RESUMO

BACKGROUND: White and colored fiber cotton cultivars have been developed to increase production and opportunities for family farming. The broad mite, Polyphagotarsonemus latus (Banks) is an important pest in cotton crops, nevertheless, different cotton cultivars may influence its host selection and population growth. For P. latus control, acaricides application is commonly performed, although less is known about the sublethal effects of these products. Thus, the host preference and instantaneous rate of increase (ri ) of P. latus were evaluated on white and colored cotton cultivars, as well as the lethal and sublethal effects of acaricides through mortality tests and population growth. RESULTS: In free-choice tests to evaluate host preference among white and colored cotton cultivars, no preference was observed for P. latus. The instantaneous ri values were positive for all tested cultivars, however, differences were observed between the colored BRS Rubi and the white BRS 201. The population growth of P. latus decreased with increasing concentrations of the acaricides abamectin, spirodiclofen, azadirachtin and spiromesifen. Nevertheless, azadirachtin and spiromesifen presented positive ri values even at the highest lethal concentrations (LC90 ), while abamectin and spirodiclofen provided negative ri values of P. latus from LC90 and LC70 , respectively. CONCLUSION: No host preference of P. latus was observed among white and colored cotton cultivar. Abamectin and spirodiclofen presented relevant sublethal effects that should be considered for the integrated management of this pest.

Assuntos

RESUMO

BACKGROUND: The evaluation of lethal and sublethal effects is of great importance for a complete assessment of the total impact of chemical compounds upon pest populations and the development of management strategies. In this study, we evaluated the lethal and sublethal effects of different synthetic and botanical products on the broad mite Polyphagotarsonemus latus (Banks), a major pest of Capsicum annuum L. and other crops. RESULTS: Abamectin had the highest lethal effect on P. latus, followed by spiromesifen, azadirachtin, neem oil and nitrogen fertiliser + citric acid. The sublethal effects of the products were indicated by the influence on mite population growth, affecting the numbers of females, males, larvae, pupae and eggs. Furthermore, a negative instantaneous rate of increase in P. latus and repellent effects were observed. CONCLUSION: The lethal and sublethal effects of abamectin, spiromesifen, azadirachtin and neem oil significantly affect P. latus population growth, as well as causing repellence to this mite on C. annuum, and they should be considered in the integrated pest management of this mite. © 2017 Society of Chemical Industry.

Assuntos

RESUMO

This study was performed under laboratory conditions to identify isolates of the fungus Beauveria spp. that can control Polyphagotarsonemus latus in the greenhouse and field. Thirty Beauveria spp. isolates were tested by spraying 1 mL conidia (1 × 108 conidia/mL) on pepper leaf discs containing 15 mites. Evaluations were performed on the 3rd and 6th day post application by counting the number of dead mites. Vegetative growth and conidial production were measured from the selected isolates, and bioassays were conducted in the greenhouse on bean seedlings in plastic pots. The isolate Unioeste 53 was selected, and a conidial suspension (1 × 108 conidia/mL) was applied with a backpack sprayer. The evaluation consisted of pre- and post-treatment counts of the number of live mites on ten leaflets in both the plots treated with the fungus and control plots, and the same procedure was followed for the field experiment. In the laboratory, the Unioeste 53 isolate resulted in total and confirmed mortality rates of 70% and 57.7%, respectively. In the greenhouse, the population decreased by 76.71% by the 16th day after application. In the field, the population decreased by 66% by the 12th day after application, demonstrating the potential of this fungus for mite management.(AU)

Este trabalho teve por objetivo selecionar isolados do fungo Beauveria bassiana em condições de laboratório com potencial de uso em casa de vegetação e campo no controle do ácaro branco. Foi realizada uma seleção com 30 isolados de Beauveria spp. através de pulverização direta de conídios (1 × 108 conídios/mL) sobre discos foliares de pimenta contendo 15 ácaros. As avaliações foram realizadas no terceiro e sexto dia contando-se o número de mortos, e confirmação do patógeno em câmara úmida. Parâmetros de crescimento vegetativo e produção de conídios foram avaliados. No bioensaio em casa de vegetação foram preparados vasos com plantas de feijão e fez-se a aplicação do Unioeste 53 (1 × 108 conídios/mL), utilizando pulverizador costal, a avaliação constou da contagem prévia e posterior à aplicação do número de ácaros vivos em 10 folíolos, tanto nas parcelas destinadas ao tratamento com fungo, quanto na testemunha. A fase de campo seguiu os mesmos padrões, porém, com área experimental total de 225 m2, com oito parcelas de 10,24 m2, sendo 4 testemunhas e 4 onde foi aplicado o isolado Unioeste 53 seguindo metodologia de aplicação e avaliação já descritas para casa de vegetação. Em laboratório o isolado Unioeste 53 causou mortalidade total de 70% e 57,7% de mortalidade confirmada. Em casa de vegetação, apresentou redução da população de 76,71% 16 dias após aplicação, já em campo, a redução da população foi de 66% após 12 dias da aplicação, demonstrando o potencial do ácaro pelo fungo.(AU)

Assuntos

RESUMO

Abstract This study was performed under laboratory conditions to identify isolates of the fungus Beauveria spp. that can control Polyphagotarsonemus latus in the greenhouse and field. Thirty Beauveria spp. isolates were tested by spraying 1 mL conidia (1 × 108 conidia/mL) on pepper leaf discs containing 15 mites. Evaluations were performed on the 3rd and 6th day post application by counting the number of dead mites. Vegetative growth and conidial production were measured from the selected isolates, and bioassays were conducted in the greenhouse on bean seedlings in plastic pots. The isolate Unioeste 53 was selected, and a conidial suspension (1 × 108 conidia/mL) was applied with a backpack sprayer. The evaluation consisted of pre- and post-treatment counts of the number of live mites on ten leaflets in both the plots treated with the fungus and control plots, and the same procedure was followed for the field experiment. In the laboratory, the Unioeste 53 isolate resulted in total and confirmed mortality rates of 70% and 57.7%, respectively. In the greenhouse, the population decreased by 76.71% by the 16th day after application. In the field, the population decreased by 66% by the 12th day after application, demonstrating the potential of this fungus for mite management.

Resumo Este trabalho teve por objetivo selecionar isolados do fungo Beauveria bassiana em condições de laboratório com potencial de uso em casa de vegetação e campo no controle do ácaro branco. Foi realizada uma seleção com 30 isolados de Beauveria spp. através de pulverização direta de conídios (1 × 108 conídios/mL) sobre discos foliares de pimenta contendo 15 ácaros. As avaliações foram realizadas no terceiro e sexto dia contando-se o número de mortos, e confirmação do patógeno em câmara úmida. Parâmetros de crescimento vegetativo e produção de conídios foram avaliados. No bioensaio em casa de vegetação foram preparados vasos com plantas de feijão e fez-se a aplicação do Unioeste 53 (1 × 108 conídios/mL), utilizando pulverizador costal, a avaliação constou da contagem prévia e posterior à aplicação do número de ácaros vivos em 10 folíolos, tanto nas parcelas destinadas ao tratamento com fungo, quanto na testemunha. A fase de campo seguiu os mesmos padrões, porém, com área experimental total de 225 m2, com oito parcelas de 10,24 m2, sendo 4 testemunhas e 4 onde foi aplicado o isolado Unioeste 53 seguindo metodologia de aplicação e avaliação já descritas para casa de vegetação. Em laboratório o isolado Unioeste 53 causou mortalidade total de 70% e 57,7% de mortalidade confirmada. Em casa de vegetação, apresentou redução da população de 76,71% 16 dias após aplicação, já em campo, a redução da população foi de 66% após 12 dias da aplicação, demonstrando o potencial do ácaro pelo fungo.

Assuntos

RESUMO

Despite the continued efforts on the search for different genotypes, Capsicum annuum (L.) is quite susceptible to attack by pest arthropods, especially the broad mite Polyphagotarsonemus latus Banks. Thus, the host preference, population growth and the injuries assessment of P. latus was studied on six C. annuum genotypes used in Brazil (Atlantis, California Wonder, Impact, Palloma, Rubia and Tendence). Host preference was accessed in choice tests, pairing the several genotypes, and the population growth was observed through non-choice tests in laboratory. The injuries assessments were evaluated in the greenhouse, comparing the injury level among the six genotypes. The results indicate that California Wonder and Palloma genotypes were more preferred by P. latus, and Impact and Tendence were less preferred. P. latus presented positive population growth rates (ri) on all the genotypes, however, Palloma and California Wonder showed the highest values of population growth rate (ri = 0.344 and ri = 0.340, respectively), while Impact had the lowest value (ri = 0.281). All the evaluated C. annuum genotypes showed low tolerance to P. latus and exhibited several injuries, but there was no statistical difference between them. California Wonder had the highest average number of mites/leaf (57.15), while Impact and Tendence obtained the lowest values (36.67 and 35.12, respectively) at the end of the evaluation period. The total average of injuries notes at the end of the bioassay did not differ between the genotypes. The number of mites/leaf was growing for the injury scale to the note 3.0, but when the injury scale approached the note 4.0, there was observed a decrease in the number of mites/leaf for all the genotypes.

Assuntos

RESUMO

Abstract This study was performed under laboratory conditions to identify isolates of the fungus Beauveria spp. that can control Polyphagotarsonemus latus in the greenhouse and field. Thirty Beauveria spp. isolates were tested by spraying 1 mL conidia (1 × 108 conidia/mL) on pepper leaf discs containing 15 mites. Evaluations were performed on the 3rd and 6th day post application by counting the number of dead mites. Vegetative growth and conidial production were measured from the selected isolates, and bioassays were conducted in the greenhouse on bean seedlings in plastic pots. The isolate Unioeste 53 was selected, and a conidial suspension (1 × 108 conidia/mL) was applied with a backpack sprayer. The evaluation consisted of pre- and post-treatment counts of the number of live mites on ten leaflets in both the plots treated with the fungus and control plots, and the same procedure was followed for the field experiment. In the laboratory, the Unioeste 53 isolate resulted in total and confirmed mortality rates of 70% and 57.7%, respectively. In the greenhouse, the population decreased by 76.71% by the 16th day after application. In the field, the population decreased by 66% by the 12th day after application, demonstrating the potential of this fungus for mite management.

Resumo Este trabalho teve por objetivo selecionar isolados do fungo Beauveria bassiana em condições de laboratório com potencial de uso em casa de vegetação e campo no controle do ácaro branco. Foi realizada uma seleção com 30 isolados de Beauveria spp. através de pulverização direta de conídios (1 × 108 conídios/mL) sobre discos foliares de pimenta contendo 15 ácaros. As avaliações foram realizadas no terceiro e sexto dia contando-se o número de mortos, e confirmação do patógeno em câmara úmida. Parâmetros de crescimento vegetativo e produção de conídios foram avaliados. No bioensaio em casa de vegetação foram preparados vasos com plantas de feijão e fez-se a aplicação do Unioeste 53 (1 × 108 conídios/mL), utilizando pulverizador costal, a avaliação constou da contagem prévia e posterior à aplicação do número de ácaros vivos em 10 folíolos, tanto nas parcelas destinadas ao tratamento com fungo, quanto na testemunha. A fase de campo seguiu os mesmos padrões, porém, com área experimental total de 225 m2, com oito parcelas de 10,24 m2, sendo 4 testemunhas e 4 onde foi aplicado o isolado Unioeste 53 seguindo metodologia de aplicação e avaliação já descritas para casa de vegetação. Em laboratório o isolado Unioeste 53 causou mortalidade total de 70% e 57,7% de mortalidade confirmada. Em casa de vegetação, apresentou redução da população de 76,71% 16 dias após aplicação, já em campo, a redução da população foi de 66% após 12 dias da aplicação, demonstrando o potencial do ácaro pelo fungo.

RESUMO

ABSTRACT Injuries caused by broad mite to the main cotton cultivar and advanced lineages available presently in Brazil were evaluated in three field experiments. In a randomized block design with 6 replications, the plots consisting of a 5-m-long row, the trials were carried out in the 2001/2002 and 2005/2006 season at Campinas, SP, and in 2003/ 2004 at Guaíra, SP, Brazil. A total of 36 different genotypes were used. Sixteen treatments were carried out in 2001/2002 and 2003/2004, and 18 in 2005/2006. Evaluation was performed by attribution of scores from 1 to 5 to the entire plots, according to the level of injury caused to plant leaves. In all the experiments, wide and gradual differences among genotypes were observed, with mean scores varying from 1.77 (IAC 23) to 4.20 (Sure Grow); 1.45 (Coodetec 401) to 4.63 (MG 0110) and 1.86 (FMT 702) to 4.74 (Stoneville 474), respectively in the 2001/2002, 2003/2004 and 2005/2006 trials. Joint analysis involving four cultivars common to the three experiments corroborates the results, indicating IAC 24 and Fibermax 966 as the least affected, and Deltaopal and Makina as the most injured.

RESUMO As injúrias causadas pelo ácaro-branco em cultivares e linhagens avançadas de algodoeiro disponíveis no Brasil foram avaliadas em três experimentos de campo conduzidos em Campinas, SP (2001/2002 e 2005/2006) e em Guairá, SP (2003/2004). As áreas experimentais foram instaladas segundo um delineamento de blocos ao acaso, com seis repetições, sendo as parcelas constituídas por uma linha de 5 m de comprimento. No total, 36 genótipos diferentes foram utilizados. Foram estabelecidos 16 tratamentos em 2001/2002 e 2003/2004 e 18 em 2005/2006. A avaliação foi feita após intensa ocorrência da praga, sem realização de controle químico, sendo atribuídas, em nível de parcelas, notas de 1 a 5, crescentes com o tipo e a intensidade dos sintomas. Verificou-se, nos três experimentos, ampla e gradual diversidade entre os genótipos, com as notas médias variando de 1,77 (IAC 23) até 4,20 (Sure Grow 821) no experimento de 2001/2002, de 1,45 (COODETEC 401) a 4,63 (MG 0110) no experimento de 2003/2004 e de 1,86 (FMT 702) a 4,74 (Stoneville 474) no experimento de 2005/2006. A análise conjunta de quatro genótipos comuns aos três experimentos corroborou as evidências de ampla e gradual diferença entre os genótipos, indicando IAC 24 e Fibermax 966 como menos danificadas e Deltaopal e Makina como as mais afetadas.