植物附生微生物与叶部病害生物防治研究进展

人们早已发现绿色植物叶面(phylloplane)栖居有大量微生物。在一百多年前微生物学家就从植物叶面分离到许多真菌和细菌。1910年Potter首先证实,叶面附生微生物在干扰真菌引起的叶部病害中起着重要作用。至本世纪上半叶,叶面微生物仍为人们所忽视。相反,在这期间土壤微生物得到很大发展,在土传植物病原菌生物防治研究方法上取得了很大进展,为后来的植物叶部病害生物防     

Biological control of Orobanche spp. with Phytomyza orobanchia, a review

This review summarises theavailable information on the biocontrol agentPhytomyza orobanchia Kalt. (Diptera, Agromyzidae). It gives an overview of a rareexample of weed biocontrol using insects in aninundative approach. A high diversity ofphytophagous insects has been collected onparasitic weeds of the genus Orobanche(Orobanchaceae). For biological control of Orobanche spp., only insects like P. orobanchia whose host range is restricted toOrobanche spp. are of interest. Of the140 Orobanche spp. described in total,P. orobanchia is reported from 21 species. The larvae of P. orobanchia minein Orobanche shoots and capsules. As aconsequence, a natural reduction of Orobancheseed production by 30 to almost 80%has been reported from different countries. Theefficacy of P. orobanchia under naturalconditions is limited by low temperatures, cultural practices and natural enemies. Tostrengthen the natural population and itsimpact, inundative releases of P. orobanchia adults at the beginning of Orobanche emergence have to be undertaken. Different methods for the application of P. orobanchia in biocontrol of Orobanche spp. have been developed in theformer Soviet Union. Releases of 500 to 1000adults/ha resulted in a reduction of up to 96%of the Orobanche seed production.However, due to the 10 to 15 year longevity ofOrobanche seeds, further infestationswill occur in the following cropping seasons.Consequently, releases of P. orobanchiahave to be repeated continuously over severalyears to reduce the infestation to a tolerablelevel.     

Biological Control of Postharvest Diseases of Peaches and Nectarines by Yeasts

Abstract Biocontrol activities of a total of 103 yeast isolates were tested against postharvest diseases of peaches. Seven isolates, with the best efficacy in reducing the number of infected wounds or lesion sizes of Penicillium expansum and Botrytis cinerea, were selected for further large‐scale experiments. In large‐scale experiments, all selected isolates were significantly effective (P ≤ 0.05) in reducing the number of infected wounds and the diameter of lesions caused by P. expansum, B. cinerea, and Monilinia fructicola. DR52 was significantly superior to all the other yeasts in effectiveness against all three pathogens. The efficacy of the other yeast antagonists against B. cinerea and P. expansum was almost equal, while the control of M. fructicola was inferior. DR52 was selected for further storage experiment because its efficacy was higher against the three pathogens and it also showed a different random amplified polymorphic DNA‐polymerase chain reaction pattern compared with other isolates. DR52 was identified by Centraalbureau voor Schimmeelcultures (Baarn, The Netherlands) as Kloeckera apiculata. K. apiculata completely controlled both pathogens after 30 days of storage. Its efficacy declined to an 83.4% reduction in B. cinerea incidence and an 87.5% reduction in P. expansum incidence after 45 days of storage.     

Biological Control of Oomycete Soilborne Diseases Caused by Phytophthora capsici,Phytophthora infestans,and Phytophthora nicotianae in Solanaceous Crops

Oomycete pathogens that belong to the genus Phytophthora cause devastating diseases in solanaceous crops such as pepper, potato, and tobacco, resulting in crop production losses worldwide. Although the application of fungicides efficiently controls these diseases, it has been shown to trigger negative side effects such as environmental pollution, phytotoxicity, and fungicide resistance in plant pathogens. Therefore, biological control of Phytophthora-induced diseases was proposed as an environmentally sound alternative to conventional chemical control. In this review, progress on biological control of the soilborne oomycete plant pathogens, Phytophthora capsici, Phytophthora infestans, and Phytophthora nicotianae, infecting pepper, potato, and tobacco is described. Bacterial (e.g., Acinetobacter, Bacillus, Chryseobacterium, Paenibacillus, Pseudomonas, and Streptomyces) and fungal (e.g., Trichoderma and arbuscular mycorrhizal fungi) agents, and yeasts (e.g., Aureobasidium, Curvibasidium, and Metschnikowia) have been reported as successful biocontrol agents of Phytophthora pathogens. These microorganisms antagonize Phytophthora spp. via antimicrobial compounds with inhibitory activities against mycelial growth, sporulation, and zoospore germination. They also trigger plant immunity-inducing systemic resistance via several pathways, resulting in enhanced defense responses in their hosts. Along with plant protection, some of the microorganisms promote plant growth, thereby enhancing their beneficial relations with host plants. Although the beneficial effects of the biocontrol microorganisms are acceptable, single applications of antagonistic microorganisms tend to lack consistent efficacy compared with chemical analogues. Therefore, strategies to improve the biocontrol performance of these prominent antagonists are also discussed in this review.     

Review of Pasteuria penetrans: Biology,Ecology, and Biological Control Potential

Pasteuria penetrans is a mycelial, endospore-forming, bacterial parasite that has shown great potential as a biological control agent of root-knot nematodes. Considerable progress has been made during the last 10 years in understanding its biology and importance as an agent capable of effectively suppressing root-knot nematodes in field soil. The objective of this review is to summarize the current knowledge of the biology, ecology, and biological control potential of P. penetrans and other Pasteuria members. Pasteuria spp. are distributed worldwide and have been reported from 323 nematode species belonging to 116 genera of free-living, predatory, plant-parasitic, and entomopathogenic nematodes. Artificial cultivation of P. penetrans has met with limited success; large-scale production of endospores depends on in vivo cultivation. Temperature affects endospore attachment, germination, pathogenesis, and completion of the life cycle in the nematode pseudocoelom. The biological control potential of Pasteuria spp. have been demonstrated on 20 crops; host nematodes include Belonolaimus longicaudatus, Heterodera spp., Meloidogyne spp., and Xiphinema diversicaudatum. Pasteuria penetrans plays an important role in some suppressive soils. The efficacy of the bacterium as a biological control agent has been examined. Approximately 100,000 endospores/g of soil provided immediate control of the peanut root-knot nematode, whereas 1,000 and 5,000 endospores/g of soil each amplified in the host nematode and became suppressive after 3 years.     

The Ecological Complexities of Biological Control: Trophic Cascades, Spatial Heterogeneity, and Behavioral Ecology

Biological control can be considered an intentional induction of a trophic cascade, whereby the addition of herbivores’ natural enemies or other habitat manipulations effectively enhance natural enemy populations, lead to reduced herbivore populations or feeding damage, and indirectly improve or protect plant health, agricultural yield, or the condition of some other biotic population or community of interest to man. The following set of papers (Denno et al., 2008; Ram et al., 2008; Stuart and Duncan, 2008; Spence et al. 2008) offer insights into the broad- and fine-scale factors that ultimately contribute to the success of biological control efforts. Many of the ideas herein were presented and discussed during a special session at the 2007 Annual Meeting of the Society of Nematologists. The goal of this session was to examine explicitly the ramifications of spatial and temporal heterogeneity in the context of effective biological control. The biological focus was primarily on interactions involving entomopathogenic nematodes (EPN), although many of the authors’ conclusions are applicable to other types of nematodes, soil fauna and natural enemies in general.     

Biological control: Premises,ecological input and Mimosa pigra in the wetlands of Australia's Top End

The adverse impacts of weeds on natural ecosystems, together with the inadequate outcomes from treating weeds as a symptom, have escalated interest in finding efficacious control methods. With the aim of protecting wetlands from invasive weeds, this contribution uses the woody shrub Mimosa pigra L. (mimosa) as a case history to examine the methodology of classical biological control and the reasons for the widely accepted 75% failure rate. Overall objectives are for all biocontrol agents to have the opportunity to fully express their potential and to insure that limited resources are spent wisely on attainable weed control. The three main conclusions were that (1) the premises on which biocontrol is based has restricted advancement of this method; (2) monitoring is the logical first step to improving the selection of agents and release sites; and (3) it may be more cost-effective to introduce fewer agents that have undergone agent/plant and host/home range pre- and post-release ecological studies. Weed control may remain elusive unless advantage is taken of every beneficial result. Innovative assistance to agents and the integration of different control methods may preserve a role for weed biological control and has the potential to be of great importance for future weed management. It is proposed that the climate in the Top End of the Northern Territory and the lack of competition on the floodplains has contributed to mimosa's invasiveness. Climate may also underly the difficulties faced by agents. Agents appear unable to impart effective control in the dry season because of low numbers which relates to mimosa's poor growth; nor in the wet season, when the impact from high numbers of agents is outstripped by mimosa's growth.     

Isolation of Pythium Acanthicum,P. oligandrum,and P. periplocum from Soil and Evaluation of Their Mycoparasitic Activity and Biocontrol Efficacy Against Selected Phytopathogenic Pythium Species

Mycoparasitic Pythium species with spiny oogonia were surveyed in 50 Palestinian agricultural fields subject to different cropping practices using the Sclerotia Bait Technique (SBT) and the Surface-Soil-Dilution-Plate method (SSDP) with the selective VP3 medium. The mycoparasitic Pythium species were obtained from 21 (42%) soils using the SSDP method and from 37 (74%) soils using SBT. Pythium acanthicum and P. oligandrum were isolated by both methods, whereas P. periplocum was isolated only by the SBT. Using a newly modified dual plate culture method (MDPCM), the three mycoparasites showed varying antagonistic performance against several Pythium host species under a range of in vitro conditions. However, P. periplocum and P. oligandrum were found to be active biocontrol agents against P. ultimum, the damping-off organism of cucumber. This pathogen was antagonized, on thin films of water agar, by the three mycoparasites, and was moderately susceptible to P. periplocum while slightly susceptible to P. acanthicum and P. oligandrum. In direct application method in which antagonistic mycoparasites were incorporated into peat/sand mixture artificially infested with P. ultimum under growthroom conditions, Pythium oligandrum and P. periplocum (at 500 CFUg⁻¹) significantly improved seedling emergence and protected seedlings from damping-off. In the seed coating method, biocontrol by two types of seed dressing (homogenate- or oospore coated seeds), was comparable to that achieved by direct application. This revised version was published online in June 2006 with corrections to the Cover Date.     

Biological Control of Fusarium Wilt in Tomato Caused by Fusarium oxysporum f. sp. lycopersici by AMF Glomus intraradices and some Rhizobacteria

In the present study, the effects of the arbuscular mycorrhizal fungus (AMF) Glomus intraradices Schenck & Smith and four rhizobacteria (RB; 58/1 and D/2: Pseudomonas fluorescens biovar II; 17: P. putida; 21: Enterobacter cloacae), which are the important members of the rhizosphere microflora and biological control agents against plant diseases, were examined in the pathosystem of Fusarium oxysporum f. sp. lycopersici [(Sacc) Syd. et Hans] (FOL) and tomato with respect to morphological parameters (fresh and dry root weight) and phosphorous (P) concentration in the roots. Treatments with single and dual inoculation with G. intraradices and RB strains reduced disease severity by 8.6–58.6%. Individual bacteria inoculations were more effective than both the single AMF and dual (G. intraradices + RB) inoculations. In addition, the RB and G. intraradices enhanced dry root weight effectively. Significant increases in root weights were recorded particularly in the triple inoculations compared with single or dual inoculations. Compared with the non‐treated controls all biological control agents increased P‐content of treated roots of plants. Colonization with RB increased especially in triple (FOL + G. intraradices + RB) inoculations whereas colonization of G. intraradices was significantly decreased in treatment of FOL + G. intraradices compared with triple inoculations. The results suggest that suitable combinations of these biocontrol agents may ameliorate plant growth and health.     

Potential of Prokelisia spp. as Biological Control Agents of English Cordgrass, Spartina anglica

Spartina anglica, English cordgrass, has been isolated from North American herbivores since its 19th century amphidiploid hybrid origin in England. We found a population of this estuarine plant, introduced to Puget Sound, Washington, to be highly vulnerable to Prokelisia spp. planthoppers from California. More than 90% of plants died in greenhouse culture with high planthopper densities, while <1% died at the very low hopper densities of the control. English cordgrass invades the open intertidal mud of Pacific estuaries of North America, jeopardizing native flora and fauna of saltmarshes. This invasive plant alters the hydrology of marshes by accreting sediment. If intolerance to Prokelisia spp. in the field correlates with that in the greenhouse, biological control by this planthopper could contribute to management of cordgrass populations sensitive to this insect. Prokelisia spp. are stenophagous and pose little apparent threat to other plant genera. Neither the biological basis nor the inheritance of cordgrass vulnerability to the Prokelisia spp. are known. If genetic variability in vulnerability to this planthopper exists within the population of S. anglica, care would be needed to prevent increase of more resistant plant genotypes as a result of introduction of the insect.     

Biocontrol of Damping-off Diseases Caused by Rhizoctonia solani and Pythium ultimum with Alginate Prills of Gliocladium virens, Trichoderma hamatum and Various Food Bases

Alginate prills were formulated with the biomass of isolates of Gliocladium virens and Trichoderma spp. and various food bases (wheat bran, corn cobs, peanut hulls, soy fiber, castor pomace, cocoa hulls and chitin). Alginate prills with G. virens (Gl-21) biomass and all food bases except cocoa hull meal significantly reduced the damping-off of zinnia in a soil-less mix caused by Rhizoctonia solani and Pythium ultimum. The prills with bran, soy fiber, castor pomace or chitin resulted in stands similar to those in the non-infested control. In soil, prills with all the food bases and Thrichoderma hamatum (TRI-4) biomass controlled the damping-off of cotton caused by R. solani and gave stands comparable to, or better than, those in the non-infested control soil. Prills with all the food bases resulted in a proliferation of Gl-21 in a soil-less mix and of Gl-21 and TRI-4 in soil. Prills with food bases and TRI-4 biomass reduced the survival of R. solani in infested beet seed to less than 30%, with bran and chitin being the most effective food bases; prills with Gl-21 biomass and all food bases also reduced the survival of R. solani in beet seed, but not as much as did prills with TRI-4 biomass. In prills containing wheat bran, soy fiber or chitin, the biocontrol isolate Th-58 (T. harzianum) was almost as effective as TRI-4, but isolate Gl-3 (G. virens) was less effective. There was no significant interaction between the biocontrol fungus and the food base. The results suggest that the intrinsic properties of a selected fungus isolate are more important than some formulation variables in biocontrol.     

The microbial ecology of high-risk, chilled food factories; evidence for persistent Listeria spp. and Escherichia coli strains

AIMS: The intention of this study was to provide evidence of any Listeria spp. or Escherichia coli strain persistence, and to identify whether strains of these organisms adapt to specific environmental or product niches in food factories. METHODS AND RESULTS: A 3-year assessment of the microbial ecology of four, ready-to-eat food-processing factories was undertaken in which approx. 196 000 and 75 000 product and environmental samples were examined for Escherichia coli and Listeria spp. respectively. A total of 152 E. coli isolates (44 environmental and 108 product in 62 ribogroups) and 260 Listeria spp. isolates (174 environmental and 86 product in 30 ribogroups) were identified and ribotyped. The overall prevalence of E. coli (0.08%), all Listeria spp. (0.35%) and L. monocytogenes (0.23%) was very low. Some 10 E. coli ribogroups and 14 Listeria spp. ribogroups showed evidence for persistence, defined as the isolation of the same strain, from the same site, over a prolonged time period. The majority of E. coli strains were product niche oriented whilst the majority of Listeria spp. strains were environmental niche oriented. CONCLUSION: Current UK high-risk food factory designs, personnel hygiene and cleaning and disinfection regimes are sufficient to control Listeria spp. and E. coli to very low levels. SIGNIFICANCE AND IMPACT OF THE STUDY: Persistent strains of these organisms, however, can remain within factory high-risk production areas over considerable time periods, warranting an examination of the strain persistence mechanisms and alternative hygiene controls.     

Control of invasive marine invertebrates: an experimental evaluation of the use of low salinity for managing pest corals (Tubastraea spp.)

This study investigated the use of low salinity as a killing agent for the invasive pest corals Tubastraea coccinea and Tubastraea tagusensis (Dendrophylliidae). Experiments investigated the efficacy of different salinities, the effect of colony size on susceptibility and the influence of length of exposure. Experimental treatments of colonies were carried out in aquaria. Colonies were then fixed onto experimental plates and monitored in the field periodically over a period of four weeks. The killing effectiveness of low salinity depended on the test salinity and the target species, but was independent of colony size. Low salinity was fast acting and prejudicial to survival: discoloration, necrosis, fragmenting and sloughing, exposure of the skeleton and cover by biofoulers occurred post treatment. For T. tagusensis, 50% mortality (LC₅₀) after three days occurred at eight practical salinity units (PSU); for T. coccinea the LC₅₀ was 2?PSU. Exposure to freshwater for 45–120?min resulted in 100% mortality for T. tagusensis, but only the 120?min period was 100% effective in killing T. coccinea. Freshwater is now routinely used for the post-border management of Tubastraea spp. This study also provides insights as to how freshwater may be used as a routine biosecurity management tool when applied pre-border to shipping vectors potentially transporting non-indigenous marine biofouling species.     

PCR-based,rapid diagnosis of parasitism of Lygus spp. (Hemiptera: Miridae) by Peristenus relictus (Hymenoptera: Braconidae)

Several species of Lygus (Heteroptera: Miridae: Mirini) are serious crop pests in North America where their parasitism rate by native nymphal parasitoids is generally lower than in Europe. Peristenus relictus (Ruthe) (formerly P. stygicus Loan) (Hymenoptera: Braconidae: Euphorinae) is the predominant nymphal parasitoid of several Lygus spp. in the warm Mediterranean region and has been a candidate for introduction against Lygus hesperus Knight and L. lineolaris (Palisot de Beauvois) in the southern US. We report a rapid, sensitive, and specific PCR-based assay for diagnosis of P. relictus immature stages within Lygus nymphs that entails three steps: DNA extraction, PCR of the partial mitochondrial COI gene, and agarose gel electrophoresis. The PCR-based methodology is species-specific because the target DNA of other sympatric, congeneric species was not amplified with use of the primers developed for P. relictus diagnosis. The sensitivity of the PCR method, assessed through spike tests, was established by the detection of a ratio of 1:10,000 P. relictus DNA to Lygus DNA. Molecular diagnosis of parasitism of field collected nymphs is achievable in one day, eliminating the need to rear nymphs to obtain adult parasitoids for morphological identification.     

Biology and host range of Ophiomyia camarae Spencer (Diptera: Agromyzidae), a potential biocontrol agent for Lantana spp. (Verbenaceae) in Australia

The life history and host range of the herringbone leaf-mining fly Ophiomyia camarae, a potential biological control agent for Lantana spp., were investigated. Eggs were deposited singly on the underside of leaves. Although several eggs can be laid on a single leaf and a maximum of three individual mines were seen on a single leaf, only one pupa per leaf ever developed. The generation time (egg to adult) was about 38 days. Females (mean 14 days) lived longer than males (mean 9 days) and produced about 61 mines. Oviposition and larval development occurred on all five lantana phenotypes tested. Eleven plant species representing six families were tested to determine the host range. Oviposition and larval development occurred on only lantana and another nonnative plant Lippia alba (Verbenaceae), with both species supporting populations over several generations. A CLIMEX model showed that most of the coastal areas of eastern Australia south to 30°16′ S (Coffs Harbour) would be suitable for O. camarae. O. camarae was approved for release in Australia in October 2007 and mines have been observed on plants at numerous field sites along the coast following releases.     

Establishment of Peristenus digoneutis and P. relictus (Hymenoptera: Braconidae) in California for the control of Lygus spp. (Heteroptera: Miridae)

Lygus hesperus Knight is native to the western United States and is a perennial pest of numerous crops in California. It is responsible for triggering the early season application of insecticides on cotton, Gossypium hirsutum L., and strawberries, Fragaria L. Despite several surveys conducted in alfalfa (Medicago sativa L.) grown in central California, nymphal parasitoids associated with L. hesperus and L. elisus have not been found. Two exotic parasitoids were released into California beginning in 1998. Peristenus relictus (Ruhte), formerly P. stygicus Loan, and P. digoneutis Loan were collected from several locations in southern Europe and released at up to six locations over a 6-year period. At the original release site in Sacramento, a 0.25-ha plot of alfalfa, parasitism by P. digoneutis and P. relictus combined increased from zero to 90%, 3 years after the last releases were made. Parasitoids have been recovered from vacant fields of weedy annuals within 2 km of this site. Recoveries at more southerly release sites in central California have been poor.     

Growth inhibition of the cereal root pathogens Rhizoctonia solani AG8, R. oryzae and Gaeumannomyces graminis var. tritici by a recombinant 42-kDa endochitinase from Trichoderma harzianum

The objective of this study was to determine the effectiveness of a 42-kDa endochitinase coded by the ThEn42 gene from Trichoderma harzianum as a potential source of transgenic resistance to Rhizoctonia root rot of barley caused by Rhizoctonia solani AG8 and/or R. oryzae. The gene cThEn42 was codon optimized (GC content increased from 53.3 to 65.1%) and then synthesized to produce the modified cThEn42GC in Pichia pastoris for in vitro tests. Two expression vectors were constructed: one with the fungal signal peptide and the fungal activation peptide [FSP-FAP-cThEn(GC)] and the other with barley chitinase 26 signal peptide followed by the fungal signal and activation peptides [SP(HVChi26)-FSP-FAP-cThEn(GC)]. N-terminal sequencing showed that, of two proteins secreted into liquid medium, FSP was cleaved off faithfully in one protein and both FSP and FAP were cleaved from the other protein. Purified endochitinase provided strong in vitro inhibition of both R. solani AG8 and R. oryzae. The enzyme had an intermediate inhibitory activity against Gaeumannomyces graminis var. tritici, and no inhibitory activity against Fusarium graminearum, F. pseudograminearum, and F. culmorum.     

Eggs of Ephestia kuehniella and Ceratitis capitata,and motile stages of the astigmatid mites Tyrophagus putrescentiae and Carpoglyphus lactis as factitious foods for Orius spp.

Several factitious foods were assessed for rearing the anthocorid predators Orius thripoborus (Hesse) and Orius naivashae (Poppius) (Hemiptera: Anthocoridae) in the laboratory. Developmental and reproductive traits of both Orius species were examined when offered frozen eggs of the Mediterranean flour moth, Ephestia kuehniella Zeller, frozen processed eggs of the medfly, Ceratitis capitata Wiedemann, or mixed motile stages of the astigmatid mites Tyrophagus putrescentiae (Schrank) or Carpoglyphus lactis (L). Whereas C. lactis and T. putresecentiae proved to be an inferior food for rearing O. thripoborus and O. naivashae, eggs of C. capitata fully supported development and reproduction of both predators. Results on medfly eggs were similar or slightly inferior to those on E. kuehniella eggs, which is the standard food for culturing these anthocorid bugs. O. thripoborus could be maintained for 4 consecutive generations on C. capitata eggs indicating that processed medfly eggs can be a suitable and cheaper alternative to E. kuehniella eggs for prolonged rearing of these Orius spp.