Terpene Rich Essential Oil of Dracocephalum kotschyi Boiss as Efficient Alternative to Synthetic Chemicals in Management of Callosobruchus maculatus Fabricius

The application of plant-derived essential oils has been revealed to proficiently insect pest control agents, meaningfully decreasing the side-effects caused by chemical insecticides. In the present study, the toxicity of essential oil isolated from Dracocephalum kotschyi has been assessed against cowpea weevil (Callosobruchus maculatus Fabricius) as one of the most damaging and cosmopolitan insect pest of stored beans. The other objective of current study was to identify the chemical composition of D. kotschyi essential oil as one of the medicinal plants endemic to Iran. Bioassays results revealed sound fumigant toxicity of essential oil, in which a concentration of 16.41 μl/l produced up to 50% insect mortality after 72 h. Increases in concentrations of the essential oil and exposure times augmented the insect susceptibility so that the highest mortality (96.25%) was achieved at a highest tested concentration (44.12 μl/l) after 72 h. A concentration of 44.12 μl/l was enough to achieve the 50% mortality of tested insects within 10.761 h. The 24 h-LC50 value of essential oil was 24.947 μl/l which decreased to 17.794 μl/l after 72 h. Gas chromatography-mass spectrometry (GC-MS) analysis of the essential oil exposed terpenes including geranyl acetate, citral, z-citral, methyl geranate, limonene, α-pinene and α-campholenal were the main components. Based on the results of present study, the terpene rich essential oil of D. kotschyi may be  considered as promising alternative to the synthetic chemicals for C. maculatus management. Keywords: Callosobruchus maculatus, chemical profile, essential oil, Dracocephalum kotschyi, toxicity

Modeling of the toxicity of Eucalyptus globulus Labill essential oil against red flour beetle, Tribolium castaneum Herbst

Although the application of synthetic chemicals is the main method in the management of insect pests, their overuse has led to public concerns about environmental pollution, threats to human health, and acute and chronic toxicity on non-target organisms. Plant essential oils have introduced as healthy, available, and effective alternatives to detrimental chemicals in recent years. Further, it is necessary to predict the exact amount of required pesticide to save costs and determine the optimal conditions for achievement to the best outcomes. Accordingly, the toxicity of Eucalyptus globulus Labill essential oil against the adults of a cosmopolitan pest Tribolium castaneum Herbst (red flour beetle) along with its modeling and optimization was assessed using Response Surface Methodology (RSM). The coefficients of the essential oil concentration and time as independent variables are positive, showing their increase results in the augmentation of insect pest mortality. E. globulus essential oil showed prospective concentration-time dependent fumigant toxicity against T. castaneum. A quadratic polynomial equation was achieved for the toxicity of E. globulus essential oil using multiple regression analysis: 7.33413 + 0.20191A + 0.47313B + 4.64054E-003AB + 0.016349B2, in which A and B are the exposure time and essential oil concentration. The accuracy of the introduced model was approved through the analysis of variance. Results of the optimization indicated that 45.50 μl/l of essential oil and 72.00 h-exposure time would be adequate to achieve 92.45% mortality of T. castaneum. According to the results of current study, E. globulus essential oil has high potential in the management of T. castaneum and the Response Surface Methodology (RSM) is a suitable method to the optimization and modelling of this bio-effect

Optimization of the antifungal activity of essential oil isolated from aerial parts of Thymus kotschyanus Boiss & Hohen (Lamiaceae)

Although utilization of synthetic chemicals is inevitable for management of economically detrimental agents, numerous side-effects such as environmental contaminations and effects of non-target organisms associated with them. Plant essential oils with low/without toxicity on mammals and as bio-degradable natural materials have been considered for different pests and fungi management in the recent years. In the present study, the essential oil of Thymus kotschyanus isolated by a Clevenger apparatus and its mycelial growth inhibition was measured against two phytopathogenic fungi Botrytis cinerea and Fusarium graminearum. The best models for predicting of antifungal effects were quadratic models. The essential oil showed a prospective mycelial growth inhibition against both phytopathogenic fungi. Optimization of the antifungal effects indicated that 206.207 ppm of the essential oil caused 50% mycelial growth inhibition of B. cinerea after 89.651 h. This value was 85.600 ppm for F. graminearum within 117.194 h. Results of the present study designated a great potential of T. kotschyanus essential oil for management of pathogenic fungi B. cinerea and F. graminearum.Keywords: Essential oil, mycelial growth inhibition, response surface, Thymus kotschyanu

Modeling of the Toxicity of Eucalyptus globulus Labill Essential Oil against Red Flour Beetle, Tribolium castaneum Herbst

Although the application of synthetic chemicals is the main method in the management of insect pests, their overuse has led to public concerns about environmental pollution, threats to human health, and acute and chronic toxicity on non-target organisms. Plant essential oils have introduced as healthy, available, and effective alternatives to detrimental chemicals in recent years. Further, it is necessary to predict the exact amount of required pesticide to save costs and determine the optimal conditions for achievement to the best outcomes. Accordingly, the toxicity of Eucalyptus globulus Labill essential oil against the adults of a cosmopolitan pest Tribolium castaneum Herbst (red flour beetle) along with its modeling and optimization was assessed using Response Surface Methodology (RSM). The coefficients of the essential oil concentration and time as independent variables are positive, showing their increase results in the augmentation of insect pest mortality. E. globulus essential oil showed prospective concentration-time dependent fumigant toxicity against T. castaneum. A quadratic polynomial equation was achieved for the toxicity of E. globulus essential oil using multiple regression analysis: 7.33413 + 0.20191A + 0.47313B + 4.64054E-003AB + 0.016349B2, in which A and B are the exposure time and essential oil concentration. The accuracy of the introduced model was approved through the analysis of variance. Results of the optimization indicated that 45.50 \u3bcl/l of essential oil and 72.00 h-exposure time would be adequate to achieve 92.45% mortality of T. castaneum. According to the results of current study, E. globulus essential oil has high potential in the management of T. castaneum and the Response Surface Methodology (RSM) is a suitable method to the optimization and modelling of this bio-effect

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

Evaluation of the Insecticidal Activities of Three Eucalyptus Species Cultivated in Iran, Against Hyphantria Cunea Drury (Lepidoptera: Arctiidae)

In the current study, the larvicidal activity of leaf essential oils from three eucalyptus species (Eucalyptus largiflorens Meull, Eucalyptus oleosa Meull, and Eucalyptus spathulata Hook) against American white moth, Hyphantria cunea Drury 1773 (Lepidoptera: Arctiidae), was investigated. Mortality was recorded daily for three days after treatment. Leaf disc bioassays revealed that all three oils had strong insecticidal activity on the experimental insects insofar as 50% lethal concentrations (LC50) for E. oleosa, E. spathulata, and E. largiflorens at 24 h exposure time were 0.36, 0.61, and 1.24%, respectively. The time needed to kill 50% (LT50) values were calculated as 9.09 h with E. largiflorens, 11.03 h with E. oleosa, and 13.03 h with E. spathulata at the highest concentrations (2.5% for E. largiflorens, 2% for E. oleosa, and 2.5% for E. spathulata). Based on probit analysis, an increase in the susceptibility of the insect was associated with an increase in the different concentrations of all oils and the increase in the time of exposure. The results of this study show that leaf essential oils of E. largiflorens, E. oleosa, and E. spathulata might be considered as a potent source for the production of fine natural larvicides

Evaluation of the hepatoprotective effects of curcumin and nanocurcumin against paraquat-induced liver injury in rats: Modulation of oxidative stress and Nrf2 pathway

Paraquat (PQ) is a widely used herbicide all over the world, which is highly toxic for animals and humans. Its cytotoxicity is based on reactive radical generation. The aim of this study is to evaluate and compare the hepatoprotective effects of curcumin and nanocurcumin against liver damage caused by sub-acute exposure with PQ via modulation of oxidative stress and genes expression of nuclear factor erythroid 2-related factor 2 (Nrf2) pathway. Rats were exposed to PQ (5 mg/kg/day, orally) + curcumin or nanocurcumin (100 mg/kg/day, orally) for 7 days. Then rats were anesthetized and serum and liver samples were collected. Next, serum enzymatic activities, liver histopathology, oxidative stress, and expression of genes involved in Nrf2 signaling pathway were assessed by biochemical and enzyme-linked immunosorbent assay methods, hematoxylin and eosin staining, and real-time polymerase chain reaction analysis. PQ significantly increased malondialdehyde, alanine transaminase, aspartate aminotransferase, alkaline phosphatase levels, and Kelch-like ECH-associated protein 1 gene expression and also decreased total antioxidant capacity, total thiol group levels, Glutathione S-transferases, heme oxygenase 1, Nrf2, and NAD(P)H:quinone oxidoreductase 1 genes expression, causing histological damages to liver tissue. These changes were significantly modulated by curcumin and nanocurcumin treatments. Our findings showed that nanocurcumin had better hepatoprotective effect than curcumin in liver damage after PQ exposure most likely through modulation of oxidative stress and genes expression of Nrf2 pathway. © 2021 Wiley Periodicals LL