Disease protection and growth promotion of potatoes (Solanum tuberosum L.) by Paenibacillus dendritiformis

One of the challenges in developing plant‐beneficial bacterial agents for agricultural application is ensuring that an effective selection and screening procedure is in place. The sporadic success of using bacterial agents in the field is usually due to the inability of added bacteria to compete with the local microorganisms. In the present study, the effectiveness of Paenibacillus dendritiformis, a unique pattern‐forming, Gram‐positive, soil bacterium, to reduce disease indices and increase yield in potato crops was examined. This bacterium was chosen as a potential agent based on genome analysis carried out in previous studies. In vitro laboratory experiments, as well as three greenhouse and one field experiment, were conducted. The results show that, in agreement with the hypothesis, P. dendritiformis significantly reduced the maceration area of tuber slices infected by Pectobacterium carotovorum subsp. carotovorum, significantly reduced disease indices in greenhouse experiments and significantly increased tuber yield of infected plants in the field. This work demonstrates the potential of preliminary screening based on genome analysis to identify effective biocontrol agents.     

Presence–absence sampling for Tetranychus urticae and its predator Neoseiulus californicus (Acari: Tetranychidae; Phytoseiidae) on strawberries

The use of snails as biocontrol agents against other snails and against aquatic weeds is reviewed, evaluating their success and their impacts on non-target organisms. The predatory snail Euglandina rosea (and other species), although widely used against Achatina fulica (the giant African land snail) on Pacific and Indian Ocean islands, has not been shown to control A. fulica but has seriously impacted endemic island species. The facultative predator Rumina decollata , used in California against Helix aspersa (brown garden snail), is widely considered to be environmentally benign. However, evidence of its effectiveness is weak and it will also consume native snails. Ampullariid and thiarid freshwater snails have been used as competitors (and incidental predators) of snail vectors of human schistosomes, the parasites causing schistosomiasis (bilharzia). Successful control has been reported but impacts on native biotas have been essentially ignored. Ampullariids have been used in attempts to control aquatic weeds, sometimes successfully, but again with little consideration of impacts on native biota. Most snails have generalist feeding habits. Thus they are inappropriate biocontrol agents because of their potential nontarget effects. Rarely has adequate pre-release testing of snails been undertaken and post-release monitoring of non-target impacts has always been incidental. The use of non-native snails for biocontrol purposes is poorly regulated; many introductions are unofficial and sometimes illegal. Use of snails as biocontrol agents, if implemented, must be based on adequate pre-release testing, post-release monitoring and genuine concern for preservation of native biodiversity.     

Performance of three endophytic actinomycetes in relation to plant growth promotion and biological control of <Emphasis Type="Italic">Pythium aphanidermatum</Emphasis>, a pathogen of cucumber under commercial field production conditions in the United Arab Emirates

In the current study, the performance of three endophytic actinomycetes identified as Actinoplanes campanulatus, Micromonospora chalcea and Streptomyces spiralis previously shown to reduce seedling damping-off, and root and crown rots of mature cucumber (Cucumis sativus) caused by Pythium aphanidermatum in pots under greenhouse conditions were further evaluated to determine their potential as biological control agents and as plant growth promoters in the field under the conditions of commercial production of cucumbers in the United Arab Emirates (UAE). When applied individually or in combination to cucumber seedlings, the three isolates significantly promoted plant growth and yield and reduced seedling damping-off and root and crown rots of mature cucumber plants. Individually the performance level of S. spiralis was relatively the best followed by A. campanulatus and then by M. chalcea. The three isolates (which were not inhibitory to each other) performed better, both as biological control agents as well as plant growth promoters, when applied together than when they were inoculated individually. The ability of these three isolates to colonize the internal tissues of roots, stems and leaves under field conditions, and to persist up to 8 weeks after seedling inoculation, showed that they can easily adapt to an endophytic habit systemically within healthy cucumber plants. As the three endophytic actinomycete isolates also colonized the rhizosphere and showed outstanding rhizosphere competency it is clear that they are facultative and not obligate endophytes. The success with the three inoculants indicated that they could well be used in place of the fungicide metalaxyl which is currently recommended for the management of Pythium diseases in the UAE. This is the first successful field use of endophytic actinomycetes as promising plant growth promoters and biological control agents against Pythium diseases of cucumber.     

Photostabilization of biocontrol agents by berberine

We studied the photostabilizing effect of the isoquinoline alkaloid berberine on the following three model photounstable biocontrol agents: the bacterium Bacillus thuringiensis ( Bt ), the baculovirus Spodoptera littoralis nucleopolyhedrosis virus ( SlNPV ), and the entomopathogenic fungus Beauveria bassiana . The photoprotection provided by berberine was evaluated following various periods of simulated sunlight-UV irradiation. Insecticidal activity of Bt and SlNPV , as well as the rate of B. bassiana spore germination served as parameters for the photostabilizing effects. Only a berberine- Bt complex is effective, as practically no photostabilization was evident by just mixing the two components. The UV-sensitive SlNPV and B. bassiana spores were considerably photostabilzed by berberine. The role of the cationic nature of the berberine molecule and the importance of its absorbance spectrum in photostabilization of biocontrol agents are discussed.     

Host range comparison of the causal agents of pepper yellow vein and lettuce big vein

A number of solanaceous and composite plant species were tested as hosts for the causal agents of pepper yellow vein (PYVA) and lettuce big vein (LBVA), transmitted by a pepper and a lettuce isolate ofOlpidium brassicae, respectively. The agents had the following artificial hosts in common:Lycopersicon esculentum, Solanum melongena, Physalis floridana, Nicandra physaloides, Lactuca sativa, Sonchus oleraceus andL. virosa. Capsicum annuum, S. villosum, S. nigrum, Crepis vesicaria andSenecio vulgaris were infected by PYVA, but not by LBVA.Cichorium endivia andTaraxacum officinalis were not infected by any of the two agents.N. physaloides, although not colonized by the pepper isolate ofOlpidium, still became infected by PYVA.     

Work of the EPPO/IOBC Panel on biological control agents

EPPO started work on biological control agents (BCAs) in 1996, and the joint EPPO/IOBC Panel was established in 1997. The history of the Panel is provided and EPPO Standards developed by the Panel are described. These Standards are: PM 6/1 ‘First import of exotic biological control agents for research under contained conditions’, PM 6/2 ‘Import and release of non‐indigenous biological control agents’ and PM 6/3 ‘List of biological control agents widely used in the EPPO region’. The last of these has been annually updated as a ‘Positive List’ of BCAs for which EPPO recommends its member countries to use a simplified procedure for import and releases. EPPO activities in biological control have been focused on the safety aspects of the introduction of invertebrate BCAs. However, the scope of EPPO's work in this area is now under review, and a number of issues are being considered by the Working Party on Phytosanitary Regulations. These include the remit of the Panel and Standards in relation to micro‐organisms, the evaluation of potential environmental benefits as well as potential risks from releases and the potential for use of BCAs against regulated pests and those recommended for regulation.     

Prospects for the use of biological control agents against Anoplophora in Europe

This review summarises the literature on the biological control of Anoplophora spp. (Coleoptera: Cerambycidae) and discusses its potential for use in Europe. Entomopathogenic fungi: Beauveria brongniartii Petch (Hypocreales: Cordycipitaceae) has already been developed into a commercial product in Japan, and fungal infection results in high mortality rates. Parasitic nematodes: Steinernema feltiae Filipjev (Rhabditida: Steinernematidae) and Steinernema carpocapsae Weiser have potential for use as biopesticides as an alternative to chemical treatments. Parasitoids: a parasitoid of Anoplophora chinensis Forster, Aprostocetus anoplophorae Delvare (Hymenoptera: Eulophidae), was discovered in Italy in 2002 and has been shown to be capable of parasitising up to 72% of A. chinensis eggs; some native European parasitoid species (e.g. Spathius erythrocephalus) also have potential to be used as biological control agents. Predators: two woodpecker (Piciformis: Picidae) species that are native to Europe, Dendrocopos major Beicki and Picus canus Gmelin, have been shown to be effective at controlling Anoplophora glabripennis Motschulsky in Chinese forests. The removal and destruction of infested and potentially infested trees is the main eradication strategy for Anoplophora spp. in Europe, but biological control agents could be used in the future to complement other management strategies, especially in locations where eradication is no longer possible. © 2014 Crown copyright. Pest Management Science © 2014 Society of Chemical Industry     

Thermal behaviour and biological activity of pyrethroids in smoke-generating formulations

Smoke-generating insecticide formulations are nowadays very important for the control of Chagas' disease vectors. In this work, the thermal decomposition of different pyrethroid insecticides in smoke-generating formulations has been studied. Their recovery from the smoke has been determined, and the effect on this of the addition of foaming agents such as cyanoguanidine (CNG) or azodicarbonamide (ADC), or antioxidant agents such as butylated hydroxytoluene (BHT) or butylated hydroxyanisole (BHA) has been assessed. In each case the best smoke-generating formulation was established. Calorimetric studies were done to justify the behaviour of the smoke-generating mixtures. The isomerization process for different pyrethroids was also studied, to establish the influence of the foaming agents in inhibiting isomerization to less active pyrethroids. Smoke-generating mixtures containing β-cypermethrin and cis-permethrin as insecticides and CNG or ADC as foaming agents were evaluated for their insecticidal activity against nymphs I of Triatoma infestans, vector of Chagas' disease. The best effect was found with β-cypermethrin formulated with ADC, with LT₅₀ values lower than 5 min. © 1999 Society of Chemical Industry     

Brachypodium distachyon exhibits compatible interactions with Oculimacula spp. and Ramularia collo‐cygni,providing the first pathosystem model to study eyespot and ramularia leaf spot diseases

Brachypodium distachyon (Bd) has established itself as an essential tool for comparative genomic studies in cereals and increasing attention is being paid to its potential as a model pathosystem. Eyespot and ramularia leaf spot (RLS) are important diseases of wheat, barley and other small‐grain cereals for which very little is known about the mechanisms of host resistance despite urgent requirements for plant breeders to develop resistant varieties. This work aimed to test the compatibility of interaction of two Bd accessions with the cereal pathogens Oculimacula spp. and Ramularia collo‐cygni, the causal agents of eyespot and RLS diseases, respectively. Results showed that both Bd accessions developed symptoms similar to those on the natural host for all pathogen species tested. Microscopy images demonstrated that R. collo‐cygni produced secondary conidia and both Oculimacula spp. formed characteristic infection structures on successive tissue layers. Visual disease assessment revealed that quantitative differences in disease severity exist between the two Bd accessions. The results presented here provide the first evidence that Bd is compatible with the main causal agents of eyespot and RLS diseases, and suggest that future functional genetic studies can be undertaken to investigate the mechanisms of eyespot and RLS disease resistance using Bd.     

Use of fungal antagonists for biocontrol of damping-off and sclerotinia diseases

Two mycoparasites, Pythium oligandrum and Coniothyrium minitans, have been tested for their ability to act as disease biocontrol agents. P. oligandrum oospores, grown in a cane molasses liquid medium and coated onto cress and sugar-beet seeds using commercial thin-film or pelleting techniques, gave significant control of damping-off in cress and sugar-beet caused by Pythium ultimum and Aphanomyces cochlioides respectively, in glasshouse pot trials. In some cases, the control was equivalent to fungicide drenches or standard fungicide seed treatments, but little control was achieved with any treatment when the pathogen inoculum potential in the soil was high. Pre-planting application of a solid substrate preparation of C. minitans gave reproducible control of sclerotinia disease in the glasshouse. The degree of control was equivalent to that achieved with regular foliar sprays of vinclozolin, when there was less than 40% disease in the control plots naturally infested with Sclerotinia sclerotiorum. At higher disease levels biocontrol was lost. Nevertheless, C. minitans survived in the soil for over one year and continued to degrade sclerotia and reduce apothecial production. The commercial potential of these biocontrol agents is discussed.     

Honeybees can spread Colletotrichum acutatum and C. gloeosporioides among citrus plants

Postbloom fruit drop (PFD) is an important citrus disease that causes up to 100% yield losses during years in which conditions are favourable for the occurrence of epidemics. The conidia of Colletotrichum acutatum and C. gloeosporioides, causal agents of PFD, are predominantly dispersed by rain splash. At the beginning of epidemics, the distribution of diseased plants is random and the disease progress rate is very high, which is unusual for pathogens spread by rain splash. As the pathogen produces abundant conidia on diseased petals, pollinating insects may contribute to disease dispersal. This study investigated honeybees (Apis mellifera) as dispersal agents of C. acutatum and C. gloeosporioides among citrus plants. Two experiments were carried out in a screenhouse in which citrus plants were protected (or not) in insect‐proof cages. The source of inoculum was placed on one side of the screenhouse, and a honeybee hive was placed on the opposite side. All uncaged plants showed symptoms of the disease, and none of the caged plants exhibited PFD symptoms. The monomolecular model showed a good fit to disease progress in both experiments. Conidium‐like structures of Colletotrichum spp. were identified attached to the bodies of the honeybees by scanning electron microscopy. These results have revealed that honeybees disperse Colletotrichum among citrus plants.     

Combined application of chitinolytic bacterium Paenibacillus sp. D1 with low doses of chemical pesticides for better control of Helicoverpa armigera

Helicoverpa armigera is a serious pest of Cajanus cajan in many parts of world. Rapid development of resistance against number of insecticides and cry toxin-based biocontrol agents has led to search for biocontrol agents with alternative mode of action. The ability of chitinolytic bacteria to degrade vital chitinous structure in insects suggests their potential in insect control. The present investigation was carried out to study insect control potential of a high chitinase producing bacterium, Paenibacillus sp. D1. Biocontrol studies with Helicoverpa larvae showed Paenibacillus sp. D1 and its chitinase to be potent antifeedant that reduced the feeding rate and body weight of the larvae. The decreased body weight was attributed to hydrolysis of the chitinous structures of the larvae. This was evident from decrease in the total chitin content and increased mortality of the larvae fed on the leaves treated with Paenibacillus sp. D1 and chitinase as compared to untreated controls. A combined dose of Paenibacillus sp. D1 or its chitinase with an organophosphate insecticide, acephate, was found to be more lethal than their individual treatments suggesting integrated insect control potential of the bacterium.     

Insect Enemies of Aquatic Weeds

Abstract

The Agricultural Research Service of the USDA has been actively engaged in research on the biological control of aquatic weeds since 1959. Research emphasis until 1967 was on alligatorweed, Alternanthera philoxeroides (Mart.) Griseb. As a result of this research, three species of insects from Argentina were released in the southeastern United States. Alligatorweed control with these natural enemies has been variable; but indications are that control will be substantial over most of the range of the weed.

One species of weevil, Neochetina eichhorniae Warner, has been released against water hyacinth, Eichhornia crassipes (Mart.) Solms, in the USA as a result of research in Argentina. A second closely related species, N. bruchi Hustache, is presently undergoing final clearance procedures. Several other arthropods are being studied in Argentina as possible biological control agents of water hyacinth.

A USA sponsored programme in Yugoslavia under the direction of Dr M Leki? resulted in the discovery of two insect species that show potential as control agents for eurasian watermilfoil, Myriophyllum spicatum L. Further testing for host specificity of these insects will be carried out in the USA in quarantine in Florida.

A USA sponsored Pakistan programme under Dr M. A. Ghani is investigating insects and other phytophagous organisms attacking Hydrilla verticillata Royle. The results are encouraging. PANS 20: 444–450, 1974.     

Potential biological control of clubroot on canola and crucifer vegetable crops

Clubroot caused by Plasmodiophora brassicae is an emerging threat to canola (Brassica napus) production in western Canada, and a serious disease on crucifer vegetable crops in eastern Canada. In this study, seven biological control agents and two fungicides were evaluated as soil drenches or seed treatments for control of clubroot. Under growth cabinet conditions, a soil‐drench application of formulated biocontrol agents Bacillus subtilis and Gliocladium catenulatum reduced clubroot severity by more than 80% relative to pathogen‐inoculated controls on a highly susceptible canola cultivar. This efficacy was similar to that of the fungicides fluazinam and cyazofamid. Under high disease pressure in greenhouse conditions, the biocontrol agents were less effective than the fungicides. Additionally, all of the treatments delivered as a seed coating were less effective than the soil drench. In field trials conducted in 2009, different treatments consisting of a commercial formulation of B. subtilis, G. catenulatum, fluazinam or cyazofamid were applied as an in‐furrow drench at 500 L ha^?1 water volume to one susceptible and one resistant cultivar at two sites seeded to canola in Alberta and one site of Chinese cabbage in Ontario. There was no substantial impact on the susceptible canola cultivar, but all of the treatments reduced clubroot on the susceptible cultivar of Chinese cabbage, lowering disease severity by 54–84%. There was a period of 4 weeks without rain after the canola was seeded, which likely contributed to the low treatment efficacy on canola. Under growth cabinet conditions, fluazinam and B. subtilis products became substantially less effective after 2 weeks in a dry soil, but cyazofamid retained its efficacy for at least 4 weeks.     

国内外杀虫绿僵菌制剂的登记现状与剂型技术进展

生物农药在植物保护工作中日益受到重视。绿僵菌是重要的昆虫病原真菌,作为真菌杀虫剂已被成功应用于蝗虫、金龟子、象甲等多种害虫的田间防治。近40年来,已有83个绿僵菌产品在13个国家或地区获得注册,制剂研究与加工技术方面取得了新进展,可湿性粉剂、悬浮剂等传统剂型质量得到改善,超低容量剂、浸渍剂等新剂型可适应特殊应用环境,产品的防治对象涵盖范围更广。本文就国内外绿僵菌产品注册登记情况、制剂类型特性及制剂技术的载体、助剂和加工过程等主要因素进行综述,以期为我国真菌生物农药的科研、应用及产业发展提供基础依据。     

Susceptibility of larvae and adults of Monochamus galloprovincialis to entomopathogenic fungi under controlled conditions

Six entomopathogenic fungal isolates were tested under controlled conditions, as biological control agents against Monochamus galloprovincialis (Coleoptera: Cerambycidae) (Olivier), the vector of the pine wood nematode Bursaphelenchus xylophilus (Nematoda: Parasitaphelenchidae) (Steiner and Buhrer). The fungi Beauveria bassiana (Bals.-Criv.) Vuill, Metarhizium anisopliae (Metchnikoff) Sorokin, Metarhizium sp. and Fusarium sp. were tested against larvae and adults of the insect, by comparing two exposure techniques: continuous contact and spraying. Regarding the larvae, only Fusarium sp. and Metarhizium sp. killed more than 40% of the individuals, while B. bassiana and M. anisopliae were found to kill 50% of the adults (LT₅₀) within five days. Exposure to B. bassiana reduced adult longevity by 19 days, when compared to untreated beetles, and had a direct efficacy of 46%. Continuous contact with the fungi proved to be more effective than spraying. A larval disinfection protocol was developed to eliminate other fungal isolates from the wood-collected tested individuals. The implications of the results and possible applications of selected strains as bio-control agents against M. galloprovincialis are discussed.     

Western flower thrips (Frankliniella occidentalis)—occurrence and possibilities for its control in Hungary1

Frankliniella occidentalis was first recorded in Hungary in 1989. The pest has endangered the mass-rearing and distribution of the biological control agents Encarsia formosa and Phytoseiulus persimilis being conducted at the Hódmezövásárhely Institute. Different insecticide active ingredients were studied for elimination of the pest from experimental glasshouses and new methods for monitoring populations of the new thrips. The fungus Verticillium lecanii has been tested as an indirect control agent.     

Virulence of Verticillium lecanii (Z.) against cereal aphids; does timing of infection affect the performance of parasitoids and predators?

BACKGROUND: Entomopathogenic fungi such as Verticillium lecanii (Z.) (Mycotal^®) are used for pest control as an alternative to chemical control. In this study, the effect of V. lecanii on cereal aphids is assessed. In addition, an investigation is carried out to determine whether the use of V. lecanii affects the performance of two natural enemies of aphids, the predator Harmonia axyridis (P.) and the parasitoid Aphidius colemani (V.), in no‐choice experiments under laboratory conditions. RESULTS: The number of Rhopalosiphum padi (L.) and Sitobion avenae (F.) killed was increased by increasing the concentration of V. lecanii. The timing of application of fungus to aphids affected the efficacy of other biocontrol agents, a parasitoid and a predator. Parasitation by A. colemani (V.) in both cereal aphids (S. avenae and R. padi) was not affected by V. lecanii when aphids were first treated with V. lecanii and then exposed to A. colemani. The emergence of adults from parasitised mummies was, however, lower in infected aphids than in uninfected aphids when the aphids were first exposed to the parasitoids and then treated with fungus. The female sex ratio in the emerging adults was lower in V. lecanii‐treated aphids in both species. When aphids were first treated with V. lecanii, 72 h before predation, fewer aphids of both species were consumed by H. axyridis (P.). CONCLUSION: Use of entomopathogenic fungus as a biological control agent could be a complementary strategy in an integrated pest management programme against cereal aphids, but it can reduce the efficiency of other biocontrol agents (parasitoids and predators) when applied simultaneously. © 2012 Society of Chemical Industry     

Assessment of three killing agents’ impact on the capturing of Coleoptera species infesting stored wheat

The introduction of three killing agents (propylene glycol, DDVP and water) inside perforated probe traps was evaluated for their efficiency in trapping Coieoptera adults infesting stored cereals. The experiment was carried out in nine steel bins containing wheat, located in Central Greece, in August 1997. For the most of the 26 beetle species found, no significant differences were observed among treatments. ForSitophilus spp.,Typhaea stercorea, Aloasverns advena, Oryzae-philus surinamensis, Latheticus oryzae, Palorns ratzeburgii, P. subdepressus, andTenebroides mauritanicus, significantly less adults were found in the control traps (with no killing agent). Significant differences among three killing agents were observed only forT. stercorea andT. mauritanicus. Given that the traps supplied with killing agents were found to contain adults even in locations where control traps did not, is concluded that the addition of killing agents has increased the detection sensitivity of traps.