BIOLOGICAL CONTROL OF PESTS AND PLANT DISEASES
Year:2014 | Volume:2 | Issue:2|Papers Count:8

In this investigation the effect of Trichodermaisolates ininhibition of Aspergillus flavus growth and reducing of aflatoxin B1 (AFB1) was studied in culture media and pistachio nuts. Among Trichodermaisolates, T1, T3, T4 and T17 isolates showed significant impact on inhibiting of A. flavus R5 growth. T3 and T4 isolates were the most effective isolates, which caused 84.40% and 77.88% reduction of aflatoxin produced by A. flavus R5on pistachio and 88.03% and 79.73% reduction of aflatoxin B1 which was added to the medium respectively. In order to study the way the Trichodermaisolates affected the pathogen, the in fluence of volatile compounds and filtrate culture extract of Trichodermaisolates on A. flavus R5 growth were investigated. Study on volatile compounds effect showed that T1, T3, T4 and T17 isolates with 60.66%, 68.88%, 63.33% and 59% reduction of fungal growth, resp ectively. The results showed that T1, T3, T4 and T17 isolates could in hibitthe mycelia growth of A. flavus in PDB liquid medium. Isolates of T3 and T4caused 58.88% and 50.01% reduction of fungal biomass, followed by90.76% and 86.25% reduction of aflatoxin B1 (AFB1), respectively. Results of the most experiments that was d one in this study showed that T3 and T4is olates are the m ost effective isolates in biological control of A. flavus R5. According to IT S1- 5.8s- ITS2 Gene Sequence analysis, T1, T3 and T4 isolates belonged to T. harzianum, T. longibrachiatumand T. harzianum, respectively.

The aim of this study was to comparable application cultural, biological and chemical control methods of pests, diseases and weeds in rice among paddy farmers in Sari County. A sample of 260 farmers was selected by using proportional random sampling method. Data were collected by means of a q uestionnaire. Validity of questionnaire was confirmed by Agricultural Jihad experts of Sari County and some faculty members at University of Tehran. Cronbach’s alpha was used to estimate the relia bility which founding to be acceptable. According to the findings, farmers’ awareness of pests, diseases and weeds control methods in the 53.5% of paddy farmers is relatively high. The most of t he paddy farmers in order to crop pests management applicatedcultural and c hemical control methods. In addition, biological control practices had al located last priority to itself. In order to control of ri ce diseases, the most of t hem used cul tural and chem ical control methods. In contrastpaddy farmers didn’t use biological practices to control of rice diseases. The most of farmers applicate weeds cultural and chemical controlmethods, in contrast, biological practices to weeds control had allocated last priority to itself.

OoencyrtusfecundusFerriere & Voegele (Hymenoptera: Encyrtidae) is one of the gregarious egg parasitoids of sunn pest that can superparasitize the host. Super parasitism has inverse effects on fitness, reproductive potential, competition ability and adult size of gregarious parasitoids. In this study, the effects of su perparasitism and its intensity (four levels including singleton, twin, triplet and quadruplet females) was in vestigated on biological features of O. fecundus under laboratory conditions. Stable population growth parameters were co mpared as fitness indicators among four treatments. Significant differences were observed in all parameters except generation time (T). In trinsic rate of increase (rm) was estimated to be 0.2529±0.0024, 0.2480±0.0019, 0.2389±0.0023 and 0.2354±0.0019 per day in single, twine triple and quadruple females, respectively. On the other hand, net reproductive rate (R0) was 198.14±7.22, 188.63±6.72, 170.54±2.04 and 139.77±2.01offsprings and generation time (T) was 20.9±0.29, 21.12±0.18, 21.5±0.21 and 20.98±0.15 days in those treatments, respectively. Although parameters were close to each other, their differences were still significant because their variance was low. In m ost cases, parameter values were significantly different between singleton and twin females with triplet and quadruplets. Superparasitism affected fitness of individuals, however this effect was not so strong that causessuperparasitism remove and it seems that it can also grant considerable advantage to the wasp when host density is scarce.

Entomopathogenic nematodes (EPNs) are one of the most important biocontrol agents. The identification of these agents has become very important issue due to the developing trend of their applications in the recent decades. A survey for isolat ion of EPNs was conducted in Boj nourd regi on, from three different habitats. Subsequently, morphological and molecular characteristics as well cross breeding tests were used to identify those native isolates. Among 50 soil samples, 5 samples were positive including 10 populations. Both Steinernema and Heter orhabditisgenera were isolated using Galleria trap method. According to morphological and morphometric characters, four isolates, namely Boj1, Boj7, Boj8 and Boj9 were from "feltiae" species group of Steinernema. Another isolate, HBoj was a member of "bacteriophora" species group of Heterorhabditis. The phylogenetic analysis on sequence data of ITS showed that Boj1, Boj7, Boj8 and Boj9 attributed to “feltiae” group, while HBoj isolate belonged to “bacteriophora” group. Reconstruction of phylogenetic trees using ITS sequences showed that four isolates, Boj1, Boj7, Boj8 and Boj9 were grouped in a clade with other species of "feltiae" group (of Steinernema). Phylogenetic analysis on those genes for HBoj isolate grouped this isolate with H.bacteriophora species in a clade. Cross breeding tests between Boj1, Boj7, Boj8 and Boj9 isolates an d reference strain of S. feltiaeshowed that Boj1 belongs to the S. feltiaespecies. The other three isolates (Boj7, Boj8 and Boj9) were species from Steinernema genus. Current survey is the first study on native populations of EPNs in North Khorasan.

Many of i nsects have re-mating behavoiur during their reproductive period. The re-mating phenomenons have been observed in many ladybirds, too. In current study, the change of proportion of male to female (sex ratio) was used in order to changing of possibility and times of re-mating in Hippodamiavariegata. In previous studies it has been indicated that males make up about 50% of this predator’s population. To examine change in sex ratio, one day old and virgin females and males have been used. Treatments included: 10 females without male, 10 females with the presence of 2 males, 10 females with the presence of 4 males, 10 females with the presence of 6 m ales, 10 females with the presence of 8 m ales and 10 pairs of females and m ales together. Number of eggs was counted and recorded for 20 days. Then, effect of the male: female ratio on egg production and hatching rate was evaluated. The re sults of this research showed that there wa s no significant difference between treatments about egg production. In other words, decreasing the ratio of male, female havenot got any negative effect on female egg production. Evaluating the fertility in different treatments showed that, despite popular perception, the presence of 10 males with 10 females not only did not increase the amount of fertility but also decreased it. This illustrates that incidence of re-mating causes declining female’s fitness. This finding has been discussed from practical point of view.

In the present study, the effects of two arbuscularmycorrhizal fungi, Glomusmosseae and Glomusintraradices, alone and in combination, on the growth parameters, chlorophyll and the root-rot disease of pea (Pisumsativum) caused by Fusariumsolanif.sp. pisiwere evaluated under greenhouse conditions. Eight different treatments in four replications were d esigned in randomized blocks. Compared with the non-treated controls all AM treatm ents increased plant growth parameters and chlorophyll of treated plants. Based on the results individual inoculation with G. mosseae was more effective than G. intraradices and dual (G. intraradices +G. mosseae) inoculations. Inoculation of F. solani f. sp. pisi without G. mosseae and G. intraradices treatments caused a significant reduction in plant growth parameters and chlorophyll of treated plants (at 1%) over the uninoculated control. In the presence of G. mosseae, G. intraradices and dual inoculation of G. mosseae plus G. intraradices, root colonization by F. solani f. sp. pisiwas decreased but individual inoculation with G. mosseae was more effective than other treatments. Inoculation of G. mosseae and G. intraradices caused a significant increase in plant growth parameters and chlorophyll of pathogen inoculated plants compared with inoculated pea plants with F. solani f. sp. pisi. Based on the results, application of G. mosseae found to be the best for reducing the root rotdisease severity and improving plant growth parameters of pea.

The distribution pattern of pest population is one of the factors not only effects on sampling program and data analysis method, but also can be used to measure the density of pests and their natural enemies. Thus, the spatial distribution pattern of the pea aphid, Acyrthosiphonpisum Harris (Hem.: Aphididae) and its two major predators, HippodamiavariegataGoeze (Col.: Coccinellidae) and Coccinellaseptempunctata (Linnaeus, 1758) (Col.: Coccinellidae) was inv estigated by different dispersion indices through 2012 and 2013 growing season s. Dispersion pattern was determined by using Taylor's power law, Iwao's patchiness regression method and variance to mean ration test. Obtained results showed an aggregated distribution pattern of pea a phid and lady beetles. Based on R2 and p-value of regression analysis, Iwao's patchiness regression model provided a slightly more adequate description of variance/mean relationships than Taylor's power law. Among the species studied, the pea aphid adults and H. variegatashowed the highest and C. septempunctata showed the smallest coefficients of Taylor's power law respectively. These results provide a reliable basis to develop efficient sampling plans for estimating aphid and their natural enemies populations.

The purpose of this research was to design a sem i-industrial culture medium to obtain the maximum biomass production from bacterium Bacillus subtilis UTB96. In the first step, in order to reduce the cost of culture medium components, commercial products and industrial byproducts including, sugar beet molasses, sugar cane molasses, potato waste water an d milk serum as carbon s ources and corn steep liquor, as a nitrogen source were studied. In addition some inorganic compounds including ammonium sulfate, urea, granular fertilizer urea, dihydrogen ammonium phosphate were co mparatively evaluated. The designed culture medium with defined components were applied in both laboratory and semi-industrial scale bioreactors and the biomass production and antagonistic effect of bacterium were compared with together. The results showed, sugar cane molasses and corn steep liquor as industrial carbon and nitrogen sources respectively, at co ncentrations of 10 and 2 g/lit respectively can be used in high-scale production of biological control agent B. subtilis UTB96. Finally, the designed culture medium application in semiindustrial scale bioreactor resulted in biomass production of 0.32 g/lit. The bacterium grown in this culture medium had antifungal activity on both pathogenic agents, Aspergillus flavus and Phytophthoradrechsleri with 50 and 70% inhibition respectively. Whereas the application of designed culture medium in laboratory scale bioreactor resulted in biom ass production of 0.31 g/lit. Bacteri um grown in this bioreact or has antifungal effect on A. flavus and P. drechsleri with 78 and 54% inhibition, respectively.