ABSTRACT
The parasitoid Spalangia endius Walker is an efficient controller of Dipteran pupae, such as Musca domestica L. The entomopathogenic fungus Beauveria bassiana (Bals.) Vuil. is a regulator of insect populations, including these synanthropic pests. The aim of this work was to explore the possibilities of utilizing both agents in a combined form for the biocontrol of the domestic fly. Recently formed M. domestica pupae were inoculated by immersion in conidia suspension (10(8) conidia/ml) with two strains of B. bassiana (Bb6 and Bb10). The inoculated pupae were offered to the female parasitoid. In one bioassay they were offered pupae inoculated a single day and in other, pupae inoculated the following day as well. In both bioassays non inoculated (control) pupae were offered to the parasitoids until their death. Thirty females of S. endius were used for each strain and bioassay. From the study of the parasitoid offspring, life tables were built and the reproduction net rate (R0) and intrinsic natural increase (r m) were obtained among other demographic parameters; the parasitism percentages and sex ratios were also analyzed. B. bassiana did not affect significantly the biodemography of the parasitoid when pupae were inoculated a single time. On the other hand the R0 and the rm were smaller than that of the control without the fungus when pupae were inoculated twice, although sporulation was not observed in the cadavers of S. endius.
El parasitoide Spalangia endius Walker es un reconocido controlador de pupas de dípteros, tal como la Musca domestica L. El hongo entomopatógeno Beauveria bassiana (Bals.) Vuil. es un regulador de poblaciones de insectos, incluidas estas plagas sinantrópicas. El objetivo del trabajo fue explorar las posibilidades de utilización conjunta de ambos agentes para el control de la mosca. Se trataron pupas recién formadas de esta plaga con una suspensión de conidios (10(8) conidios/ml). Pupas inoculadas con dos cepas (Bb6 y Bb10) del hongo fueron ofrecidas a los parasitoides hembra. En un ensayo se les ofreció pupas inoculadas el primer día y en otro, inoculadas también al día siguiente; en los dos ensayos se les colocaron pupas normales hasta la muerte del parasitoide. Se usaron 30 hembras de S. endius para cada cepa y ensayo. A través del estudio de la progenie del parasitoide se construyeron tablas de vida, obteniéndose las tasas netas de reproducción (R0) e intrínsecas de incremento natural (r m) entre otros parámetros demográficos, así como el porcentaje de parasitoidismo y la proporción de sexos. B. bassiana no afectó significativamente la biodemografía del parasitoide cuando se lo expuso una sola vez, en cambio la R0 y la rm fueron más bajas que en el testigo sin el hongo cuando fueron expuestos dos veces, aunque no se observó esporulación en los cadáveres de S. endius.
Subject(s)
Diptera , Hymenoptera/anatomy & histology , Hymenoptera/classification , Hymenoptera/parasitology , Mitosporic FungiABSTRACT
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 25.5°C while lower and upper developmental thresholds were 11°C and 30°C, respectively. The rate of development for conidia release was stable from 18°C to 26°C. 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.
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 25,5°C, enquanto os limites mínimo e máximo foram estimados em 11°C e 30°C, respectivamente. A taxa de conidiação foi estável dos 18°C aos 26°C. 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.
Subject(s)
Fungi , Growth , Growth Inhibitors , Insect Control , Insecta , Plant Growth RegulatorsABSTRACT
The mortality of Triatoma infestans (Klug) treated with Beauvaria bassiana (Bals.) Vuill. under several temperature regimes was analyzed. Mortality rates were highest at 26°C and 22°C and lowest at constant 34°C. The combinations 26/34°C or 34/26°C (12:12h cycles) were significantly different from the combinations 18/26°C and 26/18°C, showing that high temperatures (34°C) affect mortality most significantly. The combinations also indicate that when an extreme high temperature is associated with an optimal temperature of 26°C, the susceptibility of T. infestans to B. bassiana infection decreases. Exposure to extreme temperature (18°C or 34°C) associated with an optimal temperature of 26°C in 8:8:8h cycles, reduces the mortality of T. infestans. In cycles of 6:6:6:6h, only the mortality associated with the 34/30/26/22°C combination was similar to the combinations at constant 22°C and 26°C. Extreme temperatures during the first stage affect mortality less than when this period is not longer than 6h. Mortality decreases significantly when an extreme high initial temperature is followed by an abrupt fall (34/22/26/30°C). Our results indicate that Beauvaria bassiana should be applied to the field in the late afternoon to avoid the negative impact of abrupt changes in temperature, or of high temperatures during the critical first stages of the infectious cycle of this entomopathogenic fungi.
En el presente trabajo se analizó la mortalidad de Triatoma infestans (Klug) tratada con Beauveria bassiana (Bals.) Vuill. bajo diferentes régimenes de temperatura. Los porcentajes de mortalidad a 26°C y a 22°C fueron más altos mientras que los más bajos se registraron a 34°C constantes. Las combinaciones 26/34°C o 34/26°C (12:12h) fueron significativamente diferentes a las de 18/26°C o 26/18°C mostrando que es mayor el efecto de altas temperaturas (34°C) sobre la mortalidad e indicando también que con una temperatura extrema alta unida a una óptima de 26°C, decrece la susceptibilidad de T. infestans a la infección por parte de B. bassiana. Se observó que la exposición a temperaturas extremas (18°C o 34°C) junto a la óptima de 26°C en ciclos de 8:8:8h reduce la mortalidad de T. infestans. Con alternancia de 6h (6:6:6:6h) se observó que sólo la mortalidad de la combinación 34/30/26/22°C fue similar a las de 22°C y 26°C constantes. La ocurrencia de temperaturas extremas durante el primer tramo afectan menos la mortalidad si el período en que ocurren no es tan largo (p.ej. 6h). Sin embargo, si a una temperatura extrema inicial le sigue una caída abrupta (34/22/26/30°C), la mortalidad se ve significativamente reducida. Los resultados indicarían que es preferible realizar las aplicaciones en el campo al atardecer, para evitar la influencia negativa de cambios bruscos de temperaturas o temperaturas elevadas durante las primeras etapas críticas del ciclo infeccioso de los hongos entomopatógenos.
Subject(s)
Beauveria , Fungi , Insect Control , InsectaABSTRACT
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 22°C to 26°C. No differences between the proportion of sporulation of colonies maintained at 20°C and 26°C were detected. Few or no colonies sporulated at 12, 16 and 30°C. 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.
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. As 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.
ABSTRACT
Se determinó el incremento poblacional potencial del parasitoide Spalangia endius Walker (Hymenoptera: Pteromalidae) sobre pupas de Musca domestica L. (Diptera: Muscidae) en condiciones de laboratorio, en oscuridad a 27°C y 50 ± 10 por ciento HR. Se colocaron individualmente 30 hembras con menos de 12h de emergidas sobre 15 pupas de Musca domestica L de menos de 24h de edad, renovándolas diariamente. La supervivencia preimaginal fue del 90,3 por ciento. La longevidad de los adultos fue estimada en 8,3 días en promedio con una tasa neta de reproducción de 24,549; tasa intrínseca de crecimiento natural de 0,119; tasa finita de crecimiento de 1,126; tiempo generacional medio de 28,162 días y tiempo de duplicación de 5,849 días. Estos valores de los parámetros indican el alto potencial de S. endius comparadas con otras especies congenéricas.
The potential increase of the parasitoid Spalangia endius Walker was determined under laboratory conditions at 27°C, 50 ± 10 percent RH. and 24h darkness. Thirty <12h-old females of the parasitoid were individualized with 15 Musca domestica L. pupae <24h old. Survival of S. endius immature was 90.3 percent. Adult females mean longevity was estimated in 8.3 days with a net rate of reproduction of 24.549; intrinsic rate of natural increase of 0.119; finite rate of increase of 1.126; mean generation time of 28.162 days; and duplication time of 5.849 days. These values indicate the high potential of S. endius as a parasitoid of M. domestica, as compared to other congeneric species.
ABSTRACT
Os objetivos deste estudo foram comparar, dos pontos de vista biológico e econômico, o impacto de várias estratégias de controle e avaliar os seus efeitos sobre a Musca domestica L., resistente à ciromazina, e sobre parasitóides benéficos da pupas de mosca doméstica em aviários (240.000 frangos) na Argentina. As estratégias avaliadas foram: controle químico, controle químico + cultural, e químico+ cultural + biológico (manejo integrado de pragas). Os produtos utilizados foram: ciromazina 1% e 50%, DDVP, azametifós com e sem z-9-tricoseno, calcário, e os parasitóides Spalangia endius Walker e Muscidifurax raptor Girault & Sanders. No caso de ausência de medidas de controle, a densidadepopulacional da mosca aumentou rapidamente e a média de parasitismo foi de 12%. Quando somente o controle químico foi utilizado, as populações de moscas foram reduzidas para 40 por grupo e a média de parasitismo foi de 2%. Quando a ciromazina tópica foi utilizada em conjunto com o controle cultural (calcário), a população de moscas foi reduzida mais rapidamente que nos tratamentos com moscas alimentadas com ciromazina 1%. Com o uso subseqüente de vespas parasitas, altos índices de parasitismo foram observados e a população de mosca doméstica foi reduzida aos níveis de tolerância em tempo menor que em todos os outros tratamentos. Dos pontos de vista biológico e econômico, o melhortratamento para controle de mosca doméstica resistente à ciromazina foi o controle biológico + cultural + químico com aplicações localizadas de ciromazina tópica.
The objectives of this study were to compare, from both biological and economic viewpoints, the impact of various control strategies and evaluate their effect on cyromazine-resistantMusca domestica L., and beneficial house fly pupal parasitoids on caged-layer farms (240,000 hens) in Argentina. The strategies evaluated were: chemical, chemical + cultural, and chemical + cultural + biological (integrated management). The products used were: cyromazine 1% and 50%, DDVP, azamethiphos with and without z-9-tricosene, lime, and the parasitoids Spalangia endius Walker and Muscidifurax raptor Girault & Sanders. In the absence of control measures, fly density increased quickly and the average parasitism rate was 12%. When only chemical control was used, fly populations were reduced to ca. 40/grid and parasitism averaged 2%. When topical cyromazine was used in conjunction with cultural control (lime), fly populations were reduced more rapidly than those treated with cyromazine 1% feed-through. With the subsequent use of parasitic wasps, high parasitism levels were observed andhouse flies were reduced to tolerance levels in the shortest time. From an economic and biological point of view, the best treatment for house flies resistant to cyromazine was biological + cultural + chemical with localized applications of topical cyromazine.