نشریه مهار زیستی در گیاه پزشکی
سال دوم شماره 2 (پاییز و زمستان 1393)

Appropriate functional response to prey or host densities is one of the most important criteria for evaluating efficacy of natural enemies in biological control programs. Functional responses of the adult male and female mealybug destroyer, Cryptolaemus montrouzieri, and its 3rd instar larvae on Pseudococcus citri were studied at seven constant temperatures ranging from 15 to 40°C, % 60 ± 10 RH, and a photoperiod of 16:8h (L:D). Determination type of functional response model and estimation of related parameters were carried out based on two-stage analysis method by using SAS software. Results showed that functional responses of adult female and male coccinellids and its 3rd instar larvae were type II, except for the 3rd instar larvae at 40°C, which was type III. Estimated values for the functional response parameters showed that with increasing temperature from 15 to 35°C, searching efficiency of C. montrouzieri (adult females and males) increased, while values of handing time decreased. At 40°C, the trend was reverse and the values of searching efficiency decreased and handling time increased. In the 3rd instar larvae, by increasing temperature from 15 to 28°C,searching efficiency increased and handling time decreased. While, the trend for temperatures between 30 and 40°C was reverse. The results confirmed that functional response of the C. montrouzieri was affected significantly by temperature.

White rot caused by Sclerotium cepivorum (Berk).is one of the most widespread and damaging fungal diseases of garlic This diseas causes significant losses to garlic crops in Iran including Hamadan province evey year. At the present, the most common control control method of the disease is the use of chemical fungicides. This control measure is costly and contaminates the agricultural environment. Moreover, since the pathogen is soil-borne, this control method is not quite effective in controlling the disease. In this study, the effects of two antagonistic fungi including Trichoderma and Talaromyces as bio-control agents in the control of the causal fungal pathjogen were investigated under laboratory and greenhouse conditions. For this purpose, ten isolates of the antagonistic fungi, four isolates of T. harzianum (Th), two isolates of T. asperellum (Ta) and four isolates of T. flavus (Tf) were selected. The effects of antagonistic agents on the growth of the pathogen were evaluated in in vitro using dual culture method. Moreover, the impact of the volatile and non-volatile metabolites of the antagonistic agents on growth of the pathogen was also investigated. The results of the laboratory experiments showed that six isolates (two isolate from each species) significantly reduced the pathogen growth. Several new bioformulations were then developed and prepared using rice bran (RB) as an organic carrier and the most effective antagonistic isolates. The effectiveness of the developed bioformulations in controlling the white rot disease of garlic was studied under green-house conditions. The experiment was conducted as completely randomized design consisted of nine treatments (six bioformulations, one fungicide and two controls) each with four replications. The results of the greenhouse experiments indicated that regarding disease incidence and severity, there were significant differences among the treatments (P<0.05). The highest infection rate (53.82%) was observed in the positive control (treatment without biological agent or fungicide). The lowest infection rates were belonged tohealthy control (9.24%), fungicide (11.23%), RBTh1 (11.33%), RBTa2 (11.37%) and RBTh2(11.42%) respectively which were placed in the same statistical group.These overall results indicate that the biological control of Allium white rot disease using antagonistic fungi is possible as an effective alternative method.

Plant diseases are one of the main limitations in crop production which impose annually great losses. Threatens and hazards resulted from ample and repetitive application of chemical pesticides against plant diseases tended to pay attention to natural, safe and environment-friendly products. Lichens due to possessing of great antimicrobial substances has been considered as one of the best sources for natural alternative products. In this research study, growth inhibition, bacteriostatic and bactericidal potential of methanol extract of five lichens including Pleopsidium gobiensis, Parmelina tiliacea, Anaptychia setifera and Lecanora argopholis obtained from Arasbaran, East Azarbaijan province of Iran on some plant pathogenic bacteria such as Pectobacterium atrosepticum, Pseudomonas syringae pv. syringae, Xanthomonas arboricola pv. juglandis and Rhizobium tumefaciens were studied using disc diffusion, minimal inhibitory and bactericide concentration methods. All lichen methanol extracts were bacteriostatic and bactericide on the above-mentioned bacteria. However, R. tumefaciens was the lowest senility to these extracts. Methanol extract of P. gobiensis was as inhibitive as streptomycin on P. syringae pv. syringae growth. In additionm, P. atrosepticum and X. arboricola pv. juglandis were highly sensitive to lichen extracts and streptomycin. The most bactericidal extracts was related to P. gobiensis on P. atrocepticum and P. tiliacea on X. arboricola pv. juglandis. Considering the results, it is suggested that lichen extracts may have remarkable potential in plant pathogenic bacteria and more investigations are required in the future studies.

Neem extract has been used as a botanical pesticide with a long history in the world. In this study, we compared lethal and antifeedant effects of 1, 2, 5 and 10 percent of neem seed water extract with 1, 2, 3 and 5 ml/litter of a neem based pesticide with 1% Azadirachtin (NicoNeem) on Retithrips syriacus. This experiment was conducted with a completely random design with 9 treatments and one control each with four replications. Mortality of the insect was recorded and damage points were counted as damage criteria. The obtained data were analyzed using R ver. 2.15.1 statistical softawre. Both water extract and neem-based pesticide reduced longevity of insect significantly. Two of the most effective treatments of water extracts at 5 and 10 percent reduced longevity of adult insect respectively to 3.03 and 3.34 and nymphs to 3.36 and 2.82 in comparison with the control (7.6 and 8.32). Two high concentrated of neem-based pesticide (3 and 5ml/Li) also reduced longevity of adult respectively to1.54 and 1.52 and nymphs to 2.14 and 1.64 compared with those of control (9.15 and 7.25). In comparing antifeedant effects, all neem-based pesticide treatments showed significantly higher effect in comparison with the water extracts. Based on thes eresults, we can conclude that in thirips population management neem-based pesticides are the most effective products to reduce longevity and leaf damage of thrips on the plants.

Bacterial wilt caused by Ralstonia solanacearum is one of the most destructive disease which negatively affects the tomato production worldwide. Considering the importance of the disease, searching for resistant varieties and using biological control agents could be effective approaches in reducing the damage of the pathogen. In this study, the cultivars including Super CH, falat-111, Peto, Falkata, Queen and Early Urbana were studied. The experiments were conducted with completely randomized factorial design with a disease factor in two levels as inoculated and not inoculated. Seven cultivars (treatments) with four replicates were evaluated. Statistical analysis were performed using SAS software. The antagonistic strains of Bacillus subtilis B7, Pseudomonas flourecsens CHAO and Trichoderma harzianum T.BI and mobil cultivar were utilized. In vitro anti-bacterial evaluations were conducted and T. harzianum T.BI and B. subtilis B7 showed 3 and 5 mean distance of inhibition zone respectively but P fluorescens CHAO showed no inhibition effects. The results of means comparison showed that the stem length of cultivar Queen had the lowest reduction while the highest reduction in stem length was related to the cultivar early urbana. Regarding the fresh weight, the minimum reduction was related to cv Queen while the maximum ones were relevant to cvs Super CH, falat and Falkata cultivars. Moreover, the minimum decrease of dry weight was associated with the Queen cultivar.The results of using antagonists showed that T. harzianum T.BI and B. subtilis B7 regarding index of stem length, shoot and root fresh weight, dry weight of roots and shoots are the best options to control bacterial wilt.

The role of aculeate wasps in natural control and natural balance of arthropod pests is discussed. They are predator or parasitoid on a wide range of insects and other arthropods. Some species may potentially be applied as biological control agents. Some activities for supporting or enhancing their population are discussed. The Iranian aculeate wasp fauna is also reviewed and the most common species in the families Vespidae, Scoliidae, Sphecidae, Crabronidae, Mutillidae, Formicidae, Chrysididae, Tiphiidae, Bethylidae, Pompilidae and their hosts are listed.

The safflower fly, Acanthiophilus helianthi is one of the most important pests of safflower in Iran. Using parasitoids is always considered as one of the integrated pest management methods. In order to evaluate parasitism rate and fluctuations of the safflower fly by parasitoids, seven safflowerr cultivars including Goldasht, Padideh, Zarghan, Varamin, PI, Acataria and Mec163 were cultivated with a Completely Randomized Block Design field experiment with four replicates in research field of Shahed University Research Center (south of Tehran).Goldasht cultivar was cultivated under experimental plots in four replicates in Shahed University, research fields in 2012. Sampling was carried out from safflower bolls every seven weeks. Results showed that two wasp parasitoids including Microdontomerus annulatus (Spinola, 1808) (Hym.: Torymidae)and Ormyrus gratiosus (Forster, 1860) (Hym.: Ormyridae)were active on the larvae and pupae of the safflower fly. The highest parasitism rate of O. gratiosus species in the 19th and 35th July (12.3%) was observed on the Mec163 cultivar. In these dates the lowest parasitism rate (6.58%) was occurred on PI and Padideh cultivars. The highest parasitism rate by M. annulatus parasitoid species was observed as 7.56% and 7.52% on the Padideh and Mec163 cultivars, respectively and the lowest parasitism (6.49%) was observed on the Varamin cultivar. Overall, it can be concluded that due to the application of insecticides for controlling safflower pests, especially A. helianthi in the cultivated areas, parasitoids activity was very low. Therefore, the use of selective insecticides and planting flowering plants as a living host of parasitoids can enhance their performances.

Entomopathogenic nematodes are obligatory parasites of insects, which are used in many integrated pest management programs. The effect of a native isolate of Heterorhabditis bacteriophora on different larval instars of tomato leafminer Tuta absoluta were evaluated under Invitro and Invivo conditions. The isolates of H. bacteriophora were collected from the soil of alfaalfa fields located in Firoozkouh area by using last instars larvae of wax moth, Galleria mellonella, by baiting technique. The isolated nematode was reared on the last larval instars of G. mellonella to produce sufficient population of the nematode (Fig.1- A). The tomato plants infected by T. absoluta were collected from greenhouses under tomato cultivation in Varamin, and different larval instars pest were also obtained from the same locations. In Invitro experiment, 10 different larval instars of tomato leafminer were placed individually in a Petri dish. About 1000 third stage infective juveniles (IJs) were added to each Petri dish and preserved at laboratory conditions. In addition, a control treatment was considered without entomopathogenic nematodes. The results showed that H. bacteriophora infected all the larval stages of Tuta within 48 hours and caused 100% mortality. Infected larvae were inactive and accumulation of the nematodes on the surface of larval body was visible after 72 hours. IJs of nematode and females and males were gradually appeared (Fig. 1- B). InInvivo experiment, adult leafminer were released on tomato seedlings, after establishment of pest on tomato leaves and observation the egg lying and larval instars, the seedlings were sprayed with 2×103 IJs/ lit of water every alternative day for 4 days. Infected tomato seedlings by Tuta was checked as control and sprayed with water. 96 hours after spraying the leafminer larvae were collecteded from leaves and transferred to Petri dishes and incubated by using White method (White, 1927). The infected larvae of Tuta showed the presence of nematodes on their body surface after 72 hours. The results of Invivo experiments showed that the infective juveniles of H. bacteriophora were capable of penetrating the parenchymal tissues channels made by Tuta and caused 100% infection and mortality of the leafminer larvae. This to our knowledge is the first report of the parasitism of the tomato leafminer by H. bacteriophora in Iran. We suggest complementary research studies on this nematode and its host.

During collecting fauna of the family Platygasteridae in the East-Azarbaijan province, some specimens of the subfamily Teleasinae were collected and identified under the genus Teleas. These specimens were collected using a Malaise trap and was identified as Teleas rugosus Kieffer which is a new record for the fauna of Iran.

Bemisia tabaci (Gennadius) (Homoptera, Aleyrodidae) is one of the most important whitefly pests in different parts of the world including subtropical and tropical region as well as in the reenhouse production systems. In order to search for an effective biocontrol agent against this pest, we conducted this study to determine the effectiveness of the entomopathogenic fungus, Paecilomyces fumosoroseus against B. tabaci. The viability of P.fumosoroseus isolates conidia was determined by culturing them on potato dextrose agar (PDA) culture medium and assessing their germination after 24 h of incubation at 24 ±2 °C. Results of this experiment showed that percent of germination was 100, 100, 98 ±1, 97 ±1, 96 ±2, 100, 95 ±1, 100, 98 ±2, and 97 ±1 for isolates P.F.UPM, P.F.49, P.F.39, P.F.24, P.F.40, P.F.29, P.F.16, P.F.1, P.F.12, and P.F.2, respectively. Mortality of egg and nymph of B. tabaci caused by different isolates of P. fumosoroseus was studied under laboratory conditions using fungal conidia suspension with a concentration of 1×106 conidia mL-1. The mortality of B. tabaci eggs and second, third and fourth instars nymphs caused by the P. fumosoroseus isolates was from 42 to 91, 38 to 90, 37 to 89, and 41 to 86%, respectively. The P.F.UPM as the most lethal isolate caused 91, 90, 86 and 89% mortality on eggs and second, third and fourth instars respectively. Mortality caused by the other isolates ranged between 42 to 76%, 38 to 74%, 37 to 85%, and 41% to 84% for eggs and second, third and fourth instars respectively. There was a significant difference between various isolates for causing mortality on eggs and second, third and fourth instars respectively. According to the results, there was a strong correlation between mortality in all stages of B. tabaci life cycle and the fungal isolates. Conidia concentrations of P. fumosoroseus (UPM)isolate for concentration mortality response test were 1 × 108, 1 × 107, 1 × 106, 1 × 105 and 1 × 104 conidia mL-1. In the concentration-mortality response tests with the second instar nymphs mortality reached up to 95% within 6 days after application of conidia suspension at the concentration of 1×108 conidia mL-1 and there were significant differences among various concentrations. The Lc50 of this fungus against the second instar nymph of B. tabaci six days after application was determined as 2.77×105 conidia mL-1. The P. fumosoroseus isolate UPM obtained from B. tabaci was more effective against all stages of B. tabaci compared with the fungi isolated from Pteroma pendula. However, further studies have to be carried out to determine effectiveness of this isolate in the field conditions.