فصلنامه تحقیقات حشره شناسی
سال سیزدهم شماره 2 (پیاپی 50، تابستان 1400)

Nowadays, extensive research is being done on plant compounds to find safer and low-risk alternative for controlling pests. In this study, two formulations, containing Artemisia sieberi Besser essential oil based on biodegradable polymers were prepared as powders to control the rice weevil, Sitophilus oryzae. These formulations were different in the amounts and types of polymers and surfactants. The repellency effect of these formulations and A. sieberi oil was compared at two sublethal concentrations of 5 and 10 µI/I air. The surface morphology of powders was also studied by the transmission electron microscope (TEM). The average size of particles was measured about 41.19 and 37.86 nm for formulations 1 and 2, respectively, using the software Image j. The result shows that, after 96 hours, the percentage of repellency in essential oil, formulation 1 and formulation 2 for 5 ppm concentration is calculated 45%, 65% and 70% respectively, and for 10 ppm concentration it is calculated 55%, 70% and 75% respectively. Also, the repellency effects of normal essential oil and the formulations prepared at different times showed that with increasing the concentration of all compounds, the amount of repellency increases. Based on the results, to maintain the biological activity of essential oils and prevent the evaporation of their constituents, it is necessary to formulate essential oils, therefore encapsulation of plant essential oils as a safe pesticide with gradual release and maintenance of fumigant toxicity can be considered in integrated pest management.

A Quantitative Structure–Activity Relationship (QSAR) study based on Genetic Algorithm  Multiple Linear Regressions (GA-MLR) were carried out for the prediction of the toxicity (logIC50) and the logarithm of octanol-water partition coefficient (logPow) of some carbamate derivatives as insecticides. The optimized conformation of compounds were obtained at HF/6-31G* level with Gaussian 98 software. Dragon software is used to calculate molecular descriptors. A data set of these compounds was randomly divided into 2 groups: training and test sets. The QSAR models were optimized using multiple linear regressions (MLR).The most relevant molecular descriptors were collected by Genetic Algorithm (GA) and backward regression. The best GA-MLR models are obtained using statistical parameters, such as squared correlation coefficient (R2), adjusted squared correlation coefficient (R2adj), root mean square error (RMSE) values for training and test sets. The best QSAR models are obtained based on the statistical parameters Leave-one-out (LOO) cross-validation, external test set, external validation parameters (Q2F1, Q2F2, Q2F3) and the concordance correlation coefficient (CCC) were used to quantify the predictive ability of GA-MLR models. The results showed that GA-MLR models could be used to predict the activities of carbamate derivatives.

Pistachio is one of the most important agricultural products of the country.  It is extremely important and accounts for about 81 percent of the country's non-oil revenues. In this study, the degradation of two pesticides, metacystox and fenitrithion was investigated by ultraviolet radiation. These three pesticides are commonly used in a wide range in pistachio gardens in the country. One of the most important agricultural and plant protection tasks is to produce safe crops with residual pesticides below the MRL level. The aim of this study was to investigate the effect of UV radiation combined with the photocatalytic effect of titanium dioxide and hydrogen peroxide on the degradation of these two pesticides in pistachio products.The samples were extracted by LLE method and determinated by GC-MS. Exposur times were 30, 60,120 and 300 minutes.The results showed that the highest percentage of degradation of pesticides was related to metasystox and affected by uv / H2O2 at 38.5%. The optimum time in all trials was 300 min. UV irradiation alone at 300 min time on metasistox and fenitrothion in pistachio reduced the toxin by 24/2and 17/1, respectively.Experiments showed that degradation of the studied toxins was possible using UV irradiation and the destructive effect of UV on chemical structures was proved in experiments. Therefore, UV radiation in a specific dose can remove residues of pistachio pesticides. Combined with UV agents, hydrogen peroxide and titanium dioxide can more effectively remove contamination from agricultural products.

Bemisia tabaci (Gennadius.) (Homoptera: Aleyrodidae) is one of the most important pests of crops, greenhouses, and ornamental plants. In this study, the sub-lethal effect of Teucrium polium(Lamark)(Lamiales:Lamiaceae) on parameters of life table age- bisexual stage of B. tabaci (Gennadius.) was evaluated on the sensitive cultivar ( Ergon) and resistant cultivar (Cal-JN3) of Lycopersicon esculentum . 2-4 leaves seedlings of L. esculentum from sensitive and resistant cultivar were submerged in methanol extract of T. polium and water+ methanol (control) and were placed in cup cages. 30 imago insects of the same age were released in the cup cage and after 24 hours the imago insects were omitted and the eggs whose age was less than 24 hours were kept. The sexuality of the imago insects exiting these eggs exposed to the contaminated plant was determined and the rate of spawning of the female insect was daily recorded to the last day of its life. The experiment was investigated in a glass greenhouse and 27+ 2  temperature and relative moisture of 50 ± 5 and in lighting conditions of 16 hours of light and 8 hours of darkness. The results showed that there is a significant difference in the one percent level. The intrinsic value of population increase, reproduction gross rate, and reproduction net rate on the sensitive cultivar (Ergon) and resistant cultivar (cal-JN3) of the L. esculentum treated with T. polium L. was acquired 0.069, 31/43 and 11.03 and 0.061, 18.51 and 6.66 respectively.  Generally, in this study conjugate application of resistant plant cultivar and extract caused more loss and considerable reduction of the intrinsic rate of population increase comparing other treatments which subsequently lower the population of B. tabaci. So, the combined application of using resistant cultivar and the herbal extract is considerable in the population control of this pest.

The cotton Whitefly is one of the most important pests in crops, greenhouses and ornamental plants. Due to the multiplicity of generations and the short time of one generation, this pest has the potential to be resistant to various insecticides. Over the years, control of cotton whitefly by common insecticides has not been effective. In this study, the susceptibility of adult whitefly to Dichlorvos, Imidacloprid, Spinozad and Chlorantranilpyrrol alone and pre-treated with PBO (Pyrphenyl butoxide), TPP (triniphenyl phosphate) and DEM (MEM) synergists was investigated. . Leaf dipping method was used for bioassay. The lowest level of LC50 on adults was related to the insecticide Chlorantranilpyrrole (1.25 mg a.i / L) and the highest level of LC50 was related to the Dichlorvos (269.59 mg (a.i / L)). The levels of LC50 Spinozad and Imidacloprid (mg a.i / L) were estimated to be 3.22, 87.61, respectively. The interaction of  Dichlorvos, Imidacloprid, Spinozad and Chlorantranilpyrrol with synergistic pre-treatments showed an  increase in efficacy of insecticieds so that with TPP The LC50was 2.35, 3.89, 2.36 and 1.68, respectively. The interaction between DEM and Imidacloprid, Spinozad and Chlorantranilpyrol increased mortality to 2.84, 4.79, 3.15 and 1.71mg ai.l. respectively. Resistance to Diclorus and Imidacloprid observed in this study is likely to be due to overuse of these pesticides. To prevent resistance, it is recommended to apply these pesticides inside the frame of pest manangment program

Residues of chemical pesticides in agricultural products have always been a concern for food health experts. In this study, 15 cucumber plants were sprayed with a concentration equal to the recommended dose (25 grams per liter for Acetamiprid and 2 ml/ liter for Dichlorvos) and twice the recommended doses. After 24 hours, the residue in cucumbers twice the recommended doses was 1.5 mg/kg for Acetamiprid and 0.5 mg/kg for Dichlorvos. Then, to investigate the biochemical effect of these amounts of residues, 60 mice were selected which 20 of them were divided into four groups. Consisted of the control group and groups 1, 2 and 3. The control group received only pure water but each group of 1 and 2 received 0.5 mg/kg Dichlorvos and 1.5 mg/kg Acetamiprid, respectively. The group 3 received one dose of both pesticides in drinking water.The results showed that, these pesticides reduced the blood Albumin significantly (Control 2.96, Acetamiprid 2.00, Dichlorvos 1.86 and the mix 1.6 g/dl). The ratio of Albumin to Globulin was 0.96 for control, and 0.68, 0.06, 0.55 g/dl for groups of 1, 2, and 3 respectively. Total protein 6.06 for control, and 4.92, 4.98, 4.48 g/dl for groups of 1, 2, 3 respectively. Also the weight loss was 8.8, Dichlorvos 0.0, Acetamiprid -0.8 and Mix -0.8g and food consumption weight loss was 666.2, Dichlorvos 372.4, Acetamiprid 392.0 and Mix 356.2g and cause changes in fertility and Follicle-stimulating hormone, Luteinizing hormone levels as well as Testosterone hormone. It can be stated that adding these pesticides to drinking water of laboratory mice can cause liver and kidney disorders, immunocompromised, and primary testicular defect, which is recommended that Monitoring programs should be performed continuously to assess the presence of pesticides in food.