RESUMO

Entomopathogenic nematodes (EPNs) from Heterorhabditidae and Steinernematidae families are extensively used to control insect pests. In Brazil, however, relatively few studies have identified and characterized these entomopathogens. The objective of this study was to identify and characterize an EPN isolate obtained from soil samples collected in the state of Paraná, Brazil. An isolate (UEL 08) of Heterorhabditis was detected in a soil sample collected from a pasture area cultivated with Brachiaria grass in Londrina, state of Paraná, Brazil (23°34ʹ311ʹʹS, 050°58ʹ298ʹʹW), using the insect-baiting technique with Galleria mellonella larvae as hosts. The nematode was identified through morphometric studies and molecular analyses based on amplification of the rDNA ITS region. Although we identified certain morphometric differences compared with the original description, the molecular data indicated that the ITS sequence obtained for the UEL 08 isolate is identical to the reference sequence of H. amazonensis (DQ665222) and presented 100% similarity. Thus, the findings of our morphological and molecular studies confirmed that the isolated nematode is H. amazonensis, which is the first time this species has been registered in Paraná. Study of the biological characteristics of H. amazonensis (UEL 08) revealed that the isolate has two distinct life cycles ­ one short (216 h) and the other long (288 h) ­ and produces two generations in both cycles. We observed that H. amazonensis (UEL 8) was pathogenic and virulent to the three evaluated hosts, although with different virulence against these hosts. The larvae of G. mellonella and Alphitobius diaperinus were more susceptible than adult Dichelops (Diacereus) melacanthus, with 100%, 85%, and 46% mortality, respectively. Furthermore, an in vivo production assay revealed a mean daily yield of 3.4 × 103 infective juveniles/g host larvae.

Nematoides entomopatogênicos (NEP) das famílias Heterorhabditidae e Steinernematidae são amplamente utilizados no controle de insetos-pragas. No Brasil, os estudos relacionados a caracterização e identificação destes entomopatógenos são recentes e escassos. Nesse sentido, o objetivo deste estudo foi isolar NEP de amostras de solos coletadas em diferentes áreas no estado do Paraná, Brasil. Um isolado Heterorhabditis (UEL 08) detectado em amostra de solo em área de pastagem cultivada com braquiária, localizada em Londrina, Paraná, Brasil (23º34´311´´S, 050º58´298´´W), utilizando o método de "inseto-isca" com lagartas de Galleria mellonella. Para a identificação foram realizados estudos de morfometria e identificação molecular a partir da amplificação da região ITS. Algumas diferenças foram encontradas em termos de morfometria em comparação com a descrição original, entretanto, os dados moleculares demonstraram que a sequência obtida para o isolado UEL 08 é idêntica à sequência de referência de H. amazonensis (DQ665222), com a qual apresentou 100% de similaridade. Os estudos das características biológicas de H. amazonensis (UEL 08) revelaram que o isolado tem dois ciclos de vida distintos, um curto (216 h) e outro longo (288 h), sendo que ocorrem duas gerações em ambos os ciclos. O isolado UEL 08 H. amazonensis foi patogénico e virulento sobre os três hospedeiros avaliados. Notadamente, as larvas de G. mellonella e Alphitobius diaperinus foram consideradas mais susceptíveis do que os adultos do percevejo Dichelops (Diacereus) melacanthus, com percentagens de mortalidade de 100%, 85% e 46% de mortalidade, respectivamente. O ensaio de produção in vivo revelou um rendimento médio diário de 3,4 × 103 juvenis infectantes/g de larva hospedeira.

Assuntos

RESUMO

Entomopathogenic nematodes (EPNs) from Heterorhabditidae and Steinernematidae families are extensively used to control insect pests. In Brazil, however, relatively few studies have identified and characterized these entomopathogens. The objective of this study was to identify and characterize an EPN isolate obtained from soil samples collected in the state of Paraná, Brazil. An isolate (UEL 08) of Heterorhabditis was detected in a soil sample collected from a pasture area cultivated with Brachiaria grass in Londrina, state of Paraná, Brazil (23°34'311''S, 050°58'298''W), using the insect-baiting technique with Galleria mellonella larvae as hosts. The nematode was identified through morphometric studies and molecular analyses based on amplification of the rDNA ITS region. Although we identified certain morphometric differences compared with the original description, the molecular data indicated that the ITS sequence obtained for the UEL 08 isolate is identical to the reference sequence of H. amazonensis (DQ665222) and presented 100% similarity. Thus, the findings of our morphological and molecular studies confirmed that the isolated nematode is H. amazonensis, which is the first time this species has been registered in Paraná. Study of the biological characteristics of H. amazonensis (UEL 08) revealed that the isolate has two distinct life cycles - one short (216 h) and the other long (288 h) - and produces two generations in both cycles. We observed that H. amazonensis (UEL 8) was pathogenic and virulent to the three evaluated hosts, although with different virulence against these hosts. The larvae of G. mellonella and Alphitobius diaperinus were more susceptible than adult Dichelops (Diacereus) melacanthus, with 100%, 85%, and 46% mortality, respectively. Furthermore, an in vivo production assay revealed a mean daily yield of 3.4 × 103 infective juveniles/g host larvae.

Assuntos

RESUMO

Successful parasitoid rearing is crucial for augmentative biological control. A low temperature preservation protocol allowing the availability of host and parasitoid year-round was evaluated in this study in four bioassays: (1) host eggs [Euschistus heros (Fabricius)] stored at - 196, - 80, and - 20°C for up to 70 days prior to exposure to Telenomus podisi Ashmead parasitism; (2) Euschistus heros eggs removed from storage at - 196°C after 70 days and kept at 5°C for up to 9 days prior to exposure to T. podisi parasitism; (3) Telenomus podisi adult emergence of insects stored as pupae at 5°C; and (4) fitness of adults of T. podisi stored at 5°C. Higher parasitism was observed in parasitoids reared on E. heros eggs stored at - 196 and - 80°C. Host eggs removed from - 196°C and stored at 5°C for up to 6 days did not impact T. podisi parasitism and development. Storage of T. podisi pupae for more than 7 days negatively affected parasitoid biology. Storing T. podisi adults at 5°C for up to 6 days does not alter the biological parameters of the parasitoid. Thus, parasitoids can be stored as pupae or adults as well as its host E. heros eggs. Our findings can be applied to improve the feasibility of year-round insect production.

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RESUMO

The objective of this study was to evaluate the effects of natural phytosanitary products (NPs) on spores and crystals of Bacillus thuringiensis subsp. kurstaki S-1905 (Btk S-1905). For the spore assay, NPs and bacteria were applied in combination and individually. For the combined application, Btk S-1905 + NP mixtures were inoculated on nutrient agar (NA), and for the separate applications, the NPs were spread on NA plates, which were later inoculated with the pathogen. The number of colony-forming units (CFU) per milliliter was quantified after 18 h of incubation. For the crystal protein degradation assay, the Btk S-1905 + NP mixtures were added to the diet of Anticarsia gemmatalis (Lepidoptera: Erebidae), and mortality was evaluated at the following time points: 12, 24, 48, and 72 h. Scanning electron microscopy and agarose gel electrophoresis were carried out. Biogermex and Ecolife® reduced the CFU ml-1 in both combined and separate applications. Biogermex, Ecolife®, and Planta Clean were antagonistic to the action of bacterial toxins, and no product affected the morphology or resulted in the degradation of the crystal proteins. The remaining products evaluated did not reduce the CFU ml-1 and had additive effect when combined with the crystal toxin.

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RESUMO

The purpose was to evaluate the side effects of strains Metarhizium anisopliae (Metsch.) Sorokin sensu lato Unioeste 43 and M. anisopliae sensu stricto ESALQ 1641 on Trichogramma pretiosum Riley (Hymenoptera: Trichogrammatidae) under controlled conditions. A free-choice test for parasitism was performed, with the confinement of T. pretiosum females mated with cards (1 × 5 cm) containing age-standardized Anagasta kuehniella Zeller eggs, either sprayed with a fungal strain (109 conidia/ml) or 0.01% v/v Tween 80 (control). For the no-choice tests, T. pretiosum females mated were confined with cards sprayed with fungal strains before or after parasitism, and cards with fungal applications at different times. The number of parasitized eggs, percentage of emergence, longevity, egg-to-adult period, sex ratio, total and confirmed mortality by the fungus, and longevity of females that parasitized previously sprayed eggs, were assessed. Histological analysis of immature phases was also performed. The fungus was repellent to T. pretiosum in the free-choice test, while in the no-choice test, fungal applications before and after parasitism did not affect the number of eggs parasitized by T. pretiosum or the sex ratio of emerging adults. However, both strains affected adult emergence rates, the egg-to-adult period, and longevity. Overall, both M. anisopliae strains had minor effects on these biological parameters of T. pretiosum under controlled conditions. Hyphae were not detected in histological observations of immature stages of the parasitoid.

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RESUMO

The citrus fruit borer, Ecdytolopha aurantiana (Lima, 1927) (Lepidoptera: Tortricidae), is responsible for major losses to the citrus industry because it causes rot and drop of fruits. The current study aimed to select and characterize Bacillus thuringiensis (Berliner, 1911) strains toxic to E. aurantiana. For this purpose, 47 B. thuringiensis strains were evaluated in selective bioassays using first instar larvae of E. aurantiana. The lethal concentration (LC50) of the most toxic strains was estimated, and the strains were characterized by morphological, biochemical, and molecular methods. Of the 47 strains tested, 10 caused mortality above 85% and showed mean lethal concentrations between 1.05E+7 and 1.54E+8 spores mL-1. The lowest LC50 values were obtained for the HD-1 standard strain and the BR145, BR83, BR52, and BR09 strains. The protein profile showed the presence of Cry proteins of 60, 65, 70, 80, and 130 kDa. The molecular characterization showed the presence of cry1, cry2, cry3, and cry11 genes. The morphological analysis identified three different crystalline inclusions: bipyramidal, round, and cuboidal. The cry1 and cry2 genes were the most frequent among the B. thuringiensis strains evaluated and encode Cry proteins toxic to insects of the order Lepidoptera, which agree with the toxicity results obtained by the selective bioassays against E. aurantiana. The results showed four different B. thuringiensis strains toxic to E. aurantiana at the same level as the HD-1 standard strain, and these strains have biotechnological potential for E. aurantiana control through the production of transgenic plants or the formulation of biopesticides.

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RESUMO

The selectivity of various entomopathogens and one insecticide (chlorpyrifos = positive control) to Trichogramma pretiosum Riley (Hymenoptera: Trichogrammatidae) was evaluated in the laboratory, using the protocol established by the Working Group on "Pesticides and Beneficial Organisms" of the IOBC. The evaluated parameters were parasitism (%), adult emergence (%), and product repellency to the parasitoid when sprayed on host eggs prior to parasitism (free-choice and no-choice tests). Most of the studied entomopathogens (Bacillus thuringiensis var. kurstaki, Bacillus thuringiensis var. aizawai, Beauveria bassiana, Metarhizium anisopliae, and Trichoderma harzianum) had no effects on biological parameters and were classified as harmless to T. pretiosum. Emergence of parasitoids (progeny viability) was reduced, but remained above 90%, when host eggs were sprayed with Baculovirus anticarsia prior to parasitism in the free-choice test, and B. anticarsia was therefore considered harmless. Chlorpyrifos (positive control) caused high adult parasitoid mortality in all bioassays. While T. pretiosum and the tested entomopathogens may be used simultaneously in integrated pest management programs, the use of chlorpyrifos should be avoided.

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RESUMO

A Brazilian isolate of Beauveria bassiana (CG425) that shows high virulence against the coffee berry borer (CBB) was examined for the production of subtilisin-like (Pr1) and trypsin-like (Pr2) cuticle-degrading proteases. Fungal growth was either in nitrate-medium or in CBB cuticle-containing medium under both buffered and unbuffered conditions. In unbuffered medium supplemented with cuticle, the pH of cultures dropped and Pr1 and Pr2 activities were detected in high amounts only at a pH of 5.5 or higher. In buffered cultures, Pr1 and Pr2 activities were higher in medium supplemented with cuticle compared to activities with nitrate-medium. The Pr1 and Pr2 activities detected were mostly in the culture supernatant. These data suggest that Pr1 and Pr2 proteases produced by strain CG425 are induced by components of CBB cuticle, and that the culture pH influences the expression of these proteases, indicating the occurrence of an efficient mechanism of protein secretion in this fungus. The results obtained in this study extend the knowledge about protease production in B. bassiana CG425, opening new avenues for studying the role of secreted proteases in virulence against the coffee berry borer during the infection process.

O isolado brasileiro de Beauveria bassiana (CG425) que apresenta alta virulência contra a broca do café (CBB) foi analisado quanto à produção de proteases degradadoras de cutícula, tipo-subtilisina (Pr1) e tipo-tripsina (Pr2). O crescimento fúngico foi realizado em meio contendo nitrato e em meio contendo cutícula da broca em condições de pH tamponado e não tamponado. Em meio não tamponado, suplementado com cutícula, o pH da cultura caiu e as atividades de Pr1 e Pr2 foram detectadas somente em valores de pH igual ou superior a 5,5. Em culturas tamponadas, as atividades Pr1 e Pr2 foram superiores em meio suplementado com cutícula, comparativamente as atividades em meio contendo nitrato. As atividades Pr1 e Pr2 ocorreram predominantemente no sobrenadante de cultivo. Os dados obtidos sugerem que Pr1 e Pr2 produzidas pelo isolado CG425 são induzidas por componentes da cutícula da broca do café (CBB), e que o pH da cultura influencia a expressão destas proteases, indicando a ocorrência de um mecanismo eficiente de secreção por este fungo. Os resultados obtidos neste estudo aumentam o conhecimento a respeito da produção de proteases por B. bassiana CG425, abrindo novos caminhos para o estudo do papel de proteases na virulência contra a broca do café durante o processo de infecção.

Assuntos

RESUMO

A Brazilian isolate of Beauveria bassiana (CG425) that shows high virulence against the coffee berry borer (CBB) was examined for the production of subtilisin-like (Pr1) and trypsin-like (Pr2) cuticle-degrading proteases. Fungal growth was either in nitrate-medium or in CBB cuticle-containing medium under both buffered and unbuffered conditions. In unbuffered medium supplemented with cuticle, the pH of cultures dropped and Pr1 and Pr2 activities were detected in high amounts only at a pH of 5.5 or higher. In buffered cultures, Pr1 and Pr2 activities were higher in medium supplemented with cuticle compared to activities with nitrate-medium. The Pr1 and Pr2 activities detected were mostly in the culture supernatant. These data suggest that Pr1 and Pr2 proteases produced by strain CG425 are induced by components of CBB cuticle, and that the culture pH influences the expression of these proteases, indicating the occurrence of an efficient mechanism of protein secretion in this fungus. The results obtained in this study extend the knowledge about protease production in B. bassiana CG425, opening new avenues for studying the role of secreted proteases in virulence against the coffee berry borer during the infection process.

RESUMO

A Brazilian isolate of Beauveria bassiana (CG425) that shows high virulence against the coffee berry borer (CBB) was examined for the production of subtilisin-like (Pr1) and trypsin-like (Pr2) cuticle-degrading proteases. Fungal growth was either in nitrate-medium or in CBB cuticle-containing medium under both buffered and unbuffered conditions. In unbuffered medium supplemented with cuticle, the pH of cultures dropped and Pr1 and Pr2 activities were detected in high amounts only at a pH of 5.5 or higher. In buffered cultures, Pr1 and Pr2 activities were higher in medium supplemented with cuticle compared to activities with nitrate-medium. The Pr1 and Pr2 activities detected were mostly in the culture supernatant. These data suggest that Pr1 and Pr2 proteases produced by strain CG425 are induced by components of CBB cuticle, and that the culture pH influences the expression of these proteases, indicating the occurrence of an efficient mechanism of protein secretion in this fungus. The results obtained in this study extend the knowledge about protease production in B. bassiana CG425, opening new avenues for studying the role of secreted proteases in virulence against the coffee berry borer during the infection process.

O isolado brasileiro de Beauveria bassiana (CG425) que apresenta alta virulência contra a broca do café (CBB) foi analisado quanto à produção de proteases degradadoras de cutícula, tipo-subtilisina (Pr1) e tipo-tripsina (Pr2). O crescimento fúngico foi realizado em meio contendo nitrato e em meio contendo cutícula da broca em condições de pH tamponado e não tamponado. Em meio não tamponado, suplementado com cutícula, o pH da cultura caiu e as atividades de Pr1 e Pr2 foram detectadas somente em valores de pH igual ou superior a 5,5. Em culturas tamponadas, as atividades Pr1 e Pr2 foram superiores em meio suplementado com cutícula, comparativamente as atividades em meio contendo nitrato. As atividades Pr1 e Pr2 ocorreram predominantemente no sobrenadante de cultivo. Os dados obtidos sugerem que Pr1 e Pr2 produzidas pelo isolado CG425 são induzidas por componentes da cutícula da broca do café (CBB), e que o pH da cultura influencia a expressão destas proteases, indicando a ocorrência de um mecanismo eficiente de secreção por este fungo. Os resultados obtidos neste estudo aumentam o conhecimento a respeito da produção de proteases por B. bassiana CG425, abrindo novos caminhos para o estudo do papel de proteases na virulência contra a broca do café durante o processo de infecção.

RESUMO

ABSTRACT This study was carried out in order to compare the effectiveness of liquid and powder preparations of the fungusBeauveria bassiana, and to verify the potential effects of soil type and poultry farm bedding on the fungus, under laboratory conditions. The powder proved more effective than the liquid formulation, causing a confirmed larval mortality of 83.3% and a confirmed adult mortality of 33.4%, against 18.7 and 12%, respectively, for larvae and adults. LC50 values of 2.41 x 107 and 5.33 x 107 conidia/g, and LT50 values of 4.7 and 5.3 days were obtained with the powder preparation for larvae and adults, respectively. When in contact with the poultry farm soil, the fungus had its effectiveness reduced by about 40% compared to the hillside soil treatment, and no differences in larval mortality were observed between fresh and soiled bedding. Adult mortality was low in the soil combined with either fresh (11.5%) or soiled bedding (25%), as was larval mortality in the application of the fungus over (58.7%) or below (38.7%) the fresh bedding. It was verified that an increased contact time of the insects with the substrates tended to decrease mortality by about 12 times, regardless of substrate.

RESUMO O trabalho foi desenvolvido com o objetivo de comparar a eficiência de preparações líquida e em pó do fungo Beauveria bassiana e também verificar quais efeitos que o tipo de solo e cama de aviário podem causar sobre o fungo, em condições de laboratório. A formulação em pó mostrouse mais eficiente que a líquida, causando mortalidade confirmada de larvas de 83,3 e de 33,4% de adultos, contra 18,7 e 12%, respectivamente para larvas e adultos. A CL50 da preparação em pó foi de 2,41 x 107 e 5,33 x 107 conídios/g e TL50 de 4,7 e 5,3 dias para larvas e adultos, respectivamente. O fungo em contato com o solo de aviário teve sua eficiência reduzida em cerca de 40% em relação ao tratamento com solo de barranco, e a mortalidade de larvas não diferiu quando se utilizou cama nova ou usada. A mortalidade de adultos foi baixa tanto para solo combinado à cama nova (11,5%) quanto usada (25%), bem como a mortalidade de larvas na aplicação do fungo sobre (58,7%) e abaixo (38,7%) da cama nova. Constatou-se que o aumento do tempo de contato dos insetos com os substratos tende a diminuir a mortalidade em cerca de 12 vezes, independente do substrato.

RESUMO

ABSTRACT The coconut cockroach (Coraliomela brunnea) is a serious pest of coconut trees, and may cause severe damage when efficient control techniques are not used. The present study was aimed to evaluate two entomopathogenic fungi species for the control of C. brunnea. The larvae where collected at a coconut plantation and carried to the laboratory. Spore suspensions of Beauveria bassiana at different concentrations where sprayed over the 2-cm-long larvae, in acrylic boxes and kept at 26º C, 12 h photoperiod. B. bassiana did not show any negative effect against C. brunnea larvae. All spore concentrations of M. anisopliae tested where pathogenic and caused significant insect mortality (P 0.001), the concentrations that caused mortality above 50%, after 19 days of treatment, were: 1 x 108, 5 x 107, and 1 x 107 conidia/mL, which caused 85%, 63.8% and 51.3% of larval mortality, respectively.

RESUMO A barata-do-coqueiro (Coraliomela brunnea) constitui numa das principais pragas para o coqueiro, podendo causar severos danos, quando medidas de controle eficientes não forem tomadas. Esse trabalho teve como objetivo estudar o efeito de duas espécies de fungos entomopatogênicos no controle de C. brunnea. As larvas foram coletadas em lavoura de coqueiro e transportadas para o laboratório. Suspensões de esporos em diferentes concentrações de Beauveria bassiana foram pulverizadas sobre as larvas, com aproximadamente 2 cm, em caixas de acrílico e foram acondicionadas a 26º C com fotoperíodo de 12 horas de luz. B. bassiana não apresentou nenhum efeito sobre as larvas da barata-do-coqueiro, Metarhizium anisopliae, emtodas concentrações testadas, foram patogênicas causando mortalidade significativa ao inseto (P 0,001), as concentrações que causaram mortalidade acima de 50% foram: 1 x 108, 5 x 107, 1 x 107 conídios/mL sendo 85%, 63,8% e 51,3% das larvas após 19 dias do tratamento, respectivamente.

RESUMO

ABSTRACT The objective of this study was to verify the effectiveness of control of A. diaperinus, using a combination of Beauveria bassianaand chemical insecticides, and to evaluate possible synergistic, antagonistic, or additive interactions. In treatments against larvae, 0.1mL of the insecticide, 0.1mL of the fungus, and 0.1 mL of the mixture (insecticide + fungus) were spayed separately. One minute after application, the larvae were transferred and individualized in acrylic boxes, and adults transferred to a Petri dish. In the treatment containing the fungus alone, the adults were submersed in 5 mL of a conidial suspension. In the treatment consisting of insecticide + fungus, the insects were sprayed with insecticide and after 24 hours were submersed in a conidial suspension. The second stage of the experiment was carried out with fungus + insecticide, the insects being submersed in a conidial suspension and after 24 hours sprayed with insecticide. There was a predominance of antagonistic effects in the interaction between insecticides and fungi, which occurred in 52.27% of the cases. In general, higher concentrations of the fungus led to additive effects. The experiments showed that regardless of the lethal concentrations of both insecticides used, applied either on adults or on larvae, the additive effects were observed when the LC70 of the fungus was used.

RESUMO Este trabalho teve como objetivo verificar a eficiência do controle de Alphitobius diaperinus, utilizando uma combinação de Beauveria bassiana e inseticidas químicos, avaliando as possíveis interações de sinergismo, antagonismo ou aditivismo. Nos tratamentos para larvas foi pulverizado, separadamente, 0,1 mL do inseticida, 0,1 mL do fungo e 0,1 mL da mistura (inseticida + fungo). Após um minuto da aplicação, as larvas foram transferidas e individualizadas em caixas de acrílico e os adultos em placa de Petri. No tratamento contendo apenas fungo, os adultos foram mergulhados em 5 mL da suspensão de conídios. No tratamento combinado, os insetos foram pulverizados com inseticida e, após 24 horas, submersos em suspensão de conídios. Em uma segunda etapa foi realizado um experimento fungo + inseticida onde os insetos foram mergulhados em suspensão de conídios e, após 24 horas, pulverizados com inseticida. Na interação entre inseticidas e fungos houve predominância de efeitos antagônicos, que ocorreram em 52,27% dos experimentos. De modo geral, maiores concentrações de fungos levaram a efeitos aditivos. Os experimentos mostraram que, independentemente das Concentrações Letais dos dois inseticidas utilizados, aplicados tanto em adultos como em larvas, na maioria dos resultados os efeitos aditivos foram observados quando se utilizou a CL70 do fungo.

RESUMO

ABSTRACT The aim of this study was to compare techniques for the invitro evaluation of the effect of fungicides on Bacillus thuringiensis var. kurstaki (Btk). The fungicides epoxiconazole, fentin hydroxide, azoxystrobin, tebuconazole, and carbendazim were tested at two concentrations, on cells and spores, in nutrient agar (NA) solid medium (SM), and in nutrient broth (NB) liquid medium (LM), with an evaluation also being made of their metabolization (MT) by Btk. For cells, the fungicides in NA were tested incorporated into the medium and on filterpaper disks. The evaluation consisted, respectively, of the number of CFU/mL and of the formation of an inhibition halo. For cells, the Bt+products + NB mixture was incubated in Erlenmeyer flasks (30 ± 2° C, 150rpm, 24h) and then was diluted and inoculated onto NA; the number of CFU/mL was evaluated. The MT and spore tests were performed in liquid medium (water). The effects of the products varied with their concentration, technique used, contact time, and developmental stage of the pathogen. The LM test is the most recommendable for evaluating the effect on cells. It was observed that most fungicides were compatible with cells, and only epoxiconazole and azoxystrobin were metabolized. Fentin hydroxide was the only fungicide incompatible with spores.

RESUMO Objetivou-se comparar técnicas para a avaliação in vitro do efeito de fungicidas sobre Bacillus thuringiensis var. kurstaki (Btk). Foram testados os fungicidas epoxiconazole, fentin hidróxido, azoxystrobin, tebuconazole e carbendazin em duas concentrações, sobre células e esporos, em ágar nutriente (AN)-sólido (MS) e caldo nutriente (CN)-líquido (ML), além da metabolização (MT) destes por Btk. Para células em AN, os fungicidas foram testados incorporados ao meio e em discos de papel-filtro. Avaliou-se, respectivamente, as UFC/mL e a formação de halo de inibição. Para células, a mistura Bt + produtos + CN foi incubada em erlemmeyers (30 ± 2° C, 150 rpm, 24h), e em seguida, diluida e inoculada em AN, avaliandose o número de UFC/mL. Os testes de MT e esporos foram realizados em líquido (água). O efeito dos produtos variou conforme a concentração, técnica, tempo de contato e fase/estágio do desenvolvimento do patógeno. O teste ML é o mais indicado para a avaliação do efeito em células, sendo observado que a maioria dos fungicidas mostrou-se compatível com as mesmas, e apenas epoxiconazole e azoxystrobin foram metabolizados. Fentin hidróxido foi o único incompatível com esporos.