Journal of Applied Research in Plant Protection
Year:2018 | Volume:7 | Issue:2 |Papers Count:12

Several studies showed that increasing the total available time for parasitoid causes biases in parameter estimation of functional response experiments. Hence direct observations are required for unbias estimating of handling time. In addition there is some difference among geographical populations of parasitoid. Therefore in this study, two populations of Trissolcus vassilievi (Mayr), (Tabriz and Varamin) were chosen and time allocated for different activities were recorded by direct observations. The time budget of a female parasitoid (24h-old fertile females of the 3rd generation) was divided to four components including drumming, parasitism, host marking and performing actions and duration of each behavior was recorded for three hours in an experimental arena. Time spent for whole clutch was 1071± 70. 25, 4288. 6± 293. 26, 874. 2± 60. 38 and 972. 0± 133. 89 seconds in Tabriz wasps and 1237. 2± 94. 03, 4911. 6± 365. 72, 935± 87. 08 and 1136. 8± 69. 20 seconds in Varamin wasps, for above respect of behaviors. Furthermore, per capita times assigned for above behaviors were 31. 87± 1. 16, 127. 64± 2. 18, 26. 02± 0. 83 and 28. 93± 6. 75 seconds for Tabriz wasps and 31. 40± 0. 83, 124. 66± 1. 88, 23. 73± 0. 77 and 28. 85± 6. 05 seconds for Varamin wasps respectively. Handling time increased slowly until the end of the experiment. It was concluded that the classical functional response experiments should be accompanied by direct recording of insect behavior and parasitoids/predators should be allowed to determine the patch time themselves in a host arena. Otherwise, handling time will be overestimated due to time wasted by predator/parasitoid during satiation or depletion of egg reservoires.

The cabbage aphid, Brevicorne brassicae L., is an important pest of canola in Iran. In this study, the behavioral response of B. brassicae was evaluated on leaves of five canola cultivars (Zarfam, Parade, Hyola401, Syn-3 and RG4403) at the laboratory condition. Development of rate and fecundity were the lowest on Zarfam and highest on RG4403 cultivars. The intrinsic rate of natural increase (rm), finite rate of increase (λ ) and net reproductive rate (R0) were lowest on Zarfam (0. 24± 0. 005 day-1, 1. 27± 0. 013 day-1 and 15. 8± 1. 09 33 female/ female, respectively) and highest on RG4403 (0. 34± 0. 009 day-1, 1. 40± 0. 006 day-1 and 72. 4± 3. 47 female/female, respectively). There was no significant difference in generation time (T) of B. brassicae among the studied canola cultivars. The lowest and highest values of mean relative growth rate (MRGR) were observed on Zarfam (0. 197 mg day-1) and RG4403 (0. 243 mg day-1), respectively. Xylem feeding by the cabbage aphid on resistant canola cultivars was indicated by red color of honeydew on seedlings treated with safranin. The highest numbers of red honeydew spots were seen on Zarfam and the lowest on RG4403. In conclusion, RG4403 was the most suitable cultivar, and Zarfam was the less suitable cultivar among tested plants for B. brassicae.

Use of fungicides against wheat powdery mildew disease caused by biotrophic Blumeria graminis f. sp. tritici (Bgt)), is not taken into consideration. Therefore, employment of artificial activator of defense mechanism that can induce resistance in plants, is very important. For this purpose, Falat cultivar as a susceptible genotype to powdery mildew, was inoculated with B. graminis after colonizing with endomycorrhizal fungus, Piriformospora indica, together with control plants. In another experiment, two weeks old Falat plants were treated with salicylic acid after 48h and then, were inoculated with the pathogen. Then, the pattern of catalase, peroxidase and ascorbate peroxidase antioxidant enzymes were compared at 0, 12, 24 and 48 hours after infection in three replications. The results of this study showed that the enzyme activity of the Falat treated with SA were less than the control plant before and after the disease (except peroxidase enzyme, which increased before and after infection). In symbiont plants, there was no significant difference in the amount of enzyme activities than control plants, except overexpression of peroxidase enzyme. Therefore, it seems that the symbiotic fungi is hot effect for inducing resistance via enzymatic pathway. Probably these fungi can play an important role through the activation of other pathways such as activation of pathogens related proteins. While, SA can suppress the biotrophic pathogen by reducing the capacity of the antioxidant enzymes and inducting the rapid cell death. Therefore, the application of SA against powdery mildew is recommended.

Resistance to insecticides is one of the several factors responsible for control failures of Tuta absoluta (Meyrick), but this phenomenon has been very little studied to date. The aims of the present study were to: 1) assess the susceptibility of seven greenhouse populations of T. absoluta to deltamethrin, in comparison with the most susceptible population 2) assess the likelihood of deltamethrin control failures in the surveyed populations. 3) determine the stability of resistance to deltamethrin in greenhouse populations of Tuta absoluta. Bioassays were done using 2nd instar lande and dipping method to determine the resistance level. Calculated resistance ratios varied from 1. 25-to 13. 91 fold. Additionally, the control failure likelihood, the narrow meaning of insecticide resistance, was surveyed using the insecticide recommended label rate as the discriminating concentration, and the 80% efficacy in greenhouse populations of the tomato leaf miner. The 80% mortality is the lowest expected efficacy level without control failure due to resistance to insecticides. Mortality due to treatment with deltamethrin at the label rate was considered significantly lower than 80%, when the recommended label rate was lower than the lower threshold of the 95% fiducial limits of LC80. Deltamethrin exhibited the expected control efficacy (between 85% and 100%) against the tomato leaf miner populations at the recommended label rates with the exception of two populations that were resistant to this insecticide. The significant decrease in resistance ratio over seven generations without any selection pressure indicated that resistance to deltamethrin remained obviously unstable.

One of the most devastating plant parasitic nematodes of the world is the root lesion nematode Zygotylenchus guevarai. This nematode was recorded from most of the countries in association with the roots of various hosts. In a lovage (Levisticum officinale ) farm with vascular wilt symptoms at Boyer-Ahmad county, the fungus Fusarium oxysporum was isolated from the infected roots and plant-parasitic nematode Zygotylenchus guevarai was also recovered from the roots and rhizospheric soil. After that, infected lovage plants with Z. guevarai were treated by 0. 0, 0. 05 and 0. 1 g cadusafos (Rugby)/Kg of soil. The experiments were carried out in a completely randomized design with four replications under greenhouse conditions and distilled water treatment was used as control. Results showed that Rugby with concentration of 0. 05 g/Kg of soil showed 81, 47. 9 and 48 while concentration of 0. 1 g/Kg of soil showed 91. 4, 73. 7 and 73. 5 percent reduction of nematode population in soil, final population and reproduction factor, respectively. Also, Rugby with concentration of 0. 05 and 0. 1 g/Kg of soil showed 281 and 149 percent increase in nematode population in root, respectively.

Predation rate is one of the most important parameters in determining the performance of a predator. Gaeolaelaps aculeifer Raumilben is one of the important soil predators. It has main role in reduction population of the phytophagous agents of the soils. In this study predation rate and life table parameters of G. aculeifer fed on second instar larvae of Lycoriella auripila Winnertz were studied under laboratory conditions: 25± 1oC and 75± 10 R. H. Result showed that the larva stage not feeds on the sciarid larvae but other stages could feed very well. Consumption of protonymph and deutonymph stages were 2/56± 0/1 and 6/6± 0/12, respectively. Consumption rate of male and female were 149/38± 1/95 and 381/38± 5/99, respectively. The intrinsic rate of increase (r), finite rate of increase (λ ), mean generation time (T), net reproductive rate (R0) and gross reproductive rat (GRR) the values of which were 0/17± 0/0089 d-1, 1/19± 0/01 d-1, 18/95± 0/3 d, 30/27± 3/94 offspring and 42/17± 4/7, respectively. Pre-adult longevity was 11/5± 0/1 days. Maximum longevity of male and female were 79 and 93 days, respectively. The longevity of pre-oviposition was 3/39± 0/16 days and total fecundity was 71/69± 2/03 eggs. Therefore G. aculeifer can be good agent to reduction of sciarid larvae population and can be used for integrated pest management of the sciarid flies in the mushroom farms.

Bull thistle Cirsium vulgare (Savi. ) Ten. 1835 (Asteraceae) is a biennial weed that causes serious problem in grassland and cultivated areas. The biology of bull thistle seedhead weevil, Rhinocyllus conicus as a biocontrol agent of C. vulgare were studied in Urmia region. The results showed that, the R. conicus has a single generation per year and overwinter as adult. Adults emerge from hibernation at the end of May. They establish on host plant and feed on the leaves and soft stems of them. Adults mate from time to time throughout their life span. Then, fertilized females lay eggs below the capitula. Eggs are laid singly into a hole bored by female. The incubation period was 5-8 days in natural conditions. Upon hatching, the young larvae penetrate into the seedhead where they feed on receptacle tissue and developing seeds. Up to 6 larvae can develop in larger capitula. Larval development in natural conditions takes 27± 5 days. Once larvae are mature, they consume and destroy the seedhead. Mature larvae make an egg shape and black color pupal cell in capitula and then pupate. The pupa completes its development in 9-14 days. Emergences of new adults begin in early July, then leave the capitula and search for suitable overwintering site. They reemerge in May of following year. The larvae of R. conicus were parasitized by two species of parasitic wasps namely, Baryscapus crassicornis (Hym.: Eulophidae) and Bracon armeniacus (Hym.: Braconidae). The species B. armeniacus is newly recorded from Iran.

Leaf crinkle symptoms in some strawberry plants were observed in field, and therefore 55 leaf samples (symptomatic and asymptomatic) were collected from Kurdistan province and tested for infection with Strawberry crinkle virus (SCV) by RT-PCR. Total RNA was extracted by silica-capture method and subjected to cDNA synthesize with random hexamer primers. RT-PCR was done by specific SCV-primers and PCR products were observed on 1. 2% agarose gels. RT-PCR results were showed that 51. 9% of the samples were infected by SCV. Based on the geographical origin, cultivar and symptom, seven isolates were selected, sequenced and analyzed for molecular characterization and phylogenetic studies on SCV L-gene. Phylogenetic analysis showed that all the seven isolates from Kurdistan were placed in a distinct subgroup, phylogenetic group II. The average genetic distance between the isolates from Iran was 0. 031 ± 0. 005 but between these isolates and the other isolates, available in GenBank, was 0. 069 ± 0. 014. Pairwise comparisons of the sequences showed that isolate SAr6 had the highest nucleotide similarity (95. 1%) to isolate 4MM of Argentina whereas isolate SS26 had the lowest nucleotide identity with isolate HB-A1 of Netherlands. This is the first report on occurrence of SCV on strawberry in Kurdistan province and also the first report of molecular detection of SCV in Iran.

During years 2016-2017 surveys in apple orchards of Maragheh region, 73 samples of Gala and Red delicious cultivars with symptoms resembling to those caused by Apple dimple fruit viroid (ADFVd) were collected and subjected to two-step RT-PCR. Total RNA from stem bark and leaves of symptomatic plants showing dimple fruit and irregular yellow spots on fruit was extracted and full-length 306-307 base pairs genome of the isolates were amplified by using specific primer pairs. Ten amplicons with expected size were directly sequenced on both strands. Blast analysis and multiple sequence alignment of the sequences with those full-length ADFVd sequences deposited in GenBank, showed identities ranging from 74. 4-100%. Iranian ADFVd isolates had the highest and lowest identity with two Italian isolates, accession Nos. EF088662 and KF788291, respectively. The region between CCR and TR domains was the most divergent. In phylogenetic analysis by maximum likelihood method, all Iranian isolates were clustered together with the Italian isolates and variants.

Potato tuber moth, Phothorimaea operculella (Zeller), is one of the most damaging pests of potato especially in the tropical and sub-tropical regions of the world. Management of this pest is commonly based on chemical control, but due to activity of the pest larvae inside the tubers chemical control of the pest is usually unsatisfactory. Therefore, the use of alternative and more efficient methods are necessary. In this study, the potato moth injury on nine cultivars of potato including Marfona, Sprit, Fontane, Agria, Jelly, Bamba, 82-10, S-12, and S-16 was assessed in the farm and greenhouse conditions. The effect of two important cultural factors including re-hilling of the soil and four different harvesting times were also evaluated against the potato tuber moth damage. The lowest and highest numbers of larval entry holes were observed on the cultivars Jelly and Marfona respectively. Also the samples taken from the plots that had been re-hilled displayed that there was significant differences in the contamination values (percentage of larvae holes) and there was less contamination for treatment groups. Also, the results obtained from samples taken on different harvesting dates showed that the lowest and highest percentages of infested tubers were in the harvesting dates of August 23 and October 7, respectively. Based on the results of present study, along with utilization of the Jelly and S-12 cultivars, the re-hilling of the plant and early harvesting of the tubers in late August are recommended to reduce potato tuber moth damage.

Leptinotarsa decemlineata (Say) is a key pest of potatoes worldwide. Need for the new control methods are inevitable regarding undesirable effects of chemical pesticides. In this study inhibitory activities of seed extracts of some legume plants were investigated on α-amylase activity of Colorado potato beetle larvae and adults. Enzyme and inhibitory activities were measured by using diagnostic α-amylase Kit (Pars Azmon, Iran). Percent of inhibition was calculated by comparing activity in control and inhibitor incubated enzyme solutions. Among 17 legumes seeds (8 bean and 2 pea genotypes, lentil, vetches, broad bean, peanut, tamarind, sainfoin and alfalfa), four genotypes of Phaseolus vulgaris L. (Pinto bean, green bean, kidney bean and white bean) as well as tamarind, had high inhibitory activity against the enzyme in comparison with the other studied legumes. In this study three fractions of five effective legumes prepared by precipitation of proteins in 0-20, 20-40 and 40-60% Ammonium sulfate. Three concentrations of inhibitors (1, 0. 7 and 0. 3 mg protein/ml) were compared for inhibitory activity. Overall 20-40 and 40-60% fractions of all five selected legumes had more inhibitory activity compared to 0-20 fraction (70-90% inhibition vs. 5-30%). In the studied range of concentrations, the inhibitory activity was concentration dependent and increased by increasing the concentration of inhibitors in constant concentration of enzyme. Crude proteinaceous extracts and fractions of different types of beans evaluated in this study showed high inhibitory activity against alpha-amylase of last larval instar and adults of Leptinotarsa decemlineata (Say).

The mass production of insects is a key element in biological control programs. The most important problem in successful release programs is the cost-effectiveness of mass rearing, and release at right time. In recent years, cold-storage of biocontrol agents has been considered as an effective method for increasing survival and providing sufficient number of natural enemies for using in biological control programs. In this study the effect of cold storage of Anagasta kuehniella eggs was investigated on Trichogramma brassicae at 4 ° C for 0, 1, 4, 7, 15 and 30 days in terms of life history parameters. Results showed that developmental time, longevity, fecundity, parasitism rate, emergence rate and oviposition period were significantly different (1%). The highest longevity was in control (9. 56± 0. 66 days) while the lowest one was in 30 day treatment (5. 12± 0. 71 days). It was also found that all population parameters except life generation time (T) differed significantly between control and cold-stored treatments. The lowest net reproductive rate (R0) (13. 22± 0. 71) and intrinsic rate of increase (rm) (0. 2178± 3. 80) were recorded in 30-day storage treatment. The results showed that by increasing cold-storage duration of the host eggs, the efficiency of the T. brassicae declined.