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.     

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.     

Evaluation of microbial and chemical insecticides for the control ofSpodoptera exigua (Lep., Noctuidae) on soybean plants

Field experiments have been carried out to evaluate the potency of the biological control agentBacillus thuringiensis (Dipel), the pyrethroid Fenvalerate and their combinations for the control of the lesser cotton leafwormSpodoptera exigua on soybeans in Qualubia governorate. Molasses was combined with all treatments to enhance their effectiveness. One spray application with either Dipel or Fenvalerate showed an obvious reduction in larval counts ofS. exigua, associated with a significant increase in the crop yield but in varying degrees, in correlation with the tested dose. Treatments with combinations of both biological and chemical insecticides at the lowest tested doses (62 g ofB. t. +50 ml of Fenvalerate/feddan) showed to be highly potential, and caused 2.8 fold increase in the crop yield. It may be recommended that a combination of both preparations may be used for the control ofS. exigua.     

NorA efflux pump inhibitory activity of coumarins from Mesua ferrea

The purpose of this investigation was to study the modulator and efflux pump inhibitor activity of coumarins isolated from Mesua ferrea against clinical strains as well as NorA-over expressed strain of Staphylococcus aureus 1199B. Seven coumarins were tested for modulator activity using ethidium bromide (EtBr) as a substrate. Compounds 1, 4–7 modulated the MIC of EtBr by ≥ 2 fold against wild type clinical strains of S. aureus 1199 and S. aureus 1199B, whereas compounds 4–7 modulated the MIC of EtBr by ≥ 16 fold against MRSA 831. Compounds 1, 4–7 also reduced the MIC of norfloxacin by ≥ 8 fold against S. aureus 1199B, and 4–6 reduced the MIC of norfloxacin by ≥ 8 fold against MRSA 831 at half of their MICs. Inhibition of EtBr efflux by NorA-overproducing S. aureus 1199B and MRSA 831 confirmed the role of compounds 4–6 as NorA efflux pump inhibitors (EPI). Dose-dependent activity at sub-inhibitory concentration (6.25 μg/mL) suggested that compounds 4 and 5 are promising EPI compared to verapamil against 1199B and MRSA 831 strains.     

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.     

Antagonismusin vitro vonBacillus spp. gegenüberRhizoctonia solani undPythium spp.

Zusammenfassung Es konnten 132Bacillus-Stämme isoliert und gegenüber7 Rhizoctonia-solani- und 6Pythium-Stämmen auf Antagonismusin vitro untersucht werden. Die gefundenen Antagonisten hemmten die Pilzisolate unterschiedlich stark, so daß Gemische von Antagonisten für die Praxis zu empfehlen sind.

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Antagonismin vitro ofBacillus spp. againstRhizoctonia solani andPythium spp.

There were 132Bacillus-strains isolated and tested for antagonism against 7 strains ofRhizoctonia solani and 6 strains ofPythium spp. The isolated antagonists didn't show a uniform effect against the tested strains ofRhizoctonia solani andPythium spp. For an application in practice it will be better to use a mixture of antagonists.

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Mit 4 Abbildungen und einer Tabelle     

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.     

Combinations of several insecticides used for integrated control of Colorado potato beetle (Leptinotarsa decemlineata, Say., Coleoptera: Chrysomelidae)

The Colorado potato beetle (Leptinotarsa decemlineata Say.) (CPB) is the main potato pest in Croatia. The main problems in CPB control are related to a number of treatments and resistance development. In order to investigate the efficacy of combinations a reduced dose of spinosad (33% of the full doses) with the reduced doses (33% of full doses) of B.t.t., neem and pyrethrin against CPB larvae, 3-year field trials and one laboratory trial were conducted. Joint actions of the insecticides in combinations were analyzed. The CPB attack on experimental fields in all 3 years of investigation was high to moderate. In 2001 the maximum number of larvae on untreated plots was 11.7 larvae per plant, while in 2002 and 2003 it was lower, 5.5 and 6.1 larvae/plant, respectively. The efficacy obtained with a full dose of B.t.t. reached 75% in the field, and 78% in the laboratory trial. The residual efficacy of a full dose of B.t.t. lasted 7–10 days. The application of both, full and reduced doses of B.t.t., did not result in a significant yield increase. The results indicate that only one treatment with B.t.t. insecticide alone is not enough for efficient protection of potato against the attack of CPB larvae. The application of neem resulted in an efficacy of between 54 and 87.9%. The residual activity of neem was too short to ensure significant yield increase in 2 out of 3 years of the investigation. The application of a full dose of pyrethrin ensured an efficacy of between 86 and 89% with residual activity of 7–10 days. Only in the trial in 2003 significant yield increase (40% higher than untreated control) after the application of a full dose of pyrethin was recorded. The application of both, full and reduced doses of spinosad resulted in very high efficacy (over 90%), with residual activity between 10 and 20 days. The application of spinosad resulted in a significant yield increase in 2003, both in full and reduced doses, and in 2001 in the full dose (the reduced dose was not tested alone in 2001). High efficacy of the reduced dose of spinosad indicated its high biological activity and possibility for the reduction of the recommended dose. However, applications of combinations of insecticides in reduced doses (spinosad with B.t.t., neem and pyrethrin) resulted in efficacies of over 97% with residual activity of up to 21 days. Significant yield increase was noted after the application of the combinations of spinosad with B.t.t. and pyrethrin. The results of the laboratory trial confirmed the results of field trials. The joint action of insecticides was mainly described as independent synergism. It can be concluded that applied combinations are suitable in IPM in potato.     

Zur Wirkung von Precocen 2 und Fenarimol auf die Kohlblattlaus,Brevicoryne brassicae (L.) und ihren ParasitoidenDiaeretiella rapae (M'Intosh)

The anti-hormone compounds, precocene-2 (anti-juvenile hormone) and fenarimol (anti-ecdysone) were evaluated against the green cabbbage aphid,Brevicoryne brassicae (L.) alone and for their compatibility with the endoparasiteDiaeretiella rapae (M'Intosh). The results revealed that precocene-2 provided more than 90% control ofB. brassicae acted on larvae within 72 h after the treatment, while fenarimol was less effective. Moreover, either precocene-2 or fenarimol extremely reduced the reproductive potentiality ofB. brassicae surviving adults. Both anti-hormone compounds demonstrated compatibility withD. rapae, a parasitoid ofB. brassicae. No considerable difference was detected when parasite emergence was compared from treated and untreated individuals.     

Note on radiation processed wood-plastic materials

Summary Specimens ofAbies sp. (fir),Pinus longifolia (chir),Vateria indica (vellapine),Dichopsis elliptica (pali) andMangifera indica (mango) were impregnated with monomers of styrene and methylmethacrylate and irradiated under different conditions. The treated specimens were tested as to their crushing strength, their bending strength and their water absorption. The results first indicate and increase in density due to impregnation. A reduction in moisture absorption and volumetric swelling as compared with untreated controls and increase in crushing strength were observed. The properties varied due to a non-uniform penetration of the polymer. Further experiments on the resistance against degradation by fungi were carried out and respective results are listed and discussed.     

Bio-efficacy of bacterial insecticide,Bacillus thuringiensis Berl. as biological control agent against snails vectors of Schistosomiasis in Egypt

The molluscicidal activity of Thuricide used as bacterial insecticide,Bacillus thuringiensis, againstBiomphalaria alexandrina andBulunus truncatus was tested.The obtained results indicate that Thuricide possess a mollus-cicidal activity against both snails species.B. truncatus was more sensitive to the action of Thuricide. However the slope function of the LC₅₀ forB. alexandrina was significantly higher than that forB. truncatus. The mortality rate of exposedB. alexandrina increased by increasing the exposure time.Exposure ofB. alexandrina to low concentration of Thuricide caused a significant decrease in both ovipository activity and size of egg masses and reduced the percentage of egg hatchability.

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Zusammenfassung Es wurde die molluscizide Wirkung von Thuricide (Bac. thuringiensis) gegen die SchneckenBiomphalaris alexandrina undBulunus truncatus getestet. Die Ergebnisse zeigen, daß Thuricide für beide Schnecken molluscizid war.B. truncatus erwies sich als empfindlicher, doch war die Neigungs-Funktion des LC₅₀-Wertes fürB. alexandrina signifikant höher als fürB. truncatus. Die Mortalitätsrate vonB. alexandrina erhöhte sich mit zunehmender Expositionszeit. Die Exposition vonB. alexandrina gegenüber geringen Konzentrationen von Thuricide verursachte eine signifikante Verringerung sowohl der Eiablage-Aktivität als auch der Größe der Eigelege sowie des Schlüpfprozents der Eier.

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With 3 tables     

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).     

Utilization ofBacillus thuringiensis to controlSpodoptera littoralis in Egyptian clover fields

The efficacy of the commercial product Dipel 2X (Bacillus thuringiensis var.kurstaki), was assessed as a biological control means of the cotton leaf wormSpodoptera littoralis attacking clover cultivations (Trifolium alexandrinum) in Egypt. Field experiments using the biological agent were carried out in two localities as compared with the conventional chemical insecticide lannate. The percentage of reduction in the larval population increased at higher doses ofB. t. and the infestation levels reached very low levels, almost similar to those obtained after using lannate. The yield of the first cut of clover was estimated. The data obtained indicate that the yield significantly increased after treatment with eitherB. t. or lannate. In Menoufia, the yield was significantly higher after two successive spray applications withB. t. at 750 g/f compared to that obtained withB. t. when used at 500 g/f. In Giza Governorate, the yield was slightly higher after a single treatment withB. t. at 500 g/f as compared with lannate.     

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.

     

The use of Bacillus thuringiensis to control two lepidopterous insect pests (Agrotis ypsilon and Spodoptera littoralis)

An area of 50 feddans cultivated with soybeans was treated withBacillus thuringiensis (B.t.) baits againstAgrotis ypsilon and 60 feddans were sprayed withB.t. spray againstSpodoptera littoralis. WhenB.t. baits were used, the percentage of kill ofA. ypsilon reached 96.1–96.4% compared to 97.4–98% kill on using hostathion baits. WhenB.t. was sprayed againstS. littoralis, a percentage of larval kill 88.3% was obtained. This increased to 97.3% after the second application. On the other hand, the precentage of kill reached 96.8% when lannate was sprayed once. The average yield was 1.54 tons/fed. whenB.t. was sprayed twice againstS. littoralis and 1.42 tons/fed. when sprayed once. Areas, treated with lannate gave 1.44 tons/fed., while in the untreated area the yield was comparatively low being 0.83 tons/fed.Mith 4 tables     

Über das Schutzsystem der Kiefer gegen Befall durchAradus cinnamomeus Panz. (Heter., Arad.) undEvetria buoliana Schiff. (Lep., Tortr.)

Summary On aetheric oils as factors of resistance of Pinus silvestris against insect pests. The aetheric oils contained in the issues ofPinus silvestris are of importance for the mechanism of resistance ofPinus against the bark-bug and the stem-worm. They represent a natural system of protection which shows differences in effectiveness adequat to the different concentrations of aetheric oils. The most important ingredients of the system are: -Pinen, -Pinen, Limonen und ³-Karen. Mathematic models of the relation between system of protection and system of attack are given. In connection with the utilization of samples (not fewer than 0,4% of the trees) they enable to evaluate the resistance of pines against the pests and to give a prediction of their outbreaks.     

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.     

Biology and life table of the predacious mite,Agistemus exsertus Gonz. (Acari: Stigmaeidae)

The predacious mite,Agistemus exsertus Gonz. was reared on 4 types of animal egg diets (eggs ofTetranychus urticae Koch,Eutetranychus orientalis Klein,Brevipalpus pulcher [C. & F.] andBemisia tabaci [Genn.]). Life table parameters of each diet (net reproduction rate [Ro], mean generation time [T], intrinsic rate of increase [rm] and finite rate of increase [erm]) were determined. Eggs ofT. urticae were found to be preferred above other egg diets as food byA. exsertus and promoted a higher rate of oviposition. The intrinsic rate of increase was 0.15 individuals//day; the population multiplied 57.91 times in a generation time of 26.21 days. Rearing on eggs ofB. tabaci exhibited more attractive compared withB. pulcher. The average number of eggs consumed daily by female was 17, 12, 9 and 7 eggs ofT. urticae, E. orientalis, B. tabaci andB. pulcher respectively. In the sex ratio of the progeny, predator females fed inT. urticae andB. tabaci gave rise to more females.

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Zusammenfassung Die RaubmilbeAgistemus exsertus Gonz. wurde im Labor unter Fütterung mit veschiedenen Milben- und Insekteneiern (Tetranychus urticae, Eutetranychus orientalis, Brevipalpus pulcher, Bemisia tabaci) aufgezogen. Die life table-Parameter bei jeder Nahrung (Netto-Reproduktionsrate Ro, mittlere Generationsdauer T, Innere Zuwachsrate rm sowie Gesamt-Zuwachsrate erm) wurden bestimmt. Die Eier vonT. urticae wurden allen anderen Eiern vorgezogen und bewirkten die höchste Eiablege-Rate der Raubmilbe. Die innere Zuwachsrate betrug 0,15 Indiv.//Tag. Die Population nahm während der Generationszeit von 26,2 Tagen um das 57,9fache zu. Die Eier vonB. tabaci wurden jenen vonB. pulcher vorgezogen. Die durchschnittliche Zahl der täglich von einem Raubmilben-Weibchen verzehrten Eier betrug 17, 12, 9 und 7 Eier vonT. urticae, E. orientalis, B. tabaci undB. pulcher. Bezüglich des Weibchen-Anteils der Nachkommen brachten Raubmilben-Weibchen bei Fütterung mitT. urticae- undB. tabaci-Eiern die meisten Weibchen hervor.

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With one table     

Cytotoxicity of chemical constituents from the stems of Dalbergia parviflora

Three new compounds, dalberpene (1), dalparvinene B (2) and dalparvone B (3), as well as 12 known compounds were isolated from the heartwood of Dalbergia parviflora. Isoflavanone 13 showed strong cytotoxicity against KB, MCF-7 and NCI-H187 cell lines with IC₅₀ values ranging from 3.5 to 5.4 μg/mL and it was inactive against normal cells.     

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.