Evaluation of nine strains ofBacillus thuringiensis Berliner against the giant looper,Boarmia (Ascotis) selenaria Schiffermüller (Lepidoptera,Geometridae)

Nine isolates ofBacillus thuringiensis Berliner belonging to var.kenyae, var.aizawai and var.entomocidus, were bioassayed against 1st instar larvae ofBoarmia (Ascotis) selenaria Schiffermüller and compared withB. thuringiensis var.kurstaki, HD-1-S-1980. None were found to have a higher potency than HD-1-S-1980, which is used for commercial control of young larvae of this pest in avocado plantations in Israel.     

Vorläufige Untersuchungen über die Virulenz von 13 Bazillus-Präparaten gegenüber 3 Ägyptischen Noctuiden

Zusammenfassung Die Virulenz von 13 Bacilluspr?paraten (2 Handelspr?parate vonBacillus thuringiensis var,thuringiensis Berliner und 11 Laboratoriums-Pr?parate von verschiedenen Arten und Variet?ten) gegen 3 ?gyptische Noctuiden (Agrotis ypsilon Rott.,Laphygma exigua Hbn. undProdenia litura Fab.) wurden untersucht. 50 Raupen von jeder Art (6–7 Tage alt) wurden für jede Behandlung und die Kontrolle verwendet (einen Tag auf behandeltes Laub vonTrifolium alexandrinum gesetzt). Die Resultate ergaben, da?Laphygma in 9 F?llen sehr empfindlich ist, wobei sich ein deutlicher Unterschied zu den beiden anderen Arten ergab. In 7 dieser F?lle folgte aufLaphygma Prodenia und in 2 F?lleAgrotis. Besonders wirksame Pr?parate waren: Biospor 2802 gegenLaphygma, Bacillus thuringiensis var.thuringiensis 2172 gegenProdenia undB. entomocidus var.subtoxicus 1179 gegenAgiotis. In den meisten F?llen wurde kein direkter Zusammenhang zwischen Virulenz und Zahl der lebenden Sporen gefunden.

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Summary The virulence of 13 Bacillus preparations (2 commercial formulations ofBacillus thuringiensis var.thuringiensis Berliner and 11 laboratory preparations of different varieties and species) on 3 Egyptian noctuids (Agrotis ypsilon Rott.,Laphygma exigua Hbn. andProdenia litura Fab.) was tested. Fifty larvae of each species (6–7 days-old) were used for each treatment and for the control (one day voluntary ingestion on foliage ofTrifolium alexandrinum). Results revealed thatLaphygma is most susceptible in 9 cases with marked difference between it and both other species. In 7 of these casesLaphygma was followed byProdenia and in 2 cases byAgrotis. Most virulent preparations were: Biospore 2802 againstLaphygma, Bacillus thuringiensis var.thuringiensis 2172 againstProdenia andB. entomocidus var.subtoxicus 1179 againstAgrotis. In most cases no direct relationship was observed between virulence and number of viable spores in dose.

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Die Autoren sind zu Dank verpflichtet Herrn Dr. A. Burgerjon, Station des Recherches de Lutte Biologique (La Miniere), Herrn Dr. G. Benz ETH-Entomological Institute (Zürich), Herrn J. Wolf, Department of Agriculture (Leeds) und der N. R. R. L. (Illinois) für die Beschaffung der Bakterien-Pr?parate, die in vorliegender Arbeit verwendet wurden.     

Über kombinierte Wirkungen eines Juvenoids (Altosid) und eines Bacillus-thuringiensis-Präparats (Bactimos) auf Larven der Stechmücken Culex pipiens molestus Forsk. und Theobaldia longiareolata Macq. (Dipt., Culicidae)

Exposing second and fourth instar larvae ofCulex pipiens molestus for 24 h to Altosid increased their tolerance to Bactimos. The interaction was apparent in fourth instar larvae treatment especially at the higher concentrations. Exposure bactimos to Altosid for 72 hours decreased its efficacy against the fourth instar larvae ofCulex pipiens molestus. The LT₅₀ values were significantly lower in larvae treated with Bactimos only than that treated with Altosid and Bactimos. Altosid briquets increased significantly the tolerance ofTheobaldia longiareolata larvae toBacillus thuringiensis var.israelensis at all concentrations tested. Generally, pretreatment mosquito larvae with Altosid followed by Bactimos, increased the tolerance of larvae to the bacterium, this may be due to the toxic effect of Altosid on the bacterium or to the changes in the physiological status of the treated larvae to tolerate the effect of bacterium. On the light of these studies, Altosid exhibited detrimental effect on the efficacy ofB. thuringiensis var.israelensis againstC. pipiens molestus andT. longiareolata larvae. Therefore, interactions between Altosid and Bactimos could not fit the integrated control of mosquitoes.     

Bekämpfung von Insekten im Pflanzenschutz mitBacillus thuringiensis-Präparaten und deren Einfluß auf die Umwelt. 2. Mitteilung

During the application ofBacillus thuringiensis for control of pest insects in forestry and agriculture not only wood or target crops are treated with viable spores, but also the air and soil will be contaminated. The fate of these spores is especially relevant with regard to residues and protection of drinking water supply. Concerning the ecology ofB. thuringiensis experimental results are discussed in connection with informations on the natural level of bacterial contaminations of plants, air, soil and water. On this base, however, no arguments could be obtained concerning a risk assessment on human health or environmental pollution in connection with application of commercial preparations ofB. thuringiensis at recommended doses, even not in water catchment areas.     

Über die Wirkung vonBacillus thuringiensis var.thuringiensis-Exotoxin auf Wachsmotten-Raupen (Galleria mellonella)

Zusammenfassung Es werden die kürzlich (1966) vonVaková publizierten Befunde bestätigt und ergänzt, wonach Exotoxin vonBacillus thuringiensis var.thuringiensis aufGalleria mellonella-Raupen nach peroraler Applikation wirksam ist. Die Tatsache, daß andere Autoren bisher mit ihren Exotoxin-Präparaten keine Wirksamkeit gegenüber diesem Wirt erzielen konnten, kann verschiedene Ursachen haben. Die bisher vorliegenden Versuchsergebnisse bringen allerdings auch weiterhin noch keinen Entscheid in der Frage, obB. thuringiensis var.thuringiensis qualitativ verschiedene Exotoxine zu produzieren vermag oder nicht.

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Summary Laboratory trials withGallelia mellonella have shown that the caterpillars are susceptible to peroral application of the exotoxin ofBacillus thuringiensis var.thuringiensis. These results confirm and complete findings ofVaková (1966) which were obtained with another application technique. The fact that other authors could not find any reaction ofG. mellonella. larvae against exotoxin may be based on several reasons: The results presented here cannót decide whetherB. thuringiensis var.thuringiensis is able to produce qualitatively different exotoxines or not. Such a decision can only be made by an adequate comparison of different exotoxin-preparations on the same test-insects.

     

Application of some bacterial varieties ofBacillus thuringiensis and its bioproduct Delfin onSynanthedon myopaeformis Borkh. (Lep. Aegeriidae) in apple orchards

Field experiments were conducted using the biological agentBacillus thuringiensis to control the clearwing moth,Synanthedon myopaeformis (Lep. Aegeriidae) in apple orchards at Alexandria governorate during 1995, 1996 and 1997. Three bacterial varieties ofB. thuringiensis showed significant influence on the reduction of borer infestation. Four applications with the sporic concentration 12×10⁷ spores/ml of each ofB. th. var.kurstaki, B. th. var.alesti andB. th. var.thuringiensis induced 82.5, 51.1 and 42.1% reduction of infestation, respectively. Methods of application showed highly significant effect on infestation level. Sparying after scraping was the best method (80.0%, reduction) followed by painting after scraping (71.5%, reduction) then spraying alone (59.7%, reduction) or painting alone (43.0%, reduction). A control programme was carried out using three applications of the biomaterial, Delfin at the rate of 200 g/100 I.w. during mid-March, early June and mid-August resulted in 88.5–91.4% reduction of infestation.     

Activity ofBacillus thuringiensis isolates on the corn borers,chilo agamemnon Bles. (Crambidae) andOstrinia nubilalis Hbn. (pyraustidae)

The potential activity of different varieties ofBacillus thuringiensis was evaluated against the second instar larvae of the two lepidopterous corn borersChilo agamemnon andOstrinia nubilalis. Data on the LC₅₀, slopes, 95% confidence limits and potencies of the tested varieties were determined. WithO. nubilalis, Dipel 2X (Bacillus thuringiensis. var.kurstaki HD-1) was the most potent and the LC₅₀ was 2.68 μg/g diet. The LC₅₀ for other varieties ranged between 3.12 and 31.95 μg/g. In the case ofC. agamemnon, the lowest LC₅₀ was also determined with Dipel 2X being 3.68 μg/g diet; this ranged between 6.2–15.11 μg/g for other tested varieties.     

Pilot-Versuch zur Bekämpfung von Stechmückenlarven im Freiland mit einem UV-behandelten Präparat von Bacillus thuringiensis var. israelensis

Preparations derived from sporulated cultures ofBacillus thuringiensis var.israelensis were used in a small field trial for control of mosquito larvae (Aedes cantans, Aedes rusticus, Culiseta morsitans). In the test two liquid formulations (suspension) were compared: (1) a native preparation containing living spores and toxic crystals, and (2) a preparation in which the spores have been inactivated to a high degree (99.99%) by ultraviolet rays. The efficacy of both preparations against mosquito larvae showed no difference: doses of 10⁴ to 10⁵ spore equvalents/ml, induced 100% mortality of the target insects. But no harmful effect on non-target organisms (especially water arthropods with exception of Chironomidae larvae) could be observed. To minimize the contamination of surface water with living spores, the use of UV-inactivated preparations ofB. t. var.israelensis is indicated for mosquito control.     

Evaluation of Bacillus thuringiensis Berliner as an alternative control of small hive beetles, Aethina tumida Murray (Coleoptera: Nitidulidae)

Small hive beetles, Aethina tumida Murray, are parasites and scavengers of honeybee colonies, Apis mellifera L., and have become an invasive species that can cause considerable damage in its new distribution areas. An effective subspecies of Bacillus thuringiensis Berliner (=Bt) would provide an alternative to chemical control of this pest. Therefore, we tested three different Bt strains [B. thuringiensis, var. aizawai (B401^®), B. thuringiensis var. kurstaki (Novodor^®) and B. thuringiensis var. San Diego tenebrionis (Jackpot^®)] and Perizin^® (3.2% coumaphos), each applied on combs with a pollen diet fed to pairs of adult beetles. This evaluates the products for the suppression of successful small hive beetle reproduction. While none of the tested Bt strains showed a significant effect on the number of produced wandering larvae, we could confirm the efficacy of coumaphos for the control of small hive beetles. We further show that it is also efficient when applied with a lower concentration as a liquid on the combs. We suggest the continued search for efficient Bt strains naturally infesting small hive beetles in its endemic and new ranges, which may become a part of the integrated management of this pest.     

Neue Ergebnisse überBacillus thuringiensis var.tenebrionis unter besonderer Berücksichtigung seiner Wirkung auf den Kartoffelkäfer (Leptinotarsa decemlineata)

Especially younger larval stages (L₁...L₃) ofLeptinotarsa decemlineata are sensitive toB. thuringiensis var.tenebrionis (strain BI 256-82). The ingestion of parasporal crystals and spores by larvae caused feeding stop, gut paralysis, and final mortality by septicemia. Adults exposed to contaminated leaves stopped both feeding and egg-laying. The specific action on the gut epithelium is related to the crystal toxin. A non-specific effect caused by -exotoxin could be excluded as, contrary toB. t. var.thuringiensis, ourB. t. var.tenebrionis-strain does not produce this toxin. In contrast toB. t. var.tenebrionis, other strains of the same serotype (H 8a, 8b) belonging toB. t. var.morrisoni, as well as other strains ofB. t. (e. g. HD-1 of var.kurstaki) showed no activity againstL. decemlineata. — In field trials it was demonstrated that a dosage of 5×10¹⁴ spore equivalents per hectar is sufficent for an effective control of the Colorado beetle withB. t. var.tenebrionis. No side-effects on entomophageous insects, such asCoccinella septempunctata andChrysopa carnea, were noted.

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Neue Ergebnisse überBacillus thuringiensis var.tenebrionis unter besonderer Berücksichtigung seiner Wirkung auf den Kartoffelkäfer (Leptinotarsa decemlineata)

Zusammenfassung Besonders jüngere Larvenstadien (L₁...L₃) vonLeptinotarsa decemlineata reagieren empfindlich aufB. thuringiensis var.tenebrionis (Stamm BI 256-82). Die Applikation von parasporalen Kristallen und Sporen verursacht zunächst Fraßstop und Darmparalyse sowie schließlich den Tod der Larven durch Septikämie. Käfer stellen auf behandeltem Kartoffellaub Fraß und Eiablage ein. Die spezifische Wirkung auf das Darmepithel wird dem Kristalltoxin zugeschrieben. Eine unspezifsiche Wirkung durch -Exotoxin konnte ausgeschlossen werden: Unser Stamm vonB.t. var.tenebrionis produziert im Gegensatz zuB. t. var.thuringiensis kein derartiges Toxin. Im Gegensatz zuB. t. var.tenebrionis zeigten andere Stämme des gleichen Serotyps (H 8a, 8b), dieB. t. var.morrisoni angehören, ebenso wie andereB. t.-Stämme (z. B. HD-1 der var.kurstaki) gegenüberL. decemlineata keinerlei Wirksamkeit. — Feldversuche ergaben, daß eine Dosis von 5×10¹⁴ Sporenäquivalenten pro Hektar für eine wirksame Bekämpfung des Kartoffelkäfers mitB. t. var.tenebrionis ausreicht. Dabei wurden Entomophagen, wie z. B.Coccinella septempunctata undChrysopa carnea, nicht beeinträchtigt.

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Mit 5 Abbildungen

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Vortrag gehalten auf dem XVII. Internationalen Entomologenkongreß, 20.–26. August 1984 in Hamburg (Titel: A new isolate ofBacillus thuringiensis effective against Coleoptera).     

Über die molluscizide Wirkung vonBacillus thuringiensis-Präparaten zur biologischen Bekämpfung vonBiomphalaria alexandrina-Schnecken,den Zwischenwirten des Bilharziose-SaugwurmsSchistosoma mansoni in Saudi Arabia

The comparative molluscicidal activity of different preparations ofBacillus thuringiensis as Thuricide, SAN 401, SAN 402 and SAN 415, onB. alexandrina snails was studied. The results showed that different preparations ofBac. thuring. have a remarkable molluscicidal activity onB. alexandrina snails. However, the obtained results proved thatBac. thuring. with its preparation SAN 415 was the most effective in killing the snails comparing with the other preparations at the same experimental condition. Prolonged exposure ofB. alexandrina to subletal concentration (250 ppm) of SAN 415 delayed its ovipositary activity. Increasing the dose to 500 ppm resulted in a complete loss of egg production. Comparatively exposure of snail groups to the same doses of Thuricide, SAN 401 and SAN 402 resulted only in decreasing its egg laying capacity. These results proved the high potentially effectiveness ofBac. thuring. in its preparation SAN 415 as a biological control agent forB. alexandrina snails. The wayes by which this biological agent acts on the reproductive system of the snails were discussed.     

Studies on biological control of Pigeonpea Pod Borers in India

Results of two field experiments, one on SA 1 pigeonpea in rainfed and the other on Co.5 pigeonpea in irrigated conditions revealed thatBacillus thuringiensis var.kurstaki (B.t.k.) (Delfin), its combinations with nuclear polyhedrosis virus ofHeliothis armigera andChrysoperla carnea were as effective as endosulfan in reducing the pod borers,Heliothis armigera andExelastis atomosa. However,B.t.k. 1.25 kg+endosulfan 175 g/ha orB.t.k. 2.5 kg+HaNPV, 250 LE/ha gave better control of damage to flowers and pods thanB.t.k. applied alone on SA 1 pigeonpea. The yield differences between these treatments were not significant. A combination of HaNPV 250 LE/ha+endosulfan 175 g/ha was superior toB.t.k. Similar trend was seen on Co.5 pigeonpea. Release ofC. carnea second instar larvae 1 lakh/ha was not effective in increasing the yield of pigeonpea.     

Effect of larval selection with two bioinsecticides on susceptibility levels and reproductive capacity ofAedes aegypti (L.)

Two bacterial insecticides,Bacillus thuringiensis H-14 andB. sphaericus 1593 were evaluated for larvicidal potency against mosquito larvae ofAedes aegypti. LC₅₀ values showed thatB.thuringiensis H-14 (4×10⁵ spores/ml) had a higher pathogenicity against fourth larval instars ofA. aegypti thanB. sphaericus (3.1×10⁶ spores/ml) by about 7.75 times. Larval selection with LC₉₀ of both pathogens for 8 successive generations caused a decrease in the susceptibility levels of selected strains ofA. aegypti as compared with the original strain. Moreover, the results indicated that the effect of larval selection with the above bioinsecticides led to an obvious reduction in the egg production and hatchability of eggs produced by mosquito adults that developed from surviving larvae.     

Unterschiedliche Wirkungen vonBacillus thuringiensis (B.) aufOrgyia antiqua (L.) in Abhängigkeit von der Frapflanze

Summary Effects of foodplants on the toxicity ofBacillus thuringiensis againstOrgyia antiqua.The effects ofB. thuringiensis onO. antiqua in dependence of various foodplants were investigated. The food showed a great effect on the virulence ofB. thuringiensis. The results are summarized in a table.

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Herrn. Prof. Dipl.-Ing. Dr. ERWIN SCHIMITSCHEK zum 75. Geburtstag.     

Factors affecting efficacy ofBacillus thuringiensis H-14 against mosquito larvae with special reference to the joint action of the pathogen with three chemical insecticides

In laboratory trials with the pathogenBacillus thuringiensis H-14 (B. t. H-14) against culicine larvae ofCulex pipiens L. andAedes aegypti (L.), the following factors significantly influenced larvicidal activity: larval instars, mosquito species, exposure time and temperature. Variation in water pH, however, did not significantly affected efficacy. Different levels of potentiation and additive effects were also obtained when the bacterial agentB. t. H-14 applied jointly with the chemical insecticides malathion, dursban and fenvalerate against mosquito larvae.     

Effect of the nematodeHeterorhabditis bacteriophora and the bacteriumBacillus thuringiensis as integrated biocontrol agents of the black cutworm

The entomopathogenic nematodeHeterorhabditis bacteriophora Pionar (HP 88) and the bacteriumBacillus thuringiensis Berliner var.kurstaki were tested in the laboratory against the black cutworm, a widely distributed polyphagous insect pest of vegetables and field crops. The experiment was conducted under 15.7 °C (14 to 19 °C) to simulate the average winter temperature in Egypt. The two biocontrol agents influencedAgrotis ipsilon differently whereH. bacteriophora had a more promising control levels than that ofB. thuringiensis. Generally, nematode concentration of ca 500 infective juveniles/insect vial was highly effective (100% mortality) within nine days post nematode infection. The highest concentration of the bacteriumB. thuringiensis var.kurstaki (2,000 Intern. Units/mg) gave significant larval control after 12 days of bacterial infection. Combined effect of both the nematodes and the bacteria did not result in significantly greater control than that achieved by the nematodes used alone. The present results indicated that nematodes could be used successfully against the black cutworm,Agrotis ipsilon larvae during the winter which is the active season of this insect pest in Egypt.     

Produktion von Präparaten auf der Basis von Bacillus thuringiensis var. israelensis mit UV-inaktivierten Sporen zur biologischen Bekämpfung von Mückenlarven

Zusammenfassung Zur Bekämpfung von Stechmücken-Larven geeignete Präparate vonBacillus thuringiensis var.israelensis (B. t. i. = Serotyp H₁₄) enthalten Sporen und parasporale Toxinkristalle. Um die Belastung von Oberflächenwasser mit aktiven Sporen bei einer solchen Bekämpfung möglichst gering zu halten, wurden Untersuchungen durchgeführt mit dem Ziel, die Keimzahl des Biopräparates zu reduzieren. Bei Versuchen mit einem UV-Entkeimungsgerät für Trinkwasser wurde eine 99,99%ige Inaktivierung der Sporen erzielt. Im Biotest bewirkte das bestrahlte Präparat nahezu den gleichen Effekt gegenüber Mückenlarven wie die nichtbestrahlte Suspension. Bei der Anwendung dieses neuenB. t. i.-Präparates in der kalkulierten Aufwandmenge in Oberflächenwasser wird nicht einmal die Toleranzgrenze für die Trinkwasser-Qualität überschritten. Das bedeutet, daß der Einsatz eines UV-behandeltenB. t. i.-Präparates zur Mückenbekämpfung hygienisch unbedenklich ist.

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Production of preparations based on Bacillus thuringiensis var. israelensis with UV-inactivated spores for biological control of mosquito larvae

Preparations ofBacillus thuringiensis var.israelensis (B. t. i.= serotype H₁₄) contain spores and toxic parasporal crystals. To minimize the loading of surface water with active spores in connection with mosquito control, studies were carried out to reduce the germination index of the spores using an UV equipment for sterilization of drinking water. With this method an inactivation rate of 99.99% could be obtained. In our biotest with mosquito larvae the irradiated preparation induced the same effect as the non treated one. For use ofB. t. i. in the calculated dosage in surface water the tolerance limit for drinking water will not be exceeded. Therefore, application of an UV-treatedB. t. i.-preparation for mosquito control should not be hampered by safety considerations.

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Mit 2 Abbildungen und 2 Tabellen

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Arbeitsgruppe Prof. Dr.H. W. Ludwig und Dr.W. Schnetter.     

Übertragung zweler bakterieller Pathogene in den Körper von Sesamia cretica Led. (Lep., Tortricidae) mittels des Legebohrers von Bracon brevicornis Wesm. (Hym., Braconidae)

Laboratory trials were undertaken to investigate the transmission of 2 bacterial pathogens (Serratia marcescens Bizio andBacillus thuringiensis Berliner) by the ovipositor of a braconid parasitoid,Bracon brevicornis Wesmael into the body cavity ofSesamia cretica Lederer. The braconid's ovipositor was able to transmit the 2 bacterial pathogens and plays as inoculating needle. The host larvaeS. cretica were significantly immobilized faster by the contaminated ovipositor of a parasitoid (in case of the 2 pathogens). After successful transmission of the bacterial pathogen into the body cavity of host larvae, different deleterious effects were significantly found for the parasitoid and its progeny specially in case ofS. marcescens. Through contamination of the ovipositor, the non-sporeforming bacterium,S. marcescens has more pathogenic effects on the parasitoid and its progeny than the sporeforming bacterium,B. thuringiensis.     

Empfindlichkeit der Raupen vonLymantria dispar L. (Lep., Lymantriidae) gegenüberBacillus thuringiensis und 2 Häutungshemmstoffen,allein und in Mischung

Field trials were made on the efficacy of the new inhibitor of chitin synthesis in insects, Nomolt 15 SC with teflubenzuron as an effective substance, to larvae ofLymantria dispar, using Nomolt pure or in combination withBacillus thuringiensis. In further experiments another moulting inhibitor, Dimilin, was tested pure or in combination with the Bacillus. The mixture of Bathurin 82 S (Bac. thuring. var.kurstaki), 16 BIU/ha and Nomolt, 10 or 50 ml/ha proved to be very efficacious even during cold and rainy weather, when it showed 20% higher efficacy than the pure biopreparation. The combination with Nomolt as stressor proved to have higher selectivity and efficacy against the pest larvae than those with Dimilin.     

Neues über insektenpathogene,kristallbildende Bazillen

Summary A report is given of recent observations about crystalliferous bacilli (Bac. thuringiensis andBac. entomocidus) and their entomogenous properties: Infectivity of the spores, effect of the endotoxin localized in parasporal bodies, and activity of so-called exotoxin which is excreted into the medium of the cultures. After a short survey about the host-spectrum of the different toxic components, the possibilities of biological control of harmful insects by crystalliferous bacteria is dicussed in connection with the harmlessness of these microbes to mammals and their effect upon useful arthropods (e.g. bees).

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Vortrag gehalten auf einem Kolloquium der Biologischen Bundesanstalt am 9. 2. 1962 in Berlin-Dahlem.