Phytoallexins

Abstract The effects of temperature on the biological parameters of T. urticae were evaluated at six constant temperatures: 12.5, 15, 20, 25, 30, and C, with relative humidity maintained at and a photoperiod of 16:8 h (L:D). Experiments were conducted using the leaf-disc method in a completely randomized design. Leaf discs were cut from fresh cucumber or squash leaves and placed on a moist cotton layer inside disposable plastic Petri dishes. A narrow strip of cotton was placed around each leaf disc to prevent mite escape. One freshly laid egg of the same age was transferred to the center of each disc using a fine brush. Leaf discs were replaced weekly to maintain leaf freshness and avoid nutritional degradation.

Abstract Introduction: Aphis gossypii Glover (Hemiptera: Aphididae) is one of the most important pests of agriculture worldwide. To control the pest population, research on the use of the environmental and plant-based compounds has increased in recent decades. Essential oils due to volatility and very short-term persistence in the environment, as biocompatible pesticides can be considered as one of the best alternatives to chemical pesticides in aphid's control. Materials and Methods: In the current study, phytochemical and insecticidal toxicity of the essential oil from Avishan-e-denaii, Thymus daenensis Celak. (Lamiaceae) was studied against the melon aphid, Aphis gossypii Glover. in the laboratory conditions under 25±2°C, 60±5% RH and 16L:8D photoperiods. The essential oil was obtained by hydrodistillation method, using a modified Clevenger-type apparatus. Mortality was evaluated at different concentrations that ranging from 0.1 to 0.9 µL/150 ml air, and with three replications at the interim of 24 hours. Also nymph production deterrent effect of the oil at sublethal concentration was studied against parthenogenesis form of aphid. Results and Discussion: Results indicated that essential oil of T. daenensis is toxic to the A. gossypii. The major components in the oil were 3-Methyl-4-isopropylphenol (26.94%), Thymol (22.40%), P-Cymene (13.81%), γ-Terpinene (6.74%), Borneol (5.24%) and Linalool (4.31%). Probit analysis showed that the LC₅₀ values for nymphs and adults of A. gossypii were 0.0087 and 0.0016 µl/150 ml air, respectively. Also, degree of nymph production deterrent effect was calculated for essential oil of T. daenensis as 46.49 ± 4.71%. Conclusion: The overall results showed that the Avishan-e-denaii essential oil has high potential in controlling the melon aphid especially in protected areas such as geenhouses.  

Abstract Introduction: The use of plant pesticides in pest control has become necessary due to the expansion of the use of chemical pesticides that has led to environmental damage. Extracts obtained from plants, which are mainly extracted from natural sources and different parts of plants, have been considered as a natural and efficient alternative to replace chemical pesticides. One of the obvious advantages of plant pesticides is high biological degradability and less toxic effects on non-target organisms and plants. High biodegradability means the ability of these materials to be broken down and transformed into harmless materials by microorganisms and natural environmental processes. Plant pesticides usually contain compounds that are produced through natural processes in plants and are responsible for defending the plant against pests. The expansion of the use of plant pesticides is not only due to their efficiency in pest control but also due to their compatibility with the principles of sustainable agriculture and the protection of biological diversity. Materials and Methods: In this study, effects of concentrations of (5%, 15% and 30% of Punica granatum) and concentrations of (5%, 10% and 20% of Juglans regia extract) on Galleria mellonella were studied. For this purpose, one microliter of the desired concentration was injected to the abdominal wall of the larva, and then one of the second abdominal pair’s legs was cut, and the extracted hemolymph of the leg was studied and blood cells were counted. In addition, concentrations of 5%, 10%, 15% and 20% of extracts were evaluated to determine the degree of repellency by using an olfectometer tube and concentrations of (100, 170, 200, 300 and 400 μl) of Juglans regia extract and concentrations (500, 700, 900 and 1000 μl) of Punica granatum extract was studied to determine the fumigant toxicity. Results and Discussion: The results showed that the highest amount of repellency for J. regia extract and P. granatum extract was obtained at 20% concentration and created 12 hours and 18 hours after treatment, respectively. In addition, the results showed that the fumigant toxicity of J. regia extract was much higher than that of P. granatum extract for G. mellonella.  Also, the total number of blood cells and plasmatocytes after injection of J. regia extract and the number of granulocytes and the total number of cells after injection of P. granatum extract decreased with increasing concentrations and the number of granulocyte cells after injection of J. regia extract as well as the number of plasmutocytes after injection of P. granatum extract had a different process. 

Abstract Introduction: The tomato leaf miner moth, Tuta absoluta (Povolny) (Lep.: Gelechiidae), is one of the most significant pests of tomato, posing a serious threat to tomato production in Iran. One of the main tools for managing this pest is the use of chemical insecticides; however, excessive reliance on chemical insecticides quickly leads to the development of resistance in the pest. The use of essential oils and plant extracts in pest control is a suitable method for reducing the environmental side effects of chemical insecticides. Materials and Methods: The contact toxicity of bitter olive oil extract was evaluated on the egg, second instar larva, and pupa stages. The plant extract was obtained using hexane as a solvent. All experiments were conducted at a temperature of 27 ± 2°C, relative humidity of 65 ± 5%, and a photoperiod of 16 hours light and 8 hours dark. The chemical compounds of the extract were identified using a GC/MS device. Results and Discussion: In the chinaberry extract, the major chemical constituents were methyl linoleate (69.375%), methyl oleate (17.231%), and methyl palmitate (7.361%). The results showed that increasing the concentration of the extract led to higher mortality rates in the egg, second instar larva, and pupa stages of the pest. Probit analysis of the data revealed that the LC₅₀ values of the bitter olive extract for the egg, second instar larva, and pupa stages were 948.93, 346.72, and 1.75 µL/mL, respectively. Conclusion: The results indicated that this extract has high potential for controlling the tomato leaf miner moth (Tuta absoluta) in both open-field and greenhouse environments, and is recommended for protecting the environment and user health.

Abstract Conducted in 2023 at Shahed University's Horticulture Laboratory, Tehran, Iran, the experiment used mature D. lotus seeds from Taleghan, sterilized with 1% sodium hypochlorite for 10 minutes, and rinsed. Treatments: 0 mM (control), 25 mM, 50 mM, 100 mM, 200 mM NaCl. Seeds (20/replicate) in 15-cm Petri dishes with Whatman No. 1 filter paper, moistened with 10 mL solution, incubated at 25 ± 2°C, 70 ± 5% RH, 16/8-hour light/dark for 21 days. Solutions refreshed bi-daily. Completely randomized design, three replicates. Parameters: Germination percentage (14 days, radicle emergence); growth traits (leaf, stem, root lengths on 10 seedlings via digital caliper); seedling fresh/dry weights (dried 70°C, 48 hours); electrolyte leakage (conductivity pre/post 95°C heat, (C1/C2) × 100); chlorophyll content (SPAD-502 on three leaves); chlorophyll fluorescence (F0, Fm, Fv/Fm via PAM-2500 after 20-min dark adaptation). Data normalized, ANOVA via SAS 9.3; means compared by Duncan's test (P ≤ 0.05); graphs in Excel 2021.

Abstract This study was conducted to evaluate the effects of five different host plant species—Alhagi maurorum, Prosopis farcta, Amaranthus retroflexus, Lactuca serriola, and Conyza canadensis —on the morphological traits, seed yield, and accumulation of key phytochemicals in C. epithymum. The experiment was carried out in a randomized complete block design with three replications under field conditions at Shahed University’s medicinal plants research farm (Tehran, Iran).

Abstract This paper is structured as a systematic literature review. A thorough search was conducted across major international scientific databases including Web of Science, Scopus, PubMed, ScienceDirect, and Google Scholar using key terms such as Pyrethrum, Pyrethrins, Pyrethrin biosynthesis, HPLC analysis of pyrethrins, LC–MS/MS pyrethrins, and botanical insecticides. The search spanned publications from 1970 to 2025, with particular emphasis on analytical advancements in the last decade. Peer-reviewed research articles, review papers, book chapters, and reports from authoritative bodies like the WHO and FAO were critically evaluated. The focus was on integrating current knowledge regarding the chemical profile of pyrethrins, their biosynthetic pathways, the impact of environmental and genetic variables on accumulation, extraction methods (both classical and modern), and validated analytical techniques especially high-performance liquid chromatography (HPLC) and liquid chromatography–tandem mass spectrometry (LC–MS/MS) used for quality control and residue monitoring.