Source Of Biological Control Agents Research Articles

Effective biological control of southern blight of Dendrobium officinale by Streptomyces sp. MEPF0303

Southern blight is a common and devastating disease adversely affecting the yield and quality of cultivated Dendrobium officinale plants. The pathogens responsible for this disease are Sclerotium delphinii and S. rolfsii, although S. delphinii is more pathogenic than S. rolfsii. Plant endophytes are potential sources of biological control agents. In this study, 18 microbial strains were isolated from wild Dendrobium shixingense plants (e.g., Streptomyces, Bacillus, and Trichoderma), among which strain MEPF0303 significantly inhibited S. delphinii mycelial growth. Based on 16S rRNA gene sequence, this strain was identified as Streptomyces sp. In addition, the volatile organic compounds and cell-free supernatant of MEPF0303 had significant inhibitory effects on S. delphinii growth. Moreover, MEPF0303 effectively controlled southern blight of D. officinale. A total of 1,797 differentially expressed genes were identified by a comparative transcriptome analysis of S. delphinii mycelia treated with MEPF0303 and the untreated control mycelia. Strain MEPF0303 significantly altered the expression of genes related to cell membrane morphological development and integrity, pathogenicity, energy metabolism, and oxidative stress responses. Furthermore, the transcriptome sequencing results were validated by analyzing gene expression via a quantitative real-time polymerase chain reaction. The study results showed that MEPF0303 can inhibit the growth and pathogenicity of S. delphinii, with potential implications for the biological control of southern blight of D. officinale.

Plant–pathogen interaction with root rot of Panax notoginseng as a model: Insight into pathogen pathogenesis, plant defence response and biological control

AbstractPlant diseases are a major threat affecting the sustainability of global agriculture. Although the breeding of new resistant cultivars is considered to be the primary approach to prevent and control plant diseases, it is dependent on an in‐depth understanding of plant–pathogen interactions. At present, we have an in‐depth understanding of the interactions between model plants and pathogens, such as Arabidopsis thaliana and rice, but we are still in the beginning stage for more non‐model plants (e.g., medicinal plants). Panax notoginseng is the primary source of the high‐value active ingredient triterpenoid saponins. Root rot disease in P. notoginseng has attracted research attention because of its high destructiveness. Understanding the infection stages and strategies of pathogens, plant resistance mechanisms and induced plant defence against pathogens is essential to support agricultural sustainable development of P. notoginseng. Here, we review and summarize, with root rot of P. notoginseng as a model, the current knowledge of plant–pathogen interaction, and feasability of use of microorganisms and secondary metabolites as sources of biological control agents at a low cost. Finally, we also discuss the importance of plant–pathogen interactions in resistance breeding, thereby providing a new strategy to develop green agriculture for non‐model plants.

Heritage grapevines as sources of biological control agents for Botryosphaeria dieback pathogens

Grapevine trunk diseases cause severe damage in grapevines. Management strategies focus on protection of grapevine pruning wounds using chemical fungicides or biological control agents. Botryosphaeria dieback, caused mainly by Lasiodiplodia spp., is one of the main trunk diseases in northwest Mexico. This study obtained endophytic bacteria and fungi from the heritage grapevine Vitis vinifera cv. ‘Mission’ for potential biological control of Botryosphaeria dieback. A collection of 135 bacterial and 37 fungal isolates were obtained and initially tested for antagonistic activity against Lasiodiplodia brasiliensis. The most promising isolates belonging to Trichoderma and Bacillus spp. were selected and characterized to determine their modes of action. Bacillus isolates produced volatile organic compounds that inhibited growth of Neofusicoccum parvum, and diffusible organic compounds with antifungal effects against L. brasiliensis and N. parvum. Trichoderma isolates produced diffusible organic compounds and were mycoparasites. In greenhouse assays, plants inoculated with three Trichoderma asperellum isolates (T20BCMX, EF09BCMX, and EF11BCMX), B. amyloliquefaciens (BEVP26BCMX) or Bacillus sp. (rbES015), applied preventively in soil, gave up to 50% smaller necrotic lesions when compared with the plants inoculated only with L. brasiliensis. In the field, plants inoculated with three Bacillus isolates (BEVP02BCMX, BEVP26BCMX, BEVP31BCMX) or five Trichoderma (T11BCMX, T15BCMX, T17BCMX, T20BCMX, and EF11BCMX) had lesions up to four times smaller than control plants inoculated only with L. brasiliensis. This study has demonstrated the potential of heritage grapevines to provide biological control agents for Botryosphaeria dieback.

Omnipresence of Partitiviruses in Rice Aggregate Sheath Spot Symptom-Associated Fungal Isolates from Paddies in Thailand.

Partitiviruses are one of the most prevalent double-stranded RNA viruses that have been identified mostly in filamentous fungi and plants. Partitiviruses generally infect host fungi asymptomatically but infrequently exert significant effect(s) on morphology and virulence, thus being considered a potential source of biological control agents against pathogenic fungi. In this study, we performed a screening for mycoviruses of a collection of Thai isolates of rice fungal pathogen Rhizoctonia oryzae-sativae, a causal agent of rice aggregated sheath spot disease. As a result, 36% of tested isolates carried potentially viral double-stranded RNAs with sizes ranging from 2 to 3 kbp. By conventional cDNA library construction and RNA-seq, we determined six new alphapartitiviruses that infected three isolates: tentatively named Rhizoctonia oryzae-sativae partitivirus 1 to 6 (RosPV1-6). Furthermore, RT-PCR detection of each virus revealed their omnipresent nature in different R. oryzae-sativae isolates. Although virus-curing of basidiomycetous fungi is generally difficult, our repeated attempts successfully obtained virus-free (for RosPV1, RosPV2, and uncharacterized partitiviruses), isogenic strain of R. oryzae-sativae TSS190442. The virus-cured strain showed slightly faster colony growth on the synthetic media and severe symptom development on the rice sheath compared to its virus-infected counterpart. Overall, this study shed light on the distribution of partitiviruses in R. oryzae-sativae in a paddy environment and exemplified a virus-curing protocol that may be applicable for other basidiomycetous fungi.

Endophytic Microorganisms Associated with Reversion of Silverleaf Disease Symptoms in Apple

Silverleaf is caused by the fungus Chondrostereum purpureum, which produces wood necrosis and foliar silvering in woody plants. Field observations and studies in apple have shown the reversion of foliar symptoms. Since plants were clones and received identical agronomical management, it was hypothesized that reversion is driven by endophytic microbiota. Thus, the objectives of this study were to compare healthy, diseased and reverted plants with respect to their physiology, endophytic microbial communities, antagonistic ability of their endophytes against C. purpureum and defense-genes-expression. Water-potential, stomatal-conductance, chlorophyll-content and fluorescence were measured. Endophytic bacterial and fungal DNA were analyzed by DGGE, and communities richness and similarity were calculated. Wood cores were collected and bacterial and fungal endophytes were isolated and confronted with C. purpureum virulent strains in dual-culture assays. Defense-genes-expression were measured by qPCR. Results indicated that there were no differences in physiological parameters between healthy and reverted plants, except for fluorescence, and both type of plants differed from diseased ones. Bacterial and fungal communities richness were similar in healthy and reverted plants, and higher than in diseased ones. Endophytes from reverted and healthy plants showed high antagonism to C. purpureum. Furthermore, NPR1-gene-expression was upregulated in reverted plants, while PAL and PGIP showed higher values in diseased plants. Overall, physiological, molecular and microbial characteristics were similar between healthy and reverted plants, and both differed from diseased ones. Therefore, reversion of symptoms is associated with changes in the endophytic microbiota, which seems to be a promising source of biological control agents against C. purpureum.

Influence of Fungicide Application and Vine Age on Trichoderma Diversity as Source of Biological Control Agents

Fungi from the genus Trichoderma have a worldwide distribution and are commonly found in agricultural lands. Further, it has been described as a non-virulent and symbiont microorganism that can contribute to minimize the pernicious effects of pathogens. In the present work we have isolated Trichoderma spp. from bark of grapevine in different orchards in order to determine the influence of fungicide application and vine age on Trichoderma diversity in plant. An opposite correlation between the number of fungicides sprayed per campaign and the diversity of Trichoderma spp. isolates was found. Moreover, the older are grapevine plants the higher is the diversity of Trichoderma spp. isolates. The different Trichoderma strains isolated were tested against Phaeoacremonium minimum, a grapevine trunk pathogen, to evaluate their biocontrol capacity. Three Trichoderma strains shown a significant capacity to control P. minimum and were selected as candidates to be used as biological control agents. In addition, a rapid and easy method for isolating Trichoderma spp. from grapevine plants has been developed, which allowed to determine that the reduction in the amount of pesticide use, together with the preservation of old vineyards, lead to healthier agroecosystems containing higher levels of beneficial microorganisms.

Antifungal activity of marine-derived Paenibacillus sp. PNM200 against Fusarium oxysporum f. sp. lycopersici, the causal agent of tomato vascular wilt

Marine-derived bacteria are known for producing a wide range of specialized metabolites with antifungal activity against phytopathogens. Assessing the marine bacteria's ability to establish themselves in the rhizosphere and inhibit soil-borne phytopathogens under in vivo conditions could provide evidence that supports their use for biological control, widening biological control agent’s isolation sources. The current study evaluated the antifungal activity of a marine-derived bacterial collection against the tomato phytopathogen Fusarium oxysporum f. sp. lycopersici (FOL). Out of 152 isolates, 28 Firmicutes strains showed antifungal activity against ten isolates of F. oxysporum in in vitro testing. From them, Paenibacillus sp. PNM200 was identified as a potential PGPR and as a biocontrol agent against Fusarium vascular wilt. PNM200 colonized the tomato plant root system, increased plant growth, and reduced vascular wilt severity on greenhouse assays. Interestingly, plants treated with the spent supernatants of PNM200 cultures did not show a decrease in vascular wilt severity. This result indicates that the ability of PNM200 to act as a biocontrol agent against FOL does not depend on the diffusible antifungal metabolites produced during the fermentation process. Other Paenibacillus sp. PNM200 traits like chemotactic response towards tomato root exudates, biofilm, IAA, enzyme activity, and phosphate solubilization may contribute to PNM200 rhizospheric competence and biological control ability. Overall, the obtained results suggest that marine-derived bacteria could be a new source of biological control agents for integrated pest management of soil-borne diseases like Fusarium vascular wilt.

Exploring Rain as Source of Biological Control Agents for Fire Blight on Apple.

Poor survival on plants can limit the efficacy of Biological Control Agents (BCAs) in the field. Yet bacteria survive in the atmosphere, despite their exposure to high solar radiation and extreme temperatures. If conditions in the atmosphere are similar to, or more extreme than, the environmental conditions on the plant surface, then precipitation may serve as a reservoir of robust BCAs. To test this hypothesis, two hundred and fifty-four rain-borne isolates were screened for in vitro inhibition of Erwinia amylovora, the causal agent of fire blight, as well as of other plant pathogenic bacteria, fungi and oomycetes. Two isolates showed strong activity against E. amylovora and other plant pathogenic bacteria, while other isolates showed activity against fungal and oomycete pathogens. Survival assays suggested that the two isolates that inhibited E. amylovora were able to survive on apple blossoms and branches similarly to E. amylovora. Pathogen population size and associated fire blight symptoms were significantly reduced when detached apple blossoms were treated with the two isolates before pathogen inoculation, however, disease reduction on attached blossoms within an orchard was inconsistent. Using whole genome sequencing, the isolates were identified as Pantoea agglomerans and P. ananatis, respectively. A UV-mutagenesis screen pointed to a phenazine antibiotic D-alanylgriseoluteic acid synthesis gene cluster as being at the base of the antimicrobial activity of the P. agglomerans isolate. Our work reveals the potential of precipitation as an under-explored source of BCAs, whole genome sequencing as an effective approach to precisely identify BCAs, and UV-mutagenesis as a technically simple screen to investigate the genetic basis of BCAs. More field trials are needed to determine the efficacy of the identified BCAs in fire blight control.

Selection of fungal endophytes with biocontrol potential against Fusarium head blight in wheat

Fusarium head blight (FHB) is a major disease in wheat and other cereal crops. Biological control is a promising alternative for control of this disease as current control options are not efficient. Fungal endophytes could represent a new source of biological control agents since they colonise plant tissues asymptomatically whilst sharing the same biological niche as pathogens. Here, we show that healthy wheat spikes and leaves collected in areas with high FHB incidence harbour fungal isolates that reduce disease severity and pathogen biomass inside the spikes. We employed an in planta screening method using detached spikelets to observe the performance of 15 fungal strains against Fusarium infection. The results were validated in greenhouse spike inoculation assays. Isolates Sarocladium strictum C113L, Anthracocystis floculossa P1P1, A. floculossa F63P and Penicillium olsonii ML37 were identified as potential biocontrol agents of FHB in wheat. Timing of application was important: the endophytes needed to be applied at least two days before the pathogen to have a significant effect. Reduced symptom expression correlated with reduced biomass of Fusarium graminearum in the infected spikelets. Interestingly, none of these isolates reduced Fusarium growth in confrontation assays on agar plates. Our results suggest that naturally occurring endophytes could be a new source of biological control agents to be used in integrated pest management strategies.

Culturable bacterial diversity from the chestnut (Castanea sativa Mill.) phyllosphere and antagonism against the fungi causing the chestnut blight and ink diseases.

The phyllosphere supports a large and complex bacterial community that varies both across plant species and geographical locations. Phyllosphere bacteria can have important effects on plant health. The sweet chestnut (Castanea sativa Mill.) is an economically important tree species affected worldwide by the fungal pathogens Cryphonectria parasitica and Phytophthora cinnamomi. We examined the culturable phyllosphere bacterial community of the sweet chestnut at two nearby locations in Central Spain in order to know its geographical variability and to explore its potential as source of biological control agents against these two pathogenic fungi. The bacterial diversity at strain level was high but it varied significantly between locations; however, phylotype richness and diversity were more comparable. The isolates were affiliated with the phyla Actinobacteria, Firmicutes and Proteobacteria. Most of them were members of recognized bacterial species, with a notable proportion of representative of the genera Dietzia and Lonsdalea, but a small fraction of the strains revealed the existence of several potential novel species or even genera. Antagonism tests showed the occurrence in the chestnut phyllosphere of bacterial strains potentially useful as biological control agents against the two pathogenic fungi, some of which belong to species never before described as fungal antagonists. Chestnut phyllosphere, therefore, contains a great diversity of culturable bacteria and may represent an untapped source of potential biocontrol agents against the fungi causing blight and ink diseases of this tree species.

Evaluation of Local Isolates of Trichoderma Spp. against Black Root Rot (Fusarium solani) on Faba Bean

Faba bean (Vicia fabae L.) is one of the most important pulse crops in Ethiopia and is now cultivated on large areas in many countries. In most growing areas, however, the production of the crop is constrained by several disease infections, including fungal diseases. Black root rot caused by Fusarium solani is the most destructive disease of faba bean. The antagonistic potentials of locally isolated Trichoderma spp. from rhizosphere soils of faba bean plants in the highlands of northeastern Ethiopia were evaluated against F. solani, responsible for black root rot. All isolates of Trichoderma spp. had strong biological control activity against F. solani in vitro as well as in vivo pot experiment. Under dual culture, the percentage of mycelial growth inhibition of F. solani by the Trichoderma ranged from 33.9 to 67.0%. The highest (67.0%) inhibition was obtained from isolate TS036, while the lowest (33.9%) by isolate TS015. Pathogen-inoculated faba bean plants grown in pots that were treated with antagonists had taller plant heights and biomass than the Trichoderma untreated control inoculated with F. solani. The Trichoderma isolates significantly reduced black root rot severity on faba bean seedlings with disease reduction ranging from 64.4 to 74.6% over control. Use of Trichoderma species can be a potential source of biological control agents for the management of black root rot in faba beans grown in the region. Hence, the potential Trichoderma isolates under field condition might used as a components in the integrated management of F. solani that caused faba bean black root rot in the highlands of northeastern Ethiopia.

Probiotic Efficacy of <em>Lactobacillus reuteri</em> Culture Filtrates against Certain Groups of Proliferating Bacteria Isolated from Acne Abscess

Acne is a common disease in Saudi nationals particularly among adolescents and young adults. The disease has substantial effects on quality of life which making treatment essential. Probiotics nowadays is becoming a method of first choice to combat the disease. The present study was carried out to evaluate and to identify the causative agents of acne disease in Shaqra region. Subsequently, the effects of culture filtrate of the bacterium Lactobacillus reuteri on the in vitro growth of bacterial isolates obtained from acne i.e., Staphylococcus aureus, Staphylococcus epidermidis, Propionibacterium acnes and Propionibacterium granulosum were also carried out along with the subsequent inhibitory impacts on acne symptomatology. It was observed that the culture filtrates of L. reuteri were significantly inhibitory to the growth of the four bacterial species. Increase in zone of inhibition was directly correlated with concentration of L. reuteri. L. reuteri at both diluted and concentrated doses was inhibitory at 24, 48 and 72 h of incubation periods. The most inhibitory incubation period was 48 h using well-diffusion agar technique with concentrated filtrate. The toxicity of the culture filtrate was largely influenced by the dilution and incubation period. Antibiotics sensitivity tests against different bacterial isolates was tested using Triclosan, Benzoyl peroxidase, Erythromycin, Retinoid, Tetracycline and Clindamycin. All of the bacterial isolates were vulnerable (susceptible, sensitive) to Triclosan and Benzoyl peroxidase, Retinoid, Tetracycline and Clindamycin, but all of the isolates were resistant to Erythromycin antibiotic. It could be concluded that the culture filtrate of L. reuteri could be used as probiotics and a source of biological control agents to cure acne disease in the area.

Pest species distribution modelling: origins and lessons from history

Pest species distribution modelling was designed to extrapolate risks in the biosecurity sector in order to protect agricultural crops against the spread of both endemic and introduced pest species. The need to identify sources of biological control agents for importation added to this demand. Independently, biogeographers mapped species distributions to interpolate their niche requirements. Recently the threat of climate change caused an explosion in demand for guidance on likely shifts in potential distributions of species. The different technology platforms in the two sectors resulted in divergence in their approaches to mapping actual and potential species distributions under rapidly changing environmental scenarios. Much of the contemporary discussion of species mapping ignores the lessons from the history of pest species distribution modelling. This has major implications for modelling of the non-equilibrium distributions of all species that occur with rapid climate change. The current review is intended to remind researchers of historical findings and their significance for current mapping of all species. I argue that the dream of automating species mapping for multiple species is an illusion. More modest goals and use of other approaches are necessary to protect biodiversity under current and future climates. Pest risk mapping tools have greater prospects of success because they are generic in nature and so able to be used both to interpolate and to extrapolate from field observations of any species based on climatic variables. In addition invasive species are less numerous and usually better understood, while the risk assessments are applied on regional scales in which climate is the dominant variable.

Biological control of fire blight of apple and pear with antagonistic Lactobacillus plantarum

Lactic acid bacteria (LAB) can be a source of biological control agents (BCA) of fire blight disease. Several species of LAB are inhabitants of plants and are currently used as biopreservatives of food because of their antagonistic properties against bacteria, and are considered as generally safe. Candidates to BCA were selected from a large collection of LAB strains obtained from plant environments. Strains were first chosen based on the consistency of the suppressive effect against E. amylovora infections in detached plant organs (flowers, fruits and leaves). Lactobacillus plantarum strains PC40, PM411, TC54 and TC92 were effective against E. amylovora in most of the experiments performed. Besides, strains PM411, TC54 and TC92 had strong antagonistic activity against E. amylovora and also other target bacteria, and presented genes involved in plantaricin biosynthesis (plnJ, plnK, plnL, plnR and plnEF). The strains efficiently colonized pear and apple flowers; they maintained stable populations for at least 1 week under high RH conditions, and survived at low RH conditions. They were effective in preventing fire blight on pear flowers, fruits and leaves, as well as in whole plants and in a semi-field blossom assay. The present study confirms the potential of certain strains of L. plantarum to be used as active ingredient of microbial biopesticides for fire blight control that could be eventually extended to other plant bacterial diseases.

Enemigos naturales de las moscas de los estigmas del maíz: Euxesta stigmatias (Loew), Chaetopsis massyla (Walker) y Eumecosommyia nubila (Wiedemann) en Guasave Sinaloa, México

El complejo de moscas de los estigmas Euxesta stigmatias (Loew), Chaetopsis massyla (Walker) y Eumecosommyia nubila (Wiedemann) han adquirido importancia como plagas en el cultivo de maíz en Sinaloa, y sus daños están asociados a pudriciones que afectan la calidad del elote y el rendimiento del grano. Este trabajo tiene por objetivo presentar el resultado de la búsqueda de enemigos naturales (parasitoides, depredadores y nematodos entomopatógenos) con potencial para el control biológico de este complejo de moscas. El trabajo se realizo durante el ciclo agrícola primavera verano de 2011. Se hicieron 8 muestreos semanales con red entomológica y colecta de frutos, en la etapa de fructificación y maduración del grano en lotes de maíz sembrados con el hibrido Asgrow Garañon, predominando dos avispas del orden Hymenoptera de las familias Pteromalidae y Eurytomidae, que parasitan a la mosca de los estigmas en el estado de pupa; Spalangia spp., se observó con mayor frecuencia ejerciendo un parasitismo natural del 47 % sobre Euxesta stigmatias (Loew) durante las etapas de fructificación y maduración de los frutos. La chinche pirata Orius insidiosus (Say) estuvo presente durante los meses de marzo a julio depredando a huevecillos y larvas de la mosca. Por otro lado, se realizaron muestreos de suelos para aislar e identificar poblaciones de nematodos entomopatógenos, utilizando al insecto trampa Galleria melonella (L)., se aislaron poblaciones en tres sitios sembrados con maíz localizados en el CIIDIR-IPN Unidad Sinaloa, en los ejidos Guasave y Maximiliano R. López, todos ubicados en el municipio de Guasave. Los nematodos encontrados en los sitios pertenecen a especies de la familia Rhabtitidae, la identificación a nivel de género está en proceso. Los enemigos naturales encontrados se caracterizan por tener potencial para evaluarse como agentes de control biológico del complejo de moscas de los estigmas. .

Potential antagnosim of cultivated and wild grass–endophyte associations towards Meloidogyne incognita

Potential antagonism towards plant-parasitic nematode Meloidogyne incognita by grass–endophyte associations and their corresponding endophytes was evaluated. The following grass-endophyte associations were studied: (1) the cultivated grass Schedonorus arundinaceus-Neotyphodium coenophialum, (2) the wild grass Leymus chinensis-Neotyphodium sp. and (3) the wild grass Achnatherum sibiricum-Neotyphodium sibiricum. The cultivated grass Schedonorus arundinaceus was used to evaluate the effect of the endophyte fungus on chemotaxis of M. incognita. The results showed a significant negative effect on chemotaxis of the second-stage juveniles (J2) of M. incognita towards S. arundinaceus-N. coenophialum plants (P<0.05). The associations of the grass S. arundinaceus-N. coenophialum and the wild grass A. sibiricum-N. sibiricum were used for testing their effect on penetration of grasses by J2. The wild grass A. sibiricum-N. sibiricum association appeared to suppress J2 penetration. N. coenophialum, Neotyphodium sp. and N. sibiricum isolated from cultivated and wild grasses respectively were used for measuring their effect on J2 mortality. Undiluted culture filtrates of all endophytic fungi caused significantly high J2 mortality 72.6% for N. coenphialum, 91.7% for Neotyphodium sp. and 66.8% for N. sibiricum. Finally, the penetration of cucumber roots by J2 pretreated by the filtrates of the three endophytic fungi was also tested. N. sibiricum filtrate significantly reduced the number of J2 penetrations by 44.5% and no significant effect in the treatment of the filtrates of Neotyphodium sp. from L. chinensis. Taken together, endophytic fungi of the genus Neotyphodium might be a potential source of biological control agents for plant parasitic nematodes.

Hedgerow effects on the distribution of beneficial arthropods in a pear orchard in Southern France

Farming intensification in recent decades has led to an alarming level of degradation and loss of wildlife and its habitat such as hedgerows. The relationship between biodiversity and ecosystem functioning has emerged as a central issue in ecological sciences, but the impact of regarding hedgerow function as a potential source of biological control agents against agricultural pests remains poorly understood. In this paper, we assessed effects of the arthropod community in a neighbouring hedge on the distribution of the pest psylla, Cacopsylla pyri, in a pear orchard over three consecutive years (1999-2001). We measured the diversity of the arthropod community in the hedge and in the orchard at increasing distances from the hedge using Shannon index diversity. Other indices and statistics such the Hellinger and L1 distances were used to measure dissimilarities between spatial and temporal population distributions patterns. Our results showed in particular a decreasing diversity gradient as distance from the hedge increased and a convergence between predator populations in the orchard and the hedgerow during psylla proliferation. The beneficial arthropod exchanges occurring between the mixed hedgerow and the pear orchard during the pest proliferation period suggested that field border management could be used in an integrated pest management strategy aimed at reducing insecticide use.

Occurrence of Fungal Endophytes in Species of Wild Triticum

Seedborne, nonpathogenic, fungal endophytes are commonly found in symbiotic relationships with many members of the cool‐season grass subfamily Pooideae The beneficial effects on plants possessing fungal endophytes, and the detrimental effects on consumers of fungal endophyte‐infected plants are widely known. The objective of our research was to determine if fungal endophytes exist in indigenous, wild Triticum (wheat) species from Turkey. From the Triticum species collected, we found two different fungal endophytes. Fungi identified morphologically as members of the genus Neotyphodium were found in the diploid Triticum species T. dichasians (Zhuk.) Bowden and T. tripsacoides (Jaub. &amp; Spach) Bowden. The second endophyte, an Acremonium species, was found in T. columnare (Zhuk.) Morris &amp; Sears, T. cylindricum Ces., T. monococcum L., T. neglecta Morris &amp; Sears, T. recta Morris &amp; Sears, T. triunciale (L.) Raspail, T. turgidum L., and T. umbellulatum (Zhuk.) Bowden. No fungal endophytes were found in T. kotschyi (Boiss.) Bowden, T. ovatum (L.) Raspail, T. peregrinum Morris &amp; Sears, T. speltoides (Tausch) Gren. ex Richter, and T. tauschii (Coss.) Schmal., although the number of samples tested was small for some of these species. Both Acremonium endophyte‐infected and Acremonium endophyte‐free plants of T. triunciale were found to occur at different frequencies at four collection sites on the Anatolian Plateau. Through two selfed generations of the plants, it was found that the Neotyphodium endophyte was transmitted to 100% of the progeny of T. dichasians and T. tripsacoides However, the Acremonium endophytes were not transmitted in all plants that originally possessed them. We concluded that fungal endophytes of the genera Neotyphodium and Acremonium inhabit some wild wheat species grown indigenously in Turkey. These endophytes may influence the ecology and distribution of Triticum species, and may also serve as a source of biological control agents of pests or abiotic stress factors in wheat.

Black stem galls on aspen and their relationship to decay by Phellinustremulae

Efficient use of trembling aspen (Populustremuloides Michx.) is often limited by the presence of extensive decay and stain. Aspen trees with black stem galls of unknown cause reportedly have less advanced decay caused by the fungus Phellinustremulae (Bond.) Bond. &amp; Boriss. than do adjacent trees without galls. Nine field sites having large numbers of galled aspen were surveyed for the presence of P. tremulae conks. Logistic regression showed that the odds of a gall tree having at least one conk was 44% of that for trees without galls, and that the occurrence of conks varied among sites and increased with increasing tree diameter. Inclusion of black galls in models used to predict decay might result in greater accuracy on sites where these galls are prevalent. Black galls may also be potential sources of biological control agents against decay-causing organisms in aspen.

THE INSECT FAUNA OF THE WEED PTERIDUM AQUILINUM (L.) KUHN (POLYPODIACEAE) IN PAPUA NEW GUINEA: A POTENTIAL SOURCE OF BIOLOGICAL CONTROL AGENTS.

AbstractIn Papua New Guinea 16 Coleoptera, 1 Diptera, 1 Hemiptera, 5 Lepidoptera and 1 Orthoptera species attacked Pteridium aquilinum; 3 of the Coleoptera and 1 Lepidoptera also attacked other ferns. Papua New Guinea Pteridium contained HCN and phytoecdysones. The potential of the insects as a source of biological control agents is discussed.