insecticidal potential.

Methods

In this study, Carum copticum L. essential oil-loaded nanoparticles (OLNs) were prepared via an oil-in-water emulsion, followed by droplet solidiffication via ionic gelation using a cross-linker, sodium tripolyphosphate (TPP). The nanoparticles were characterized by ultraviolet and visible (UV-Vis) spectrophotometry, Fourier-transform infrared spectroscopy (FTIR), laser light scattering (LS), transmission electron microscopy (TEM), and scanning electron microscopy (SEM). Moreover, the insecticidal activity of C. copticum EO and OLNs was evaluated against Rhyzopertha dominica (F.) (Coleoptera: Bostrychidae) and Tribolium confusum Jacquelin du Val. (Coleoptera: Tenebrionidae). In addition, their effectiveness was assessed on the progeny production of tested insect species.

Results and discussion

The loading efficiency ranged from 34.33 to 84.16% when the chitosan to EO weight ratio was 1:1.25 and 1:0.5, respectively. The loading efficiency decreased with increasing EO content in the nanoparticles. The OLN particles exhibited spherical shape. The particle size was in the range 120-223.6 nm and increased with the increase of EO to chitosan ratio. So that the largest mean particle size (223.6 nm) was reported in the 1:1.25 weight ratio of chitosan to the EO. The mortality percentage of R. dominica and T. confusum adults were 74 and 57% when exposed for 7 days to 2000 mg/kg of OLNs at the 1:1.25 weight ratio, while EO caused 62 and 44% mortality on both insect species, respectively. Therefore, OLNs can potentially improve the insecticidal activity of C. copticum EO and could be applied to facilitate control of stored-product insect pests.

Some Physiological Effects of Nanofertilizers on Wheat-Aphid Interactions

The increasing use of nanofertilizers in modern agriculture and their impact on crop yield and pest management require further research. In this study, the effects of nano-Fe, -Zn, and -Cu (which are synthesized based on nanochelating technology), and urea (N) fertilizers on the antioxidant activities of wheat plants (cv. Chamran), and the wheat green aphid Schizaphis graminum (Rondani) are investigated. The authors observed the highest levels of phenolics in non-infested nano-Zn-treated plants (26% higher compared with control). The highest H₂O₂ levels are in the infested and non-infested nano-Zn-treated and infested nano-Fe-treated plants (in infested nano-Zn and nano-Fe treated plants, 18% and non-infested nano-Zn-treated plants, 28% higher compared with control). The highest peroxidase (POX) activity is observed in the infested and non-infested N-treated and non-infested water-treated plants (almost 14%, 37%, and 46% higher than control, respectively). The lowest activity is in the infested plants' nano-Zn and -Fe treatments (almost 7 and 5 folds lower compared to the control, respectively). The highest and lowest catalase (CAT) activity are in the infested N-treated plants (almost 42% higher than control) and water-treated plants, respectively. The infested nano-Zn, -Fe, -Cu and Hoagland-treated plants showed the highest superoxide dismutase (SOD) activity. Regarding the antioxidant enzyme activities of S. graminum, the highest POX activity is in the nano-Cu treatment (more than two folds higher compared with control); the highest CAT and SOD activities are in the nano-Cu and -Zn treatments. It can be concluded that the application of nanofertilizers caused increasing effects on the wheat plant's antioxidant system and its resistance to S. graminum.

Synergic effects of some plant-derived essential oils and Iranian isolates of entomopathogenic fungus Metarhizium anisopliae Sorokin to control Acanthoscelides obtectus (Say) (Coleoptera: Chrysomelidae)

Introduction

The bean weevil, Acanthoscelides obtectus, is one of the most important pests of the common bean, Phaseolus vulgaris. The pest attacks P. vulgaris seeds while they are still in the field. However, the damage continues during storage, where it causes the most significant losses.

Methods

The present study was conducted to evaluate the insecticidal activity, and synergic effects of three essential oils (EOs) extracted from fennel (Foeniculum vulgare), tarragon (Artemisia dracunculus), and lavender (Lavandula angustifolia), and three isolates from an entomopathogenic fungus (EPF), Metarhizium anisopliae, including IRAN2273C, IRAN2252C, and IRAN1018C against the adults of A. obtectus. The effects of EOs were also evaluated on mycelial growth and conidiation of the fungal isolates.

Results and Discussion

The results showed that all the EOs and the EPF exhibited insecticidal activity against A. obtectus. According to calculated LC50, L. angustifolia (1.2526 µl/l) and F. vulgare (0.9247 µl/l) EOs caused significantly higher mortality than A. dracunculus (3.1980 µl/l) against A. obtectus. The results of the pathogenicity of M. anisopliae isolates revealed that all isolates had insecticidal activity against A. obtectus. The cumulative mortality of insects varied from 59.12% in IRAN1018C to 80.86% in IRAN2273C. According to the compatibility test results, all EOs were compatible with fungal isolates except for A. dracunculus, which was toxic to the IRAN2252C isolate and showed incompatibility. The mortality of A. obtectus adults differed significantly among combined treatments of EOs and M. anisopliae isolates. According to the calculated synergic ratio, combinations of essential oils and fungal isolates had additive or synergistic effects on the mortality of A. obtectus. Based on the present findings, A. obtectus adults were susceptible to fennel, and lavender EOs, and their mortality was amplified when the EOs were combined with M. anisopliae isolates. These results can be helpful for the integrated management of A. obtectus during storage.

Oviposition preference and life-history parameters of Callosobruchus maculatus (Coleoptera: Chrysomelidae) on different soybean (Glycine max) cultivars

BACKGROUND

Callosobruchus maculatus (F.) (Coleoptera: Chrysomelidae) is one of the most destructive pests of stored legume seeds in many regions of the world. Evaluation of varietal resistance of host seeds to C. maculatus infestation can be useful in preventing severe damage. We studied the susceptibility and resistance of eight conventional soybean cultivars (Caspian, Kosar, L17, Nekador, Sari, Tapour, Williams and Zane) based on the oviposition preference (choice and no-choice tests) and population growth parameters of the pest.

RESULTS

Compared with other cultivars tested, oviposition preference of C. maculatus was the lowest on Nekador. The developmental time of C. maculatus differed from 40.34 days on Nekador to 48.35 days on L17, and was negatively correlated with the seed protein content. Other performance measures of C. maculatus did not match the oviposition preference. Immature survival and female longevity were highest on Caspian. The intrinsic rate of increase (r_m ) was higher on Tapour, Nekador and Caspian than on Zane, Williams, and Kosar. A positive correlation was observed between the r_m value of the pest and moisture content of the cultivars. Cluster analysis showed that cvs Nekador, Sari, Tapour, and Caspian were relatively susceptible, and cvs Kosar, Zane, Williams and L17 were partially resistant to this pest.

CONCLUSION

Protein and moisture contents of soybean cultivars play an important role in the development and population growth of C. maculatus, and these traits could be used to develop safe and effective management strategies for this pest on stored soybean seeds. © 2022 Society of Chemical Industry.

Physicochemical Properties of Sugarcane Cultivars Affected Life History and Population Growth Parameters of Sesamia nonagrioides (Lefebvre) (Lepidoptera: Noctuidae)

The use of resistant cultivars is an efficient management strategy against S. nonagrioides. The effects of different sugarcane cultivars, CP48-103, CP57-614, CP69-1062, CP73-21, SP70-1143, and IRC99-02 were evaluated on the oviposition preference (free-choice assay), life history, and life table parameters of S. nonagrioides at 27 ± 1 °C, 60 ± 5% RH and a photoperiod of 16: 8 (L: D) h. The longest and shortest developmental times were on cultivars SP70-1143 and CP48-103, respectively. The oviposition preference of S. nonagrioides was the highest on cultivars CP48-103 and CP69-1062, and negatively correlated with the shoot trichome density and shoot rind hardness of the cultivars. The highest intrinsic rate of increase of S. nonagrioides was on cultivar CP48-103 and the lowest was on cultivar SP70-1143. The shortest mean generation time was on CP48-103 and the longest was on SP70-1143. The results indicate that cultivars CP48-103 and CP69-1062 were susceptible, and cultivar SP70-1143 was partially resistant against S. nonagrioides. This information could be useful for developing integrated management programs of S. nonagrioides, such as the use of resistant cultivars to reduce the damage caused by this pest in sugarcane fields.

Effects of High-Pressure Carbon Dioxide on the Sensory and Chemical Properties of Dried Dates and Its Toxicity against Galleria mellonella (L.) and Plodia interpunctella (Hübner)

ABSTRACT

The use of chemical pesticides can have many detrimental side effects, including environmental pollution, and be a threat to human health. Carbon dioxide (CO2) treatment, a relatively new method for storage pest management, can replace harmful chemicals. Dates, an important food worldwide, contains many minerals, fiber, and a variety of vitamins and are an important dried fruit export from Iran annually. Thus, control of the pests of dried dates by using eco-friendly agents that do not affect quality features are critical. In this study, larval mortality of the Indian meal moth (Plodia interpunctella (Hübner)) and the greater wax moth (Galleria mellonella (L.)), two key pests of stored products, especially dried dates, was studied after exposure to different CO2 pressures within 24 h. Mortality percentages of the third-instar larvae of both pests were increased with an increase in CO2 pressure. Sensory tests on the qualitative characteristics of the dates revealed that CO2 pressures did not affect their aroma, color, sweetness, sourness, crispness, firmness, and overall acceptance. The highest tested pressure (33.4 mol%) of CO2 also had no significant effects on the chemical properties of the date samples, including moisture content, pH, acidity, Brix value, reducing sugar, and total sugar. We conclude that atmospheric CO2 gas can provide a cost-effective and environmentally friendly method for controlling the insect pests of dried dates in addition to preserving their sensory and quality properties.

HIGHLIGHTS

Nanoencapsulation of Acetamiprid by Sodium Alginate and Polyethylene Glycol Enhanced Its Insecticidal Efficiency

Nanoformulation has been considered one of the newly applied methods in integrated pest management strategies. In this research, a conventional neonicotinoid insecticide acetamiprid was nanoencapsulated via AL (Sodium Alginate) and PEG (Polyethylene Glycol) and tested against the elm leaf beetle Xanthogaleruca luteola. The synthesized particles had spherical-like morphology and nanoscale based on TEM (Transmission Electron Microscopy) and DLS (Dynamic Light Scattering). The encapsulation efficiency and loading percentages of acetamiprid in AL and PEG were 92.58% and 90.15%, and 88.46% and 86.79%, respectively. Leaf discs treated with different formulations by the leaf-dipping method were used for oral toxicity assays. The LC₅₀ values (Lethal Concentration to kill 50% of insect population) of acetamiprid and Al- and PEG-nanoencapsulated formulations on third-instar larvae were 0.68, 0.04, and 0.08 ppm, respectively. Based on the highest relative potency, AL-encapsulated acetamiprid had the most toxicity. The content of energy reserve protein, glucose, and triglyceride and the activity of detoxifying enzymes esterase and glutathione S-transferase of the larvae treated by LC₅₀ values of nanoformulations were also decreased. According to the current findings, the nanoencapsulation of acetamiprid by Al and PEG can increase its insecticidal performance in terms of lethal and sublethal toxicity.

Antifungal Activities of Pure and ZnO-Encapsulated Essential Oil of Zataria multiflora on Alternaria solani as the Pathogenic Agent of Tomato Early Blight Disease

The utilization of plant essential oils (EOs) and nanomaterials due to their safety compared with synthetic chemicals has been considered in the management of plant diseases. In this study, the inhibitory effects of Zataria multiflora, Nepeta haussknechtii, Artemisia sieberi, and Citrus aurantifolia EOs in pure and Zinc Oxide (ZnO) nanocapsulated formulations were evaluated on the mycelial growth of Alternaria solani to find a suitable alternative for synthetic chemicals. The crystal structure and morphological properties of the fabricated nanomaterials were assessed via X-ray diffraction (XRD) and scanning electron microscope (SEM) analyses. The textural features of the prepared nanoparticles were investigated with Brunauer-Emmett-Teller (BET) analysis, and the presence of elements in the samples was studied with energy-dispersive X-ray (EDX) technique. The mycelial growth inhibitory (MGI) was performed in the laboratory by mixing with potato dextrose agar (PDA) medium at concentrations of 100, 300, 600, 1,000, 1,500, and 2,000 ppm. Based on the results, major differences were monitored between different concentrations. At the highest studied concentration, the inhibition of Z. multiflora EO was 100%, which was 43.20, 42.37, and 21.19% for N. haussknechtii, A. sieberi, and C. aurantifolia, respectively, and the inhibition of their nanocapsules was 100, 51.32, 55.23, and 26.58%, respectively. In the greenhouse study, Z. multiflora EO and its nanocapsule (ZnO-ZmEO) were compared with the ZnO and chlorothalonil fungicide based on the highest inhibitory of Z. multiflora in vitro. The highest antifungal effect was related to the ZnO-ZmEO by 53.33%. Therefore, the ZnO-ZmEO formulation can be recommended as a biofungicide for managing and controlling tomato early blight disease after further research.

Chemical Profiles and Insecticidal Potential of Essential Oils Isolated from Four Thymus Species against Rhyzopertha dominica (F.)

Although chemical pesticides have been efficiently used to manage insect pest, their overuse has led to environmental contamination and threats to human health, enticing researchers to introduce eco-friendly and effective agents. In this study, the insecticidal effectiveness of essential oils isolated from Thymus species, including T. eriocalyx, T. kotschyanus, T. fallax, and T. vulgaris, was evaluated against the adults of Rhyzopertha dominica. The terpenes p-cymene, 1,8-cineole, linalool, α-terpineol, and carvacrol were the prominent compounds in the hydrodistilled essential oils. All essential oils produced significant fumigant at 24, 48, and 72-exposure times. The energy reserves protein by all essential oils, glycogen by T. kotschyanus and T. vulgaris, and lipid by T. fallax and T. vulgaris were significantly decreased compared to control. All essential oils except T. vulgaris affected the amylolytic and proteolytic activity of the pest. The pest increased the α- and β-esterase enzyme activity in response to the essential oils. Nutritional indices of adults were also affected by essential oils, in which feeding deterrence index was calculated from 20.41% to 61.11%. Accordingly, based on lethal and extensive sub-lethal insecticidal activities, T. eriocalyx, T. kotschyanus, T. fallax, and T. vulgaris essential oils can be considered as efficient agents for R. dominica management.

Encapsulation of Eucalyptus largiflorens Essential Oil by Mesoporous Silicates for Effective Control of the Cowpea Weevil, Callosobruchus maculatus (Fabricius) (Coleoptera: Chrysomelidae)

Although the use of synthetic chemicals is the principal method for insect pest management, their widespread application has led to numerous side effects, including environmental pollution and threats to human and animal health. Plant essential oils have been introduced as promising natural substitutes for synthetic insecticides. However, high volatility and/or low durability are the main limiting factors for essential oil application for control of insect pests. Accordingly, along with an evaluation of the fumigant toxicity of Eucalyptus largiflorens essential oil against the cowpea weevil, Callosobruchus maculatus, essential oil was nanoencapsulated by two mesoporous silicates, MCM-41 and zeolite 3A, to enhance fumigant persistence and toxicity. The chemical profile of essential oil was also analyzed through gas chromatographic-mass spectrometry. E. largiflorens essential oil showed significant concentration-dependent toxicity against insect pests; a concentration of 5.16 μL/L resulted in 100% mortality after 48 h. The toxicity of essential oil could be attributed to the presence of various insecticidal terpenes, such as spathulenol (15.6%), cryptone (7.0%), and 1,8-cineole (5.8%). Fumigant persistence was increased from 6 days to 19 and 17 days for pure and capsulated essential oil with MCM-41 and Zeolite 3A, respectively. The insect mortality also increased from 99 insects in pure essential oil to 178 and 180 insects in MCM-41 and Zeolite 3A encapsulated formulations, respectively. Therefore, the encapsulation of E. largiflorens essential oil by MCM- 41 and Zeolite 3A is a beneficial method for enhancing its persistence and toxicity against C. maculatus.

Promising Insecticidal Efficiency of Essential Oils Isolated from Four Cultivated Eucalyptus Species in Iran against the Lesser Grain Borer, Rhyzopertha dominica (F.)

Simple Summary

Eucalyptus essential oils have shown promising insecticidal effects on several insect pests. The lesser grain borer, Rhyzopertha dominica (F.), causes economically significant damage to stored grains as an internal primary insect pest. In this study, the chemical compositions of essential oils isolated from four Eucalyptus species. E. microtheca, E. procera, E. spatulata, and E. torquata were detected and identified using a gas chromatography-mass spectrometer, and their lethal and sublethal insecticidal effects were evaluated against the adults of R. dominica. Although all essential oils have significant fumigant toxicity, due to the high relative potency, R. dominica was more susceptible to the E. procera essential oil than the others. The total protein, glycogen, and lipid contents and digestive amylase and protease enzyme activities of the treated insects were reduced. The nutritional indices consumption index, relative consumption rate, and relative growth rate were also reduced in the treated adults. The findings of this study reveal that E. microtheca, E. procera, E. spatulata, and E. torquata essential oils can be potentially used for the development of eco-friendly natural agents for the management of R. dominica.

Abstract

The lesser grain borer, Rhyzopertha dominica (F.), causes damage to stored grains resulting in both quantitative and qualitative losses. The use of synthetic fumigants in the management of stored-product pests resulted in undesirable side effects such as environmental contamination and threat to human and animal health. In this study, the lethal and sublethal effects of essential oils from four Eucalyptus species, E. microtheca, E. procera, E. spatulata, and E. torquata were studied against R. dominica adults. Gas chromatographic–mass spectral analysis of the essential oils was carried out, in which terpenes such as 1,8-cineole and globulol were abundant in essential oils. The pest was susceptible to the fumigation of the essential oils and, considering concentrations and exposure times (24, 48, and 72 h), had significant effects on the pest mortality. The total protein, glycogen, and lipid contents and digestive amylolytic and proteolytic activities of the adults treated with tested essential oils were reduced. The consumption index, relative consumption rate, and relative growth rate were also reduced in the treated adults. According to the insecticidal effects on the adults of R. dominica, the essential oils of E. microtheca, E. procera, E. spatulata, and E. torquata can be candidates for further investigations as grain protectant agents.

Evaluation of the Potential of a Lectin Extracted from Polygonum persicaria L. as a Biorational Agent against Sitophilus oryzae L

Rice weevil, Sitophilus oryzae L. (Coleoptera: Curculionidae), is one of the most destructive stored-product pests that is resistant to a wide range of chemical insecticides. In the present study, we investigated whether a lectin extracted from Polygonum persicaria L. (PPA) can be used as a biorational agent to control such insect pests. Along with the lethal digestive assay, the sub-lethal insecticidal activities of PPA, including the effects on digestive, detoxifying, and antioxidant enzyme activities, were evaluated against S. oryzae adults. The effect of feeding a diet containing PPA and carob extract as a food attractant on the mortality of S. oryzae adults was also investigated. Feeding on the diet containing PPA resulted in a significant mortality of S. oryzae adults with a LC₅₀ (Lethal Concentration to kill 50% of insects) of 3.68% (w/w). The activity of digestive enzymes, including α-amylase, α-glucosidase, TAG-lipase, trypsin, chymotrypsin, elastase, and carboxy- and aminopeptidase, were decreased by the sub-lethal concentration of PPA. Detoxifying and antioxidant enzymes, including esterase, superoxide dismutase, catalase, glutathione-S-transferase, ascorbate peroxidase, glucose 6-phosphate dehydrogenase, and malondialdehyde, were activated in adults affected by PPA. These findings indicated that PPA, in addition to causing digestive disorders, leads to oxidative stress in S. oryzae. The presence of carob extract had no effect on the PPA-induced mortality of the insect. According to the results of the present study, PPA has promising insecticidal efficiency against S. oryzae. In addition, the usage of PPA with a food attractant carob extract in bait traps can be recommended as a new biorational formulation in S. oryzae management.

Antifungal activity of TiO2/AgBr nanocomposites on some phytopathogenic fungi

TiO2/AgBr composites were synthesized by a simple ultrasonic strategy. Various instruments such as SEM, EDX, XRD, and FT-IR were exploited to investigate their characteristics. Antifungal activities of the as-obtained samples were assessed through the inactivation of Fusarium graminearum in the spore suspension method and mycelial growth inhibition of F. graminearum, Botrytis cinerea, and Sclerotinia sclerotiorum in the microdilution method. The results represented that the TiO2/AgBr samples possess higher antifungal activities on F. graminearum spores than the pure TiO2. The sample with 20 wt% silver bromide represented the highest inhibitory effect on the growth of F. graminearum so that all fungal spores were degraded in the initial times of the treatment process. The inactivation of fungal spores after 60 min was 35.2%, 97.8%, 98.9%, and 98.7%, in respect, for 5, 10, 20, and 30 weight percent of AgBr in the binary nanocomposites, while the inhibition rate was 13.4% for the pure TiO2. With increasing ultrasound irradiation time for more than 30 min, the inactivation rate constant decreased. It was also found that the antifungal activity of the nanocomposites without calcination was higher than those of the calcined materials. Considering the antifungal potential against phytopathogenic fungi and advantages such as simple synthesis and eco-friendly nature, it seems that TiO2/AgBr nanocomposites can be used instead of synthetic chemicals after additional field investigations and mass production.

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.

High-Pressure Carbon Dioxide Use to Control Dried Apricot Pests, Tribolium castaneum and Rhyzopertha dominica, and Assessing the Qualitative Traits of Dried Pieces of Treated Apricot

One of the new ways of warehouse pest control is the carbon dioxide treatment, which had no residues on the target products. In the present research, at first, CO₂ gas was applied to control two important pest species infesting dried apricots. Dry apricots infested with adults of Tribolium castaneum (Herbst) or Rhyzopertha dominica (F.) were exposed to CO₂ gas pressures correspond to 9.1, 16.7, 23.1, 28.6, and 33.4 mol% for 24 h. The results showed higher mortality rates with increasing the gas pressures in all the experiments. The minimum and maximum losses of the pests were determined at concentrations of 9.1 and 33.4 mol%, respectively. Evaluation of CO₂ gas effects on the quality characteristics of dried apricots showed no impacts on the color, brittleness, hardness, sweetness, sourness, and general acceptance of products. CO₂ gas treatments at the concentration of 33.4 mol% showed no significant influences on the chemical features of dried apricots, including pH, acidity, Brix, humidity percentage, reducing sugar, and total sugar. It was concluded that CO₂ gas had the potential to control T. castaneum and R. dominica in warehouses of dried apricots, without any significant impacts on product qualities.

Mulberry Protection through Flowering-Stage Essential Oil of Artemisia annua against the Lesser Mulberry Pyralid, Glyphodes pyloalis Walker

In the present study, the toxicity and physiological disorders of the essential oil isolated from Artemisia annua flowers were assessed against one of the main insect pests of mulberry, Glyphodes pyloalis Walker, announcing one of the safe and effective alternatives to synthetic pesticides. The LC₅₀ (lethal concentration to kill 50% of tested insects) values of the oral and fumigant bioassays of A. annua essential oil were 1.204 % W/V and 3.343 μL/L air, respectively. The A. annua essential oil, rich in camphor, artemisia ketone, β-selinene, pinocarvone, 1,8-cineole, and α-pinene, caused a significant reduction in digestive and detoxifying enzyme activity of G. pyloalis larvae. The contents of protein, glucose, and triglyceride were also reduced in the treated larvae by oral and fumigant treatments. The immune system in treated larvae was weakened after both oral and fumigation applications compared to the control groups. Histological studies on the midgut and ovaries showed that A. annua essential oil caused an obvious change in the distribution of the principal cells of tissues and reduction in yolk spheres in oocytes. Therefore, it is suggested that the essential oil from A. annua flowers, with wide-range bio-effects on G. pyloalis, be used as an available, safe, effective insecticide in the protection of mulberry.

Toxicity and deleterious effects of Artemisia annua essential oil extracts on mulberry pyralid (Glyphodes pyloalis)

Botanical extracts are an important source of bio-pesticides and are generally considered safe to the environment. Artemisia annua L, a medicinal plant, well known for its antimalarial potential, was evaluated as a source of a type of essential oil collected during vegetative growth stage against Glyphodes pyloalis Walker. The main chemical components of the essential oil at vegetative stage of Artemisia annua was analyzed by GC- MS and contained 1,8-cineole (18.68%), Camphor (11.4%), α-Pinene (9.3%) and 3-Carene (6.3%). The LC₅₀ of this plant oil was estimated to be 0.652% W/V and 2.585 μL/L air incorporated orally and fumigation, respectively. The digestive enzymes such as α-amylases, Proteases, Lipases and α- and β-glucosidases were considereably inhibited in treated larvae compared with controls. Similarly, the amount of protein, glucose, and triglyceride were decreased in the treated larvae by methods used. The lower hemocyte numbers, nodule formation and activity of phenoloxidases after injection of Beauveria bassiana and latex beads showed its EO effect on immunity. The anatomy of the larval midgut after treatment showed degeneration in digestive cells. Emerging adult's ovaries showed significant changes in the ovarian sheath and lack of yolk spheres. The present investigation in accordance with our previous studies may ultimately lead to a formulation in controlling this notorious pest especially in mulberry orchards where the use of conventional chemicals is restricted.

Analysis of the Essential Oils of Eucalyptus camaldulensis Dehnh. and E. viminalis Labill. as a Contribution to Fortify Their Insecticidal Application

The use of synthetic chemicals, with harmful effects on the environment and human health, is the principal strategy in the management of stored-product insect pests such as Oryzaephilus surinamensis and Sitophilus oryzae. Various studies in recent years have highlighted the possibility of using plant essential oils as available and low-risk factors in insect pest management. Therefore, in the present study, the possibility of controlling O. surinamensis and S. oryzae was investigated using Eucalyptus camaldulensis and Eucalyptus viminalis leaf essential oils. The essential oils were obtained by hydrodistillation of the leaves of the 2 Eucalyptus species, and the chemical compositions were determined by gas chromatographic-mass spectral analysis. The essential oil of E. camaldulensis was dominated by p-cymene (24.8%), cryptone (18.9%), and spathulenol (12.4%), while the major components in E. viminalis essential oil were 1,8-cineole (51.6%) and α-pinene (15.8%). The essential oils displayed promising fumigant toxicity against insect pests, which was positively dependent on utilized concentrations and exposure times. Oryzaephilus surinamensis, with low median lethal concentrations, was more susceptible than S. oryzae to the essential oils after 24, 48, and 72 hours. Also, E. viminalis essential oil, with a high level of insecticidal monoterpenes such as 1,8-cineole and α-pinene, was more toxic to insect pests than E. camaldulensis oil. According to the results of the current study, E. camaldulensis and E. viminalis essential oils, rich in insecticidal terpenes, can be alternative candidates to synthetic chemicals in the management of O. surinamensis and S. oryzae.

Evaluation of the Toxicity of Satureja intermedia C. A. Mey Essential Oil to Storage and Greenhouse Insect Pests and a Predator Ladybird

The use of chemical insecticides has had several side-effects, such as environmental contamination, foodborne residues, and human health threats. The utilization of plant-derived essential oils as efficient bio-rational agents has been acknowledged in pest management strategies. In the present study, the fumigant toxicity of essential oil isolated from Satureja intermedia was assessed against cosmopolitan stored-product insect pests: Trogoderma granarium Everts (khapra beetle), Rhyzopertha dominica (Fabricius) (lesser grain borer), Tribolium castaneum (Herbst) (red flour beetle), and Oryzaephilus surinamensis (L.) (saw-toothed grain beetle). The essential oil had significant fumigant toxicity against tested insects, which positively depended on essential oil concentrations and the exposure times. Comparative contact toxicity of S. intermedia essential oil was measured against Aphis nerii Boyer de Fonscolombe (oleander aphid) and its predator Coccinella septempunctata L. (seven-spot ladybird). Adult females of A. nerii were more susceptible to the contact toxicity than the C. septempunctata adults. The dominant compounds in the essential oil of S. intermedia were thymol (48.1%), carvacrol (11.8%), p-cymene (8.1%), and γ-terpinene (8.1%). The high fumigant toxicity against four major stored-product insect pests, the significant aphidicidal effect on A. nerii, and relative safety to the general predator C. septempunctata make terpene-rich S. intermedia essential oil a potential candidate for use as a plant-based alternative to the detrimental synthetic insecticides.

Essential Oils Extracted from Different Species of the Lamiaceae Plant Family as Prospective Bioagents against Several Detrimental Pests

On the basis of the side effects of detrimental synthetic chemicals, introducing healthy, available, and effective bioagents for pest management is critical. Due to this circumstance, several studies have been conducted that evaluate the pesticidal potency of plant-derived essential oils. This review presents the pesticidal efficiency of essential oils isolated from different genera of the Lamiaceae family including Agastache Gronovius, Hyptis Jacquin, Lavandula L., Lepechinia Willdenow, Mentha L., Melissa L., Ocimum L., Origanum L., Perilla L., Perovskia Kar., Phlomis L., Rosmarinus L., Salvia L., Satureja L., Teucrium L., Thymus L., Zataria Boissier, and Zhumeria Rech. Along with acute toxicity, the sublethal effects were illustrated such as repellency, antifeedant activity, and adverse effects on the protein, lipid, and carbohydrate contents, and on the esterase and glutathione S-transferase enzymes. Chemical profiles of the introduced essential oils and the pesticidal effects of their main components have also been documented including terpenes (hydrocarbon monoterpene, monoterpenoid, hydrocarbon sesquiterpene, and sesquiterpenoid) and aliphatic phenylpropanoid. Consequently, the essential oils of the Lamiaceae plant family and their main components, especially monoterpenoid ones with several bioeffects and multiple modes of action against different groups of damaging insects and mites, are considered to be safe, available, and efficient alternatives to the harmful synthetic pesticides.

Tritrophic Interactions of Cucumber Cultivar, Aphis gossypii (Hemiptera: Aphididae), and Its Predator Hippodamia variegata (Coleoptera: Coccinellidae)

The melon aphid, Aphis gossypii Glover, is a cosmopolitan pest that infests and damages a wide range of crop plants, especially cucurbits. It is a host of the coccinellid predator, Hippodamia variegata (Goeze), that has the potential to suppress the pest on leaves of cucumber plants grown in greenhouses. Melon aphids were reared on either Storm or Khasib cucumber cultivars to determine whether there would be a difference in their development and reproduction. The aphids from each cultivar were fed to H. variegata adults to assess their effects on the life history of the predator. The aphid population reared on Khasib leaves increased faster than the population on Storm leaves; however, the predators fed aphids from Storm leaves had a higher rate of population growth. Thus, the intrinsic rate of increase and net reproductive rate were greater for aphids reared on Khasib leaves but lower for H. variegata fed those aphids compared with aphids reared on the Storm cultivar. Additionally, clean and aphid-infested leaves from both cultivars were analyzed for total flavonoids, phenol, and chlorophyll, and the density of leaf trichomes was measured. The Storm leaves contained higher amounts of flavonoids and phenol, less chlorophyll, and a greater density of trichomes. Regardless of cucurbit cultivar, aphid feeding increased the flavonoids and phenol content and decreased the amount of chlorophyll.

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.

Separate and Combined Effects of Mentha piperata and Mentha pulegium Essential Oils and a Pathogenic Fungus Lecanicillium muscarium Against Aphis gossypii (Hemiptera: Aphididae)

In the present study, the toxicity of essential oils of Mentha piperata L. and Mentha pulegium L. and pathogenicity of Lecanicillium muscarium (Zare & Gams) were studied in the melon aphid, Aphis gossypii Glover. Analyses of the essential oils by GC-MS indicated limonene (27.28%), menthol (24.71%), menthone (14.01%), and carvol (8.46%) in the M. piperata essential oil and pulegone (73.44%), piperitenone (5.49%), decane (4.99%), and limonene (3.07%) in the essential oil of M. pulegium as the main components. Both essential oils and the pathogenic fungus had useful toxicity against A. gossypii. Probit analysis indicated LC50 values (lethal concentrations to kill 50% of population; 95% confidence limits in parentheses) of M. piperata and M. pulegium essential oils as 15.25 (12.25-19.56) and 23.13 (19.27-28.42) µl/liter air, respectively. Susceptibility to the pathogenic fungus increased with exposure time. Aphid mortality also increased when the essential oils were combined with L. muscarium, although the phenomena was additive rather than synergistic. Mycelial growth inhibition of L. muscarium exposed to the essential oils was also very low. Based on our results, M. piperata and M. pulegium essential oils and the pathogenic fungus L. muscarium have some potential for management of A. gossypii.

Acaricidal Potentials of the Terpene-rich Essential Oils of Two Iranian Eucalyptus Species against Tetranychus urticae Koch

There is a rapid growth in the screening of plant materials for finding new bio-pesticides. In the present study, the essential oils of E. oleosa and E. torquata leaves were extracted using a Clevenger apparatus and their chemical profiles were investigated by Gas Chromatography-Mass Spectrometry (GC-MS). Among identified compounds, the terpenes had highest amount for both essential oils; 93.59% for E. oleosa and 97.69% for E. torquata. 1,8-Cineole (31.96%), α-pinene (15.25%) and trans-anethole (7.32%) in the essential oil of E. oleosa and 1,8-cineole (28.57%), α-pinene (15.74%) and globulol (13.11%) in the E. torquata essential oil were identified as the main components. The acaricidal activity of the essential oils of E. oleosa and E. torquata were examined using fumigation methods against the adult females of Tetranychus urticae Koch. The essential oils have potential acaricidal effects on T. urticae. The essential oil of E. oleosa with LC₅₀ value of 2.42 µL/L air was stronger than E. torquata. A correlation between log concentration and mite mortality has been observed. Based on the results of present study, it can be stated that the essential oils of E. oleosa and E. torquata have a worthy potential in the management of T. urticae.