سیدعلی اصغر فتحی

The citrus red mite, Panonychus citri (McGregor), can cause severe damage to citrus trees. Typhlodromips caspiansis Denmark & Daneshvar is an indigenous predatory mite that was recently reported in association with P. citri in the Northern provinces of Iran. This study aimed to investigate the bottom-up effect of potassium and salicylic acid on the development and life table parameters of T. caspiansis on P. citri reared under host-plant treatment. Two-year-old citrus seedlings were sprayed with a solution containing potassium fertilizer (0.02 g/L) plus salicylic acid (1 mM). The survival rate and duration of the immature stages of the predator, as well as the longevity of adults and fecundity, were recorded. There was no significant difference in the egg and larval duration of T. caspiansis fed on P. citri reared on potassium+salicylic acid-treated and untreated (control) citrus seedlings. In comparison to the control, the duration of deutonymph was prolonged by the application of this treatment. Also, the longevity of females that came from immatures under host-plant treatment. The net reproductive rate (R0), intrinsic rate of increase (r), and finite rate of increase (λ) of T. caspiansis did not show significant differences between potassium+salicylic acid-treated and untreated citrus seedlings; while the mean generation time (T) differed significantly. It can be concluded from the previous study and the present study that the positive effects of potassium+salicylic acid on P. citri control entail no negative outcomes regarding predator fitness. However, further field-based studies are needed for more realistic conclusions.

The melon aphid, Aphis gossypii Glover (Hemi.: Aphididae), is a polyphagous aphid species that causes severe damage to many crops worldwide. It feeds on the host plants by sucking the sap from leaves, flower buds, and stems. A. gossypii can also transmit several plant viruses. The population of A. gossypii is usually controlled by chemical insecticides. However, the excessive use of insecticides has resulted in developing resistance to the insecticides. For sustainable management of A. gossypii on host plants, alternative methods such as the use of resistant plant cultivars and plant hormones seem to be effective strategies. Host plant resistance is a fundamental factor for a successful integrated pest management (IPM) system. Gibberellic acid is one the most important plant hormones that regulates many aspects of plant growth and promotes plant resistance to some insect pests. In this study, we investigated the involvement of gibberellic acid in the defense responses of two caltivers (Capsicum annuum L.) against A. gossypii.

The effects of gibberellic acid and two cultivars [poblano (as susceptible cultivar) and paprika (as resistant cultivar)] on A. gossypii were determined by analyzing the life history and life table parameters of the pest at 25 ± 2 ˚C, 65 ± 5 % RH, and a photoperiod of 16L: 8D h. The initial colony of A. gossypii was obtained from the laboratory of Department of Plant Protection, University of Mohaghegh Ardabili (Ardabil, Iran). The plants were grown individually in 16 cm-diameter plastic pots filled with a mixture of soil and sand (1:1). When they had reached the four- or six-leaf stage, they were used either for rearing the aphids or for the experiments. The experiments were initiated by spraying the entire leaves of each pepper cultivar with a solution of gibberellic acid at a concentration of 0.005 g. The control plants were treated with distilled water. After 24h, apterous adults were randomly selected from the colony and transffered to the clipcages (6 cm diameter) set on the tested cultivars leaves. They were permitted to produce nymphs for 24h. Then, the adults and all nymphs except one were removed from the clipcages. Each cage were monitored daily for the aphid’s survival and developmental time. After maturity, daily observations were continued until the death of last individual. The numbers of nymphs produced per female aphid were counted daily, and then all nymphs were eliminated from the clipcages. The obtained data were analyzed via the TWOSEX-MSChart program based on the age-stage, two-sex life table theory.

The results show that, A. gossypii exhibited a longer nymphal period and lower adult longevity on the tested cultivars sprayed with gibberellic acid than on the control. The oviposition period and fecundity of the aphid were lower in the plants treated with gibberellic acid than in control. Finally, the lowest and highest lifespan were 6.97 days (gibberellic acid treatment in Paprika) and 10.25 days (control treatment in Poblano), respectively. In addition, spraying the pepper cultivars with gibberellic acid significantly decreased the gross reproductive rate (GRR), net reproductive rate (R0), intrinsic rate of increase (r), and finite rate of increase (λ) of A. gossypii compared to the control. The minimum and maximum values of r were 0.2839 (gibberellic acid treatment in Paprika) and 0.4046 day (control treatment in Poblano). The results exhibited that the gibberellic acid was more effective in decreasing the life -history and -table parameters of A. gossypii on cultivar paprika. These parameters are appropriate indexes to compare insect pests’ performance on different host plants as well as the host plant’s induce resistance versus the insects. Comparing the results of the life history and life table parameters of A. gossypii on the tested treatments indicated that pepper plants especially the cultivar paprika treated with gibberellic acid was more effective in controlling A. gossypii due to slow development, poor fecundity, and low r value of the aphid. The lower performance of A. gossypii on this treatment would result in a lower population growth that in turn would lead to lower subsequent infestations. 

The results of the current study showed that, gibberllic acid had a suitable potential for controlling the population of A. gossypii and can be used in the integrated pest management (IPM) programs.

In this study, the effect of three cucumber cultivars (Vihan, Shahab, and Saba) and two types of culture substrates (soil and hydroponic) was investigated separately on the functional response of 3rd instar larvae of Chrysoperla carnea (Stephens) to different densities (2, 4, 8, 16, 32, 64, and 128) of 4-day-old nymphs of Aphis gossypii Glover. The 3rd instar larvae of predator were starved for 16 h before the experiment. The experiment was conducted for 24 h in leaf cages at 25±2 ̊C, 65±5 % RH, and 16:8 h (L: D). Logistic regression analyses revealed that the functional response of the C. carnea to A. gossypii in all treatments was type II. The attack rate (a) of 3rd instar larvae of the predator in hydroponic culture treatments was significantly higher than the soil culture. The handling times (Th) of the predator varied from 0.1310 to 0.1665 h on different treatments.  The 3rd instar larvae demonstrated the highest feeding attack rate on A. gossypii when associated with the Vihan cultivar, followed by the Shahab and Saba cultivars across both culture substrates. The results revealed that the culture substrates and plant cultivars can affect the functional response parameters of 3rd larval instar of C. carnea.  Further research is necessary to gain a deeper understanding of how plant culture substrates and cultivars influence the interactions among cucumber, A. gossypii, and C. carnea.

Different cultivars of a host plant can have an important effect on the behavioral charectristics of natural enemies. In this ‎study, the effect of three wheat cultivars (Ehsan, Morvarid, and Tirgan) on functional responses of 4th instar larvae and adult ‎males and females of Hippodamia variegata Goeze on different‏ ‏densities (2, 4, 8, 16, 24, 32, 64, 96, 128, and 160) of 4-d-old ‎nymphs of Schizaphis graminum Rondani‏ ‏was studied. The experiments were conducted at 25±2 ˚C, 65±5% RH and 16L:8D h ‎photoperiod. The logistic regression analyses revealed that the functional responses of different growth stages of H. variegata ‎to S. graminum on differen wheat cultivars were type II. According to the results, the highest attack rate was estimated for 4th ‎instar larvae of H. variegata on Ehsan and Tirgan cultivars (0.152 and 0.154 h-1, respectively). Also, the lowest handling time ‎‎(0.127 h) was valued for 4th instar larvae on Ehsan cultivar. The predation rate of 4th instar larvae of H. variegata was also ‎highest on Ehsan cultivar. The results of this study revealed the high efficiency of 4th instar larvae of H. variegata in feeding ‎on S. graminum on Ehsan cultivar followed by Tigasn and Morvarid cultivars. Similar results were obtained for adult femles ‎and males of the predator. However, further studies are necessary to evaluate the effect of these cultivars on searching ‎bahavior and consumption rate of different stages of H. variegata on S. graminum under natural conditions. ‎

Strip cultivation is one of the effective methods to reduce the population of pests and increase the abundance and diversity of natural enemies in any habitat. Onion thrips, Thrips tabaci Lind., is a pest of onion (Allium cepa L.) worldwide. Larvae and adults of thrips feed on cell sap and cause silver spots on the surface of leaves of onion plants that consequently result in a significant reduction in onion yield. Control of onion thrips is difficult due to the short generation time, high fecundity, and the emergence of insecticide-resistant genotypes. Predators in each region, such as hemipterans, ladybugs, syrphid flies, carabid beetles, mites, and spiders, are effective in the biological control of the onion thrips population in fields. Intercropping systems can affect the biological control of pests by providing food and habitat resources for natural enemies. Therefore, designing effective and appropriate methods to reduce the population of onion thrips and increase the diversity and abundance of natural enemies can effectively manage T. tabaci in fields.

In this study, the effect of intercropping four rows of onion (Allium cepa L.) with two rows of fenugreek (Trigonella foenum-graecum L.) (4O:2F) and four rows of onion with two rows of safflower (Carthamus tinctorius L.) (4O:4S) was investigated on densities of the onion thrips, biodiversity of predators, and crop yields in 2022 and 2023. The experiments were accomplished in a randomized complete block design with two intercrops of 4O:2F and 4O:4S along with the sole crops. The density of onion thrips and predators per plant was counted and recorded on weakly sampling dates by direct counting using a magnifying glass. The predatory species that we suspected in their identification were transferred to the laboratory and carefully identified through morphological characteristics under a stereomicroscope. The average annual abundance of each predator species and the abundance of predators per plant in each plot were calculated during the onion growing season. In addition, Shannon's diversity index (H') and Pielou's evenness index (J') were calculated for the complexity of predators in each plot and in each tested year to compare the cropping systems. The onion, fenugreek, and safflower yield per square meter were estimated in strip intercropping systems and single crops. Then, the land equality ratio (LER) was calculated for both intercrops to estimate the yield advantage regarding the monoculture of each crop.

Three intercrops led to a significant reduction in the densities of larvae and adults of onion thrips compared with sole onion. Further, the leaf damage index was lower in intercrops than in single onion in two seasons. A significant coefficient of determination (R2) was calculated between the leaf damage index and the dry weight of onion per plant in two intercrop and sole onions. The total abundance of predators was higher in intercrops, especially 4O:2F than in the sole crop. More values of the Shannon diversity index and the Pielou's evenness index for predators were recorded in intercrops compared with the sole crop in two seasons. The dry yield of onions per square meter was more significant in both strip intercropping systems compared to single onions in 2022 and 2023. On the contrary, the dry yield of fenugreek and safflower per square meter was insignificant among intercrops and single crops in two years. The highest land equivalent ratio (LER) was calculated for 4O:2F.

Overall, the intercropping of onion and fenugreek (4O:2F) and onion and safflower (4O:2S) demonstrated a reduction in the population of onion thrips. Both intercrops, particularly 4O:2F, contributed to an increase in the abundance and diversity of predators and the values of LER when compared with sole crops. As a result, farmers could consider implementing both intercrops, particularly 4O:2F, as an environmentally conscious approach to managing T. tabaci in the field.

Sowing cover crops is one of the agricultural practices in habitat management for enhancing the diversity of beneficial arthropods. In this study, the impact of sowing cover crops between the lines of pear trees, Pyrus communis L., was assessed on the densities and damage of the pear psylla, Cacopsylla pyricola (Förster), and natural enemies on the pear orchards over two growing seasons (2022 and 2023). Experimental cover crops were (1) red clover, Trifolium pratense L., (2) rosemary, Rosmarinus officinalis L., (3) canola, Brassica napus L., (4) mix cultivation clover-rosemary-canola, and (5) absence of cover crops (as control). The results indicated that the lowest densities of the eggs, nymphs, and adults, and the percent of infested leaves and fruits of the pear psylla per 30-cm branch were observed in the plots with mixed cultivation of clover-rosemary-canola. Moreover, the highest total abundance of predators was recorded in the mix of clover-rosemary-canola plots. Among the collected natural enemies, Anthocoris nemoralis (Fabricius), Orius niger (Wolff), Hippodamia variegata (Goeze), Chrysoperla carnea (Stephens), and Episyrphus balteatus De Geer, respectively indicated the higher abundance. The greatest values of the Shannon diversity index (H΄ = 2.22 in 2022 and 2.20 in 2023) and the Pielou's evenness index (J' = 0.96 in two years) for the combination of predators were calculated in the mix clover-rosemary-canola plots. Therefore, it could be concluded that cultivating of the mix clover-rosemary-canola between pear trees results in the rise of diversity and abundance of predators and the reduction of pear psylla.

The melon aphid, Aphis gossypii Glover is one of the most important pests in pepper fields and greenhouses, which is of special economic importance due to its wide distribution and large host range. In this research, biological and reprodutive parameters of A.gossypii on two pepper cultivars (Poblano and Paprika) treated with salicylic acid, were investigated at laboratory conditions (25 ± 2 ˚C, 65 ± 5 % RH, and a photoperiod of 16L: 8D h). According to the results, the use of salicylic acid in both cultivars had a significant effect on most of the demographic parameters of the A.gossypii, compared to the control (spraying with distilled water) and decreased its life span, life cycle length, and Survival. The lowest and highest lifespan were 5.91 days (salicylic acid treatment in Paprika) and 10.25 days (control treatment in Poblano), respectively. Also, the use of this hormone had a significant effect on the reducing gross reproductive rate (GRR), net reproductive rate (R0), intrinsic rate of increase (r), and finite rate of increase (λ) of the aphid. The minimum and maximum values of r  were obtained in salicylic acid treatment on Paprika and control treatment on Poblano (0.2570 and 0.4046 d-1 respectively). So, salicylic acid can considerably reduce biological and reprodactive parameters of A.gossypii in pepper and can be used in integrated pest management programs of melon aphid.

The khapra beetle, Trogoderma granarium (Everts) is one of the most important insect pests of stored products, especially wheat grains, in Iran and some other countries of the world. In this research, effect of various wheat genotypes including Heidari, Aftab, Gaskojen, Kouhdasht, Tirgan, N-91-9, and N-92-19 was studied on biology and two-sex life table parameters of T. granarium under 33 ± 1°C, relative humidity of 65 ± 5%, and a photoperiod of 14:10 (L:D) h. Our results showed that the immature period of T. granarium was the longest on N-91-9, Heidari, and Aftab. The net reproductive rate (R0) ranged from 9.03 offspring on N-92-19 to 34.13 offspring on Gaskojen. The lowest intrinsic rate of increase (r) was for T. granarium reared on Heidari, Aftab, N-91-9 and N-92-19. The results of this study indicated that Heidari, Aftab, N-92-19 and N-91-9 were unfavorable genotypes for T. granarium development and population increase. These genotypes could be used as one of the sources of resistance in management programs of T. granarium.

Trogoderma granarium (Everts) is an economic insect pest of stored grains in Iran and many tropical and subtropical regions. If stored products contaminated with this insect are consumed by humans, it would cause serious digestive diseases. To control T. granarium in storage, chemical insecticides and fumigants are often used, but due to their extreme toxicity to humans and other dangerous side-effects, their application has been limited. Therefore, in order to develop alternative control methods with minimal harmful effects to humans and other non-target organisms, there is a need to understand feeding performances of the pest on different cultivars. The use of insect-resistant plants is one of the effective methods in integrated pest management programs. Study of nutritional indices of stored product insects is one of the important methods of measuring the resistance in plant cultivars.

Nutritional indices of T. granarium larvae were investigated using the gravimetric method provided by Wadbauer (1968). The grains of wheat genotypes including N-91-9, Heidari, Aftab, Tirgan, N-92-19, Gaskojen and Kouhdasht were crushed using a grinder. Then, first instar larvae were reared on the grains of these genotypes under 33 ± 1°C, 65 ± 5% R.H., and 14:10 (L:D) h. After emergence of fifth instar, the weight of larvae, before and after feeding, and the amount of grain eaten by the larvae were measured. The data were analyzed using one-way ANOVA using SPSS ver.16. Then, Tukey's HSD test, with a probability level of 5%, was used to investigate the statistical differences among the means.

There were significant differences in the nutritional indices of T. granarium fifth instar larvae on grain of different wheat genotypes. The larvae raised on line N-91-9 had the lowest weight of food consumption (24.33 ± 3.38 mg/10 larvae) compared to other genotypes tested. Larvae fed with line N-91-9 (5.33 ± 0.33 mg/10 larvae) and cultivars Aftab (3.00 ± 0.57 mg/10 larvae) and Heidari (3.00 ± 0.57 mg/10 larvae) showed lower weight gain than those fed with other genotypes. The highest efficiency of conversion of ingested food (ECI) was on cultivars Gascojen (36.56 ± 1.46 %) and Tirgan (33.42 ± 0.60 %), and the lowest was observed on cultivars Aftab (7.32 ± 1.51 %) and Heidari (7.86 ± 1.38 %). The highest relative consumption rate (RCR) was found on cultivar Gascojen (1.08 ± 0.05 mg/mg/day) and line N-92-19 (0.95 ± 0.02 mg/mg/day), and the lowest was seen on line N-91-9 (0.16 ± 0.03 mg/mg/day), and cultivars Heidari (0.19 ± 0.02 mg/mg/day) and Aftab (0.24 ± 0.02 mg/mg/day). As compared with the other examined genotypes, the relative growth rate (RGR) was the highest on cultivar Gascojen (0.394 ± 0.022 mg/mg/day). Larvae feeding from cultivar Gascojen (5.61 ± 0.17 mg/day) had the highest growth rate (GR), and larvae feeding from line N-91-9 (0.76 ± 0.04 mg/day) and cultivars Heidari (0.42 ± 0.08 mg/day) and Aftab (0.42 ± 0.08 mg/day) had the lowest GR value. The change in the nutritional indices of T. granarium larvae can be due to the differences in physical and chemical characteristics of the grains of tested wheat genotypes. The ECI index represents the ability of an insect to use eaten food to increase its body size and weight. In other words, the increase in ECI value on cultivars Gaskojen and Tirgan indicates the high ability of fifth instar larvae to convert the eaten grain into body biomass. This finding may be due to the high protein content and low grain hardness of these cultivars. The low weight of food eaten and body weight in larvae fed with cultivar Heidari and line N-91-9 may be due to the high grain hardness of these genotypes.

Our results showed that line N-91-9 and cultivars Heidari and Aftab had lower nutritional value than the other tested genotypes for T. granarium larvae, because the amount of food eaten, larval weight gain and nutritional indices of larvae fed with these genotypes were lower than other genotypes tested. So, these two genotypes can be used in genetic engineering programs to minimize the damage of T. granarium. The presence of defensive chemical compounds, grain hardness or the lack of essential nutrients for the development of the pest may be the reason why some of the tested cultivars are unsuitable for T. granarium feeding.

The green lacewing, Chrysoperla carnea, plays an important role in biological control of various aphid species. In this study, the functional responses of the second and third instar larvae of C. carnea were studied on the citrus aphid, Aphis spiraecola and melon aphid, A. gossypii. The experiments were carried out on orange (cv. Thompson Navel) leaves in a growth chamber at 27 ± 2°C, 65 ± 5% RH and a photoperiod of 16 L: 8 D h. Different densities of the preys were offered to the predators, and the number of consumed preys was calculated after 24 h. Based on the logistic regression analysis, both second and third larval instars of the predator exhibited a Type II functional response to both aphid species. With increasing of the larval instar, the attack rate (a) of the predator on A. spiraecola was significantly increased and the handling time (Th) decreased. Attack rate of second larval instar of the predator on A. gossypii was significantly higher than that on A. spiraecola. Furthermore, the third instar larvae fed on A. gossypii showed significantly lower handling time and higher attack rate compared to A. spiraecola. The results of this study revealed that the larvae of C. carnea, especially the third instar, had a good predation potential in controlling A. spiraecola and A. gossypii. However, further field-based studies are needed for a comprehensive estimation of biocontrol abilities of C. carnea toward these two aphids on the citrus.

Potato tuber moth, Phthorimaea operculella (Zeller), is the most important pest in potato fields in the world and Iran. The use of appropriate agricultural and protection strategies to prevent oviosition of Ph. operculella on newly formed potato tubers at the end of the cropping season can be effective in reducing its damage. The effects of cover crops on damage reduction on newly formed potato tubers were investigated in a randomized complete block design with three replications during two years 2020 and 2021. After the senescence of potato foliage, the cover crops including of vetch (Vicia sativa), grass pea (Lathyrus sativus), rye (Secale montanu), and strengthening of the natural field vegetation were used as cover crops in the field. Tuber infestation (%) during two years in vetch, grass pea, reinforcement of field vegetation and rye was 8.00, 12.33, 26.33 and 26.17%, respectively and all treatments significantly reduced the damage on potato tubers when compared with control (39.17%). The number of larvae in the infested tubers showed a significant difference between treatments, and the treatments of vetch, grass pea, reinforcement of field vegetation and rye showed a lower larval density, respectively. Based on results, vetch is the most effective plant to cover the soil and prevent Ph. operculella oviposition on the potato tubers. Moreover, maintaining and strengthening of weeds in the field at the end of the growing season and after the drying of potato foliage could be a low-cost method to prevent damage by Ph. operculella on tubers in the soil.

The khapra beetle, Trogoderma granarium (Everts), 1898 is one of the damaging pests of different stored cereal grains in Iran. In this research, effect of four cereal grain species including wheat (varieties N-91-9 and Aftab), barley (varieties Dasht and Oxin), maize (varieties AR and 704), and rice (varieties Hashemi and Fajr) was studied on nutritional indices and digestive proteolytic and amylolytic activities of T. granarium fifth instar at 33±1˚C, relative humidity of 65±5% and a photoperiod of 14: 10 (L: D) h. The results showed that the highest food consumption by larvae was observed on wheat N-91-9 and the lowest value was seen on maize 704 and rice Fajr. The relative growth rate was the highest on wheat N-91-9 and barley Dasht. The highest proteolytic activity was in larvae fed on wheat Aftab, barley Dasht and rice Hashemi, and the lowest activity was in those fed on rice Fajr. The amylolytic activity of larvae fed on varieties Dasht, N-91-9, Hashemi and AR was significantly higher than those fed with other tested cereals. The results of this study indicated that barley Dasht and both wheat varieties tested were relatively more favorable than other examined cereals for feeding of T. granarium larvae.

The two-spotted spider mite, Tetranychus urticae Koch, is an important pest of agricultural crops in Iran. In this study, intercropping pepper (P),Capsicum annuum L., with garlic (G), Allium sativum L., in the three patterns 3T:5G, 3T:8G and 3T:11G (row ratios) along with sole pepper crop were assessed on the densities of T. urticae,diversity of natural enemies and crop yield in an experimental field, based on a randomized complete block design during the two growing seasons 2017 and 2018. The densities of T. urticae eggs and mobile forms were lower in the three intercrops compared with sole pepper crop (p < /em> ≤ 0.05). The values of the Shannon diversity index (H´) and the Pielou’s evenness index (J´) for the composition of T. urticae predators were greater in the three intercrops compared with sole pepper crop. In the present study, Stethorus gilvifrons (Mulsant) and Orius niger (Wolff) were the main predators of T. urticae on pepper plants. The abundance of O. niger was higher in the three intercrops compared with sole pepper crop, but the populations of S. gilvifrons had not significant difference between intercrops and sole pepper crop (p < /em> ≤ 0.05). Moreover, the values of land equivalent ratio (LER) were greater than one in the three intercrops (LER ≥ 1.14) compared to sole crops. These results revealed that intercropping pepper with garlic could be an effective method in the integrated management of T. urticae in pepper fields.

In Iran, potato Solanum tuberosum L. is an important crop, and its cultivation extends over more than 186,000 ha annually. The onion thrips, Thrips tabaci Lindeman, is a highly polyphagous species and a serious pest of a wide range of economically important crops. In Iran, T. tabaci causes damage on different agricultural crops including: potato, onion, cucumber and tobacco. Onion thrips feeds by piercing the surface of the tissues (leaves and leaf buds) and sucking up the exuded cellular contents. On infested leaves, the empty cells create silvery-white spots, silver damage, which cause yield loss. Use of insecticides for controlling T. tabaci has low efficacy because females lay eggs within leaf tissues, larvae hide in leaf domatia and between the inner leaves of plants, and pupae rest in the soil. Therefore, it is necessary to use alternative management approaches for control of T. tabaci such as resistant cultivars integrated with natural enemies. The interactions between natural enemies and resistant cultivars have a direct effect on the pest by effecting its developmental rate, fecundity and survival rate. They may also have an indirect effect on natural enemies by increasing generation time of the pest and, as a result, increasing exposure time of the pest to its natural enemies. In this study, we assumed that the different potato cultivars affect population density of T. tabaci and diversity of its natural enemies. Therefore, the present research was designed to evaluate the onion thrips density and species diversity of its natural enemies on four potato cultivars under field condition.

Tubers of four potato cultivars including Agria, Savalan, Arensa and Fantasia (commonly cultivated in Ardabil region) were selected for evaluation of population density of T. tabaci and diversity of its natural enemies under field condition during 2011-2012. The tubers were obtained from the Seed and Plant Improvement Institute of Karaj, Iran. Tubers of four tested cultivars of potato were planted in four experimental fields, each of 500 m2,at four different locations in the Ardabil plain. The fields were managed according to the local practice with flood irrigation and hand weeding once every ten days. No insecticides were applied in these fields. The onion thrips populations were monitored on the four cultivars of potato from late stem elongation to petal fall stages by examining four plants from each cultivar chosen randomly from each of four fields (16 plants per cultivar). The numbers of thripslarvae and adults and each of natural enemies per plant were counted using a 20X hand lens. Moreover, onion thrips and its natural enemies were collected from each of potato cultivars, transferred to the laboratory, and identified to species by morphological characteristics under a stereomicroscope or a microscope according to the valid identification keys. The Shannon diversity index (H), Shannon evanesces index (E), and Morisita-Horn index (CMH) were then calculated for each of four potato cultivars by use of EstimateS Win 8.20 software (6). Data on population densities of onion thrips and its dominant natural enemies were analyzed using one-way ANOVA and significant differences among cultivars were compared using Tukey's HSD test. 

In two years, the lowest densities of onion thrips larvae and adults were observed on Agria. In this study, 21 species of onion thrips predator were collected and identified. Amongst the predator species, Aeolothrips intermedius Bagnall and Orius niger (Wolff) had the highest relative abundance on each of four potato cultivar. The predator A. intermedius with small size and ability to penetrate into leaf domatia, faster development rate and higher fecundity is effective in control of herbivore thrips on host plants (19). Moreover, previous researches have reported that the species of Orius are efficient in control of onion thrips. The Shannon diversity index for the complex of predators was greatest on Agria. Species richness and their relative abundance are two main factors for measuring Shannon diversity index in each ecosystem. Moreover, the values of Morisita–Horn index for the complex of predators between the four cultivars of potato ranged from 0.948 to 0.989. The value of this index varies between 0 and 1. When the value of this index increases from 0 to 1, the species complex of predators between two cultivars becomes more identical. In two years, densities of two predator species A. intermedius and O. niger on Agria and Savalan were significantly higher than on Arensa and Fantasia. Furthermore, the greatest percentage of females of two predator species was observed on the thrips-infested plants of Agria. These results indicated that the preference and performance of two mentioned predators were higher on Agria and Savalan among the tested cultivars.

Based on the results of our study, it can be concluded that the cultivation of Agria could be useful in reduction of T. tabaci population and conservation of its predators in potato fields.

The cowpea seed beetle, Callosobruchus maculatus is one of the most destructive pests of pulses including chickpea. In this research, the effect of chickpea landraces including Abgoshtiriz bokan, Etiopi, Khardar bokan, Zard kordestan, Siah alashtar, Lablaboei arzhantin, Lablaboei bokan, Lablaboei canadaei and Lablaboei hendi, and Abijam Kermanshah cultivar were studied on population parameters of C. maculatus under laboratory conditions (28±2°C temperature, 65±5% RH, and a photoperiod of 14 L: 10 D h). Moreover, some physical and biochemical characteristics of chickpea seeds were measured and any possible correlations between them and life table parameters were investigated. According to the results, the longest larval and pupal periods and total development time of C.maculatus were on Siah alashtar landrace and the shortest one was on Lablaboei bokan landrace. The higher and lower values of net reproductive rate (R0) were observed on Lablaboei hendi (30.33 ± 3.51 offspring/individual) and Siah alashtar landraces (19.28 ± 2.71 offspring/individual), respectively. The lowest value of intrinsic rate of increase (r) of C.maculatus was observed on Siah alashtar landrace (0.079 ± 0.040 day-1) and the highest was on Lablaboei bokan landrace (0.110 ± 0.044 day-1). The highest grain hardiness index and protein content were on Siah alashtar landrace, whereas the lowest these characteristics were on Lablaboei bokan and Abijam Kermanshah. Significant correlations were observed between life history parameters and physical and biochemical traits of chickpea landraces. Our findings showed that Siah alashtar is a relatively unsuitable and Lablaboei bokan is a suitable and relatively sensitive host for feeding of C.maculatus.

The Russian wheat aphid, Diuraphis noxia (Mordvilko), is an important pest of cereal, particularly wheat (Triticum eastivum L.) and barley (Hordeum vulgare L.) in many countries. It can also be damaging as a vector of plant pathogenic viruses including Barley Yellow Dwarf Virus (BYDV), Barley Mosaic Virus (BMV), and Sugarcane Mosaic Virus (SMV). Also, a yield loss of as much as 60% has been reported in wheat in years of heavy infestation. Utilization of synthetic pesticides is a common method for control of D. noxia, but the continuous application of such chemicals caused several side-effects such as environmental hazards, insect pest resistance and the outbreak of secondary pests. Therefore, other control methods need to be investigated for effective control of the pest. The use of resistant cultivar is an environmentally safe method of insect control and is also less expensive for growers resistance of host plants against herbivore insects may be due to antibiosis. The antibiosis properties of the host plant can reduce the amount of feeding, fecundity and size of the insect. They also can lengthen the development period, and increase the mortality rate. Therefore, the use of plant tolerance for managing D. noxia has received greater emphasis than in other systems. Wheat and triticale lines [×Triti- cosecale Wittmack, a hybrid between wheat and rye (Secale cereale L.)] with tolerant traits or tolerance combined with antibiotic, antixenotic and tolerance traits have been identified.

In the present study, the possibility of existence of resistance in thirty bread wheat genotypes (Tak Ab, Ryzhav, Oohadi, Gaspard, Say Sunz, Alvand, Phishgam, Azadi, Kras Sabalan, Omid, Navid, Sabalan, Mihan, Orum, Zare, SardariHoma, Rasad, Cascogen, Tos, Shahriar, Bezostiya, Azar 2, Bak Kras Roshan, MV17, C-89-7, C-89-12, C-89-15, Zarin and Almot, respectively) and one triticale cultivar that was evaluated at 12th growth stages of the plants. The experiments were carried out in the greenhouse (23±3˚C, 50±10% RH and a photoperiod of 14L: 10D h) and using a completely randomized design. The aphids used in the experiments were provided from the stock colony reared in Department of Plant Protection, University of Mohaghegh Ardebili, (originated from Namin city infested fields). Antixenosis was determined by counting the number of adult aphids attracted to each genotype potted plants at 24, 48 and 72 hours after release. Life tables were constructed based on the method described by Birch (1948) and Meyer et al. (1986). Differences in intrinsic rate of increase (rm) and other life table parameters were estimated by the jackknife method. Before analysis, all data were tested for normality by Kolmogorov-Smirnov method. Statistical differences among means were compared using the Tukey post hoc Honestly Significant Difference (HSD) and Student-Newman- Keuls (SNK) tests at α= 0.05 using the statistical software of SPSS ver. 19.0.

In summary, the analysis of variance of number attracted adult aphids to each genotype indicated that there were no significant differences among genotypes with respect to the number of aphids attracted to them. Antibiosis evaluated in two experiments. In the first experiment, the mean number of aphids among 31 genotypes was significantly lowest on triticale (Juanilo cultivar) (1 aphid) than resistance control (35.2 aphids). In the second experiment, D. noxia intrinsic rate of natural increase (rm) evaluated on four selected genotypes in the first experiment. The highest and lowest rm values were found on Alvand cultivar (0.273 day-1) and Bezostaya cultivar (0.214 day-1), respectively. Intolerance experiment, height and dry weight of seedling between control (no infested plants) and 14 aphids-day infested plants were measured. Proportional dry weight and height changes were significantly different among the genotypes. According to the results obtained in this research, to avoid hazardous chemicals against insect pests of such crops, certain protective or curative procedures could be implied using different non-chemical methods to reduce the pest population and resultant damage. Consequently, our results indicate Kaskogen and Juanilo cultivars had relatively tolerance and antibiotic resistance to Russian wheat aphid, respectively and so it can be used in the IPM of the aphid.

Further experiments under the field conditions will be needed to validate these findings. The study on chemical components of these cultivars which is unsuitable in our lab may further reveal the chemical base of the unsuitability of cultivars Kaskogen and Juanilo.

Background and Objectives:

 The melon aphid, Aphis gossypii Glover, is one of the most important pests of tomato in Iran. This aphid causes severe damage on tomato crop in northern Iran. 

Materials and Methods:

 Present study was conducted in an experimental field, 0.3 h, in Behshahr region in Mazandaran province based on a randomized completely block design. In this study, the effectiveness of intercropping tomato (T) with clover (C) in the three combinations: (1) one row of tomato with two rows of clover (1T:2C), (2) two rows of tomato with two rows of clover (2T:2C), and (3) three rows of tomato with two rows of clover (3T:2C) along with sole tomato were assessed on the densities of melon aphid, Aphis gossypii Glover, diversity of its natural enemies and yield of both crops in 2016 and 2017.

 Results:

 The density of nymphs and adults of A. gossypii were significantly higher in sole tomato compared with intercrops. Among intercrops, the lowest density of nymphs and adults of A. gossypii were observed in 1T:2C intercrop. In present study, 13 predator species were collected and identified on aphid-infested plants of tomato in the experimental field. Among the predators, Coccinella septempunctata L., Chrysoperla carnea (Stephens) and Episyrphus balteatus DeGeer had more abundance in the two studied years.  The Shannon diversity index (H´) and the Pielou’s evenness index (J´) for composition of predator species were significantly higher in intercrops compared with sole tomato crop. Moreover, more nymphs and adults of A. gossypii were parasitized in all intercrops compared with sole tomato crop in 2016 and 2017. The highest value of land equivalent ratio was found in 1T: 2C (LER = 1.28 in 2016 and 1.30 in 2017) among intercrops in the two cropping seasons.   

Discussion:

 All the three intercropping patterns of tomato with clover including 1T:2C, 2T:2C and 3T:2C, especially 1T:2C could be recommended in management programs of the melon aphid in tomato fields.

Coriander, Coriandrum sativum L. abbreviated here as Co, belongs to Apiaceae which is an aromatic herbaceous annual plant. In this study, intercropping coriander with strawberry, Fragaria ananassa Duchesne abbreviated as S, in the two patterns 2S: 2Co and 5S: 2Co (row ratios) were assessed for controlling the two-spotted spider mite, Tetranychus urticae Koch, compared to strawberry. The results indicated that intercropping coriander and strawberry reduced the density of T. urticae eggs compared with strawberry monocropping. Furthermore, the densities of mobile forms of T. urticae were significantly lower in intercropping systems, especially 2S: 2Co compared with strawberry monocropping. Moreover, the land equivalent ratio (LER), which is used to assess the yield benefit in intercropping systems, was greater than 1 in intercrops, especially 2S: 2Co (1.413 in 2017 and 1.430 in 2018). These results indicated that intercropping strawberry with coriander could be beneficial in integrated management of T. urticae by reducing two-spotted spider mite densities and increasing the crop yields.

In this study a total of 37 syrphid species belonging to 25 genera were identified in Mazandaran province, northern Iran. One genus and species, Brachyopa (Brachyopa) bicolor (Fallén, 1817) and two species Heringia (Neocnemodon) latitarsis (Egger, 1865) and Cheilosia soror (Zetterstedt, 1843) are recorded for the first time from Iran. In addition, saproxylic syrphids of Iran are briefly discussed.

The European corn borer, Ostrinia nubilalis Hübner, is one of the most important pests of corn. In this study, the influences of corn monoculture (C), sainfoin monoculture (S) and strip-intercropping of corn with sainfoin in the four row ratios: 2C:2S, 2C:4S, 2C:6S and 2C:8S were evaluated on the population density of the European corn borer, diversity and abundance of its natural enemies and yield of both crops in an experimental field during 2016 and 2017. Our results indicated that the densities of eggs and larvae of this pest decreased significantly in the intercrops especially in 2C: 6S and 2C: 8S compared with corn monoculture. The Shannon diversity index (H´) for predators in the intercrops was significantly greater than that in the corn monoculture. Moreover, the percentage of parasitized eggs and larvae were higher in the intercrops, especially in 2C:6S and 2C:8S, compared with the corn monoculture. Furthermore, the percentage of infested plants was also lower in 2C:6S and 2C:8S compared with the other treatments. On the other hand, high values of land equivalent ratio were found in 2C:6S (1.16 in 2016 and 1.15 in 2017) and 2C:8S (1.17 in 2016 and 1.16 in 2017). Therefore, it could be concluded that 2C:6S and 2C:8S intercrops are useful in integrated management of the European corn borer in the field.

In this research, the influence of eggplant monoculture (E), soybean monoculture (S), and three intercropping systems including two rows of eggplant with four rows of soybean (2E: 4S), two rows of eggplant with two rows of soybean (2E: 2S) and four rows of eggplant with two rows of soybean (4E: 2S) were studied on population densities of Tetranychus urticae Koch, diversity and abundance of its predators, and yield of both crops in an experimental field based on a randomized block design with four blocks during two cropping seasons (2016 - 2017). In both years, the densities of T. urticae eggs and mobile forms on eggplant and soybean were significantly lower in the three intercrops compared to monoculture systems (P < 0.05). Moreover, the densities of T. urticae eggs and mobile forms were significantly higher on the soybean than the eggplant in each monoculture and intercrop system. The Shannon’s diversity indexes (H') for T. urticae predators on eggplants were significantly higher in the three intercrops compared to the monoculture. Furthermore, the values of this index were greater in soybean monoculture and 2E: 4Sintercrop than 2E: 2Sand 4E: 2S systems (P < 0.05). Values of the land equivalent ratio (LER) were higher in 2E: 4S relative to other intercrop systems in both years. Therefore, it could be concluded that 2E: 4S intercrop is the most suitable cropping system for using in integrated management of T. urticae in eggplant and soybean fields.

The green lacewing Chrysoperla carnea is one of the natural enemies, which attacks various pests on crops and orchards. Feeding preference of natural enemies is one of the most important criteria used in evaluation of their efficiency. In this research, feeding preferences and switching of the second and third instar larvae of C. carnea were studied on the citrus aphid, Aphis spiraecola and the melon aphid, Aphis gossypii. The experiments were carried out on orange leaves in a growth chamber at 27±2°C, 65±5% RH and a photoperiod of 16L: 8D h. The results showed that when A. spiraecola or A. gossypii were separately offered to the second and third instar larvae of predator, the predation rate was higher on A. gossypii compared to A. spiraecola. Providing different combinations of A. gossypii: A. spiraecola significantly affected the consumption of C. carnea larvae in switching experiment. In different combinations, the consumption of the second and third instar larvae of the predator varied from 7.90 to 21.10 and from 15.70 to 31.00 on A. spiraecola, and from 14.60 to 29.60 and from 24.50 to 38.20 on A. gossypii, respectively. The values of Manly’s preference index in equal ratios of A. gossypii: A. spiraecola were calculated 0.632:0.368 and 0.647:0.353 for second and third larval instars, respectively, showing the preference of the larvae to A. gossypii. The results of the present study showed that the types

  The European corn borer, Ostrinia nubilalis (Hübner), is an important pest of corn in Iran. Intercropping systems has been proposed as one approach that can be used for reducing pest density and improving biodiversity of natural enemies and crop yield. Therefore, the present research assessed the densities of immature stages of O. nubilalis, biodiversity of its predators, and parasitism rates of immature stages in experimental plots where corn was grown either as monoculture or strip-intercropped with sunflower. We also evaluated the effect of the intercropping systems with natural infestation of O. nubilalis on corn yield. In this research, the influence of five strip-intercropping systems of corn (C) and sunflower (S)including 2C: 2S, 4C: 2S, 8C: 2S, 4C: 4S, and 2C: 4S along with corn monoculture was studied on density of imaginal stages of O. nubilalis, its natural enemies biodiversity, the percentage of parasitized eggs and larvae, and the grain yield of corn and the percentage of grain yield loss in an experimental field in Ardabil region in 2016 and 2017. These experimets were conducted in a randomized block design with four replicates. The densities of imaginal stages (eggs, larvae and pupae) of O. nubilalis in intercrops were significantly lower than corn monoculture. Among the natural enemies of this moth, Orius niger (Wolff), Lydella thompsoni Herting, Bracon hebetor Say and Trichogramma brassicae Bezdenko had the high relative abundance in the tested cropping systems. The Shannon diversity index (H') in intercrops was significantly greater than in corn monoculture. The calculated values of Morisita–Horn index for the predator’s species composition between intercrops were CMH ≥ 0.946 in 2016 and CMH ≥ 0.934 in 2017. In both years, the percentage of parasitized eggs and larvae of O. nubilalis in intercrops was significantly higher than in corn monoculture. The highest grain yield of corn and the lowest percentage of grain yield loss of corn were found in 8C: 2S intercrop. Based on the resource concentration hypothesis, the lower density of O. nubilalis and the lower percentage of infested plants in the intercropping systems of corn and sunflower could be demonstrated by overlapping of the secreted volatile compounds of two crops that caused disruption in the host finding. Moreover, based on the enemies hypothesis, the higher attraction and conservation of predators and parasitoids in intercrops caused lower density of O. nubilalis than in corn monoculture. In this study, the competition for nutriants between corn and sunflower was also reduced with increasing of the corn rows between the sunflower rows; the percentage of grain yield loss of corn was reduced in 8C: 2S copmpared to other intercrops. Therefore, it could be concluded that 8C: 2S intercrop is the most suitable intercropping system for use in integrated management of O. nubilalis in corn fields

Grain moth, Sitotroga cerealella Olivier, is a cosmopolitan pest of stored products that it causes significant damages to the cereal grains. In the present study, the effect of 12 different maize hybrids including AR89, AS71, BC678, DC370, KSC260, KSC703, KSC704, KSC705, KSC400, PL72, SC71 and Simon on the biological characteristics and life table parameters of S. cerealella was assessed under laboratory conditions (25±1°C, 65±5% RH, and photoperiod of 12L: 12D h). The longest developmental time was evaluated on the hybrids PL72 (34.91 ± 0.24 days) and SC71 (34.39 ± 0.25 days) and its shortest value was achieved on the hybrids DC730 (27.08 ± 0.24 days), KSC704 (27.53 ± 0.45 days) and KSC260 (27.76 ± 0.28 days). The lowest and highest net reproductive rate (R0) of pest were observed on the hybrids PL72 (10.40 ± 0.09 female/female/generation) and DC 730 (28.06 ± 0.17 female/female/generation), respectively. The lowest intrinsic rate of increase (rm) was calculated on the PL72 (0.060 ± 0.00023 day-1) and its highest amount was measured on DC370 (0.109 ± 0.00022 day-1). According to the results, among considered hybrids, PL72 was identified as the lowest suitable host for feeding of S. cerealella and it can be used in the integrated management of this pest.

Weevil species Larinus spp. produce trehala on medicinal plants family of Asteraceae. In this investigation, the biology of weevil Larinus trehalanus G & Sh, was studied as a new species, on the medicinal plant Cousinia stocksii (Asteraceae)in Kerman region under field conditions during 2011 and 2012. The weevil is a univoltine insect, which annually overwinters as an adult. The female insects put their eggs individually on the host's stems, and cover then with their extinctions to protect the dry and natural enemies. The newly hatched larvaefrom eggs penetrate into the host plant stem by digging holes and start feeding on the plant sap. The larvae build trehala on host plant stem. They grow individually inside the trehala capsule. Only one larva grows inside each trehala capsule. In natural conditions, the development of L. trehalanus from egg to emerging adult takes 45.8±0.7 to 46.5±0.5 days. A new generation of adults spent some time on the host plant and then search for a protected site to pass the autumn and winter.