Journal Of Crop Protection
Volume:1 Issue: 3, Sep 2012

The genus Syntretus Foerster of the subfamily Euphorinae (Hym.: Braconidae) is recorded from Iran for the first time. The specimens were collected using malaise traps from different habitats of Northern provinces during 2010 and 2011. Two species، S. ocularis van Achterberg & Haeselbarth and S. xanthocephalus (Marshall) were collected and identified. A brief discussion about diagnostic characters، as well as comments on general distribution of both species are presented.

The Russian wheat aphid (RWA)، Diuraphis noxia has been known as a major pest of small grains، particularly wheat worldwide. This study evaluated the biological responses of RWA to six wheat cultivars including Yavarus، Pishgam، Aadl، Omid، Darab 2 and Sepahan. The experiment was conducted under greenhouse conditions of 25 ± 5 °C، 55 ± 10 % R. H. and a photoperiod of 16:8 (L: D) h. Resistance or susceptibility of cultivares against the aphid nymphal development time، adult fecundity، daily reproduction، total longevity and adult longevity were investigated. The ANOVA of the data indicated that there were significant differences (P < 0. 05) among cultivars regarding duration of nymphal development time، fecundity and daily reproduction. The longest mean nymphal development time was obtained on Omid and Sepahan، and the shortest on Yavarus. The highest and the lowest total fecundity were observed on Yavarus and Omid، respectively. Also، the highest and the lowest mean offspring produced per female per day (daily reproduction) was observed on Yavarus and Omid، respectively. On the whole، Yavarus appeared to be susceptible to the Russian wheat aphid while Omid was resistant.

The citrus leafminer، Phyllocnistis citrella Stainton (Lepidoptera: Gracillariidae) is a major invasive pest of citrus in Tunisia. In order to help the implementation of an efficient integrated management strategy، it was essential to assess the genetic diversity and population structure of the pest. For this purpose، random-amplified polymorphic DNA-polymerase chain reaction (RAPD-PCR) was applied، using eight oligo-nucleotide primers، to reveal genetic variability among eight populations of P. citrella، originating from the north، center and south of Tunisia. A total of 66 RAPD markers and 33 phenotypes were generated. Inter-population polymorphism was revealed، using the percentage of polymorphic markers (62. 12 %)، mean number of phenotypes generated per primer (4. 125) and mean genetic distance (0. 199). Hierarchical analysis، using the UPGMA method، indicated that the genetic variability was influenced by the regional distribution. This pattern of population clustering was supported by Principal Coordinate Analysis (PCO). Yet، a weak correlation (0. 69) was revealed between genetic and geographic distances، suggesting that climatic contrariety between the north and south of Tunisia plays a major role in the differentiation of P. citrella، leading to a restriction of gene flow between populations. Results obtained in this work show clear genetic differences، which should be considered in the development of control strategies.

Leptinotarsa decemlineata (Say) and Lasioderma serricorne F. are destructive pre-harvest and post-harvest pests of many plants in the family Solanaceae، and stored foodstuffs and non-food items، respectively. In this study، some biochemical characteristics of cellulase in the larval digestive tract of these pests were studied. Endo-β-1،4-glucanase activity was measured against the substrate carboxyl methyl cellulose. Maximum activity of the enzyme in L. decemlineata and L. serricorne occurred at pH 7. 0 and pH 6. 0، respectively. The enzymes from L. decemlineata and L. serricorne were maximally stable at pH 7. 0 and pH 5-6، respectively. However، the enzyme extracted from L. serricorne is more stable than that of L. decemlineata. Cellulase activity was in the highest level at 50 °C in both species. EDTA and SDS reduced cellulase activity، while the Ca2+، Mg2+ and Na+ ions had a significant increasing effect on cellulase activity. K+ did not have any significant effect on the enzyme activity. The values of Km and Vmax were 0. 608 % and 0. 0187 µmol min-1 mg-1 protein in L. decemlineata، and 0. 99 %، and 0. 0035 µmol min-1 mg-1 protein in L. serricorne، respectively. Zymogram studies revealed two bands of cellulase activity in the digestive tract of both species.

Beet western yellows virus (BWYV)، a species of the genus Polerovirus in the family Luteoviridae، is an agriculturally important virus infecting over 150 plant species in 23 dicotyledonous families worldwide. A survey of BWYV in canola fields in Golestan and Tehran provinces of Iran using indirect triple antibody sandwich enzyme-linked immunosorbent assay (TAS-ELISA) indicated 8. 3 % infection. The presence of BWYV was confirmed by amplification of the coat protein (CP) gene of the virus via running a reverse transcription-polymerase chain reaction (RT-PCR) on total RNA extracted from ELISA positive leaf tissues. DNA sequences of the BWYV coat protein (CP) gene of seven Iranian isolates were determined and compared at the nucleotide (nt) and amino acid (aa) levels with those of twelve BWYV isolates from different countries deposited in GenBank. Sequence analysis data showed that the identity of BWYV-CP at nt and aa levels among the Iranian isolates were 93. 4 % to 100 % and 93. 2 % to 100 %، respectively. The maximum similarity of isolates at nt and aa levels were 97. 2 and 96. 6 %، which occurred among two Iranian isolates (Ir 8 and Ir 100) and four isolates from France (L39967 and X13063) and England (L39973 and L39970). The recombination analysis among the nineteen isolates including seven Iranian isolates revealed that there was no distinct intra-specific recombination event among BWYV isolates. This is the first report of sequencing and analyzing of the BWYV CP gene of Iranian BWYV isolates.

Habrobracon hebetor Say (Hymenoptera: Braconidae) as an ectoparasitoid of larval stage of lepidopterous pests is widely used in biological control programs. In the present research، the effect of field recommended doses of imidacloprid، indoxacarb and deltamethrin were studied on life table parameters of H. hebetor in pupal stage treatment. One hundred، two-day-old pupae were treated with 1 micro liter insecticide solution using topical method. The pupae were treated with acetone in the control. Thirty emerged adults in each treatment were transferred individually to a Petri dish along with a male for mating. Three last instar larvae of Anagasta kuehniella (Zeller) (Lepidoptera: Pyralidae) were presented to each female wasp daily as host. The numbers of eggs produced per female per day were counted until all of the females were dead. The gross and net reproductive rates in control، imidacloprid، indoxacarb and deltamethrin treatments were 204. 6، 207. 7، 209. 1 and 112. 1 and also 75، 41. 3، 64. 6 and 14. 9، respectively. Intrinsic rate of increase was estimated to be 0. 215، 0. 154، 0. 205 and 0. 14 female offspring/female/day، respectively. Deltamethrin and imidacloprid had the most adverse effects on life table parameters of H. hebetor. Intrinsic rate of increase was not significantly affected by indoxacarb. These findings indicated that indoxacarb was relatively safe for H. hebetor and could be an appropriate candidate in integrated chemical and biological control.

The dry bubble disease، caused by Lecanicillium fungicola، is an important fungal disease of white button mushroom in Iranian mushroom production farms. Twenty-three isolates of the pathogen collected in Iranand identified as L. fungicola var. fungicola، were compared for genetic polymorphism، diversity in growth rate and virulence. Ten Universal Rice Primers (URP) were used to evaluate the genetic diversity of L. fungicola var. fungicola. URP analysis showed that the genetic diversity of Iranian isolates was low (average 10 % over the 10 primers used) and that they were almost clonal. Relative correlations between geographical origins of isolates and molecular grouping were observed but there was no correlation between mycelial growth rate، virulence assays and URP patterns. Significant differences were observed between isolates based on mycelial growth rate and virulence assays. The high level of genetic homogeneity is attributed to the effect of fungicides used for control of the mushroom diseases which might have imposed a significant selection pressure on the fungal populations.

In order to study the role of Pythium species associated with cantaloupe root and crown rot، samples were collected from infected fields in different areas of Khorasan Razavi province during 2009-2010. The Root pieces were washed and cultured on CMA-PARP medium. The pythium isolates were then purified by hyphal tip method and identified based on van der Plaats-Niterink mycological key. The pathogenic species were identified as Pythium aphanidermatum، P. ultimum var. ultimum، and P. deliense. The pathogenicity of isolates on cantaloupe seedlings was tested under greenhouse conditions by using wheat grain inoculum. The results indicated that P. aphanidermatum was the most prevalent species and was recovered in all the regions. P. ultimum was isolated from Neyshabour، Fariman and Mashhad whereas P. deliense was detected in Khaaf. This to our knowledge، is the first report on occurrence and distribution of Pythium species causing root and stem rot on cantaloupes in Khorasan province.

The biocontrol activity of two isolates of Candida membranifaciens against grey mold of apple fruit caused by Botrytis mali and their ability to induce biochemical defense responses in apple tissue were investigated. Apple fruit (Malus domestica) wounds were inoculated with 50 µl yeast suspension (1 × 107 CFU/ml) of C. membranifaciens followed 4 h later by 20 µl of conidial suspension of B. mali (1 × 105 conidia/ml). The apples were then incubated at 20 ºC for 8 days. Lesion diameter sizes were measured 4 and 8 days after pathogen inoculation. In addition to controlling grey mold، these two isolates of C. membranifaciens caused increases in peroxidase and β-1، 3-glucanase activities. These isolates also caused inhibition in catalase activity. The accumulation of phenolic compounds was increased in apple fruit treated with antagonists and inoculated with B. mali and exhibited the highest level 6 days after treatment. The ability of C. membranifaciens to affect H2O2-metobolizing enzymes and increase levels of β-1، 3-glucanase activity and phenolic compounds may be one of mechanisms responsible for its biocontrol activity.