فهرست مطالب javad karimzadeh

One of the most important and damaging pests of canola is cabbage aphid Brevicoryne brassicae L. This research was carried out to assess the damage of the pest in a randomized complete block design. The results showed that the maximum mean number of aphids per surface unit (10 cm branch length of the flowering branch) is 367.88±27.88, 439.75±36.13, 187.75±10.10 and 274.00±27.68 respectively in West Azarbaijan, Markazi, Fars and Isfahan provinces on Hydromel, Ahadi, Talaiyeh and Okapi varieties. It causes 37%, 35.5%, 25.1% and 22.9% reduction of rapeseed yield.

The diamondback moth, Plutella xylostella (L.) (Lepidoptera: Plutellidae) is one of the most destructive insect pests, feeding exclusively on wild and cultivated cruciferous species. The attacked plants produce considerable amount of glucosinolates in response to insects’ feeding. Herein, we studied digestive activities of P. xylostella on four different genotypes of family Brassicaceae including two canola cultivars (SLM046 and RGS003) and two cabbage cultivars (Green-Cornet and Glob-Master). The highest proteolytic and amylolytic activities of P. xylostella were observed on Green-Cornet and the lowest occurred on RGS003 and Glob-Master, respectively. The highest activity of α-glucosidase and β-glucosidases were observed on Green-Cornet and SLM046 and the lowest was observed on Glob-Master and RGS003. The zymogram analysis revealed different isozymes of protease, trypsin-like and α-amylase in the midgut extract of P. xylostella. Activity of the above mentioned isozymes was inhibited in larvae feeding on RGS003 and Glob Master as resistant host cultivars. Also, larvae feeding on the resistant genotypes showed more glucosidase activities, indicating possibility of high glycosinolate existence in the resistant genotypes. By these results we can state that host plant property can affect insect digestive physiology through inhibiting digestive enzyme activities. These findings provide insights into the direct effects of host plants on insect physiology which are conducive to change in insect fitness.

The carob moth, Apomyelois ceratoniae, is the chief pest of the pomegranate. Its control is only plausible using ecological pest management. Population dynamics and, in particular, population regulation is of prime importance in ecology. Different factors, including indigenous (intraspecific competition) and exogenous (climate and other organisms), may affect population size; the effects can be dependent or independent of population density (Price, 1997). In general, insect populations can go through equilibrium dynamics or non-equilibrium dynamics. In addition, a population at equilibrium level can be stable, unstable or have neutral stability. Stability denotes a return to the previous equilibrium level after a perturbation. Neutral stability, however, is a shift of the equilibrium to a new level (Cappuccino and Price, 1995; Schowalter, 2012). In the present study, the stability of the population equilibrium of the carob moth was examined.
To examine the effects of perturbation and the stability of population equilibrium of carob moths, two different experiments were performed. The first experiment included three treatments (perturbation using density reduction, perturbation using density increase, and no perturbation or the control). In the second experiment, only two treatments (perturbation using density reduction and the control) were carried out. All treatments were replicated four times using a randomized complete block design. The growth season was divided equally into two periods, and the number of infested fruits in 30 randomly selected trees per plot (orchard) was recorded weekly for each period. Data were analyzed using log-linear models to determine whether the equilibrium was stable, or if there were any shifts in the equilibrium level.
The results showed that when there was no perturbation, the equilibrium was unchanged. It was the same for perturbation using density reduction in the first experiment, since the equilibrium showed stability. However, perturbation using density reduction in the second experiment shifted population equilibrium to a lower level. In addition, perturbation using density increase also caused a change in population equilibrium such that the mean infestation of the pre-perturbation period was significantly greater than that for the post-perturbation period.Our findings indicate that creating a perturbation in the population of carob moths may significantly change the stability and population equilibrium as seen in the first experiment with perturbation using density increase. In this experiment, the equilibrium shifted to a higher level after a perturbation. Moreover, in the second experiment with perturbation using density reduction, the perturbation decreased population equilibrium, indicating a neutral stability. When there was no perturbation, carob moth populations showed persistence in a stable manner, where the same equilibrium was recorded for both time periods. It can be said that populations that were not subjected to a perturbation may persist if there are enough food resources. Therefore, these populations cannot be easily perturbed or made unstable by climate or natural enemies unless the populations are manipulated by human practices such as pest management strategies.
It was concluded that by using a perturbation, carob moth populations can be ecologically managed. With exact times and applications of ecological strategies of pest management (such as perturbation), it is possible to benefit from the method by lowering population equilibrium to below the economic injury level. Thus, the lowered level of population equilibrium is very important due to its stability, preventing usage of extra pest management practices.

The pear psylla¡ Cacopsylla pyricola (Förster) (Hemiptera: Psyllidae)¡ is a key pest of pear trees in Iran. One of the processes that regulate an insect population around the equilibrium position is the host plant effect. Therefore¡ the effect of plant variety on equilibrium level of pear psylla population was investigated for three pear varieties¡ including Shahmivea¡ Sebri and Coscia. A density-manipulation experiment was performed in a randomized complete block design with densities of 2¡ 4¡ 8¡ 16 and 32 pair of C. pyricola adults. The population models of Hassell and Ricker were fitted to the data and the minimum model was selected based on the model simplification. Populations recruitment curve were created and population equilibrium level of pear psylla was determined for each variety. The stability of the predicted equilibria was then determined. Long-term dynamics of pear psylla population was predicted for 100 generations by computer simulation of the best-fitted model. The results showed that the Ricker model could be fitted well to the data for all three varieties. The pear psylla population showed a density-dependence reaction. The equilibrium population values showed a difference of up to 36% for the three varieties. Predicted equilibrium was unstable for Shahmivea variety and while it was stable for two other varieties. In addition¡ computer simulation verified that long-term dynamics was fluctuated for Shahmivea variety and smooth for two other varieties. The effect of bottom-up forces of host plant on the magnitude and period of population fluctuations of pear psylla has been discussed.

In recent years, the diamondback moth (Plutella xylostella) has had some outbreaks in Iran (Afiunizadehand Karimzadeh, 2015). As a consequence of the development of insecticide resistance in P. xylostella populations and high insecticide residue on the crops, alternative, ecological and sustainable pest management strategies are urgently needed (Talekar and Shelton, 1993). Cultural control is simple, applied and compatible with other ecological methods and, hence, it can be used in integrated pest management. Trap cropping is a cultural and ecological pest management strategy that has been used increasingly in recent years (Shelton and Badenes-Perez, 2006).The present study is aimed at examining an ecological management of P. xylostella using native plants as trap crops in common cabbage.
For this purpose, an experiment with six treatments was performed in a 0.5-ha field of common cabbage located in Falavarjan (Isfahan Province, central Iran). In each 100-m2 plot, the first two rows were planted with a trap crop, including Chinese cabbage, white mustard, turnip, black radish, and a mixture of all the aforementioned trap crops. Common cabbage was considered as the control. The treatments were replicated four times in a randomized complete block design. Random sampling was performed fortnightly from transplantation to harvest on 10 plants of main crop (common cabbage) per plot looking for P. xylostella larvae and pupae, and on three plants of trap crop per plot looking for P. xylostella adults.
For this purpose, an experiment with six treatments was performed in a 0.5-ha field of common cabbage located in Falavarjan (Isfahan Province, central Iran). In each 100-m2 plot, the first two rows were planted with a trap crop, including Chinese cabbage, white mustard, turnip, black radish, and a mixture of all the aforementioned trap crops. Common cabbage was considered as the control. The treatments were replicated four times in a randomized complete block design. Random sampling was performed fortnightly from transplantation to harvest on 10 plants of main crop (common cabbage) per plot looking for P. xylostella larvae and pupae, and on three plants of trap crop per plot looking for P. xylostella adults.
Considering the great concerns over overuse of chemical insecticides, it is necessary to use the cultural procedures of pest management, such as trap cropping. Trap cropping provides a simple and applied tool, which is compatible with other ecological pest management strategies.

The diamondback moth, Plutella xylostella (L.) is a serious and economically important pest of cruciferous crops worldwide. The nutritional indices of this peston four host plants including two canola (SLM046 and RGS003) and two cabbage cultivars (Green-Cornet and Glob-Master) were determined under laboratory conditions (25 ± 0.5 °C, 65 ± 5% RH and 16: 8 L: D h). The highest relative consumption rate (RCR) and relative growth rate (RGR) were recorded on RGS003 (95.68 ± 14.52 mg/mg/day) and SLM046(0.382 ± 0.041 mg/mg/day), respectively. The efficiency of the conversion of ingested food (ECI) and efficiency of conversion of digested food (ECD) were significantly highest on SLM046 (2.298 ± 0.646 and 2.471 ± 0.719%, respectively). However, there was no significant difference among cultivars regarding approximate digestibility (AD) index. The highest feeding performance of the larvae of P. xylostella was found on SLM046. The nutritional indices are appropriate tools in host plant resistance evaluation and they also could provide profound understanding of the behavioral and physiological bases of insect-host plant interactions.

In recent years, plane trees showed a highly infestation to a species of clearwing moth in Isfahan. Studies on determination of the species indicated that this serious new pest was Synanthedon caucasica Gorbunov (Lepidoptera, Sesiidae). The observed plane trees were highly (95.7%) infested to the moth. The mean estimated damage index in different areas of Isfahan varied between 3.3 and 7.4, with an overall mean of 5.5.

In many entomological studies, a smaller sample is taken than a statistician would advise. Clearly, such experiments would often fail to detect any significant effects, resulting in a complete waste of time and money. The present paper introduces statistical power of a test and its importance in determining the minimum sample size required for detecting significant effects. A number of experiments fail simply because the issues of statistical power are not confronted with at the planning stage. A fundamental question that is needed to address at the planning stage concerns the number of samples required to test the hypothesis of interest. The answer depends on the variance of response variable, the size of difference in the response variable that would be detectable as significant, the risk of a Type I error and the risk of a Type II error. Here using R language of statistical computing, the specific methods of the calculation of optimum sample size for laboratory and field studies are presented for two common scenarios.