Effect of trichomes on the predation of Tetranychus urticae (Acari: Tetranychidae) by Phytoseiulus macropilis (Acari: Phytoseiidae) on tomato, and the interference of webbing.

The two-spotted spider mite, Tetranychus urticae Koch, is an important pest of tomato in different parts of the world. Biological control of this pest on this crop has not been very successful. Phytoseiulus macropilis (Banks) has been used commercially for the control of T. urticae on different crops, but no information has been published on its potential to control T. urticae on tomato. The objective of this work was to compare the performance of a Brazilian population of P. macropilis on tomato with its performance on other plant species, relating the observed variation to the respective types and densities of trichomes. It has been hypothesized that the presence of the webbing produced by T. urticae could help the predator to avoid contact with trichomes and consequently to improve its performance on tomato plants. This hypothesis was also evaluated. Phytoseiulus longipes Evans was included in the work as a control, given that it has been reported to be a promising predator of Tetranychus species on tomato. The study was conducted under laboratory conditions. It was found that the performance of P. macropilis was similar to that of P. longipes and that trichomes hampered the locomotion as well as prey consumption and oviposition rate of both predators; that the presence of webbing resulted in higher levels of prey consumption and of predator oviposition; and that the presence of webbing eliminated the negative effect of trichomes of eggplants and partially eliminated the negative effect of trichomes of the 'cerasiforme' tomato variety. The observed density of trichomes in 'Carmem' one of the most common tomato varieties grown in Brazil, seems not to have interfered significantly with the prey consumption and the oviposition rate of P. macropilis. The results suggest that the latter is a promising predator of T. urticae on tomato. Complementary studies are warranted, to further evaluate the potential of P. macropilis for use as a biological control agent of this pest.

The effects of host, geographic origin, and gender on the thermal requirements of Diaphorina citri (Hemiptera: Psyllidae).

Diaphorina citri Kuwayama (Hemiptera: Psyllidae) is the vector of the bacteria that causes citrus greening and is considered one of the world's most important citrus diseases. We examined how host, geographic region, and gender affect the thermal requirements of D. citri. The insects were reared in climatic chambers at constant temperatures of 18, 20, 22, 25, 28, 30, and 32 +/- 1 degrees C, 70 +/- 10% RH, and a 14 h photophase. Host plants for D. citri included orange (Citrus sinensis [Rutaceae]) varieties Pêra and Natal, the rootstock, Rungpur lime (C. limonia [Rutaceae]) and the natural host, Orange jessamine (Murraya paniculata [Rutaceae]). To study the influence of geographic origin on thermal requirements, we studied D. citri populations from Piracicaba, SP (warmer region) and Itapetininga, SP (cooler region). The duration and survival of the development stages and the duration of the total development (egg-adult) did not differ significantly on the different hosts, but it did vary with temperature. Nymphs of D. citri created on the different hosts have the same thermal requirements. The thermal requirements for this species collected from the two climate regions were identical; males and females also had the same thermal requirements.

[Performance of trichogrammatids as biocontrol agents of Pseudoplusia includens Walker (Lepidoptera: Noctuidae)]. / Desempenho de tricogramatídeos como potenciais agentes de controle de Pseudoplusia includens Walker (Lepidoptera: Noctuidae).

This research aimed to point out the most suitable trichogrammatid strains to control the soybean looper Pseudoplusia includes Walker. Biological parameters and parasitism ratio of 11 Trichogramma pretiosum Riley, one Trichogramma atopovirilia Oatman & Platner and one Trichogrammatoidea annulata De Santis strains reared on P. includens eggs were evaluated. Among all tested strains/species, T. pretiosum strain RV, collected in Rio Verde, GO, had the fastest development cycle and the highest percentage of parasitism of P. includens eggs. There was no difference in the parasitism and in the number of parasitoid emerged per egg among the tested parasitoid species and strains. Accordingly to the cluster analysis, T. pretiosum strain RV reared on P. includens eggs had the best performance. Considering the higher parasitism rate, shorter biological cycle, higher survival and sex ratio, T. pretiosum strain RV is the most appropriated to be used in field releases aiming at P. includens control.

Desempenho de tricogramatídeos como potenciais agentes de controle de Pseudoplusia includens Walker (Lepidoptera: Noctuidae) / Performance of trichogrammatids as biocontrol agents of Pseudoplusia includens Walker (Lepidoptera: Noctuidae)

Este estudo objetivou selecionar as linhagens de tricogramatídeos mais adequadas ao controle da lagarta falsa-medideira, Pseudoplusia includens Walker. Foram avaliados os parâmetros biológicos e a taxa de parasitismo de 11 linhagens de Trichogramma pretiosum Riley, uma linhagem de Trichogramma atopovirilia Oatman & Platner e uma linhagem de Trichogrammatoidea annulata De Santis, criadas em ovos de P. includens. Entre as espécies/linhagens avaliadas, a linhagem T. pretiosum RV, coletada em Rio Verde, GO, apresentou o ciclo de desenvolvimento mais rápido e a maior porcentagem de parasitismo em ovos de P. includens. Não houve diferença no parasitismo e no número de parasitóides emergidos por ovo entre as espécies e linhagens de parasitóides avaliadas. De acordo com a análise de agrupamento (cluster analysis), a linhagem RV criada em ovos de P. includens teve o melhor desempenho. Apresentou maior taxa de parasitismo, menor duração do ciclo biológico, alta sobrevivência e predominância de fêmeas, sendo a mais indicada a ser utilizada em liberações de campo visando ao controle de P. includens.

This research aimed to point out the most suitable trichogrammatid strains to control the soybean looper Pseudoplusia includes Walker. Biological parameters and parasitism ratio of 11 Trichogramma pretiosum Riley, one Trichogramma atopovirilia Oatman & Platner and one Trichogrammatoidea annulata De Santis strains reared on P. includens eggs were evaluated. Among all tested strains/species, T. pretiosum strain RV, collected in Rio Verde, GO, had the fastest development cycle and the highest percentage of parasitism of P. includens eggs. There was no difference in the parasitism and in the number of parasitoid emerged per egg among the tested parasitoid species and strains. Accordingly to the cluster analysis, T. pretiosum strain RV reared on P. includens eggs had the best performance. Considering the higher parasitism rate, shorter biological cycle, higher survival and sex ratio, T. pretiosum strain RV is the most appropriated to be used in field releases aiming at P. includens control.

[Vertical distribution, damage and cultural control of Stenoma catenifer Walsingham (Lepidoptera: Elachistidae) in avocado grove]. / Distribuição vertical, danos e controle cultural de Stenoma catenifer Walsingham (Lepidoptera: Elachistidae) em pomar de abacate.

Stenoma catenifer Walsingham is the major pest in avocado groves (Persea americana Mill.) in the Neotropical region. Management has been difficult for many reasons related to the reduced knowledge on its bioecology and the avocado growing systems. The goal of this work was to study the vertical distribution of S. catenifer in avocado plants, the gagging effect of infested fruit on its survival, and the losses caused. The experiments were conducted in a commercial grove located at the São Tomás de Aquino, State of Minas Gerais, Brazil, during the 2001/2002 and 2002/2003 growing season. S. catenifer was observed especially at the lower and central part of the plant, and the inner canopy was the least attacked in comparison with the north, south, east and west quadrants. These results may be important indicators for the use of am adequate sampling procedure. The highest percentage of attacked fruit had one to four larvae; in some cases up to eight individuals per fruit were found. The losses caused by the borer varied during the agricultural season, with figures close to 5% in a single evaluation, and the harvest loss may reach 27%. The bagging of infested fruit caused mortality of S. catenifer, as observed through the evaluation carried out four days later.

Distribuição vertical, danos e controle cultural de Stenoma catenifer Walsingham (Lepidoptera: Elachistidae) em pomar de abacate / Vertical distribution, damage and cultural control of Stenoma catenifer Walsingham (Lepidoptera: Elachistidae) in avocado grove

Stenoma catenifer Walsingham é a principal praga do abacateiro (Persea americana Mill.) na região Neotropical. O seu manejo tem sido dificultado por fatores relacionados à falta de conhecimento da sua bioecologia e aos sistemas de condução dos pomares. O objetivo deste trabalho foi estudar a distribuição vertical de S. catenifer em abacateiros, os danos ocasionados devido ao seu ataque e o efeito do ensacamento de frutos infestados, na sua sobrevivência. Os experimentos foram conduzidos num pomar comercial, situado no município de São Tomás de Aquino, MG, durante as safras agrícolas 2001/2002 e 2002/2003. A distribuição vertical de ataque de S. catenifer foi observada especialmente na altura inferior e média da planta, sendo que o interior da copa foi o local menos atacado quando comparado com os quadrantes norte, sul, leste e oeste. Esses resultados podem dar importante subsídio para amostragem da praga. A maior porcentagem dos frutos atacados possuía de uma a quatro lagartas, havendo casos em que foram encontrados até oito indivíduos por fruto. As perdas ocasionadas pela broca variaram ao longo do tempo, atingindo valores próximos de 5 por cento numa única avaliação, sendo que, a perda na safra alcançou 27 por cento. O ensacamento dos frutos infestados ocasionou a mortalidade das lagartas de S. catenifer, na avaliação realizada quatro dias depois.

Stenoma catenifer Walsingham is the major pest in avocado groves (Persea americana Mill.) in the Neotropical region. Management has been difficult for many reasons related to the reduced knowledge on its bioecology and the avocado growing systems. The goal of this work was to study the vertical distribution of S. catenifer in avocado plants, the gagging effect of infested fruit on its survival, and the losses caused. The experiments were conducted in a commercial grove located at the São Tomás de Aquino, State of Minas Gerais, Brazil, during the 2001/2002 and 2002/2003 growing season. S. catenifer was observed especially at the lower and central part of the plant, and the inner canopy was the least attacked in comparison with the north, south, east and west quadrants. These results may be important indicators for the use of am adequate sampling procedure. The highest percentage of attacked fruit had one to four larvae; in some cases up to eight individuals per fruit were found. The losses caused by the borer varied during the agricultural season, with figures close to 5 percent in a single evaluation, and the harvest loss may reach 27 percent. The bagging of infested fruit caused mortality of S. catenifer, as observed through the evaluation carried out four days later.

Resíduos de tiametoxam, aldicarbe e de seus metabólitos em folhas de cafeeiro e efeito no controle de Leucoptera coffeella (Guérin-Mèneville) (Lepidoptera: Lyonetiidae) / Residues of thiamethoxam, aldicarb and its metabolites in coffee leaves and effect on the Control of Leucoptera coffeella (Guérin-Mèneville) (Lepidoptera: Lyonetiidae)

O bicho-mineiro Leucoptera coffeella (Guérin-Mèneville), uma das pragas mais importantes da cafeicultura brasileira, é controlado principalmente com inseticidas. O objetivo deste trabalho foi estudar os resíduos e a translocação do inseticida tiametoxam em folhas de cafeeiros, bem como avaliar seu efeito no controle do bicho-mineiro, comparando-o com o aldicarbe, utilizado como padrão. Para isto, foi instalado um experimento no município de Garça, SP, no período de dezembro/2001 a agosto/2002. Os tratamentos utilizados foram: aldicarbe 150 G, nas doses de 2,25 e 4,50 g i.a./cova, tiametoxam 10 GR, nas doses de 0,15 e 0,30 g i.a./cova e testemunha (sem aplicação). Amostras de ramos foram colhidas em pré-contagem e aos 30, 60, 90, 120, 150, 180, 210 e 240 dias após a aplicação, em três alturas dos cafeeiros (terços inferior, médio e superior), avaliando-se a porcentagem de folhas minadas. As determinações de aldicarbe e seus metabólitos ativos, aldicarbe sulfoxido e sulfona, e os de tiametoxam foram feitas por cromatografia em fase gasosa usando-se detector de nitrogênio-fósforo e de espectrometria de massas, respectivamente. Os resultados indicaram translocação uniforme de ambos inseticidas nos três terços das plantas de café, quando aplicados no solo. Foi constatada também, a maior persistência do tiametoxam, cujos resíduos foram encontrados até oito meses após a aplicação, enquanto os metabólitos sulfóxido e sulfona foram encontrados entre quatro e seis meses após a aplicação. Foi observado controle do bicho-mineiro pela aplicação de ambos inseticidas.

[Residues of thiamethoxam, aldicarb and its metabolites in coffee leaves and effect on the control of Leucoptera coffeella (Guérin-Mèneville) (Lepidoptera: Lyonetiidae)]. / Residuos de tiametoxam, aldicarbe e de seus metabólitos em folhas de cafeeiro e efeito no controle de Leucoptera coffeella (Guérin-Mèneville) (Lepidoptera: Lyonetiidae).

The coffee leaf miner Leucoptera coffeella (Guérin-Mèneville), one of the major pests of coffee crops in Brazil, is mainly controlled with insecticides. The objective of this study was to evaluate the residues and the translocation of the insecticide thiamethoxam in coffee leaves, as well as to study its effect on the coffee leaf miner control, comparing it with aldicarb, used as standard. One experiment was set up in the county of Garça, SP from December/2001 to August/2002. The treatments used were: aldicarb 150 G at the rates of 2.25 and 4.50 g a.i./pit, thiamethoxam 10 GR, at the rates of 0.15 and 0.30 g a.i./pit and check. Twig samples were collected prior to and 30 , 60, 90, 120, 150, 180, 210 and 240 days after the application, at three coffee plant heights (lower, middle and upper third), and the percentage of mined leaves was evaluated. The determination of aldicarb residues, including their sulphoxide and sulfone metabolites and of thiamethoxam were performed by gas chromatography with a nitrogen-phosphorus and mass spectrometer detectors, respectively. The results indicated a uniform translocation of both insecticides in all three thirds of the coffee plants when applied to the soil. A higher persistence of thiamethoxam was verified with its residues being found for as far long as eight months following the application, while aldicarb residues, including the sulphoxide and sulfone metabolites, were found only until four to six months after the application. Control of the coffee leaf miner was observed with both insecticides.