Zur Verwendbarkeit von Fungiziden als experimentaltechnische Hilfsmittel bei Untersuchungen an Borkenkäfern

The fungicides, Euparen and Orthocid 50, proved to be efficient in suppressing growth of saprophagous fungi on spruce phloem chips, which are used as a food ofPityogenes chalcographus adults in laboratory experiments.Beauveria bassiana infection of the beetles is also checked, when fungicides have been applied to the food.     

Orientierende Versuche zur Kombination von Pheromonfallen mit dem insektenpathogenen PilzBeauveria bassiana (Bals.) Vuill. gegen die Borkenkäferartlps typographus L. (Col., Scolytidae)

Zusammenfassung In ersten, orientierenden Versuchen wurde die Wirkung des tschechischenBeauveria bassiana-Präparates Boverol allein und in Kombination mit Pheromonfallen auf die Mortalität und das Brutverhalten des Buchdruckers,Ips typographus, untersucht. Pathogenitätstests ergaben eine Verpilzungsrate von 88,0 bis 96,7%. Wurden Käfer nach der oberflächlichen Kontamination sofort zur Brutablage an frische, berindete Fichtenstücke gesetzt, so betrug die Reduktion der Brutleistung gegenüber der Kontrolle nur etwa 23 bis 29%. Bei der geschlüpften F₁-Generation von kontaminierten Altkäfern konnten keine Unterschiede zu den vergleichbaren Jungkäfern aus der unbehandelten Kontrolle festgestellt werden. Eine Übertragung des Pilzes vom Altkäfer auf den Jungkäfer fand nur in Ausnahmefällen statt. Im Freiland wurde die Wirkung einer Kombination von Pheromonfalle mitB. bassiana getestet, wobei das Einbohrverhalten und die Brutleistung der Käfer in einer darunter eingekäfigten Fichtenrolle überprüft wurden. Die Zahl der Einbohrlöcher war in der BOVEROL-Variante um etwa 15% verringert, die F₁-Generation jedoch um nahezu 60%. Mögliche Einsatzstrategien vonBeauveria bassiana mit Hilfe von Pheromonfallen beiIps typographus werden erörtert.

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Preliminary trials on the combination of pheromone traps with the entomopathogenic fungusBeauveria bassiana (Bals.) Vuill. against the bark beetle speciesIps typographus L. (Col., Scolytidae)

In first, preliminary experiments, the efficacy of the CzechBeauveria bassiana product Boverol alone and in combination with pheromone traps on the mortality and the breeding behavior of the bark beetle,Ips typographus, was investigated. Pathogenicity tests resulted in a mortality due to the fungus of 88.0 to 96.7%. When the beetles were given directly after superficial contamination on fresh spruce pieces with bark, the reduction of the breeding efficacy was 23 to 29% compared to the untreated control. No differences between the hatched beetles from the F1-generation of contaminated beetles and those of the untreated control beetles were observed. A transfer of the fungus from the parent beetle to the young beetle was noticed only in a few cases. In the field, the efficacy of a combination of a pheromone trap withB. bassiana was tested. The number of bore holes and the breeding was measured using a caged spruce log. In the combination, the number of bore holes was reduced by 15%, but the F1-generation nearly by 60%. Possible strategies for the use ofB. bassiana in combination with pheromone traps againstIps typographus are discussed.

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Mit 4 Abbildungen     

Versuche zur Bekämpfung des Kartoffelkäfers,Leptinotarsa decemlineata Say und der Gewächshausmottenschildlaus,Trialeurodes vaporariorum Westw. mittelsBeauveria bassiana (Bals.) Vuill.

Zusammenfassung In der SSR wurde das in Entwicklung befindliche Mykoinsektizied Boverol (auf der Basis von Luftkonidien des entomopathogenen PilzesBeauveria bassiana [Bals.] Vuill.) als Mittel gegen den Kartoffelkäfer und die Gewächshausmottenschildlaus angewandt. Es werden die Voraussetzungen zur Anwendung sowie die Wirkungen des Biopräparates, zum Teil in Kombination mit einem Stressor (chemisches Insektizid in verringerter Dosis) beschrieben.

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Trials of controlling the Colorado Potato Beetle (Leptinotarsa decemlineata Say) and the White Fly (Trialeurodes vaporariorum Westw.) byBeauveria bassiana (Bals.) Vuill.

In Czechoslovakia the mycoinsecticide Boverol (established on the basis of air-borne conidia of entomopathogenic fungusBeauveria bassiana [Bals.] Vuill.) was used against Colorado Potato Beetle and White Fly in large scale conditions. The conditions for adequate effectiveness and the criteria for application of Boverol in combination with a stressor (a small quantity of an insecticide) are described. A recommendation for rating of the stressor in dependence on the variable ecological conditions is proposed.

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Mit 2 Abbildungen und einer Tabelle     

Über ein Massenauftreten des Eichenerdflohs im Marchfeld,Niederösterreich

Zusammenfassung Aus Österreich wird ein Massenauftreten des Eichenerdflohs auf Stieleiche auf einer reduzierten Fläche von 200ha gemeldet. Nach den morphologischen Merkmalen handelt es sich um eine Mischpopulation ausAltica quercetorum quercetorum undA. quercetorum saliceti. Der Hauptfraß erfolgte im beschatteten Bestandesinneren—Bestandesränder und Kronenpartien blieben oft weitgehend verschont. Als Mortalitätsfaktoren dürfte der PilzBeauveria bassiana eine bedeutende Rolle gespielt haben. Unter den Räubern war eine für Österreich bisher selten gemeldete Marienkäferart, nämlichSynharmonia impustulata, relativ zahlreich anzutreffen.

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A gradation of the oak flea beetle in the marchfeld, lower Austria

An outbreak of the oak flea beetle attackingQuercus robur on 200ha reduced area is reported. Due to morphological features a mixed population ofAltica quercetorum quercetorum andA. quercetorum saliceti was present. Injury, skeletonizing, happened in overshadowed parts of oak stands, stand margins often kept free of attacks. An important mortality factor seemed to be the pathogenBeauveria bassiana. Among predators appeared frequently the for Austria as rare known lady beetle,Synharmonia impustulata.

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Mit 2 Abbildungen und einer Tabelle     

Laboratory and field evaluation of <Emphasis Type="Italic">Beauveria bassiana</Emphasis> for controlling Mulberry whitefly <Emphasis Type="Italic">Pealius mori</Emphasis> Takahashi (Homoptera: Aleyrodidae) in mulberry (<Emphasis Type="Italic">Morus alba</Emphasis> Linn)

In a laboratory screening of 12 isolates of entomopathogenic fungi against nymphs of the mulberry whitefly (Pealius mori Takahashi), Beauveria bassiana (Balsamo-Crivelli) Vuillemin CKB-048 was the most virulent, causing 87 ± 3% mortality at 1 × 10⁶ conidia/ml. Infection was confirmed by growth of the fungus from cadavers and by scanning electron microscopy of treated nymphs. Beauveria bassiana CKB-048 was formulated as a wettable powder (1 × 10⁹ conidia/g) and tested in two mulberry (Morus alba Linn) plantations in central and northeastern Thailand. In both locations, two spray applications of B. bassiana CKB-048 at 3.75 × 10¹² to 6.25 × 10¹² conidia/ha and at 14 day intervals provided good control of whitefly nymphs; control with B. bassiana CKB-048 was comparable to that with the pesticide buprofezin at 250 g of active ingredient/ha. In addition, no mortality of silkworm larvae occurred when the larvae were fed with mulberry leaves sprayed with B. bassiana CKB-048 7, 14, or 21 days earlier.     

Toxicity of synthetic and biological insecticides against adults of the <Emphasis Type="Italic">Eucalyptus</Emphasis> snout-beetle <Emphasis Type="Italic">Gonipterus</Emphasis><Emphasis Type="Italic">scutellatus</Emphasis> Gyllenhal (Coleoptera: Curculionidae)

Toxicity by contact and by ingestion of lufenuron, flufenoxuron, lambda (λ)-cyhalothrin, cypermethrin, thiamethoxam and five entomopathogenic insecticides (three formulations of Beauveria bassiana, a compound containing spores of Metarhizium anisopliae var. acridum, and a mixture of Brevibacillus laterosporus, Bacillus licheniformis and Bacillus chitinosporus) were evaluated on adults of the Eucalyptus snout-beetle Gonipterus scutellatus Gyllenhal (Coleoptera: Curculionidae) under laboratory conditions. By contact, entomopathogenic fungus B. bassiana EC and the pyrethroid λ-cyhalothrin exhibited the highest efficiency, achieving 100 and 97.5% mortality, respectively. By ingestion, the highest mortality was obtained by B. bassiana EC (100%) and thiamethoxam (95%). Flufenoxuron and lufenuron, bacteria mixture and M. anisopliae showed a weak toxicity. Furthermore, we found a sex-biased mortality, being males more affected. Due to the good performance and low risk to humans and environment, B. bassiana EC (strain PPRI 5339) appears to be the most promising product to promote an IPM programme in South Africa.     

Eine Methode zur integrierten Bekämpfung des Rüsselkäfers (Hylobius abietis L.)

Zusammenfassung Es wird gezeigt, da? es m?glich ist, durch die Anwendung subletaler Konzentrationen des Insektizids DTHP, d. h. durch eine allgemeine Schw?chung des Organismus erwachsener Rüsselk?fer (Hylobius abietis L.), eine geeignete Disposition dieses Sch?dlings zur Infektion durch den parasitischen PilzBeauveria bassiana (Bals-Criv.) Vuill. herbeizuführen. Die K?fer, die in Fangrinden oder Fallen an Kiefern? stchen — welche in ein kombiniertes Pr?parat einer 0,05% DTHP-Suspension (Organophosphorverbindung vom Dipterex-Typ, technischer Block 0,0-Dimethyl-2,2,2-trichlor-1-hydroxy?thyl-phosphonat) mit 0,1% Sporen vonBeauveria bassiana getaucht worden waren — konzentriert wurden, nahmen keine Nahrung mehr auf und starben allm?hlich ab. Wie die histologischen Untersuchungen gezeigt haben, wurden Erkrankung und Tod der K?fer durch den genannten parasitischen Pilz herbeigeführt. Obwohl nur zwei Vergleichsfl?chen zur Verfügung standen, ist aus dem obengesagten klar, da? bei der Anwendung des kombinierten Pr?parates mit einer gewissen selektiven Wirkung gerechnet werden kann: W?hrend an der nur mit 1% DTHP behandelten Versuchsfl?che ungef?hr 2,5% nützlicher Insekten unter den get?teten K?fern festgestellt wurden (vor allem Laufk?fer der GattungPterostichus), betrug der Prozentsatz der get?teten nützlichen Insekten bei der Anwendung des kombinierten Pr?parates (DTHPBeauveria bassiana-Sporen) nur 0,25%. Die angeführten Versuche bewiesen die Anwendbarkeit der Kombination von Insektiziden — in subletalen Dosen oder Konzentrationen — mit Sporen parasitischer Pilze.     

Laboratory evaluation and field application of bacterial and fungal insecticides on the citrus flower moth,Prays citri miller (Lep., hyponomeutidae) in lime orchards in Egypt

The efficacy of two commercial products of Bactospeine and Bio-fly onPrays citri of lime trees was studied under laboratory and field conditions throughout the two seasons of 1996 and 1997. Laboratory results indicated that the pathogenic effect of Bactospeine,Bacillus thuringiensis (Berliner) was higher than that of Bio-fly,Beauveria bassiana in spite of the latter was applied with higher doses. Bactospeine at the rate (2 cc/1 l.w.) effected on the larvae more than on the adults, that treatment reduced no. of eggs/female by 81.70% and decreased the larval infestation by 90.08%. Bio-fly at the highest concentration (4 cc/1 l.w.) reduced the infestation with the eggs, the larvae and the pupae by 65.83%, 68.45% and 72.55%, respectively. Advanced effects of bacterial and fungal treatments on the final reduction rates ofP. citri infestation were recorded. Field applications revealed that two sprays with Bactospeine or Bio-fly gave good control ofP. citri more than one spray. Bactospeine at the rate (2 cc/1 l.w.) and Biofly at the rate (4 cc/1 l.w.) reduced the infestation by (89.82–93.43%) and (76.32–78.83%), respectively. In all cases, higher doses of bioinsecticides produced potentiation effects of infestation reduction. It is recommended that two sprays of Bactospeine at a rate (2cc/1 l.w.) are adequate effective to reduce the population of P. citri in lime orchards during the main flowering period of trees without need of chemical insecticides. An erratum to this article is available at .     

Effect of aging in adult Monochamus alternatus (Coleoptera: Cerambycidae) on the susceptibility of the beetle to Beauveria bassiana (Ascomycota: Hypocreales)

To clarify the effect of aging in adult Monochamus alternatus on the susceptibility of the beetle to Beauveria bassiana, we inoculated the fungus into adult beetles 0, 3, 7, 14, and 28 days after emergence. The number of days from B. bassiana inoculation to M. alternatus death increased with the number of days from beetle emergence to inoculation up to 14 days after emergence. This indicated that the susceptibility of adult beetles to the fungus decreased with aging. However, B. bassiana-inoculated beetles 28 days after emergence died earlier after inoculation than those inoculated with the fungus 14 days after emergence; i.e., the beetle’s susceptibility to the fungus increased again. We considered this phenomenon to be the result of senescence of adult beetles. We concluded that the susceptibility of M. alternatus to B. bassiana decreased first and then increased again with aging.     

银杏大蚕蛾的生物学和防治技术研究

银杏大蚕蛾在湖北一年发生一代。幼虫5龄;4、5龄幼虫有绿色型和黑色型。幼虫取食38种植物,天敌有53种。本文还叙述了该虫发生与环境的关系。防治试验表明:喷洒2.5％溴氰菊酯5000倍液、2×10~8孢子/ml白僵菌液、25％苏脲一号500倍液、1×10~8PIB/mlDjNPV虫尸液效果均很好。     

Transformation and attachment of Beauveria bassiana conidia on the cuticle of Tribolium confusum and Sitophilus oryzae in conjunction with diatomaceous earth

Agrobacterium tumefaciens-mediated transformation (AMT) was used in order to create fluorescent conidia of Beauveria bassiana (Balsamo) Vuillemin (Ascomycota: Hypocreales). From the fungal transformants, one Enhanced Green Fluorescent Protein B. bassiana strain indicated stability (maintained the GFP characteristics) in fluorescent signal, while its pathogenicity did not differ significantly from the wild B. bassiana type. After exposure on wheat treated with the transformed conidia, fluorescence was evident on all body parts but especially on metasternon of adults of Tribolium confusum Jacquelin du Val (Coleoptera: Tenebrionidae) and on elytra in of Sitophilus oryzae (L.) (Coleoptera: Curculionidae). No significant differences were noted in fluorescence levels in the case of T. confusum between the transformed and the wild strain. However, the addition of diatomaceous earth (DE) increased attachment, especially at increased intervals after exposure. For S. oryzae, fluorescence of the transformed strain was decreased with the increased post-exposure time, but the simultaneous presence of DE increased fluorescence. The results of this study demonstrate that fluorescent conidia of B. bassiana can be utilized as a tool for the evaluation of parameters that affect the attachment of entomopathogenic fungi in insects?? cuticle.     

Effects of insect activity, soil, and cuticular factors on virulence of Beauveria bassiana toward Blissus leucopterus hirtus

The fungus Beauveria bassiana (Balsamo) Vuillemin (Ascomycota: Hypocreales) is a potential biological control agent of hairy chinch bug, Blissus leucopterus hirtus Montandon (Hemiptera: Lygaeidae), but its virulence against this important turf grass pest is limited. To gain insight into why high numbers of conidia are needed for rapid kill, conidial persistence on insects was monitored under several experimental conditions. One day after exposure to a concentrated B. bassiana suspension, most conidia were removed from insects, particularly at warmer temperatures. Removal was higher when soil was present, suggesting that the insects may have transferred the conidia to soil. Most conidia on insects lost viability within 2?days. In contrast, conidia stored in soil under the same conditions as the insects remained viable. Earlier instar nymphs were more susceptible to lethal fungal infection than were adults. Materials recovered from a hexane rinse of adult insects inhibited conidial germination. These results have implications for applied aspects of chinch bug biological control with B. bassiana.     

Potential of Metarhizium anisopliae and Beauveria bassiana in the control of tea termite Microtermes obesi Holmgren in vitro and under field conditions

Two strains of Metarhizium anisopliae (Metschnikoff) Sorokin and two strains of Beauveria bassiana (Ballsamo) Vuillemin were evaluated for their potential use as biological control agents against the tea termite Microtermes obesi Holmgren. The strains were screened for relative pathogenicity, and the median lethal time eliciting 50% mortality (LT₅₀) was calculated. In general, the M. anisopliae strains were more virulent with lower LT₅₀ values than B. bassiana strains. The LT₅₀ values ranged from 1.6 to 3.7 days. The median lethal concentrations (LC₅₀) of all the isolates were also determined. The M. anisopliae strains had low LC₅₀ values compared to B. bassiana strains. The LC₅₀ values ranged from 35 to 140 conidia per termite. The strains were also tested for survival under laboratory nest conditions. All the isolates exhibited the ability to grow, sporulate and produce an epizootic in treated nest material. Field applications of the isolates also produced promising results.     

Untersuchungen über den Einfluß von Dimilin (Diflubenzuron) auf Wachstum und Konidienkeimung einiger insektenpathogener Pilze

Zusammenfassung Der Einfluß von Dimilin, einem Chitinsynthesehemmer, auf das Wachstum von 2 Deuteromyceten (Beauveria tenella, Metarrhizium anisopliae) und von 4Entomophthora-Arten (E. aphidis, E. culicis, E. sphaerosperma, E. thaxteriana) sowie auf die Konidienkeimung vonE. aphidis undE. thaxteriana wurde untersucht. Dabei konnte festgestellt werden, daß das Wachstum vonB. tenella und vonM. anisopliae bei praxisnahen Konzentrationen geringfügig beeinträchtigt ist, nicht jedoch jenes der geprüftenEntomophthora-Arten. Dieselben Konzentrationen stimulierten die Konidienkeimung und die Bildung von Sekundärkonidien vonE. aphidis undE. thaxteriana.

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Investigations on the influence of Dimilin (Diflubenzuron) on growth and germination of conidia of some insect pathogenic fungi

The influence of Dimilin, an inhibitor of the chitin synthesis, was tested on growth of two Deuteromycetes (Beauveria tenella, Metarrhizium anisopliae) and four species ofEntomophthora (E. aphidis, E. culicis, E. spaerosperma, E. thaxteriana) and on germination of conidia ofE. aphidis andE. thaxteriana. It was demonstrated that concentrations proposed for practical applications slightly impaired the growth ofB. tenella andM. anisopliae, but did not influence the growth ofEntomophthora species. The same concentrations stimulated germination of conidia and formation of secondary conidia ofE. aphidis andE. thaxteriana.

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Mit 2 Abbildungen     

Beauveria bassiana (Vuill) Link als Parasit des Kartoffelkäfers (Leptinotarsa decemlineata Say)

Zusammenfassung 1. Infektionsversuche im Freiland an L₂- und L₃-Larven des Kartoffelkäfers haben bestätigt, daß die Anfälligkeit seiner Jugendstadien gegenBeauveria bassiana im umgekehrten Verhältnis zu ihrem Alter steht, d. h. sie sind um so anfälliger, je jünger sie sind.2. Gegenüber L₄-Larven sind Infektion und Absterbeverlauf bei L₂- und L₃-Larven wesentlich beschleunigt. Der Vorsprung beträgt 8 bis 12 Tage.3. Die Virulenz des Pilzes wird durch Kultur auf nährstoffreichem Substrat zunächst noch gesteigert, hält sich bis zur 16.Nährbodengeneration auf gleicher Höhe und verringert sich nach 30 Generationen um etwa 50%.4. Die Konidien vonB. bassiana sind sehr widerstands fähig. Ihre Keimfähigkeit bleibt bei kühler nnd trockener Aufbewahrung 2 bis 3 Jahre erhalten.     

Comparative analyses of fungal biota carried by the pine shoot beetle (Tomicus piniperda L.) in northern and southern Finland

The pine shoot beetle, Tomicus piniperda, is a secondary colonizer of pines and other conifers. Although it is necessary to understand interactions of this insect with other organisms, few studies have focused on its fungal associates. This study focused on the effect of geographical distance on the occurrence of fungi carried by the beetle. Adult beetles were collected from Scots pine (Pinus sylvestris) in North (Rovaniemi) and South (Hyytiälä) Finland. The mycota was isolated and identified using a combination of morphological and molecular data. The results revealed a great diversity of fungal taxa isolated from T. piniperda, with a total of 3073 isolates representing 20 taxonomic units. The most frequently isolated fungi in the bark beetles from North Finland were Beauveria bassiana, Kuraishia sp., whereas Penicillium velutinum was mostly observed in the insects from South Finland. Ophiostoma canum and Ophiostoma minus were also isolated from the beetles from both North and South Finland. The number of fungi isolates per insect was 2.58 in the North and 3.74 in the South, respectively. Significant differences were found between South and North Finland in fungal taxa isolated from the beetles. The highest richness and diversity of the fungal taxa was observed in the South. However, the overall fungal diversity index analysis revealed that the mycobiota was under-sampled which suggests that a proportion of the fungal species may have remained undetected.     

Residual efficacy of thiamethoxam, Beauveria bassiana (Balsamo) Vuillemin, and diatomaceous earth formulation against Rhyzopertha dominica F. (Coleoptera: Bostrychidae)

The residual efficacy of diatomaceous earth alone and in combination with Beauveria bassiana (Balsamo) Vuillemin or a neonicotinoid insecticide thiamethoxam against Rhyzopertha dominica (Coleoptera: Bostrychidae) was studied under laboratory conditions. The mortality of adult R. dominica was decreased over the 9?months of storage period and the combined application of the test materials enhanced the mortality rates compared with alone treatments. The greatest mortality was observed in the combination of DE with thiamethoxam. Progeny suppression was decreased with the extended storage period. The maximum rate of mycosis and sporulation in the cadavers of R. dominica was observed where B. bassiana was applied alone at the lowest-dose rate. The results of this study indicate that all three control measures may provide safety for an extended period of time against R. dominica.     

Effects of Neem Azal T/S and other insecticides against the pistachio psyllid Agonoscena targionii (Licht.) (Homoptera, Psyllidae) under field conditions in Syria

Different concentrations of Neem Azal-T/S, an insect growth regulator (IGR) (antiecdysone) and various other insecticides were tested against the pistachio psyllid (Agonoscena targionii) affecting pistachio (Pistacia vera L.), in northern Syria. From 1997?–?99, three applications were made annually, in April, May, June or July. Results revealed that Neem Azal-T/S, at the rate of 0.5 and 0.7?%, Flufenoxuron, Teflubenzuron, and the antagonistic fungus Beauveria bassiana Bals. were highly effective against the psyllid especially on the 1^st and 2^nd nymph instars in the April application. The possibilities of using these pesticides in integrated management against pistachio psyllid in Syria are discussed.     

Versuche zur Bekämpfung vonHylobius abietis L. (Coleopt., Curculionidae)

Zusammenfasung Als mittel zur Bekämfung des Großen Braunen Rüsselkäfers, Hylobius abietis, erfüllten unter 16 als Tauchmittel und 6 systemisch wirkenden Insektiziden nur die Wirkstoffe DDT, Lindan und Tetrachlorvinphos als Tauchmittel die Bedingung der Wirksamkeit von mindestens 3 Monaten.Nach dem DDT-Verbot ist Tetrachlorvinphos in einer Konzentration von 6.5% das am besten wirksame Mittel zur Pflanzentauchung gegenHylobius. Die Wirkung erstreckt sich mindestens über eine Vegetations- periode. Allerdings ist die hohe Konzentration von 6,5% hygienisch nicht befriedigend.Durch Stockbehandlung mit DDT + Lindan wurde die Eiablage vonH. abietis nicht verringert, dagegen der ParasitBracon hylobii ausgeschaltet.Laborversuche zur biologischen Bekämpfung des Rüßlers mit dem insektenpathogenen PilzBeauveria bassiana erbrachten nur bei Vorliegen besonderer Bedingungen (hohe Feuchtigkeit, geschwächte Käfer-population) positive Ergebnisse.     

A biochemical approach to potentiate the activity ofBacillus thuringiensis against corn borers

Due to the fact that the persistence ofBacillus thuringiensis (B.t.) is very short in the field as affected by exposure to ultraviolet radiation, some biochemical approaches have been adopted in an attempt to increase potentiation of the pathogen against the two lepidopterous corn borers,Chilo agamemnon andOstrinia nubilalis. These approaches were based on the incorporation of some selected non-toxic chemical compounds with different modes of action with the endotoxin ofB.t. fed to the larvae and thus resulting in its potentiation. Among the compounds tested, some representatives of inorganic salts, organic acids, protein and lipid solubilizing agents, amino acids and amides showed an obvious potentiation to the endotoxin activity against the target insects. Inorganic salts, such as, calcium oxide, calcium carbonate, zinc sulphate and potassium carbonate at 0.1% potentiated the activity of the product Dipel 2X (B.t. var.kurstaki) against the two tested species in varying degrees. With regard to protein solubilzing agents, urea, sodium thioglycollate and EDTA enhanced the potency ofB.t. againstO. nubilalis with a fold increase of 1.4–2.3. The lipid emulsifying agent Tween 80 (0.5%), caused 1.3 fold increase in the potency ofB.t. With respect toC. agamemnon, sodium thioglycollate and EDTA (0.1%) were effective in potentiating the activity ofB.t. with fold increase of 3.1 and 1.2, respectively, while urea caused a decrease in the potency ofB.t as compared with the control. The lipid emulsifying agent Tween 80 (0.5%) caused 1.3 fold increase in the potency ofB.t. The potentiating effect of aromatic compounds is not obvious with respect to the tested insect species. With amino acids and amides, it appears that some of the tested compounds enhanced the potency ofB.t. against the tested insect species but in varying degrees. The mode of action of the tested compounds has been discussed in the light of the results obtained.