Showing 38 results for moharrami
Volume 1, Issue 1 (3-2012)
Abstract
This study was conducted to evaluate the age-specific functional response of Psyllaephagus zdeneki Noyes & Fallahzadeh (Hymenoptera: Encyrtidae) at different nymph densities of olive psyllid, Euphyllura pakistanica Loginova (Hemiptera: Psyllidae). Due to parasitoid behaviour of feeding and parasitizing the host, both traits were separately explored on a daily functional response. Results of logistic regression revealed a type II functional response of the wasp independent of their ages. The handling time (Th) and searching efficiency (a) were estimated using the Rogers equation. The highest searching efficiency for both parasitism and feeding was observed in the first five days of the adult age. The handling time for parasitism and host feeding increased with the age of female wasp. The highest searching efficiency and shortest handling time for host attacked (Parasitism and feeding) were gained in day 5 and day 2 and maximum parasitism and host feeding in days 2 and 3 of adult female age, respectively. We conclude that P. zdeneki demonstrated a reasonable performance as a potential biocontrol agent by feeding and parasitism of E. pakistanica which gained its maximum efficiency within 2 to 5 days of its life.
Volume 2, Issue 1 (3-2013)
Abstract
The essential oils of aerial parts of three medicinal plants Artemisia khorassanica Podl., Rosmarinus officinalis L. and Mentha longifolia L. were isolated by hydrodistillation and investigated for their toxicity and repellency against Tribolium confusum Jacquelin du Val. at 27 ± 1 ºC and 60 ± 5% RH in darkness. The mortality of the adults increased with concentration from 185 to 1111 μl/l air and with exposure time from 9 to 24 h. A concentration of 185 μl/l air and exposure time of 24 h was sufficient to obtain nearly 100% kill of the adults in all of the three essential oils tested. At the highest concentration (1111 μl/l air) R. officinalis oil caused 15% mortality for an exposure time of 6-h. whilst, the oil of A. khorassanica resulted in 1% mortality at the same exposure time. The oil of A. khorassanica at 1111 μl/l air caused 81% mortality for 12-h exposure time. No significant differences were observed between the lethal time (LT50) values at essential oil concentrations of 741 and 1111 μl/l air. For 24-h exposure time, the LC50 values of A. khorassanica, R. officinalis and M. longifolia essential oils were estimated to be 22.45, 22.14 and 39.96 μl/l air respectively. Based on LC50 values, adults of T. confusum showed similar susceptibility to the A. khorassanica and R. officinalis oils, but M. longifolia oil proved to be less toxic. In contrast to their low fumigant properties, the essential oil of M. longifolia had significantly higher repellency to T. confusum adults than did the other two.
Volume 2, Issue 1 (3-2013)
Abstract
Medicinal plant powders have traditionally been used as grain protectants against stored-product insect pests. In this study, insecticidal activity of Carum copticum L. and Cuminum cyminum L. powders was assessed on adults of Sitophilus granarius L. and Tribolium confusum Jacquelin du Val. Experiments were carried out on wheat at 27 ± 1 ºCand 55 ± 5% r. h. The mortality increased with increasing concentration level and time exposed to each concentration. For S. granarius, 7 days and in case of T. confusum 14 days exposure time was sufficient to obtain considerable mortality. For example, 3500 mg/kg of C. copticum 7 days after treatment caused 80% mortality in S. granarius; while for T. confusum 29% mortality was achieved and increased to 100% after 14 days. Therefore, it can be concluded that adults of S. granarius were more susceptible than T. confusum to plant powders. Also, according to the findings, C. cyminum powder had more insecticidal efficacy than C. copticum on both insects’ species. For S. granarius, 950 and 2700 mg/kg powders of C. cyminum and C. copticum was enough to cause ca. 50% mortality after 5 days, respectively. In case for T. confusum, 3200 and 4400 mg/kg of the plant powders caused the same mortality after 7 days. Findings of the present study show that the plant powders could be applied for grain protection in small-scale storage facilities.
Volume 2, Issue 2 (6-2013)
Abstract
Hippodamia variegata is an efficient and most abundant predatory coccinellids in many countries. Understanding the ability of long-term low temperature survival in beneficial insects can be used to make better predictions about subsequent abundance and hence the biological control potential in the next spring and summer. So in this study, effects of long-term temperatures were investigated on mortality and supercooling point (SCP) of field collected (pre-diapausing) and overwintering aggregations of H. variegata adults. Unlike the pre-diapausing insects, aggregated coccinellids could easily survive at -3 and 0 °C for one month. One month acclimation at 10 °C caused more than 80% mortality in overwintering adults, indicating the higher temperatures were not appropriate for overwintering aggregated coccinellid. In December and January, when diapause was in its highest level, changing the habitat temperature did not affect SCP. Acclimation at 5 and 0 °C for one month decreased SCP of pre-diapausing adults, collected from aphid infested plants in October. Our study revealed that exposure to temperatures below 0 °C happened usually in natural condition for a long term period, may be necessary for overwintering of the coccinellid.
Volume 2, Issue 2 (6-2013)
Abstract
Plant extracts, like phytoecdysteroids, are currently studied because of the possibility of their use in plant protection. Phytoecdysteroids are insect steroid hormone analogues, and they are believed to deter invertebrates from plants, either by acting as antifeedants or by being toxic through hormonal disruption on ingestion. We describe here the effects of extract from Spinacia oleracea L. (Chenopodiaceae), a plant producing phytoecdysteroids, on the demographic parameters of Plutella xylostella L. (Lepidoptera: Plutellidae). Spinach is one of the very few crop plants which produce large amounts of phytoecdysteroids. Ecdysteroidal extracts of leaves from this plant were incorporated into food given to third instar larvae for two days. Then the larvae were reared on untreated leaves. The eggs from the emerging adults were picked up for demographic experiments. The rearing of the newly hatched larvae was continued individually on untreated leaves. All experiments were performed on 25 ± 1 ºC, 65 ± 5% RH and a photoperiod of 16:8 (L: D) hours in a growth chamber. Data analysis demonstrated that the fecundity of the females was strongly affected by ecdysteroidal extract. Values of intrinsic rate of increase and net reproduction rate decreased significantly as concentration of the extract increased. However, doubling time increased significantly as concentration of the extract increased. The present study demonstrated that the ecdysteroidal components of the spinach are effective on the demographic parameters of P. xylostella. Therefore, this extract may be potential protectants as botanical alternative agent.
Volume 3, Issue 1 (3-2014)
Abstract
Microcerotermes diversus Silvestri (Isoptera: Termitidae) is the most economically destructive wood pest in structures in Khuzestan province (Iran). Chemicals such as essential oils and plant extracts that are compatible with the environment and have high potential to be used in integrated pest management programs are extremely important resources. This study evaluated contact and digestive toxicity of Eucalyptus camaldulensis Dehneh. (Myrtaceae)essential oil in no-choice and choice bioassays and feeding inhibition trials on M. diversus. Concentrations of the essential oil ranged from 0.3 to 1.6%. The results of the choice tests and feeding inhibition trial showed that the essential oil could act as a repellent at 0.7% concentration. Concentrations used in these tests resulted in mortality of termites, and a direct relationship between concentration and mortality was observed. The essential oil also increased the mortality of termites at concentrations higher than 0.7%. Termite feeding decreased with increase in concentration. Due to the ability of termites to choose the untreated filter-paper in the choice trial, values of LT and LC, were higher than in no-choice trials. The highest effects of Eucalyptus essential oil (≈100% mortality) was obtained by the concentration 1.6%. Overall, this study reveals that Eucalyptus essential oil may be suggested as an effective toxicant with suitable contact and digestive toxicity on M. diversus.
Volume 3, Issue 2 (6-2014)
Abstract
Cold hardiness is one of the most common adaptations of insects at low temperatures. To understand the cold hardiness strategy of beet armyworm, Spodoptera exigua (Hübner), six temperature treatments were tested on the last instar larvae. Supercooling points of treatments were not significantly different. Two sugars, glucose and trehalose, as well as three polyols, myo-inositol, glycerol and sorbitol, were identified in these larvae. Trehalose was more affected in response to low temperatures in longer duration, and had a significant negative correlation with glycogen content. Despite the extensive sugar beet cultivation areas in Iran, beet armyworm population has been decreased in recent years. It seems that climate change regarding the global warming especially in autumn and winter could be a reason for decline in population outbreak of beet armyworm in the next generation. Based on findings of this study, it is suggested that overwintering larvae are freeze-intolerant insects but long term acclimation at sub-zero temperatures makes larvae tolerate presence of ice crystals in their body fluid.
Volume 3, Issue 4 (12-2014)
Abstract
The Mediterranean flour moth, Ephestia kuehniella Zeller, is one of the major pests in stored products worldwide. Several problems assossiated with the use of conventional insecticides have strongly demonstrated the need for applying alternative safe compounds such as insect growth regulators (IGRs). In the present study, growth regulating activity and hematological effects of pyriproxifen and methoxyfenozide were evaluated on E. kuehniella larvae. Effects of the insecticides were evaluated under laboratory conditions set at 26 ± 1 °C and 75% RH. Findings indicated that inhibition dose for fifty percent of population (ID50) was equal to 0.16 µg/mg larvae for pyriproxifen and 0.4 µg/mg larvae for methoxyfenozide, showing the considerable growth regulating effect on two-day-old fifth instar larvae. Then, influence of estimated doses were investigated on the insect hemocytes including total hemocyte count (THC) and differential hemocyte count (DHC). THC and the proportion of plasmatocytes were decreased as pyriproxifen doses increased, while, the granulocytes level was increased. In contrast, application of sublethal doses of methoxyfenozide caused a conciderable increase in THC and the plasmatocytes density, while, number of granulocytes was decreased. Since the total number of hemocytes and the proportion of plasmatocytes are very crucial in immune responses of insects, pyriproxifen could be used as an immunosuppressive pesticide in integrated control of E. kuehniella.
Volume 4, Issue 2 (6-2015)
Abstract
The beet moth, Scrobipalpa ocellatella (Boyd) (Lepidoptera: Gelechiidae) is one of the most destructive pests of beet. The insect overwinters as larvae of different instars in beets which are left in the field. Supercooling point (SCP) of individual larvae showed broad range variation from -6 to -25 °C. In the present study, factors affecting the broad range of SCP were investigated. Larvae showed a great increase in SCP when they were induced by exogenous ice nucleation. Defensive oral discharge (DOD) decreased SCP but it had no significant effect on supercooling ability of larvae. The presence of sufficient food in guts of field collected larvae induced an increase in SCP. Therefore it could be concluded that surface moisture and food particles in the gut may act as ice nucleating agents (INAs) that cause freezing of the body fluids at higher temperatures. Furthermore, second and third instar larvae, owing to their small size, had greater capacity to supercool in comparison to fifth feeding instars. Broad range in SCPs might be due to diversity in overwintering larvae which have different capacity for supercooling.
Volume 4, Issue 4 (12-2015)
Abstract
Control of stored-product insect by gamma radiation could be enhanced by other possible techniques such as essential oils as effective alternatives to chemical insecticides. In this study, the efficiency of gamma radiation combined with Perovskia atriplicifolia (Benth) was verified to assess their enhanced antifeedant effect against the Tribolium castaneum (Herbst). Flour disc bioassay was employed to assess the nutritional indices, such as relative growth rate (RGR), relative consumption rate (RCR), efficiency of conversion ingested food (ECI) and feeding deterrence index (FDI). The results showed that irradiation, essential oil and combination of both of them significantly reduced RGR, RCR and ECI in treated larvae and adults. As irradiation at 100 Gy reduced RGR of the larvae and adults from 0.0884 and 0.0366 to 0.0596 and 0.0332 mg/mg/day respectively, when combined with doses of P. atriplicifolia essential oil, the reduction reached to 0.051 - 0.388 and 0.01- 0.224 mg/mg/day respectively. The reduction rates in larvae were even greater when combination of irradiation and EO treatments were used. The results showed a significant increase in the feeding deterrence due to irradiation, essential oil and specially their combination. Therefore, findings led to a conclusion that irradiation can enhance antifeedant activity of essential oils.
Volume 5, Issue 2 (6-2016)
Abstract
Plant essential oils and their constituents are recognized as proper alternatives to fumigants. Thymus daenensis Celak is one of these plants that have medicinal properties and is endemic to Iran. The essential oil was isolated by hydrodistillation from dry leaves using a modified clevenger-type apparatus and the chemical composition of the oil was assessed via GC and GC-MS. Fourteen compounds (100% of the total composition) were identified. Thymol (57.4%), carvacrol (9.8%), β-caryophyllene (6.9%), γ-terpinene (6.7%) and p-cymene (6.3%) were found to be the major compounds of the essential oil. The fumigant toxicity of the essential oil was tested against 1-3 days old adults of Callosobruchus maculatus (F.) and Sitophilus granarius (L.) at 27 ± 1 °C and 65 ± 5% R. H. in darkness. The mortality of adults was tested at different concentrations (28.12, 40.62, 53.12 and 65.62 µl/l air) and different exposure times. At the highest concentration (65.62 µl/l air), T. daenensis oil caused 90 and 60% mortality with a 3 h exposure on C. maculatus and S. granarius, respectively. Based on LC50 values, C. maculatus (4.22 µl/l air) was significantly more susceptible than S. granarius (6.55 µl/l air). These results show the efficacy of T. daenensis oil for stored-products protection.
Volume 5, Issue 4 (12-2016)
Abstract
In order to examine possible integration between irradiation and botanical pesticides, combined effects of essential oil from Rosmarinus officinalis L. and gamma radiation were determined on mortality of Callosobruchus maculatus F. (Coleoptera: Bruchidae). Experiments were conducted by pretreatment with essential oil fumigation followed by irradiation and inversely, pretreatment with irradiation followed by essential oil fumigation. The mortality rate was assessed 72 h after last treatment. Integration of gamma radiation and R. officinalis oil enhanced the mortality of C. maculatus compared with control treatments of either irradiation or fumigation alone. Synergistic effects of mortality on 1-2 days old adults of C. maculatus were observed when exposed to combination of gamma radiation and essential oil. It was found that pretreatment with fumigation followed by irradiation was perfectly effective. The study showed that either of the pre- treatments could enhance the susceptibility of the pest to the other treatment. Our findings led to a conclusion that the combination of gamma radiation and R. officinalis oilfumigation has a potential for application in integrated management of C. maculatus.
Volume 6, Issue 2 (6-2017)
Abstract
The melon aphid, Aphis gossypii (Glover), is one of the major pests of cucurbits and an efficient vector of plant viruses such as Cucumber Mosaic Virus. Host-plant resistance is one of the management strategies that can be used to control this pest. In this study, choice test was conducted to identify antixenotic resistance against melon aphid in eight Cucumis genotypes, namely Hormozgan, Bushehr, Guilan, Girtap, Negeen, Sepehr, Pouya and Armenian cucumber. Choice tests were conducted at 25 ± 1 ºC, 60 ± 5% RH and a photoperiod of 16:8 (L: D) h. After introduction of apterous adult aphids to test arena, the number of aphids on each entry was counted at 2, 4, 6 and 24 hours of release. Total phenolic content, NPK essential elements, leaf thickness and leaf trichome density were also measured to discover any association between these factors and aphid host choice. The most antixenosis effect was observed on 'Bushehr'. Increase in antixenosis correlated with increase in leaf trichomes. Antixenosis can be important mode of resistance by reducing host selection and delaying aphid colonization. The identification of antixenotic resistance in several genotypes provides additional options for management of this pest. Moreover, the factors associated with this mode of resistance can be considered in plant breeding programs.
Volume 6, Issue 4 (12-2017)
Abstract
Witches' broom disease of lime (WBDL) is a lime disease that has destroyed several citrus orchards in Oman, United Arab Emirates and Iran. WBDL is caused by a bacterium ''Candidatus Phytoplasma aurantifolia'' which is spread through the citrus orchards by a leafhopper, Hishimonus phycitis (Distant) (Hemiptera: Cicadellidae). Leafhoppers are associated with symbiotic microorganisms which provide them with essential amino acids lacking in their diets. Yeast-like relationships with insects are known as common and obligate symbiotic relationship. A prerequisite for the development of future strategies for the symbiotic control of insect pests and insect-vector competence is the identification of insect-associated yeast-like symbionts. In the present study, yeast-like symbionts housed in H. phycitis were investigated in insects collected from 13 districts of citrus orchards distributed in southern Iran (Hormozgan, Kerman, Sistan-Balushestan and Fars provinces). Insects were collected from infected lime trees by a D-Vac and stored at -20 ºC up to the DNA extraction. Total DNA was extracted and PCR was conducted with specific primer sets targeting 18S rRNA and 26S rRNA genes of the symbionts. Results revealed that the vector harboured two yeast symbionts, namely Yeast like symbiont of H. phycitis (Hp-YLS)and Candida pimensis,with a similarity of (98-99%) to those reported from the other Cicadellids. These results substantiate the association of these two endosymbiotic microbiota with H. phycitis which may suggest their ecological interactions. To establish any endosymbiotic relationship and probable interfering in pathogen transmission, further studies are needed.
Volume 7, Issue 2 (7-2018)
Abstract
The combined effect of gamma radiation and Carum copticum C. B. Clarke essential oil were determined for the management of Tribolium confusum Du Val larvae and adults. Experiments were carried out at 27 ± 1 ºC and 65 ± 5% R. H. under dark condition and three steps were designed: (A) Application of gamma radiation and essential oil at the same time. (B) Irradiation followed by essential oil. (C) Essential oil followed by irradiation. Radiation doses of 100 to 500 Gy were applied in combination with 5.97, 7.52 and 10.47 μl/l air of essential oil for the adults and 1.91, 4.08 and 12.02 μl/l for the larvae. The result showed that the combination of gamma radiation with C. copticum oil increased larval and adult mortality compared with the control, so that, the interaction of 500 Gy with 10.47 μl/l air for adults and 12.02 μl/l air for larvae caused 100% mortality in 13 and 8 days, respectively; although 100% of the larvae and adults mortality at 500 Gy alone caused within 22 days. It was revealed that the combination of irradiation and essential oils could be used as an effective control method and a good alternative to fumigants.
Volume 7, Issue 2 (7-2018)
Abstract
The effect of methanolic extracts of Achillea millefolium and Teucrium polium on third instar larvae of Egyptian cotton leafworm, Spodoptera littoralis were investigated. Methanolic plant extracts were mixed with artificial diet and then nutritional indices, glutathione-S transferase, esterase, α-amylase and protease, activity were measured 72h later. Approximate digestibility was increased significantly in larvae fed on the food containing methanolic extract of T. polium but there was not any significant change in insects treated with A. millefolium. T. polium significantly decreased relative growth rate (RGR), relative consumption rate (RCR), efficiency of digested food (ECD) and efficiency of conversion of ingested food (ECI) whereas A. millefolium only decreased RGR and RCR. Feeding on artificial diet containing plant extract decreased α-amylase and protease activities in the midgut of the insect. Furthermore, the effect of methanolic extract of plants on detoxifying enzymes showed that they have no effect on glutathione S-transferase and esterase activities.
Volume 8, Issue 1 (1-2019)
Abstract
The green peach aphid, Myzus persicae (Sulzer) (Hemiptera: Aphididae), is one of the most important pests in greenhouses and its damages are economically important. The overuse of chemical pesticides has caused resistance in green peach aphid to many common insecticides. Aphidius matricariae (Haliday) (Hymenoptera: Braconidae) is an effective biological control agent against aphid populations especially in greenhouse crops. Currently, use of safe and biocompatible botanical pesticides in combination with biological control agents is being recommended. In this study, contact toxicity of Dayabon (SL 10%), a new botanical pesticide, was investigated on different life stages of M. persicae at 1000 to 7000ppm. Also, the toxicity was studied on mummies and adult parasitoids at 2000 to 14000ppm. The estimated LC50 on first, second, third, fourth instar nymphs and adults were 3254, 3387, 4194, 3839 and 3508ppm, respectively. However, concentrations up to 5000ppm caused less than 50% mortality in parasitoid mummies. Moreover, the residues of Dayabon did not cause any mortality in A. matricariae adults. Based on the standard method of IOBC/WPRS Working Group for side-effects of pesticides on natural enemies of insects, the Dayabon is recognized as safe for A. matricariae while it has acceptable mortality on green peach aphid. Therefore, the integration of Dayabon with A. matricariae could be recommended in order to achieve better control of M. persicae in greenhouse products.
Volume 8, Issue 2 (6-2024)
Abstract
Research Subject: Carbon dioxide (CO2) pollution represents a major environmental challenge in contemporary society, primarily driven by industrial expansion. A notable modern approach for CO2 separation involves the use of polymer membranes, with poly (ether-block-amide) (Pebax) recognized as a prominent industrial membrane in this field. However, this type of membrane is constrained by the permeability–selectivity trade-off, which hinders its broader application in industrial processes. One strategy to overcome this limitation is the incorporation of various functional compounds into Pebax.
Research Approach: This study selected phenol—characterized by its hydroxyl functional group—as a filler, and prepared Pebax membranes with varying phenol concentrations using advanced molecular simulation techniques. Molecular Dynamics (MD) and Grand Canonical Monte Carlo (GCMC) methods were employed to evaluate both the structural properties and gas separation performance of the membranes. Initially, structural properties—including fractional free volume (FFV), density, and polymer chain mobility—were analyzed, followed by assessments of functional properties such as diffusion and solubility coefficients.
Main Results: The incorporation of phenol led to an increase in the membranes' fractional free volume (FFV). Radial distribution function (RDF) analysis revealed that the interaction between CO2 and phenol molecules was stronger than that between CO2 and Pebax polymer chains. Furthermore, the results indicated that phenol increased the CO2 diffusion coefficient by a factor of 5.5 and the solubility coefficient by 1.3 times compared to the pure Pebax membrane, due to Lewis acid–base and π-quadrupolar interactions. Analysis of CO2 permeability and CO2/N2 selectivity in the simulated membranes showed that increasing the phenol content led to higher CO2 permeability but a continuous decrease in CO2/N2 selectivity.
Volume 8, Issue 4 (Number 4 - 2006)
Abstract
The agromyzid leafminers, Liriomyza sativae Blanchard and L. trifolii (Burgess) (Dip-tera: Agromyzidae) are major pests that attack vegetables in Varamin, Tehran Province. The parasitoids (Hymenoptera: Eulophidae) of these pests were investigated during 2003. The leafminer infested leaves were collected from different host plants, in particular cu-cumber (Cucumis sativus L.,) and preserved under laboratory conditions until the parasi-toids emerged. The vegetable leafminer were parasitized by an expected range of parasi-toids. The parasitoid species included Cirrospilus vittatus Walker, Hemiptarsenus zilahise-bessi Erdös, Closterocerus formosus Westwood, Diglyphus isaea (Walker), Diglyphus crassinervis Erdös. and Pnigalio sp. nr. pectinicornis. The most common species was D. isaea, followed by C. formosus and D. crassinervis. Although insecticides were applied con-tinuously for control of leafminers, the mean seasonal percentage of parasitism was 51.12%. The morphological characteristics of each species are given in brief.
Volume 10, Issue 1 (10-2021)
Abstract
Rapid cold hardiness in response to sudden decline in air temperature plays an important role in the aphid survival. Rapid cold hardiness is a phenomenon that increases insect’s survival at sub-zero temperatures following a brief exposure to low temperatures above 0 °C. In this regard, the cabbage aphid Brevicoryne brassicae (L.) is able to increase its cold hardiness gradually during cold season and produce large population on host plants in Brassicaceae family. In this research, rapid cold hardiness of B. brassicae, and its effects on development time, longevity and fecundity were investigated. Direct transfer of aphids from 20 °C to a series of sub-zero temperatures for 2 h, resulted in a LT80 (estimated temperature required to kill 80% of tested population) of -7.3 °C. Preconditioning of first instar nymphs for 3 h and adults for 2 h at 0 °C resulted in the highest survival rates of 63% and 71%, respectively. Acclimation of aphids, by a cooling rate of 0.05 °C/min form 20 to 0 °C, prior the exposure to LT80 (-7.3 °C) resulted in the highest survival. No detrimental effects of rapid cold hardiness were observed on development time, longevity and fecundity. Results of the present study showed that rapid cold hardiness is induced in B. brassicae and increases the aphid survival in response to unexpected changes of temperature.