Susceptibility of adults of the cerambycid beetle Hedypathes betulinus to the entomopathogenic fungi Beauveria bassiana, Metarhizium anisopliae, and Purpureocillium lilacinum.

The cerambycid beetle Hedypathes betulinus (Klug) (Coleoptera: Cerambycidae) causes severe damage to yerba mate plants (Ilex paraguariensis (St. Hilaire) (Aquifoliales: Aquifoliaceae)), which results in large losses of production. In this study, the pathogenicity of entomopathogenic fungi of the species Beauveria bassiana (Balsamo-Crivelli) Vuillemin (Hypocreales: Cordycipitaceae), Metarhizium anisopliae sensu lato (Metschnikoff) Sorokin (Hypocreales: Clavicipitaceae), and Purpureocillium lilacinum (Thom) Luangsa-ard, Hywel-Jones, Houbraken and Samson (Hypocreales: Ophiocordycipitaceae) on yerba mate were evaluated. Fifteen isolates of B. bassiana, two of M. anisopliae, and seven of P. lilacinum on H. betulinus adults were analyzed under laboratory conditions. The raw mortality rate caused by B. bassiana isolates varied from 51.1 to 86.3%, and their LT50 values varied between 8.7 and 13.6 d. The isolates of M. anisopliae caused 69.6‒81.8% mortality, and their LT50 values varied between 7.4 and 7.9 d. In contrast, isolates of P. lilacinum were not pathogenic. M. anisopliae and B. bassiana isolates were pathogenic against H. betulinus adults, suggesting that they may be useful in biological control programs for insect pests of yerba mate.

[Presence-absence sampling plan for Oligonychus yothersi (McGregor) (Acari: Tetranychidae) on mate-tea orchard]. / Plano de amostragem presença-ausência para Oligonychus yothersi (McGregor) (Acari: Tetranychidae) na cultura da erva-mate.

Mite infestations to the culture of mate-tea frequently causes losses by the premature fall of the leaves. So, it is necessary to monitor the population of these arthropods, and to adopt management strategies for their control. The objective of this research was to evaluate the trustworthiness of presence-absence sampling for Oligonychus yothersi (McGregor) on mate-tea orchard. This study was conducted in Cascavel, Paraná State, from April 2001 to July 2000, in a mate-tea tree commercial plantation. Biweekly sampling of 240 leaves were collected in different parts of 10 plants, and the number of mites was counted. The aggregation pattern was determined through the coefficients a and b of Taylor's power law. The proportion of infested leaves and the number of required samples were estimated through mathematical model. The mite O. yothersi presented aggregate distribution. The proportion of infested leaves calculated by means of mathematical model showed to be a trustworthy parameter to estimate the population density of the mite. The number of required samples was small, making feasible the practical application of the presence-absence sampling method for O. yothersi in the culture of mate-tea.

Plano de amostragem presença-ausência para Oligonychus yothersi (McGregor) (Acari: Tetranychidae) na cultura da erva-mate / Presence-absence sampling plan for Oligonychus yothersi (McGregor) (Acari: Tetranychidae) on mate-tea orchard

O ataque de ácaros na cultura da erva-mate tem freqüentemente provocado perdas pela queda precoce das folhas. Assim, há necessidade de se monitorar a população desses artrópodes e adotar estratégias de manejo. O objetivo deste trabalho foi avaliar a confiabilidade da amostragem presença-ausência para Oligonychus yothersi (McGregor) na erva-mate. O trabalho foi realizado em um erval comercial, em Cascavel, PR, de abril de 1999 a julho de 2000. Coletas quinzenais de 240 folhas foram feitas em diferentes partes de 10 plantas escolhidas ao acaso. A contagem dos ácaros nas folhas foi realizada em laboratório com auxílio de microscópio estereoscópico. Foi determinado o padrão de agregação através dos coeficientes a e b da lei da potência de Taylor; a proporção de folhas infestadas e o número de amostras requeridas foram estimados através de modelo matemático. O. yothersi apresentou distribuição agregada. A proporção de folhas infestadas calculada pelo modelo matemático mostrou ser um parâmetro confiável para estimar a densidade populacional do ácaro. O número de amostras requeridas foi pequeno, viabilizando a aplicação prática do método de amostragem presença-ausência para O. yothersi na cultura da erva-mate.

Mite infestations to the culture of mate-tea frequently causes losses by the premature fall of the leaves. So, it is necessary to monitor the population of these arthropods, and to adopt management strategies for their control. The objective of this research was to evaluate the trustworthiness of presence-absence sampling for Oligonychus yothersi (McGregor) on mate-tea orchard. This study was conducted in Cascavel, Paraná State, from April 2001 to July 2000, in a mate-tea tree commercial plantation. Biweekly sampling of 240 leaves were collected in different parts of 10 plants, and the number of mites was counted. The aggregation pattern was determined through the coefficients a and b of Taylor's power law. The proportion of infested leaves and the number of required samples were estimated through mathematical model. The mite O. yothersi presented aggregate distribution. The proportion of infested leaves calculated by means of mathematical model showed to be a trustworthy parameter to estimate the population density of the mite. The number of required samples was small, making feasible the practical application of the presence-absence sampling method for O. yothersi in the culture of mate-tea.

Dinâmica populacional de ácaros ( Acari ) em erva-mate ( Ilex paraguariensis St. Hil.: Aquifoliaceae ) / Populational dynamics of mites ( Acari ) in the mate-tea tree ( Ilex paraguariensis St. Hil.: Aquifoliaceae )

Este trabalho foi realizado em Dois Vizinhos, PR, com o objetivo de estudar a dinâmica populacional de ácaros fitófagos e seus predadores em plantas de erva-mate (Ilex paraguariensis St. Hil. Aquifoliaceae). Folhas de diferentes partes da planta foram coletadas de agosto de 2001 a julho de 2002, e os ácaros presentes foram contados sob microscópio estereoscópico. Foram encontradas associadas às plantas de erva-mate duas espécies de ácaros fitófagos Dichopelmus notus Keifer, e Oligonychus yothersi (McGregor), e três espécies de predadores identificados como sendo Euseius concordis (Chant), Iphiseiodes zuluagai Denmark & Muma e Agistemus sp. O ácaro D. notus ocorreu em maior número na face inferior de folhas, em folhas maduras e em folhas dos estratos inferior e médio. O. yothersi predominou em folhas maduras. A concentração de E. concordis e I. zuluagai sempre foi maior na face inferior de folhas, em folhas maduras, em folhas dos estratos inferior e médio e na região interna da copa. Os ácaros D. notus, O. yothersi, E. concordis e I. zuluagai tiveram picos populacionais em período de temperatura amena e baixa precipitação pluviométrica. A maior densidade populacional de Agistemus sp. ocorreu na face inferior das folhas e seu pico populacional ocorreu em período de alta temperatura e precipitação pluviométrica elevada.

[Populational dynamics of mites (Acari) in the mate-tea tree (Ilex paraguariensis St. Hil.: Aquifoliaceae)]. / Dinâmica populacional de ácaros (Acari) em erva-mate (Ilex paraguariensis St. Hil.: Aquifoliaceae).

The objective of this research was to analyze the populational dynamic of the phytophagous mites, as well as that of their natural predators in the plants Ilex paraguariensis St. Hil. (Aquifoliaceae). This study was conduced in Dois Vizinhos, State of Paraná, from August 2001 to July 2002. Leaf samples from different parts of the plant were taken and the number of mites was registered. During this period, two species of phytophagous mites, Dichopelmus notus Keifer, and Oligonychus yothersi (McGregor), and three species of predator mites identified as Euseius concordis (Chant), Iphiseiodes zuluagai Denmark & Muma, and Agistemus sp. were related to the mate-tea plant. Large numbers of D. notus appeared on mature leaves and on the inferior face of leaves. The mite was more frequent in the inferior and medium strata. O. yothersi occurred mainly on mature leaves. The concentration of E. concordis e I. zuluagai was higher on the inferior face of the leaves, and on the leaves of inferior and medium strata, as well as in the internal canopy region, and on mature leaves. The highest numbers of D. notus, O. yothersi, E. concordis and I. zuluagai occurred in periods with mild temperatures and little rain precipitation. The largest population density of Agistemus sp. occurred on the inferior face of the leaves, more often in periods of high temperature and heavy rain.

Conidia production of Beauveria sp. by solid-state fermentation for biocontrol of Ilex paraguariensis caterpillars.

Conidia production of Beauveria sp. strain LAG by solid-state fermentation (SSF) using blends of agro-industrial residues (residual potatoes and sugar-cane bagasse) was optimized with respect to cultivation conditions and the composition of substrate mixture in Erlenmeyer flasks and column-type bioreactor. With a blend of 60 % residual potatoes and 40 % sugar-cane bagasse the optimum conditions achieved were: incubation temperature 26 degrees C, initial substrate pH 6, inoculum concentration 10(7) conidia per g substrate; optimal initial moisture of the substrate was 70 % for Erlenmeyer flasks, in column-type bioreactor (with forced aeration) the optimal initial moisture of the substrate was 65 % with airflow of 60 mL/min. The highest production (1.07 x 10(10) conidia per g dry substrate) was achieved after a 10-d fermentation. The conidia were used in laboratory assays against Thelosia camina and Hylesia sp., caterpillars that are serious pests of mate plants. The mortality of T. camina was >90 % 10 d after spraying caterpillars with 1 mL conidia suspension at a concentration 10(5)-10(8)/mL. For Hylesia sp., the mortality was 70 %, 7 d after immersion in the conidia suspension containing 108 conidia per mL. Therefore, the Beauveria sp. LAG can be considered to be an important biocontrol instrument in the prospect of the Integrated Pest Management for mate plants.