Influence of generation in laboratory) temperature and host in the parasitism of two Trichogramma (Hym.: Grammatidae) species colleted on Diatraea saccharallis (Fabr.) 1794) (Lep.: Pyralidae)

Foi estudado o efeito da temperatura (18, 20, 22. 25, 30 e 32°C) e do hospedeiro Diatraea saccharalis (Fabr., 1794), Anagasta kuehniella (Zeller, 1879) e Sitotroga cerealella (Oliv., 1819) sobre duas espécies de Thichogramma, coletadas em ovos da broca da cana-de-açúcar uma delas, Thichogramma distinctum Zucchi, 1988 foi coleta da no Nordeste do Brasil e a outra, Trichogramma galloiZucchi, 1988 em Iracemápolis, São Paulo. Foram realizados testes de confinamento em laboratório e de livre escolha (olfatômetro); paralelamente, estudou-se a "qualidade" do parasitóide produzido ao longo das gerações, para se determinar o momento da introdução de populações de campo, devido à degeneração do inseto em laboratório. Com base nos resultados obtidos concluiu-se que em testes de confinamento, o tratamento com lâmpada germicida provocou o ressecamento de ovos de D. saccharalis, diminuindo o parasitismo e a emergência de T. distinctum. A temperatura não afetou o parasitismo de T. distictum em D. saccharalis. T. distinctum parasitou os ovos dos hospedeiros alternativos, preferencialmente na faixa de 22 a 25°C. A porcentagem de emergência de T. distinctum foi semelhante nas diferentes temperaturas em D. saccharalis, A. kuehniella e S. cerealella, senda maior nos hospedeiros alternativos. A razão sexual de T. distinc:tum não foi afetada pela temperatura nem pelo hospedeiro. Em testes de livre escolha, T. distinctum preferiu as hospedeiros alternativos em relação à D. saccharalis, com parasitismo e emergência maiores. O parasitismo foi semelhante nos dois hospedeiros alternativos nas temperaturas mais baixas. A. kuehniella se mostrou mais uniforme com relação ao parasitismo do que S. cerealella, pois T. distinctum naquele hospedeiro foi agressivo também a 30°C. Para D. saccharalis o parasitismo embora reduzido foi maior a 30°C. Nas diferentes faixas de temperatura, a razão sexual se manteve inalterada para D. saccharalis e para os dois hospedeiros alternativos. Nos testes de controle de qualidade, ocorreu uma degeneração da população de T. galloi a partir de F19, com uma menor capacidade de parasitismo. A emergência e a longevidade do parasitóide diminuíram a partir de F15, ocorrendo também a partir daí, uma alteração do padrão normal do ritmo de parasistismo. A partir de F15 devem ser introduzidos insetos do campo para revigorar a população de laboratório.The effect of temperature (18, 20, 22, 25, 30 and 32°C) and of the host Diatraea saccharallis (Fabr., 1794), Anagasta kuehnlella (Zeller, 1879), and Sitotroga cerealella (O1iv., 1819) on two Trichogramma species collected on sugarcane borer eggs - one, Trichogramma distinctum Zucchi, 1988, collected in northeastern Brazil and the other, Trichogramma galloi Zucchi, 1988 collected in Iracemápolis, State of São Paulo - was studied. Laboratory confinement and free choice tests (olfactometer) were carried out: at the same time, the "quality" of the parasitoid produced along generation was studied to determine the time for introducing field populations due to the degeneration of the insect in the laboratory. Based on the results obtained it was concluded that in confinement tests the germicide lamp treatment brought about the drying out of D. saccharalis eggs, reducing the parasitism and the emergence of T. distinctum. Temperature did not affect the parasitism of T. distinctum on D. saccharalis. T. distinctum parasitized the eggs of alternative hosts, preferably un the range of 22 to 25°C. The percentage of emergence of T. distinctum was similar at different temperatures on D. saccharalis, A. kuehniella and S. cerealella, and it was higher on alternative hosts. The sexual ratio of T. distinctum was not affected by temperature nor by host. In free choice tests, T. distinctum preferred the alternative hosts to D. saccharalis, with greater parasitism and emergence. Parasitism was similar on the two alternative hosts at lower temperatures. A. kuehniella was shown to be more uniform with regard to parasitism than S. cerealella, since T. distinctum on that host was aggressive also at 30°C. Under different temperature ranges the sexual ratio was maintained unchanged D. saccharalis and for the two alternative hosts. In the quality control tests a degeneration of the T. galloi occurred starting from F19, with a capacity. Also, starting from F15, lower the emergence population parasitism and the longevity of the parasitoid decreased and there was an alteration in the normal pattern of the rate of parasitism. Field insects should be introduced starting from F15 to reinvigorate the laboratory population

Bases for managing the resistance of blattella germanica (L., 1767) (Dictyoptera: Blattellidae) to insecticides.

Bases para a implementação de um programa de manejo da resistência de Blattella germanica (L.) a inseticidas foram coletadas no presente trabalho. Técnicas de bioensaio de aplicação tópica e de contato tarsal foram comparadas inicialmente para a detecção da resistência a deltametrina e clorpirifós. O bioensaio de aplicação tópica possibilitou uma melhor discriminação entre a linhagem suscetível e as populações de campo de B. germanica testadas. Resultados do monitoramento da suscetibilidade de B. germanica a inseticidas evidenciaram a presença de variabilidade genética que confere resistência a deltametrina, clorpirifós e fipronil em populações coletadas em alguns estabelecimentos comerciais dos Estados de São Paulo e Rio de Janeiro. As razões de resistência encontradas para deltametrina e clorpirifós foram de aproximadamente 43 e 6 vezes, respectivamente. A resistência de B. germanica a deltametrina foi instável, ou seja, houve uma redução significativa na freqüência de resistência na ausência de pressão de seleção. Estudos de relações de resistência cruzada revelaram uma baixa intensidade de resistência cruzada (aproximadamente 2 vezes) entre fipronil e os inseticidas deltametrina e clorpirifós. E por último, a mistura de deltametrina e clorpirifós foi avaliada para o controle de linhagens de B. germanica resistentes a deltametrina. A mistura proporcionou um melhor controle da linhagem suscetível do que os produtos utilizados isoladamente. No entanto, a discriminação entre as linhagens suscetível e resistente a deltametrina foi evidente com a mistura nas doses recomendadas comercialmente, o que inviabilizaria o emprego desta estratégia no manejo da resistência de B. germanica a deltametrina.Bases for implementing a resistance management program of Blattella germanica (L.) to insecticides were collected in this study. Initially, we compared the topical and residual tarsal-contact bioassays for detecting resistance to deltamethrin and chlorpyrifos. The topical bioassay gave better discrimination between susceptible and field-collected populations of B. germanica. Results from a survey of the susceptibility of B. germanica to insecticides revealed the presence of genetic variability that confers resistance to deltamethrin, chlorpyrifos and fipronil in field-collected populations of B. germanica from the States of São Paulo and Rio de Janeiro. The resistance ratios to deltamethrin and chlorpyrifos were approximately 43 and 6-fold, respectively. The resistance of B. germanica to deltamethrin was unstable; that is, a significant reduction in the frequency of resistance was detected under absence of selection pressure. Studies on cross-resistance relationships showed a low intensity of cross-resistance (approximately 2-fold) between fipronil and the insecticides deltamethrin and chlorpyrifos. And finally, the viabilility of the use of deltamethrin and chlorpyrifos mixture was evaluated for controlling deltamethrin-resistant strains of B. germanica. The use of mixtures gave better control of the susceptible strain than the use of the products by itself. However, the discrimination between susceptible and resistant strains was clear with the use of mixtures at recommended rates, which impairs the use of this strategy for managing B. germanica resistance to deltamethrin

Influence of generation in laboratory) temperature and host in the parasitism of two Trichogramma (Hym.: Grammatidae) species colleted on Diatraea saccharallis (Fabr.) 1794) (Lep.: Pyralidae)

Foi estudado o efeito da temperatura (18, 20, 22. 25, 30 e 32°C) e do hospedeiro Diatraea saccharalis (Fabr., 1794), Anagasta kuehniella (Zeller, 1879) e Sitotroga cerealella (Oliv., 1819) sobre duas espécies de Thichogramma, coletadas em ovos da broca da cana-de-açúcar uma delas, Thichogramma distinctum Zucchi, 1988 foi coleta da no Nordeste do Brasil e a outra, Trichogramma galloiZucchi, 1988 em Iracemápolis, São Paulo. Foram realizados testes de confinamento em laboratório e de livre escolha (olfatômetro); paralelamente, estudou-se a "qualidade" do parasitóide produzido ao longo das gerações, para se determinar o momento da introdução de populações de campo, devido à degeneração do inseto em laboratório. Com base nos resultados obtidos concluiu-se que em testes de confinamento, o tratamento com lâmpada germicida provocou o ressecamento de ovos de D. saccharalis, diminuindo o parasitismo e a emergência de T. distinctum. A temperatura não afetou o parasitismo de T. distictum em D. saccharalis. T. distinctum parasitou os ovos dos hospedeiros alternativos, preferencialmente na faixa de 22 a 25°C. A porcentagem de emergência de T. distinctum foi semelhante nas diferentes temperaturas em D. saccharalis, A. kuehniella e S. cerealella, senda maior nos hospedeiros alternativos. A razão sexual de T. distinc:tum não foi afetada pela temperatura nem pelo hospedeiro. Em testes de livre escolha, T. distinctum preferiu as hospedeiros alternativos em relação à D. saccharalis, com parasitismo e emergência maiores. O parasitismo foi semelhante nos dois hospedeiros alternativos nas temperaturas mais baixas. A. kuehniella se mostrou mais uniforme com relação ao parasitismo do que S. cerealella, pois T. distinctum naquele hospedeiro foi agressivo também a 30°C. Para D. saccharalis o parasitismo embora reduzido foi maior a 30°C. Nas diferentes faixas de temperatura, a razão sexual se manteve inalterada para D. saccharalis e para os dois hospedeiros alternativos. Nos testes de controle de qualidade, ocorreu uma degeneração da população de T. galloi a partir de F19, com uma menor capacidade de parasitismo. A emergência e a longevidade do parasitóide diminuíram a partir de F15, ocorrendo também a partir daí, uma alteração do padrão normal do ritmo de parasistismo. A partir de F15 devem ser introduzidos insetos do campo para revigorar a população de laboratório.The effect of temperature (18, 20, 22, 25, 30 and 32°C) and of the host Diatraea saccharallis (Fabr., 1794), Anagasta kuehnlella (Zeller, 1879), and Sitotroga cerealella (O1iv., 1819) on two Trichogramma species collected on sugarcane borer eggs - one, Trichogramma distinctum Zucchi, 1988, collected in northeastern Brazil and the other, Trichogramma galloi Zucchi, 1988 collected in Iracemápolis, State of São Paulo - was studied. Laboratory confinement and free choice tests (olfactometer) were carried out: at the same time, the "quality" of the parasitoid produced along generation was studied to determine the time for introducing field populations due to the degeneration of the insect in the laboratory. Based on the results obtained it was concluded that in confinement tests the germicide lamp treatment brought about the drying out of D. saccharalis eggs, reducing the parasitism and the emergence of T. distinctum. Temperature did not affect the parasitism of T. distinctum on D. saccharalis. T. distinctum parasitized the eggs of alternative hosts, preferably un the range of 22 to 25°C. The percentage of emergence of T. distinctum was similar at different temperatures on D. saccharalis, A. kuehniella and S. cerealella, and it was higher on alternative hosts. The sexual ratio of T. distinctum was not affected by temperature nor by host. In free choice tests, T. distinctum preferred the alternative hosts to D. saccharalis, with greater parasitism and emergence. Parasitism was similar on the two alternative hosts at lower temperatures. A. kuehniella was shown to be more uniform with regard to parasitism than S. cerealella, since T. distinctum on that host was aggressive also at 30°C. Under different temperature ranges the sexual ratio was maintained unchanged D. saccharalis and for the two alternative hosts. In the quality control tests a degeneration of the T. galloi occurred starting from F19, with a capacity. Also, starting from F15, lower the emergence population parasitism and the longevity of the parasitoid decreased and there was an alteration in the normal pattern of the rate of parasitism. Field insects should be introduced starting from F15 to reinvigorate the laboratory population

Mistura de deltametrina e clorpirifós no manejo da resistência de Blattella germanica (Linnaeus, 1757) (Dictyoptera: Blattellidae) a deltametrina

The viabilility of the use of deltamethrin and chlorpyrifos mixture for managing B. germanica resistance to deltamethrin was evaluated on susceptible and resistant strains of B. germanica by residual tarsal-contact bioassay. The following treatments were evaluated: (a) 12.5 mg deltamethrin/m2; (b) 240 mg chlorpyrifos/m2; (c) mixture of 12.5 mg deltamethrin + 120 mg chlorpyrifos/m2; (d) mixture of 12.5 mg deltamethrin + 240 mg chlorpyrifos/m2 and (e) control. The application of the treatments was done on tiles. The infestations of German cockroaches on treated-tiles were done on 0, 7, 14, 28, 35 and 42-day old residues. The use of mixtures gave better control of the susceptible strain than the use of the products by itself. In the mixture of 120 mg of chlorpyrifos (half of the recommended rate) in 12.5 mg of deltamethrin/m2, the discrimination of the strains was detected from 14-day old residues and with 240 mg of chlorpyrifos in the mixture, the discrimination was possible only with 42-day old residues. Thus, the commercial recommended rates of deltamethrin and chlorpyrifos in the mixture (12.5 mg deltamethrin + 120 mg chlorpyrifos/m2) should be revaluated for managing B. germanica resistance to deltamethrin

Mistura de deltametrina e clorpirifós no manejo da resistência de Blattella germanica (Linnaeus, 1757) (Dictyoptera: Blattellidae) a deltametrina

The viabilility of the use of deltamethrin and chlorpyrifos mixture for managing B. germanica resistance to deltamethrin was evaluated on susceptible and resistant strains of B. germanica by residual tarsal-contact bioassay. The following treatments were evaluated: (a) 12.5 mg deltamethrin/m2; (b) 240 mg chlorpyrifos/m2; (c) mixture of 12.5 mg deltamethrin + 120 mg chlorpyrifos/m2; (d) mixture of 12.5 mg deltamethrin + 240 mg chlorpyrifos/m2 and (e) control. The application of the treatments was done on tiles. The infestations of German cockroaches on treated-tiles were done on 0, 7, 14, 28, 35 and 42-day old residues. The use of mixtures gave better control of the susceptible strain than the use of the products by itself. In the mixture of 120 mg of chlorpyrifos (half of the recommended rate) in 12.5 mg of deltamethrin/m2, the discrimination of the strains was detected from 14-day old residues and with 240 mg of chlorpyrifos in the mixture, the discrimination was possible only with 42-day old residues. Thus, the commercial recommended rates of deltamethrin and chlorpyrifos in the mixture (12.5 mg deltamethrin + 120 mg chlorpyrifos/m2) should be revaluated for managing B. germanica resistance to deltamethrin

Mistura de deltametrina e clorpirif\uf3s no manejo da resist\ueancia de Blattella germanica (Linnaeus, 1757) (Dictyoptera: Blattellidae) a deltametrina

SALMERON E, OMOTO C. 2004. Mixture of deltamethrin and chlorpyrifos for managing Blattella germanica (Linnaeus, 1757) (Dictyoptera: Blattellidae) resistance to deltamethrin. Entomotropica 19(2):85-89. The viabilility of the use of deltamethrin and chlorpyrifos mixture for managing B. germanica resistance to deltamethrin was evaluated on susceptible and resistant strains of B. germanica by residual tarsal-contact bioassay. The following treatments were evaluated: (a) 12.5 mg deltamethrin/m2; (b) 240 mg chlorpyrifos/m2; (c) mixture of 12.5 mg deltamethrin + 120 mg chlorpyrifos/m2; (d) mixture of 12.5 mg deltamethrin + 240 mg chlorpyrifos/m2 and (e) control. The application of the treatments was done on tiles. The infestations of German cockroaches on treated-tiles were done on 0, 7, 14, 28, 35 and 42-day old residues. The use of mixtures gave better control of the susceptible strain than the use of the products by itself. In the mixture of 120 mg of chlorpyrifos (half of the recommended rate) in 12.5 mg of deltamethrin/ m2, the discrimination of the strains was detected from 14-day old residues and with 240 mg of chlorpyrifos in the mixture, the discrimination was possible only with 42-day old residues. Thus, the commercial recommended rates of deltamethrin and chlorpyrifos in the mixture (12.5 mg deltamethrin + 120 mg chlorpyrifos/m2) should be revaluated for managing B. germanica resistance to deltamethrin.SALMERON E, OMOTO C. 2004. Mistura de deltametrina e clorpirif\uf3s no manejo da resist\ueancia de Blattella germanica (Linnaeus, 1757) (Dictyoptera: Blattellidae) a deltametrina. Entomotropica 19(2):85-89. A viabilidade do uso da mistura de deltametrina e clorpirif\uf3s no manejo da resist\ueancia de B. germanica a deltametrina foi avaliada a partir de um bioensaio de contato tarsal com as linhagens suscet\uedvel e resistente de B. germanica a deltametrina. Os tratamentos testados foram (a) 12,5 mg deltametrina/m2; (b) 240 mg clorpirif\uf3s/m2; (c) mistura de 12,5 mg deltametrina + 120 mg clorpirif\uf3s/m2; (d) mistura de 12,5 mg deltametrina + 240 mg clorpirif\uf3s/m2 e (e) controle. A aplica\ue7\ue3o dos tratamentos foi realizada sobre azulejos. As infesta\ue7\uf5es de baratas sobre os azulejos tratados foram realizadas com res\uedduos de 0, 7, 14, 21, 28, 35 e 42 dias de idade. A mistura proporcionou um melhor controle da linhagem suscet\uedvel do que os produtos utilizados isoladamente. No tratamento da mistura de 120 mg de clorpirif\uf3s (metade da dose recomendada) com 12,5 mg deltametrina/m2, a sobreviv\ueancia de indiv\uedduos resistentes a deltametrina foi observada logo a partir de res\uedduos com 14 dias de idade, ao passo que com 240 mg clorpirif\uf3s na mistura, a sele\ue7\ue3o a favor de indiv\uedduos resistentes a deltametrina ocorreu somente a partir de res\uedduos com 42 dias de idade. Portanto, a mistura de deltametrina e clorpirif\uf3s nas doses atualmente recomendadas (12,5 mg deltametrina + 120 mg clorpirif\uf3s/m2) deve ser reavaliada para o manejo da resist\ueancia de B. germanica a deltametrina

Mistura de deltametrina e clorpirifós no manejo da resistência de Blattella germanica (Linnaeus, 1757) (Dictyoptera: Blattellidae) a deltametrina

SALMERON E, OMOTO C. 2004. Mixture of deltamethrin and chlorpyrifos for managing Blattella germanica   (Linnaeus, 1757) (Dictyoptera: Blattellidae) resistance to deltamethrin. Entomotropica 19(2):85-89. The viabilility of the use of deltamethrin and chlorpyrifos mixture for managing B. germanica resistance to deltamethrin was evaluated on susceptible and resistant strains of B. germanica by residual tarsal-contact bioassay. The following treatments were evaluated: (a) 12.5 mg deltamethrin/m2; (b) 240 mg chlorpyrifos/m2; (c) mixture of 12.5 mg deltamethrin + 120 mg chlorpyrifos/m2; (d) mixture of 12.5 mg deltamethrin + 240 mg chlorpyrifos/m2 and (e) control. The application of the treatments was done on tiles. The infestations of German cockroaches on treated-tiles were done on 0, 7, 14, 28, 35 and 42-day old residues. The use of mixtures gave better control of the susceptible strain than the use of the products by itself. In the mixture of 120 mg of chlorpyrifos (half of the recommended rate) in 12.5 mg of deltamethrin/ m2, the discrimination of the strains was detected from 14-day old residues and with 240 mg of chlorpyrifos in the mixture, the discrimination was possible only with 42-day old residues. Thus, the commercial recommended rates of deltamethrin and chlorpyrifos in the mixture (12.5 mg deltamethrin + 120 mg chlorpyrifos/m2) should be revaluated for managing B. germanica resistance to deltamethrin

Biological activity of Bt proteins expressed in different structures of transgenic corn against Spodoptera frugiperda

ABSTRACT: Spodoptera frugiperda (J. E. Smith) is the main target pest of Bt corn technologies, such as YieldGard VT PRO(tm) (Cry1A.105/Cry2Ab2) and PowerCore(tm) (Cry1A.105/Cry2Ab2/Cry1F). In this study, it was evaluated the biological activity of Bt proteins expressed in different plant structures of YieldGard VT PRO(tm) and PowerCore(tm) corn against S. frugiperda . Complete mortality of S. frugiperda neonates was observed on leaf-disc of both Bt corn technologies. However, the mortality in silks and grains was lower than 50 and 6%, respectively. In addition, more than 49% of the surviving larvae in silks and grains completed the biological cycle. However, all life table parameters were negatively affected in insects that developed in silks and grains of both Bt corn events. In summary, the low biological activity of Bt proteins expressed on silks and grains of YieldGard VT PRO(tm) and PowerCore(tm) corn can contribute to the resistance evolution in S. frugiperda populations

Cross-Resistance between Cry1 Proteins in Fall Armyworm (Spodoptera frugiperda) May Affect the Durability of Current Pyramided Bt Maize Hybrids in Brazil.

Genetically modified plants expressing insecticidal proteins from Bacillus thuringiensis (Bt) offer valuable options for managing insect pests with considerable environmental and economic benefits. Despite the benefits provided by Bt crops, the continuous expression of these insecticidal proteins imposes strong selection for resistance in target pest populations. Bt maize (Zea mays) hybrids have been successful in controlling fall armyworm (Spodoptera frugiperda), the main maize pest in Brazil since 2008; however, field-evolved resistance to the protein Cry1F has recently been reported. Therefore it is important to assess the possibility of cross-resistance between Cry1F and other Cry proteins expressed in Bt maize hybrids. In this study, an F2 screen followed by subsequent selection on MON 89034 maize was used to select an S. frugiperda strain (RR) able to survive on the Bt maize event MON 89034, which expresses the Cry1A.105 and Cry2Ab2 proteins. Field-collected insects from maize expressing the Cry1F protein (event TC1507) represented most of the positive (resistance allele-containing) (iso)families found. The RR strain showed high levels of resistance to Cry1F, which apparently also conferred high levels of cross resistance to Cry1A.105 and Cry1Ab, but had only low-level (10-fold) resistance to Cry2Ab2. Life history studies to investigate fitness costs associated with the resistance in RR strain revealed only small reductions in reproductive rate when compared to susceptible and heterozygous strains, but the RR strain produced 32.2% and 28.4% fewer females from each female relative to the SS and RS (pooled) strains, respectively. Consistent with the lack of significant resistance to Cry2Ab2, MON 89034 maize in combination with appropriate management practices continues to provide effective control of S. frugiperda in Brazil. Nevertheless, the occurrence of Cry1F resistance in S. frugiperda across Brazil, and the cross-resistance to Cry1Ab and Cry1A.105, indicates that current Cry1-based maize hybrids face a challenge in managing S. frugiperda in Brazil and highlights the importance of effective insect resistance management for these technologies

Comparison of fitness components of life stages of <i>S</i>. <i>frugiperda</i> strains reared on non-Bt corn.

<p>Within each development stage, bars with the same letter are not significantly different (LSD <i>t</i>-test; <i>P</i> > 0.05).</p