A influência da temperatura no desenvolvimento do fungo entomopatogênico Nomuraea rileyi (Farlow) Samson foi estudada em larvas no terceiro estágio de desenvolvimento de Anticarsia gemmatalis (Hübner), mantidas sob regime de temperatura constante. Um modelo não-linear foi utilizado para descrever as taxas de crescimento vegetativo e reprodutivo do fungo. A temperatura requerida para obter o maior crescimento vegetativo foi estimada em 25,5ºC, enquanto os limites mínimo e máximo foram estimados em 11ºC e 30ºC, respectivamente. A taxa de conidiação foi estável dos 18ºC aos 26ºC. As temperaturas mínima e máxima estimadas para o desenvolvimento vegetativo coincidem com as condições ambientais de ocorrência natural na Argentina Central. Efeitos não-lineares da temperatura no crescimento vegetativo e reprodutivo, bem como a probabilidade de distribuição in vivo de N. rileyi são descritos.

The influence of temperature on the development rate of the entomopathogenic fungus Nomuraea rileyi (Farlow) Samson in Anticarsia gemmatalis (Hübner) 3rd-instar larvae was studied under constant temperature regimes. A non linear model was used to describe temperature-dependent vegetative and reproductive development rates of the fungus. The temperature required to reach the highest vegetative development rate was estimated to be 25.5ºC while lower and upper developmental thresholds were 11ºC and 30ºC, respectively. The rate of development for conidia release was stable from 18ºC to 26ºC. The estimated lower and upper thresholds of vegetative development coincide with conditions during the natural epizootics in central Argentina. Non-linear effects of temperature on vegetative and reproductive development rates and probability distributions of N. rileyi under in vivo conditions are described.

O desenvolvimento in vitro de isolados de Nomuraea rileyi, obtidos de larvas de Anticarsia gemmatalis Hübner e de Plusiinae, foi estudados em quatro meios de cultura: Sabouraud, maltose, agar e levedura - SMAY; SMAY com extrato de arroz - SMAYR; meio completo para N. rileyi - CMNr; e maltose, agar, levedura com extrato de batata - MAYP. Seu crescimento radial em MAYP foi analisado sob cinco temperaturas. Foi estudada a esporulação em relação à temperatura, e a produção de conídios nos quatro meios testados. Dois modelos matemáticos foram aplicados para descrever as taxas de desenvolvimento radial dependentes da temperatura in vitro e in vivo. MAYP permitiu a maior taxa de crescimento, porém SMAY provocou as taxas mais baixas para os isolados testados. As temperaturas ótimas estimadas para o crescimento do micélio in vitro variam de 22°C a 26°C. A esporulação não variou entre 20°C e 26°C. Às temperaturas de 12, 16 e 30°C observou-se pouca ou nenhuma esporulação. A produção relativa dos conídios por biomassa de fungo foi muito variável, de 0,5 a 16 conídios por centigrama de micélio, não sendo considerada um critério adequado para escolher o meio de cultura. Com base nos presentes resultados, um meio à base de extrato de batata ou fatias de batata enriquecidas poderiam ser usados para a produção experimental e, eventualmente, massal de N. rileyi. Dadas as similaridades entre exigências térmicas in vitro e in vivo aqui descritas, as características térmicas da micose poderiam ser simplesmente estimadas com base na temperatura ambiente.

In vitro development - radial growth and sporulation - of Nomuraea rileyi isolates from Anticarsia gemmatalis Hübner and Plusiinae larvae was studied on four culture media: Sabouraud, maltose, agar and yeast - SMAY; SMAY plus rice extract - SMAYR; complete medium for N. rileyi - CMNr and maltose agar yeast with potato extract - MAYP. Their development on a selected medium (MAYP) was analysed at five temperatures. Two mathematical models were fitted to in vitro and in vivo temperature dependent radial growth rates and thermal requirements were estimated. The medium with potato and yeast extract induced the highest growth rate in most cases, while SMAY induced the lowest rates for the tested isolates. Estimated optimum temperatures for mycelium in vitro growth ranged from 22ºC to 26ºC. No differences between the proportion of sporulation of colonies maintained at 20ºC and 26ºC were detected. Few or no colonies sporulated at 12, 16 and 30ºC. The relative production of conidia per fungal biomass was very variable, ranging from 0.5 to 16 conidia per centigram of mycelium. Therefore, this was not a useful criterion for selecting a culture medium. Based on present findings, a medium based on potato extract, or enriched slices could be used for N. rileyi experimental and eventually mass production. Because of the similarities found between in vitro and in vivo thermal requirements, thermal traits of the mycosis could be simply estimated on the basis of the environmental temperature.

The objective of this paper was to design sequential sampling plans for the spotted alfalfa aphid (Therioaphis trifolii Monell) with fixed precision level, for density estimation and decision making. The study of spatial pattern based on Taylor's Power Law and Iwao's regression, showed different degrees of clumping of T. trifolii populations in alfalfa crops, depending on the developmental stage of aphids. The sequential sampling plan for decision making was calculated using two economic thresholds based on the height of the crop. The sequential sampling models developed by Kuno and by Green, were used to calculate stop lines. Green's model is recommended because Taylor's Power Law's regression yielded higher determination coefficients than Iwao's method.

El objetivo de este trabajo fue construir planes secuenciales de muestreo para el pulgón manchado de la alfalfa, Therioaphis trifolii Monell (Homoptera: Aphididae), con niveles fijos de precisión para estimar su densidad en función de toma de decisiones. El estudio de la disposición espacial basado en la Ley de Potencia de Taylor y regresión de Iwao, indicó que esta especie se distribuye de manera agregada en el cultivo de alfalfa, aunque con diferentes grados de agregación según el estado de desarrollo de los áfidos. Para el cálculo del plan secuencial de muestreo se usaron dos umbrales económicos según la altura del cultivo. Para el cálculo de las líneas críticas se utilizaron los modelos secuenciales de muestreo desarrollados por Kuno y por Green. Se recomienda el modelo de Green debido a que la Ley de Potencia de Taylor mostró los mayores coeficientes de determinación.

Eriopis connexa (Germar) is an important aphidophagous coccinelid, widely distributed in several South American countries. The influence of different feeding and temperature conditions on biological features of the immature and adult stages, were studied. Cohorts of cocinelids larvae were reared on the combinations of four constant temperatures (9, 15, 19 and 27ºC) and six diets based on Acyrthosiphon pisum Harris and Schizaphis graminum (Rondani) aphid species with, respectively, four and two different initial numbers and increasing rates. Tested temperatures above 15ºC did not affect the number of eggs/cluster and their viability. Incubation time varied from 2.5 days and a 92% of hatched eggs at 27ºC, to 13 days with a 71% of viability at 15ºC. At 9ºC, neither oviposition nor births were observed, although development until adult stage could be achieved at four experimental temperatures. The combination of food supply and temperature affected both aphid ingestion and immature developmental times, but not adult sizes. The number of A. pisum and S. graminum consumed varied approximately from 57 to 256 and from 104 to 641, respectively. Developmental times, from larval to adult stage, ranged from ca. 84 days at 9ºC to ca. 12 days at 27ºC. Larger adult sizes were observed at 19ºC. Body weight of adults increased when they were offered greater numbers of aphids. Pronotum widths and femur lengths were slightly influenced by prey species but these dimensions were independent on larvae ingestion of food.

Eriopis connexa (Germar) es un importante coccinélido afidófago distribuido en varios países de Sudamérica. Se estudió el impacto de la temperatura y alimentación sobre parámetros biológicos de sus estados inmaduros e imagos resultantes. Cohortes de larvas del coccinélido fueron criadas en una combinación de cuatro temperaturas constantes (9, 15, 19 y 27ºC) y 6 dietas de áfidos de las especies Acyrthosiphon pisum Harris y Schizaphis graminum (Rondani) con, respectivamente, cuatro y dos cantidades iniciales y tasas de incremento diarios. Las cantidades de huevos/postura y su viabilidad no fueron afectadas por las temperaturas superiores a 15ºC evaluadas. Los tiempos de incubación fueron desde 2,5 días y 92% de eclosión a 27ºC, hasta 13 días con una viabilidad del 71% a 15ºC. A 9ºC no se registraron oviposturas ni nacimientos aunque el desarrollo hasta adulto pudo ser completado en las cuatro temperaturas experimentales. La combinación de oferta de alimento y temperatura afectó tanto la ingesta de áfidos como los tiempos de desarrollo inmaduro, pero no las dimensiones de los adultos. Las cantidades totales de pulgones consumidos oscilaron aproximadamente entre 57 y 256 ninfas de A. pisum y desde 104 a 641 áfidos de la especie S. graminum. Los tiempos para el desarrollo, desde larva hasta adulto, fueron cercanos a 83,7 días a 9ºC hasta 11,8 días a 27ºC. Las mayores dimensiones de imagos se registraron a 19°C. El aumento del número de pulgones ofrecidos causó un incremento del peso corporal del adulto. El ancho del pronoto y la longitud del fémur del adulto fueron levemente influenciados por la especie presa pero sería relativamente independiente de la cantidad ingerida por las larvas.