فهرست مطالب alireza bandani

The two-spotted spider mite, Tetranychus urticae</em>, is a major pest of crops and ornamental plants worldwide. It is a highly polyphagous pest that has a notorious reputation for its ability to rapidly develop resistance to commonly used pesticides. Thus, in the current study, the contact toxicity of propargite (EC 57%) and chlorpyrifos (EC 40.8%) was investigated against two populations of T. urticae</em> from Iran, Mahallat (MhR) and Karaj (KrS), using a leaf-dip bioassay. Findings showed that the LC50</sub> of propargite against MhR and KrS populations was 5337.90 and 116.81 mg a.i/l, respectively. While the LC50</sub> of the chlorpyrifos against MhR and KrS populations was 2760.83 and 479.25 mg a.i/l, respectively. Based on the median lethal concentrations (LC50</sub>), MhR and KrS populations were considered as resistant and susceptible populations to both pesticides, respectively. MhR population was 5.76-fold and 45.70-fold more resistant to chlorpyrifos and propargite than the KrS population, respectively. Insecticide synergists including triphenyl phosphate (TPP), piperonyl butoxide (PBO), and diethyl maleate (DEM)) revealed the contribution of esterases, glutathione S-transferases (GST), and cytochrome P450 </sub>monooxygenases (P450</sub>s) to resistance. Nonetheless, the involvement of esterases and P450</sub>s was more evident against chlorpyrifos and propargite, respectively. The activity of P450</sub>s, GSTs, esterases, and acetylcholinesterase (AChE) was measured in susceptible and resistant populations. All enzymes showed significantly higher activity in the resistant population than in the susceptible one. Additionally, zymogram analysis of esterase showed two distinct bands in the MhR population, whereas the stronger band was absent in KrS population. These results indicate that metabolic pathways are associated with chlorpyrifos and propargite resistance in the MhR population.

In the present study, the cuticle-degrading enzymes production potential of five native Beauveria bassiana (TV, OZ, UN, DV and DE) isolates was investigated in the presence of cuticles from Eurygaster integriceps, Ephestia kuehniella and Zophobas morio. Furthermore, histopathology of infected insects by B. bassiana was studied. The level of cuticle degrading enzymes was the highest and lowest for TV (as the most virulent isolate) and DE (as the weakest isolate), respectively. E. integriceps nymphs as the most sensitive host produced the highest level of cuticle degrading enzymes (Pr2, exochitinase, and lipase) while Z. morio as the most resistant host, produced the lowest level of hydrolytic enzymes. According to histopathological study, the fungal isolate could not penetrate into Z. morio cuticle, as no mycelia or hyphae were observed in its tissues after inoculation, while fungal bodies were detected in microscopic slides of the other two insects. Overall, the chemical and topographical structure of insect cuticle had a substantial effect on the virulence of entomopathogenic fungus. Production of enzymes including proteases (especially Pr2), chitinase (N-acetyl-glucosaminidase), and lipases was positively related to virulence of fungus isolates. It can be concluded that not only the hydrolytic activity of B. bassiana isolates, but also host cuticle composition determine the pathogenesis and virulence cascade in fungus-insect interactions.

Essential oils are environmentally benign agents which are used as alternative compounds for chemical pesticides in order to control pests. Thus, in the current study, the toxicity and repellency effects of essential oils, extracted from three medicinal plants of the Lamiaceae family, including Thymus daenensis, Satureja khuzestanica, and S. bakhtiarica, were evaluated against a resistant (MhR) and a susceptible (KrS) population of Tetranychus urticae. Results based on probit analysis revealed that all extracted essential oils to some extent showed both repellency and toxicity effects on both populations of the mite. The LC50 values of S. khuzestanica extract were the lowest against the both populations (31.16 µL. L−1 air for KrS population and 56.29 µL. L−1 air for MhR population). Also, all extracted essential oils were found to be repellent to the adult females of both MhR and KrS populations, with higher repellency effect of S. khuzestanica oil. The effect of the LC20 of the essential oils on detoxifying enzymes including Glutathione S-transferases (GSTs), esterases (ESTs) and cytochrome P450 monooxygenases (P450) was tested against both populations. Significant higher activity of all enzymes was detected in MhR population regardless of essential oils treatment. The activity of GSTs and esterases increased significantly in mites treated with all essential oils, while a tendency for a decrease in P450 activity was detected following essential oils treatment. These results indicate that the essential oils of the all selected plants, especially S. khuzestanica, have a good potential to be used in integrated management programs of T. urticae which is a serious pest in the greenhouses.

During the last decade, plant and microbial-derived metabolites have received growing attention as potential tools for pest management in agriculture. Pederin (C25H45NO9) is a vesicant toxin produced by Pseudomonas-like bacterial symbionts of rove beetles within the genus Paederus (Col: Staphylinidae). In this study, the toxicity of pederin to two stored product pests, Ephestia kuehniella Zeller (Lep: Pyralidae) and Tribolium confusum Jacquelin du Val (Col: Tenebrionidae) was evaluated using laboratory bioassays. Probit analysis estimated the median lethal concentrations of pederin as 1311.96 and 596.36ppm for E. kuehniella fourth larval instar and T. confusum adults, respectively. We also measured the activity of two major digestive enzymes (amylases and proteases) as well as three major detoxifying enzymes (P450s monooxygenases, glutathione S-transferases, and carboxyl esterases) in insects treated orally with pederin. Feeding on pederin resulted in significant decrease in the activity of amylolytic, proteolytic, and carboxyl esterase enzymes, but significant increase in the activity of P450s and glutathione S-transferases. Results of this study may highlight pederin as a novel source of pesticides with unique mode of action for use in pest management programs.

Cotton bollworm, Helicoverpa armigera (Hϋbner) (Lepidoptera: Noctuidae) is a cosmopolitan and polyphagous pest that attacks many plant species including cotton. One of the most important principles of the Integrated Pest Management programs (IPM) is use of non-chemical agents such as natural enemies (parasitoids and predators), and resistant host plant to control pests. Transgenic Bt cotton is one of the substitution ways of chemical pesticide used for control of this insect pest. Production of transgenic crops was a novelty in the method of applying host-plant resistance. Crops that are genetically engineered to express Bacillus thuringiensis toxin are planted in many areas.
Material and

In the present study, effect of transgenic Bt cotton, Coker cultivar, including cry1Ab was studied on biology and digestive protease activity of the bollworm. For bioassays, gut dissection and demographic studies, H. armigera were obtained from the Division of Entomology, Department of Plant Protection, College of Agriculture and Natural Resources, University of Tehran, Karaj, Alborz, Iran. The insects were held in the growth room on the condition of 25 ± 1ºC, 60–70 % relative humidity with a 16-h day length. Proteolysis using general substrate (Azocasein 2%) was assayed after some modification. In this manner, 10 µl enzyme extract and 50 µl Azocasein 2% (substrate solution) were mixed into 40 µl of the 20 mM Tris-HCl buffer pH 8.0 and incubated during 60 min. Protease activity was measured using specific substrate with some modifications. Trypsin- and chymotrypsin-like activities were assayed using 1mM BApNA (Benzoyl-l-arginine-p-nitroanilide) and 1 mM SAAPFpNA (Succinyl-l-Ala-l-Ala-l-Pro-Phe-p-nitroanilide), respectively.

The results illustrated that the second larval instar mortality in the transgenic cotton was 68 percent and in control cotton was 6 percent. Furthermore, larvae in different instars, in transgenic Bt, had significantly lower weight and longer life time in comparison with control. Several biological characters of both treatments including survivorship, development and weight were significantly changed. On the other hand, total protease, trypsin and chymotrypsin activity in digestive lumen, after the second, fifth and sixth larval instar in transgenic cotton showed significant reduction, respectively.

Coker cotton crop with cry1Ab, will have significantly negative effects in insect biology and digestive physiology during the pest life time and can be noticeable in management of important pests such as boll worm. Bt cotton can therefore be useful in an integrated pest management program, because it resulted in a reduction in the number of insecticide applications per season

The egg parasitoids of the genus Trichogramma have become one of the most important economic insects, for they are widely used in biological control of Lepidopteran key pests. For that reason, all aspects of their mass production including diapause have been considered over the last few years. In this study, the effect of host quality on the diapause induction of sexual and asexual T. brassicae Bezdenko (Hym: Trichogrammatidae) have been investigated at two temperatures. Maternal generation developed at two distinct temperatures (14 and 20 °C) and they oviposited on four different qualities of Ephestia kuehniella Zeller (Lep: Pyralidae) eggs including fresh eggs, frozen eggs, host eggs with developing embryo and low quality eggs. Data analysis revealed significant influence of temperature and host quality on diapause induction in both sexual and asexual strains. Maximum diapause happened in host eggs with developing embryo even though they were in fetal development. A higher level of diapause was observed in T. brassicae whose maternal generation had developed at 20 °C. The diapause induction in asexual T. brassicae was less than sexual wasps. The results imply that Wolbachia causes a disturbance in the diapause process. The outcomes of this study, which are new, indicate the complexity of diapause and the importance of factors such as host quality which have received less attention in diapause induction.

In the present study, some isolates of Beauveria bassiana were isolated from different soil samples and their virulence was investigated against Sunn pest Eurygaster integriceps (Hem., Scutelleridae), flour moth, Ephestia kuehniella (Hym., Pyralidae), and king meal worm, Zophobas morio (Col., Tenebrionidae). Twenty three isolates were isolated using Galleria-baiting method from collected soil samples in different regions; Karaj, Urmia, Mako and Dezful and were identified. The insect hosts were infected using dipping method. The results showed that the fifth nymphal instars of Sunn pest and fourth larval instars of flour moth were susceptible to all isolates of B. bassiana while last larval instars of the beetle were resistant and no mortality was observed. The most virulent isolates were TV and TZ with approximately 90% mortality on E .kuehniella and E. integriceps. The isolates were categorized broadly into three classes: low virulent (0-33% mortality), medium virulent (34-67% mortality) and high virulent (68-100% mortality). On PDA medium, two distinct germination types of conidia were revealed including conidia with single and dual germ tubes. There were significant differences among isolates in their percentages of germination types but there was no significant correlation between virulence and conidial germination types.

Two-spotted spider mite, Teranychus urticae (Acari: Tetranychide), is one of the most important agricultural pests throughout the world. The high reproductive potential, short life cycle, combined with frequent acaricide applications has resulted in resistance development to a wide range of acaricides. Resistance to acaricides has an important role in inefficiency of chemical control of this pest. In the present study, the susceptibility of two populations of two-spotted spider mite collected from Karaj (KrS) and Mahallat (MhR) to spirodiclofen was investigated.
The bioassay was conducted using a leaf-dip method on same-age protonymphs. Bioassay results showed that there was a significant difference between LC50 values of KrS and MhR populations. The resistance ratio was obtained as 22.19. The synergistic effects of triphenyl phosphate (TPP), piperonyl butoxide (PBO) and diethyl maleate (DEM) were assessed using residual contact vial (RCV) bioassay method. Results of the synergistic studies showed significant differences between LC50 values of spirodiclofen with spirodiclofen PBO and spirodiclofen TPP in MhR population. The most synergistic effect in MhR population was related to PBO. The results of enzyme assays revealed that the most ratio activity in MhR population to KrS population was related to cytochrome P450 monoxygenase (3.02) and the lowest ratio activity was related to glutathione S-transferase (GST) (1.40). These results confirmed that esterase and cytochrome P450 monoxygenase are probably involved in resistance of T. urticae to spirodiclofen.

The effect of photoperiod on parasitization of the eggs of Ephestia kuehniella Zeller (Lep: Pyralidae) by Trichogramma brassicae Bezdenko (Hym: Trichogrammatidae) was investigated under several photoperiodic regimes of L: D = 0: 24, 3: 21, 6: 18, 9: 15, 12: 12, 15: 9, 18: 6, 21: 3 and absolute light on. Fecundity of T. brassicae females (the number of parasitized E. kuehniella eggs) was independent of photoperiod in the whole life time of females. However, photoperiod had a significant influence on the longevity of T. brassicae females. The least fecundity and longevity was for those that developed and were kept under 18L: 6D and the highest fecundity and longevity was for those that developed and were kept under 21L: 3D and absolute darkness, respectively. On the other hand, the proportion of T. brassicae females was dependent of photoperiod and the highest proportion of females was observed under 18L: 6D. It seems that long term photoperiods may stimulate a particular gland to secret a special hormone which results in more longevity and female proportion of parasitoid. As a conclusion, long term photoperiods may improve efficiency of the parasitoid by increasing longevity and sex ratio.

Trichogramma wasps have been the subject of intensive research because of their wide application in biological control programs since the past decades. Increasing the fitness of Trichogramma during their production and storage was one of the points that have always attracted the attention of researchers, producers and consumers of these biological control agents. Temperature as one of the main environmental factors that influence all life stages has always been effective on the fitness of insects. We investigated the effect of temperatures (10, 14 and 20°C) on the emergence rate, sex ratio, fecundity and mortality of different developmental stages of Trichogramma brassicae Bezdenko (Hym: Trichogrammatidae) in order to examine the response of parasitoid to low temperatures. Based on the obtained results, larvae and pre-pupae were the most sensitive and resistant life stages of T. brassicae to low temperatures, respectively. A direct relationship was observed between both emergence rate and fecundity of T. brassicae with temperature. The proportion of emerged females did not show a statistically significant difference when parasitoid was exposed at low temperatures. According to the results, T. brassicae can enter dormancy (diapause-quiescence) using cold storage although the diapause incidence through low temperature exposure is associated with reduced fitness of T. brassicae.

Glutathione S-transferase (GST) genes control vital traits for metabolism of the variety of toxins that expose insects to the environment (insecticide) or plant defense systems. Sunn pest is the most important pest of wheat and barley in the Middle East where it threats food security throughout the region. Sequencing the sunn pest's RNA provides an opportunity to identify the structure and function of the different gene families. To our knowledge, this is the first study to identify 43 GST candidate genes in sunn pest using bioinformatics tools. The identified candidate genes clustered in 5 cytosolic GST (Delta, Theta, Zeta, Omega, and Sigma) and Microsomal GST using phylogenetic analysis. The Sigma subclass was identified as the biggest subclass with 22 candidate genes, while microsomal GST found to be the smallest group with one candidate gene. Given the role of GST in the interactions among the insect, toxins, and environment, our results facilitate future investigations on insecticide resistance and their utilization in pest management programs against sunn pest.

In many organisms, detoxification enzymes play important roles in detoxification of xenobiotics and are considered as biomarkers of toxic effects of exposure to a variety of these agents. In the current study, the effects of thiamethoxam and pirimicarb in sublethal concentrations were evaluated on Aphis fabae Scopoli (Hemiptera: Aphididae) detoxification enzymes. The median lethal concentrations for the female aphids exposed to thiamethoxam and pirimicarb were 113.85 (68.94-625.16) and 2.94 (1.71-3.99) mg (ai)/L, respectively. The activity of monooxygenases was measured as detoxification enzymes. The effects of both insecticides on A. fabae caused significant increase in monooxygenase (P

The two-spotted spider mite, Tetranychus urticae Koch (Acari: Tetranychidae) is one of the most important agricultural pests of the world. It causes direct and indirect damage on plants which decreases in photosynthesis and crop yield. The effect of sublethal concentrations of Artemisia annua L. (Asteraceae) and Rosmarinus officinalis L. (Lamiaceae) essential oils were assessed on development and reproduction para-meters of two-spotted spider mite T. urticae. Lethal and sublethal concentrations were estimated by fumigant bioassay of essential oils on the adults of T. urticae. The raw life history data of all individuals were analyzed according to the age-stage, two-sex life table theory. LC30 and LC50 of A. annua (2.908 and 4.14 µl/80 ml air) and R. officinalis (1.339 and 2.006 µl/80 ml air) showed that rosemary essential oil has higher fumigant toxicity against T. urticae. Sublethal concentration of the two plant oils led to significant decrease in fecundity, generation time and adult longevity compare to the control. In addition, plant oils decreased the net reproductive rate (R0), intrinsic rate of increase (r), finite rate of increase (λ), and significantly increased doubling time (DT) of T. urticae in compare with control. Obtained results indicated that, sublethal concentra-tions of A. annua and R. officinalis oils could influence on biological indices of T. urticae.

The elm leaf beetle, Xanthogalerucella luteola (Muller) (Col.: Chrysomelidae) is a serious pest of elm trees and it has been distributed all over the world. The current study was undertaken to investigate the inhibitory effects of protein extracts of three weed seeds including datura Datura stramonium L., amaranth Amaranthus retroflexus L. and wild oat Avena fatua L. against X. luteola α-amylase using spectrophotometric assay as well as in gel assays. The effects of five concentrations of each seed proteinaceous extracts were tested on α-amylase activity of the larval gut. The results showed a dose dependent manner in inhibition of the insect enzyme. At the highest concentration of protein extracts (12 μg protein) of all three seed extracts including amaranth, wild oat and datura, the inhibition was 71, 79 and 31%, respectively. Whilst, at low concentration (0.75 μg protein), the inhibition observed was 15, 36 and 5%, respectively. Thus, the greatest inhibition percentage was obtained when proteinaceous extract of wild oat seed was used. These results were confirmed when in gel assays were performed. All three seed proteinaceous extracts had an optimum pH inhibition of 6.0. Thus, it is concluded that wild oat seed proteins are potentially good for detailed investigation in order to get a clear picture of its active compound/s and its structure-function relationship.

Insects are able to recognize many pathogenic microorganisms and defend against them due to their long evolutionary history. Due to the development of resistance to synthetic antibiotics, researchers are trying to apply insect immune-derived products.. The current study aimed to investigate the antibacterial effect of the American cockroach (Periplaneta americana) hemolymph on susceptible and resistant strains of nosocomial bacteria.. To stimulate adult cockroaches'' immune system, Escherichia coli cells were injected. The antimicrobial effect of the extracted induced and non-induced hemolymph was assayed on many susceptible and resistant pathogenic bacteria.. The comparison of antimicrobial effects of the induced and non-induced hemolymph strains showed that about 43% of bacteria were sensitive to induced hemolymph (P < 0.001), whereas non-induced hemolymph showed no inhibitory effect on the bacteria. Also, evaluation of induced hemolymph effect on the types of strains showed that induced hemolymph affected about 75% of the susceptible bacterial strains (P < 0.001); whereas, it did not affect the resistant strains. Among the tested bacteria, ceftazidime-sensitive E. coli and methicillin-sensitive Staphylococcus aureus showed sensitivity to the induced hemolymph (P < 0.001).. The study results showed that stimulation of the American cockroach’s immunity system lead to production of antibacterial proteins and peptides which had inhibitory effect on the bacteria, depending on the bacterial strains and their sensitivity. Likely this feature of insects can be used as therapeutic strategies to produce natural antimicrobial compounds against the pathogenic bacteria..

Essential oils are volatile mixtures of hydrocarbons with diverse functional groups. In the current study the effect of essential oils from five medicinal plants including Zataria multiflora and Nepeta cataria (Lamiaceae), Tagetes minuta and Artemisia siberi (Asteraceae), and Trachyspermum ammi (Apiaceae) were analyzed using GC-mass spectrometry. The toxicity of these plant essential oils against the adult stage of the cabbage aphid, Brevicoryne brassicae L. (Hemiptera: Aphididae) was studied using a fumigant assay.GC/Mass analysis revealed that the main essential oils varied between species. The most abundant components in N. cataria, Z. multiflora, T. ammi, T. minuta and A. sieberi were 4a-α, 7-β, 7a-α-nepetalactone (76.8%), carvacrol (62.1%), γ-terpinene (27.1%), limonene (13.0%) and artemisia ketone (48.0%) respectively. The fumigant assays showed that all of these essential oils were toxic to B.brassicae in a dose-dependent manner. The essential oils of N. cataria at 126, 63, 31, 16, 8, and 3 μl L-1 air caused 94, 76, 52, 46, 36, and 24% mortality within 24 hours, respectively. The same trend was seen when essential oils of the other plants tested against B. brassicae. These plant essential oils have great potential to be used in integrated pest management especially in greenhouses or other closed systems.

The carob moth is one of the most devastating pest of pomegranate and some other products. Various pest control measures have been undertaken in order to control this pest but none of them has been successful so far. So, in the current study the effects of cereal seed proteinaceous extracts including triticale and three wheat cultivars (MV17, Aflak, and Zare) have been studied on α-amylase and protease activity of salivary glands of this insect.Initial screening showed 38, 44, 28 and 76% inhibitory effect for triticlae, MV-17, Aflak, and Zare cereal seed extracts respectively.on α-amylase activity. were Further studies were performed with Zare wheat cultivar using various concentrations including 13, 6.5, 3.25, 1.625 and 0.8125 µg protein on the enzyme activity and results showed that they inhibited the enzyme activity by 76, 75, 68, 60, and 42%, respectively. Gel assays confirmed the spectrophotometric data i.e the effect of the seed extract on the enzyme was dose dependant. The same trend was observed when seed extracts were tested against proteinase activity. These data suggest that plants produce different proteins with different specificity toward herbivores digestive enzymes which some of them could be used for insect control in IPM program.

Sun pest (Eurygaster integriceps Puton (Coleoptera: Scutelleridae) is one of the most important pests of wheat and barley that feeds on grains. So, this pest lives in carbohydrate-rich environment and its survival depends on carbohydrase enzymes. α-Amylase plays an important role in the Sun pest digestion. The aim of the current research was to study the effects of proteinaceous extracts of bean, rice and chickpea seeds on α-amylase activity. So, the proteinaceous extractions of the seeds were extracted using 0.1 M Sodium chloride. The extractions were tested on α-amylase activity at 0.125, 0.25, 0.5, 1 and 2 mg of proteins/ml in In vitro conditions. The results showed that the bean and chickpea extracts were effective on α-amylase activity and their effects were dose-dependent meaning that with increasing of the dose, inhibition of the enzyme increases. For example, at the lowest dose (0.125 mg of proteins/ml), the bean and chickpea extracts inhibited 5 and 20% of the amylase activity, respectively. While at the highest dose (2 mg of proteins/ml) the inhibitory effects was 30 and 40%, respectively. Rice seed extraction did not produce any significant effect on α-amylase activity. These data showed that the proteinaceous extractions of chickpea and bean have the good potential for inhibition of sun pest α-amylase.

Boll worm, Helicoverpaarmigera (Hϋbner) (Lepidoptera: Noctuidae) is a cosmopolitan and polyphagous pest that attacks many plant species. The most important control method is based on the use of pesticides which is a concern to environment as well as insects\\

Fumigant toxicity of various doses of essential oils (185.2, 370.4, 555.5, 740.7, 925.4, 1111.1, and 1296.3 µl/l water) from five officinal plants, including rosemary (Rosmarinus officinalis), lavender (Lavandula vera), fennel (Foeniculum vulgare), tarragon (Artemisia dracunculus)and summer savory (Satureja hortensis)on two stored products pests, cowpea weevil (Callosobruchus maculatus) and red flour beetle (Tribolium castaneum) have been studied. The cowpea weevil was more susceptible than red flower beetle for all essential oils have been tested. The essential oil of rosemary showed the most fumigant toxicity among the tested plants so that mortality of cowpea weevil in treatment with the least dose of related essential oil reached 100% after 12 h. The mortality of red flower beetle was 5% at the same time; however, after 24 h it reached 30%. The essential oil of tarragon that showed the least fumigant toxicity caused 100% mortality in cowpea weevil after 18 h and 95% mortality in red flower beetle after 24 h. The mortality of cowpea weevil in treatments with high doses of essential oils from lavender, fennel and summer savory after 5, 18 and 18 h reached 100%, respectively. This time was 24 h for the red flower beetle, treated with mentioned treatments. The LT50 calculated for cowpea weevil and red flower beetle in treatment with lavender essential oil were 24.96 and 4.78, that of rosemary 30.14 and 11.73, of fennel 15.64 and 8.71, of tarragon 11.74 and 6.10 and essential oil of summer savor were 12.28 and 3.60 h, respectively.