BIOLOGICAL CONTROL OF PESTS AND PLANT DISEASES
Year:2020 | Volume:8 | Issue:2|Papers Count:12

Cereal cyst nematodes are one of the most important cereal diseases in the world, which are detected in 38% of Khuzestan wheat and barley fields with harmful populations. In order to study and identify of fungi associated with cereal cyst nematode, Heterodera filipjevi, in Khuzestan province 39 of root and soil samples were taken from wheat fields infested with it during 2013-14. The extracted cysts were sterilized and cultured on PDA, CMA and WA media supplemented with antibiotics. The isolated fungi were purified and identified based on macroscopic and microscopic studies. The results showed that among of the 64 isolates were purified from cysts and eggs nematode, the most frequency common isolated fungi were Fusarium spp. (6 species) with 51. 56 percent and the lowest were Spadicoides atra, Macrophomina phaseolina and Lecanicillium lecanii each of 3. 12 percent. The frequency of other fungal genera including Alternaria, Paecillomyces, Penicillium, Chaetomium and Ulocladium were 15. 62, 7. 81, 6. 25, 4. 68 and 4. 68 percent respectively. S. atra is reported for the first time in the world and other fungal species listed were reported on H. filipjevi for the first time from Iran. The effect of 10 Fusarium isolates including F. dimerum, F. chlamydosporum, F. equiseti, F. nygamai, F. solani (3 isolates), F. beomiforme and F. oxysporum (2 isolates) on the cyst nematode in antibiotic WA indicated all of the Fusarium isolates parasite eggs and larvae inside eggs by 12-90 and 3-54 percent respectively.

Puncturevine, Tribulus terrestris L. (Zygophyllaceae) is a summer annual and cosmopolitan plant species. The biology of Microlarinus lareynii, as a seed-feeding biocontrol agent of puncture vine, were conducted during the years 2017-18 in Urmia region. The results revealed that, the weevil completes three generations per year and overwinters as an adult. Adults emerge from the overwintering sites in mid-June. After emerging, they start to feed on the undersides of stems and mate alternately. Then females’ weevils make oviposition holes on the fruits, and lay eggs singly in each hole. Females cover their eggs by feces to protect them from natural enemies and dehydration. The hatching period lasted for an average of 3. 4± 0. 8 days under field conditions. Upon hatching, the young larvae penetrate into the fruit where they feed on the seeds. The larval development time takes 17. 8± 2. 6 d. but pupal stage lasted 6. 2± 1. 5 d in 22± 2 º C. Therefore, it takes around 29. 0± 2. 1d to develop from egg to adult emergence in natural conditions. The larvae of M. lareynii were parasitized by five species of braconid wasps in Urmia region. Namely, B. intercessor Nees, B. trucidator Marshall, B. murgabensis Tobias, B. concolorans Marshall and Microchelonus karakumicus Tobias. Among them, the species M. karakumicus is a new record for Iran. With the exception of B. intercessor, the parasitic association of other braconids with M. lareynii are new to the world. Furthermore, this is the first parasitoids report for M. lareynii from Iran.

This experiment was designed to investigate the antagonistic effect of six isolates of Trichoderma harzianum and Trichoderma viride on growth and eliciting plant defense responses in basil (Ocimum basilicum L. ) against fungal anthagonist Rhizoctonia solani. The basil seeds treated with two Trichoderma species were planted in infested soil and plant growth and severity of damping off were measured 40 days after planting. Peroxidase activity, total phenol and malondialdehyde levels were determined by colorimetic assay. The results showed that the antagonist species were able to significantly increase the height and dry weight of seedling shoots and root dry weight, but their effects were not significantly different on stem diameter. Severity of damping off was significantly reduced from 71. 25% in infected control plants to 8. 75-15. 75% in plants treated with fungal anthagonists. Trichoderma species and R. solani individually increased peroxidase activity and levels total phenolic compounds, but they were more pronounced in the case of applying of antagonist and pathogen combinations (Trichoderma and Rhizoctonia) in comparision to the control. Experiments indicated that maximum level of total phenol is induced by T. viride. Increases in levels of malondialdehyde were observed only in infected plants without antagonist treatments. These findings indicate that the basil growth and defense responses enhancement by Trichoderma species and can be suggested for improve plant growth and R. solani resistance as a biological approach.

The aim of this study was to evaluate the effect of concentrations (75, 150, 300, 600 and 1200μ L. L-1) of Zataria multiflora (ZEO), Cinnamomum zeylanicum (CEO), and Satureja khuzestanica (SEO) plants essential oil (EO) and expose time (18, 23, 28h) the inhibition of mycelial growth of Rhizopus stolonifer fungi in vitro condition and modeling and optimizing antifungal properties of these EOs via response surface methodology (RSM). Also the chemical components of the EOs were identified. Based on the results, in all EOs the antifungal index increased with increasing the concentration, but the effect of time was different; with the time of expose, the antifungal index increased in ZEO, but decreased in the two other EOs. Furthermore, due to the results of optimization, the CEO with 120. 133μ L. L-1 and 301. 152μ L. L-1 concentrations and 24. 380 and 22. 802h expose time and SEO with 224. 697μ L. L-1 and 550. 803μ L. L-1 concentrations and 23h expose time, for 50 and 100% inhibit mycelial growth, respectively, have the most and least effect on inhibiting mycelial growth of R. stolonifer. Also, the results of this study showed that the response surface method can be considered as a suitable and accurate method for modeling and optimizing the antifungal activity of these EOs.

Poplar trees are among the fast-growing trees and they have a special place in plantation and wood products. Poplar clear wing moth Paranthrene tabaniformis (Rott. ) is a major pest of these trees. Each year, in the poplar nurseries, the seedlings of these trees are attacked by this pest, resulting in severe damage to the production of wood and its dependent industries. In this study, normal control of population of these butterflies was evaluated by Dendrocopos syriacus (Hemprich & Ehrenberg) woodpecker. For this purpose, 2217 seedlings from 10 different poplar clones were selected in one of the nurseries at Astaneh-Ashrafieh Poplar Research Station in Guilan province. At the end of the growing season, it became clear all 670 seedlings were infected with galls. In the next step, the activity of woodpeckers and the effect of diameter and height growth characteristics of gall-contaminated seedlings on woodpecker hunting were evaluated by multiple regression analysis and Pearson correlation. The results of this study showed that Syrian Woodpeckers are capable of operating more than 36% on some infected seedlings, and in this regard, the amount of their activity intensifies with the growth of the diameter and height of the seedlings infected with the gall.

Among biological control agents of common sunn pest (CSP), Eurygaster integriceps Puton, egg parasitoids of family Encyrtidae have little been studied. The Encyrtidae can play different roles in a cereal agroecosystem depending on the level which it will occupy in the food chain. It means it can appear either as a primary parasitoid of CSP or hyperparasitoid of the platygastrids. Although at first glance hyperparasitism seems an undesirable property, but it depends mainly on preference of the parasitoid. If parasitoid prefer unparasitized hosts, may enhance control level. In this study, host preference of Ooencyrtus fecundus Ferriere & Voegele (Hym.: Encyrtidae) was evaluated in pairwise experiments between three kinds of hosts (fresh host eggs, 6d-old host eggs and 8d-old parasitized eggs by Trissolcus grandis (Thomson) (Hym.: Platygastridae)). The results revealed that the parasitoid definitely prefer the fresh eggs and the preference is not affected by relative densities of the hosts. When no suitable host was available, handling was considerably declined and negative effect of fetal development on parasitism rate was stronger than previous parasitism. It seems that the wasp partly saves its reproductive energy for subsequent fortunes in circumstances that the favorable host is unavailable.

Hymenopteran tiny egg parasitoids, as important agents in biological control of pest, attack small host eggs in a dynamic ecosystem. Considering limit adult longevity, access to the host in short-term is essential to gain reproduction success. Longevity and reproduction attributes of egg parasitoid Psix saccharicola (Mani) (Hymenoptera: Scelionidae) was determined in two physiological status, mated and virgin, depended to age 1-, 9-, 18-, 27-and 36-days old. Mating of females had no distinct effect on longevity, although aging caused a consecutive decline in fecundity of all females. Moreover, mating trigger females reproduction system to produce more progeny in the long-term. Survival of progeny and progeny sex ratio produced by mated females decreased depending to mothers aging. The results revealed that the optimum host access for females is before 27-days old. Therefore, female age is important for biological control efforts such as mass rearing, inundation and also a determination of inoculation rhythms.

15, 2018-Accepted: July 3, 2019) ABSTRACT Pathogenic fungi and bacteria infect plants and inflict important diseases leading to major economic losses. The use of beneficial Lactic Acid Bacteria (LAB) in controlling different type of human and plant pathogens, has drawn worldwide attention. The aim of this study was to assess the antifungal activity of secreted substances from two newly isolated strains of Enterococcus faecium (Kx185054 and Kx185055) from Persian oak tree sap in controlling Fusarium oxysporum and Alternaria solani fungi and Curtobacterium flaccumfaciens pv. flaccumfaciens and Pseudomonas syringae pv. tomato bacteria. Secreted substances from Enterococcus faecium strains were added to the fungi and bacteria culture media at different concentrations and the inhibition zone was recorded in three replicates. Results of this experiments together with that of scanning electron microscopy imaging revealed that secreted substances had a significant antimicrobial activity. Fungal mycelia/spores and bacterial cells became deformed, shrunken, and distorted following treatment with secreted substances from Enterococcus faecium strains, suggesting that Enterococcus faecium secretes antimicrobial chemicals/peptides preventing fungal strictures from germination, growth and penetration. The results of this study may help in elucidating the potentials of newly isolated Enterococcus faecium strains from oak tree and identifying the genes coding for antifungal peptides.

Natural enemies need to support in Environment for additional food and refuges. Additional food resources can improve their efficacy. Food resource provision could increase longevity and fecundity of natural enemies. Planting cover crop adjacent to the main crop in one of the methods to provide food resource like nectar and pollen. In current study, the effect of Alyssum on efficacy of T. cacoeciae in laboratory condition, greenhouse and apple orchard were assessed. The result shows an improvement in longevity and parasitism rate of T. cacoeciae feeding on Alyssum and sugar solution comparing to control treatments in laboratory condition (9. 6, 5. 2 and 3. 3 days and 50. 7, 42 and 28 blacked eggs respectively). In greenhouse, longevity and parasitism rate of T. cacoeciae enhanced in Alyssum cages compare with sugar solution and no feed despite the complex structure of Alyssum plant (12. 5, 9. 6 and 7. 8 days and 377. 8, 364. 3, 214. 3 blacked egg respectively). Result in apple orchard using Alyssum pots in apples rows showed a significant difference parasitism in sentinel eggs compare with control (16. 5% and 6. 23 % respectively). The parasitism also recorded for longer time in plots with Alyssum (5 days) in compare with control (one day only). In total Alyssum can provide parasitic wasp, a suitable and available food source and probably considered a suitable cover crop with good quality and accessible to enhance T. cacoeciae efficacy.

Common root and crown rot of wheat caused by Bipolaris sorokiniana is one of the most important diseases of wheat in the world. In this study, 60 isolates of Streptomyces were isolated from wheat rhizosphere and screened in laboratory condition using dual culture. UTS22, UTS3 and UTS4 isolates showed maximum inhibition with 46. 6, 45. 6 and 42% respectively. Most of the isolates had positive reaction for physiological and enzymatic activities such as colonization, nitrogen fixation, phosphate solubility, protease and chitinase. UTS3, UTS18 and UTS4 isolates showed the highest inhibition levels of pathogenic mycelial growth by producing metabolites with 67. 96, 61. 3 and 54. 63% respectively. Greenhouse studies carried out in a completely randomized design with wheat seed coat method with 108 CFU/ml concentrations of supernatant isolates. Based on the results, the UTS22 isolate showed the highest disease control with 55. 6% and also wheat growth indices increased significantly compared to healthy control treatment. Molecular identification based on the sequence of 16S showed, the UTS22 isolate belongs to Streptomyces fulvissimus. UTS22 is introduced as a superior isolate in biological control of B. sorokiniana.

Plant growth promoting (PGP) bacteria not only improve plant growth and yield but also increase plant resistance to biotic and abiotic stresses. Culture design in fermentation process has critical effects on biomass production and efficacy of these bacteria. In this work, Influence of some carbon sources have been investigated on biomass production and efficacy of Bacillus pumilus against Rhizoctonia solani, the causal agent of bean damping-off. Effect of carbon sources including glucose, molasses, brown sugar, corn meal and rice meal, in three concentrations have been examined on B. pumilus INR7 biomass production and suppression of bean damping-off in greenhouse. The highest biomass production achieved using 20 g/L of glucose and brown sugar in the culture media, respectively. Although, increasing glucose concentration decreased biomass production, but it enhanced plant growth factors. The highest plant height (17. 83 cm) and shoot dry weight (7. 16 g) have been recorded in 40 g/L as the highest concentration of glucose. Molasses also increased PGP efficiency at its mid concentration, 20 ml/l. Effect of carbon sources on biocontrol efficacy of B. pumilus INR7 revealed that glucose at 40 g/L led to the lowest root and crown infection. Molasses in 20 and 40 ml/l showed noticeable effect on biocontrol efficacy of B. pumilus INR7. In conclusion, glucose and molasses had highest effect on biomass production and biocontrol efficacy of B. pumilus INR7.

Sampling was done from sesame plants from research field of Vali-e-Asr University of Rafsanjan. Rhizoctonia solani was isolated and identified. These isolates were all multi-nucleotide, pathogenic and belonging to the AG3 anastomosis group. The possibility of biological control of Rhizoctonia rot of sesame was investigated using of Trichoderma harizianum and Rhizophagus intraradices. This experiment was conducted with 7 treatments (inoculated soil with Trichoderma, inoculated soil with arbuscular mycorrhiza, inoculated soil with Trichoderma and arbuscular mycorrhiza, inoculated seed with Trichoderma, inoculated seed with arbuscular mycorrhiza, inoculated seed with Trichoderma and arbuscular mycorrhiza and control without antagonistic agents) and 4 replicates for each treatment. According to the results obtained from different treatments, the inoculated soil with Trichoderma(mean=0. 19), the inoculated soil with Trichoderma and arbuscular mycorrhiza(mean=0. 193) and the inoculated seed with Trichoderma and arbuscular mycorrhiza(mean=0. 11) showed the highest amounts of disease control.