Phagodeterrence by Quassia amara (Simaroubaceae) wood extract fractions on Hypsipyla grandella (Lepidoptera: Pyralidae) larvae.

In Latin America and the Caribbean, precious wood species like mahoganies (Swietenia spp.) and cedars (Cedrela spp.) are seriously injured by the mahogany shootborer, Hypsipyla grandella (Zeller) (Lepidoptera: Pyralidae) larva, which bores into the main shoot of trees. In previous experiments focused on searching for a preventive method for managing this pest, a wood extract of bitterwood, Quassia amara L. ex Blom (Simaroubaceae) had been shown to cause phagodeterrence to larvae. Therefore, three fractions (water, methanol and diethyl ether) of a wood extract were tested for their phagodeterrence to larvae, by means of laboratory and greenhouse trials. Phagodeterrence was assessed by determining their effect on foliage consumption, mortality and signs of damage (number of orifices, sawdust piles, fallen shoots, number of tunnels and tunnel length) caused by larvae on Spanish cedar (C. odorata). Both the methanol and diethyl ether fractions caused phagodeterrence, by strongly reducing foliage consumption and signs of damage, while not causing larval mortality. The lowest concentration at which phagodeterrence was detected for the methanol fraction corresponded to 0.0625%, which is equivalent to a 1.0% of the bitterwood crude extract. However, results with the diethyl ether fraction were unsatisfactory, as none of the treatments differed from the solvent, possibly because of an adverse effect of the solvent on foliar tissues. Phagodeterrent principles from Q. amara derivatives may play an important role in dealing with H. grandella if they are complemented with other integrated pest management preventative tactics.

Phagodeterrence by Quassia amara (Simaroubaceae) wood extract fractions on Hypsipyla grandella (Lepidoptera: Pyralidae) larvae

In Latin America and the Caribbean, precious wood species like mahoganies (Swietenia spp.) and cedars (Cedrela spp.) are seriously injured by the mahogany shootborer, Hypsipyla grandella (Zeller) (Lepidoptera: Pyralidae) larva, which bores into the main shoot of trees. In previous experiments focused on searching for a preventive method for managing this pest, a wood extract of bitterwood, Quassia amara L. ex Blom (Simaroubaceae) had been shown to cause phagodeterrence to larvae. Therefore, three fractions (water, methanol and diethyl ether) of a wood extract were tested for their phagodeterrence to larvae, by means of laboratory and greenhouse trials. Phagodeterrence was assessed by determining their effect on foliage consumption, mortality and signs of damage (number of orifices, sawdust piles, fallen shoots, number of tunnels and tunnel length) caused by larvae on Spanish cedar (C. odorata). Both the methanol and diethyl ether fractions caused phagodeterrence, by strongly reducing foliage consumption and signs of damage, while not causing larval mortality. The lowest concentration at which phagodeterrence was detected for the methanol fraction corresponded to 0.0625%, which is equivalent to a 1.0% of the bitterwood crude extract. However, results with the diethyl ether fraction were unsatisfactory, as none of the treatments differed from the solvent, possibly because of an adverse effect of the solvent on foliar tissues. Phagodeterrent principles from Q. amara derivatives may play an important role in dealing with H. grandella if they are complemented with other integrated pest management preventative tactics. Rev. Biol. Trop. 59 (1): 487-499. Epub 2011 March 01.

En América Latina y el Caribe, algunas especies que son fuente de maderas preciosas, como las caobas (Swietenia spp.) y cedros (Cedrela spp.), son seriamente dañadas por la larva de Hypsipyla grandella, la cual barrena el brote principal de los árboles. En experimentos previos orientados hacia la búsqueda de un método preventivo para manejar esta plaga, un extracto de la madera de hombre grande, Quassia amara (Simaroubaceae), había demostrado causar fagodisuasión a la larva. Por tanto, tres fracciones de un extracto de la madera de dicho árbol (agua, metanol y éter dietílico) fueron evaluadas en cuanto a su efecto fagodisuasivo sobre las larvas, mediante experimentos de laboratorio e invernadero. Dicho efecto se determinó según el consumo de follaje, la mortalidad y los signos de daño (número de orificios, montículos, brotes caídos, número y longitud de túneles) causados por las larvas en arbolitos de cedro amargo (C. odorata). Tanto la fracción de metanol como la de éter dietílico causaron fagodisuasión, pues redujeron fuertemente el consumo de follaje y los signos de daño, sin matar las larvas. La menor concentración de la fracción metanólica a la cual se detectó fagodisuasión correspondió a 0.0625%, la cual equivale al 1.0% del extracto crudo de hombre grande. Por su parte, los resultados con la fracción de éter dietílico fueron insatisfactorios, ya que ninguna de las concentraciones difirió del disolvente, quizás debido a un efecto adverso del mismo sobre los tejidos foliares. Los principios fagodisuasivos de los derivados Q. amara podrían jugar un papel importante para manejar a H. grandella, si fueran complementados con otras tácticas preventivas de manejo integrado de plagas.

Antifeedant activity of botanical crude extracts and their fractions on Bemisia tabaci (Homoptera: Aleyrodidae) adults: I. Gliricidia sepium (Fabaceae)

Bemisia tabaci is an important virus vector on a number of crops worldwide. Therefore, a preventive approach to deal with viral epidemics may be the deployment of repellents or phagodeterrents at earlier stages of plant development (critical period). Thus, the crude extract and four fractions thereof (water, water:methanol, methanol, and diethyl ether) of mother-of-cocoa (Gliricidia sepium, Fabaceae) were tested for phagodeterrence to B. tabaci adults under greenhouse conditions, on tomato plants, in Costa Rica. Both restricted-choice and unrestricted-choice experiments showed that the crude extract and some fractions exerted such effect on the insect. In the former (in sleeve cages), three fractions caused deterrence at doses as low as 0.1% (methanol), 0.5% (water:methanol) and 1.5% (diethyl ether). However, in the latter (plants exposed in a greenhouse) no one of the fractions performed well, suggesting that the deterrent principles somehow decomposed under the experimental conditions. Rev. Biol. Trop. 56 (4): 2099-2113. Epub 2008 December 12.

Mundialmente, Bemisia tabaci es un importante vector de virus en numerosos cultivos. Por tanto, un enfoque preventivo para enfrentar las epidemias virales podría ser el empleo de sustancias repelentes o fagodisuasivas en las etapas tempranas del desarrollo de las plantas (período crítico). Así, tanto el extracto crudo como cuatro fracciones (agua, agua:metanol, metanol y éter dietílico) del madero negro (Gliricidia sepium, Fabaceae) fueron evaluadas en cuanto a su actividad fagodisuasiva sobre los adultos de B. tabaci en condiciones de invernadero, utilizando plantas de tomate, en Turrialba, Costa Rica. Tanto los experimentos de escogencia restringida como los de escogencia irrestricta revelaron que el extracto crudo y algunas fracciones mostraron dicha actividad. En los primeros experimentos (en jaulas de manga), tres fracciones causaron fagodisuasión a dosis tan bajas como 0.1% (metanol), 0.5% (agua:metanol) y 1.5% (éter dietílico). Sin embargo, en los segundos (plantas expuestas dentro de un invernadero) ninguna de las fracciones lo hizo, lo cual sugiere que los principios fagodisuasivos perdieron su actividad en esas condiciones experimentales.

Antifeedant activity of botanical crude extracts and their fractions on Bemisia tabaci (Homoptera: Aleyrodidae) adults: II. Sechium pittieri (Cucurbitaceae)

Bemisia tabaci is a key pest of vegetables and other crops worldwide, but it is a particularly serious problem in the tropics, due to its ability to transmit several types of viruses, especially begomoviruses (Geminiviridae). Therefore, a preventive approach to deal with viral epidemics may be the deployment of repellents or phagodeterrents at earlier stages of plant development (critical period). Thus, the crude extract and four fractions thereof (water, water: methanol, methanol, and diethyl ether) of wild "tacaco" (Sechium pittieri, Cucurbitaceae), were tested for phagodeterrence to B. tabaci adults under greenhouse conditions, on tomato plants, in Costa Rica. Both restricted-choice and unrestricted-choice experiments showed that the crude extract as well as some fractions exert such effect on the insect. In the former (in sleeve cages), fractions caused deterrence at doses as low as 0.1% (ether) and 0.5% (water and water: methanol), with the methanol fraction showing no activity. However, in the latter (plants exposed in a greenhouse) no one of the fractions performed well, suggesting that the deterrent principles somehow decomposed under the experimental conditions. Rev. Biol. Trop. 56 (4): 2115-2129. Epub 2008 December 12.

Bemisia tabaci es una plaga clave de hortalizas y otros cultivos, mundialmente, y representa un problema particularmente serio en los trópicos, debido a su habilidad para transmitir varios tipos de virus, especialmente begomovirus (Geminiviridae). Por tanto, un enfoque preventivo para enfrentar las epidemias virales podría consistir en la utilización de sustancias repelentes o disuasivas en las eta-pas tempranas del desarrollo de la planta (período crítico). Así, el extracto crudo y cuatro fracciones (agua, agua: metanol, metanol, y éter dietílico) de tacaco cimarrón (Sechium pittieri, Cucurbitaceae), fueron evaluadas por su posible actividad fagodisuasiva sobre B. tabaci en un invernadero, utilizando plantas de tomate, en Turrialba, Costa Rica. Tanto los experimentos de escogencia restringida como los de escogencia irrestricta mostraron dicha actividad en el extracto crudo y en algunas de sus fracciones. En el primer tipo de experimento (en jaulas de manga), las fracciones causaron fagodisuasión a dosis tan bajas como 0.1% (éter dietílico) y 0.5% (agua y agua: metanol), mientras que la fracción metanólica no la causó. Sin embargo, en los otros experimentos (plantas expuestas a B. tabaci dentro de un invernadero) ninguna de las fracciones funcionó bien, lo cual sugiere que los principios disuasivos se disiparon bajo esas condiciones experimentales.

Antifeedant activity of botanical crude extracts and their fractions on Bemisia tabaci (Homoptera: Aleyrodidae) adults: III. Quassia amara (Simaroubaceae)

Bemisia tabaci is a key virus vector on several crops worldwide. Then, a preventive approach to deal with viral epidemics may be the deployment of repellents or phagodeterrents at earlier stages of plant development (critical period). Thus, the crude extract and four fractions thereof (water, water: methanol, methanol, and diethyl ether) of bitterwood (Quassia amara, Simaroubaceae) were tested for phagodeterrence to B. tabaci adults under greenhouse conditions, on tomato plants, in Costa Rica. Both restricted-choice and unrestricted-choice experiments showed that the crude extract and some fractions exerted such effect on the insect. In the former case (in sleeve cages), all fractions caused deterrence at doses as low as 0.1 % (methanol), 0.5 % (water: methanol and diethyl ether), and 1% (water). In the latter case (plants exposed in a greenhouse) the methanol fraction stood out, followed by the diethyl ether fraction. Nonetheless, none of the fractions performed better than the deterrent control (mineral oil). Rev. Biol. Trop. 56 (4): 2131-2146. Epub 2008 December 12.

En el plano mundial, Bemisia tabaci es un importante vector de virus en numerosos cultivos. Un enfoque preventivo para enfrentar las epidemias virales podría ser el empleo de sustancias repelentes o fagodisuasivas en las etapas tempranas del desarrollo de las plantas (período crítico). Tanto el extracto crudo como cuatro fracciones (agua, agua: metanol, metanol, y éter dietílico). Evaluamos extractos del árbol llamado "hombre grande" (Quassia amara, Simaroubaceae) fueron evaluadas en cuanto a su actividad fagodisuasiva sobre los adultos de B. tabaci, usando tomate, en condiciones de invernadero, utilizando plantas de tomate, en Turrialba, Costa Rica. Tanto los experimentos de escogencia irrestricta e irrestrictam, el extracto crudo y algunas fracciones mostraron dicha actividad. En los primeros experimentos (en jaulas de manga), todas las fracciones causaron fagodisuasión a dosis de apenas 0.1% (metanol), 0.5% (agua: metanol y éter dietílico) y 1% (agua). En los segundos (plantas expuestas dentro de un invernadero) sobresalió la fracción metanólica, seguida por la de éter dietílico. Sin embargo, ninguna de las fracciones superó al testigo fagodisuasivo (aceite mineral).

Antifeedant activity of botanical crude extracts and their fractions on Bemisia tabaci (Homoptera: Aleyrodidae) adults: I. Gliricidia sepium (Fabaceae).

Bemisia tabaci is an important virus vector on a number of crops worldwide. Therefore, a preventive approach to deal with viral epidemics may be the deployment of repellents or phagodeterrents at earlier stages of plant development (critical period). Thus, the crude extract and four fractions thereof (water, water:methanol, methanol, and diethyl ether) of mother-of-cocoa (Gliricidia sepium, Fabaceae) were tested for phagodeterrence to B. tabaci adults under greenhouse conditions, on tomato plants, in Costa Rica. Both restricted-choice and unrestricted-choice experiments showed that the crude extract and some fractions exerted such effect on the insect. In the former (in sleeve cages), three fractions caused deterrence at doses as low as 0.1% (methanol), 0.5% (water:methanol) and 1.5% (diethyl ether). However, in the latter (plants exposed in a greenhouse) no one of the fractions performed well, suggesting that the deterrent principles somehow decomposed under the experimental conditions.

Antifeedant activity of botanical crude extracts and their fractions on Bemisia tabaci (Homoptera: Aleyrodidae) adults: II. Sechium pittieri (Cucurbitaceae).

Bemisia tabaci is a key pest of vegetables and other crops worldwide, but it is a particularly serious problem in the tropics, due to its ability to transmit several types of viruses, especially begomoviruses (Geminiviridae). Therefore, a preventive approach to deal with viral epidemics may be the deployment of repellents or phagodeterrents at earlier stages of plant development (critical period). Thus, the crude extract and four fractions thereof (water, water: methanol, methanol, and diethyl ether) of wild "tacaco" (Sechium pittieri, Cucurbitaceae), were tested for phagodeterrence to B. tabaci adults under greenhouse conditions, on tomato plants, in Costa Rica. Both restricted-choice and unrestricted-choice experiments showed that the crude extract as well as some fractions exert such effect on the insect. In the former (in sleeve cages), fractions caused deterrence at doses as low as 0.1% (ether) and 0.5% (water and water: methanol), with the methanol fraction showing no activity. However, in the latter (plants exposed in a greenhouse) no one of the fractions performed well, suggesting that the deterrent principles somehow decomposed under the experimental conditions.

Antifeedant activity of botanical crude extracts and their fractions on Bemisia tabaci (Homoptera: Aleyrodidae) adults: III. Quassia amara (Simaroubaceae).

Bemisia tabaci is a key virus vector on several crops worldwide. Then, a preventive approach to deal with viral epidemics may be the deployment of repellents or phagodeterrents at earlier stages of plant development (critical period). Thus, the crude extract and four fractions thereof (water, water: methanol, methanol, and diethyl ether) of bitterwood (Quassia amara, Simaroubaceae) were tested for phagodeterrence to B. tabaci adults under greenhouse conditions, on tomato plants, in Costa Rica. Both restricted-choice and unrestricted-choice experiments showed that the crude extract and some fractions exerted such effect on the insect. In the former case (in sleeve cages), all fractions caused deterrence at doses as low as 0.1% (methanol), 0.5% (water: methanol and diethyl ether), and 1% (water). In the latter case (plants exposed in a greenhouse) the methanol fraction stood out, followed by the diethyl ether fraction. Nonetheless, none of the fractions performed better than the deterrent control (mineral oil).

Distribución espacio-temporal de hormigas en un gradiente de luz, dentro de un sistema agroforestal de café, en Turrialba, Costa Rica

Temporal and spatial distribution of ants in a light gradient, in a coffee agroforestry system, Turrialba, Costa Rica. Shade trees are frequently present in coffee (Coffea arabica L.) agroforestry systems of Mesoamerica. These systems can harbor a rich entomofauna, including ants, which could be predators of key pests in these systems. However, the role of shade on the distribution and abundance of these ants is unknown, yet such knowledge could suggest guidelines for manipulating certain environmental conditions of their habitat, thereby achieving their conservation and increase. Therefore, we studied the effect of shade on the spatial and temporal distribution of three ant species (Solenopsis geminata, Pheidole radoszkowskii and Crematogaster curvispinosa) that may prey on the coffee berry borer, Hypothenemus hampei (Coleoptera: Scolytidae), and the mahogany shootborer, Hypsipyla grandella (Lepidoptera: Pyralidae). To do this, abundance was evaluated across a sun-shade gradient in a coffee plantation with four alternate plots (from pure sun to total shade) in Turrialba, Costa Rica. In the community that was studied 28 species of ants were collected, of which S. geminata was the dominant species (79 % of the total individuals), followed by P. radoszkowskii (16 %). S. geminata and C. curvispinosa preferred sunny areas, while P. radoszkowskii showed no defined preference. Likewise, with respect to location, S. geminata predominated in the soil, while P. radoszkowskii and C. curvispinosa predominated in coffee bushes. Rev. Biol. Trop. 55 (3-4): 943-956. Epub 2007 December, 28.

En los sistemas agroforestales de café (Coffea arabica L.) de Mesoamérica es frecuente la presencia de árboles de sombra. Estos sistemas pueden albergar una rica entomofauna, incluyendo hormigas, la cuales podrían depredar a plagas claves en dichos sistemas. Sin embargo, se desconoce el papel de la sombra sobre la distribución y abundancia de dichas hormigas, lo cual podría sugerir pautas para manipular ciertas condiciones de su hábitat y lograr su conservación e incremento. Por tanto, se estudió el efecto de la sombra sobre la distribución espacial y temporal de tres especies de hormigas (Solenopsis geminata, Pheidole radoszkowskii y Crematogaster curvispinosa) que pueden depredar a la broca del café, Hypothenemus hampei (Coleoptera: Scolytidae) y al barrenador de las meliáceas, Hypsipyla grandella. Para ello se evaluó su abundancia a través de un gradiente de sol-sombra en un cafetal con cuatro parcelas alternas (desde pleno sol hasta sombra total), en Turrialba, Costa Rica. En la comunidad estudiada se recolectaron 28 especies de hormigas, de las cuales S. geminata fue la dominante (79 % del total de individuos), seguida por P. radoszkowskii (16 %). S. geminata y C. curvispinosa prefirieron las áreas soleadas, mientras que P. radoszkowskii no mostró una preferencia definida. Asimismo, en cuanto a su ubicación, S. geminata predominó en el suelo, mientras que P. radoszkowskii y C. curvispinosa lo hicieron en los arbustos de café.

[Temporal and spatial distribution of ants in a light gradient, in a coffee agroforestry system, Turrialba, Costa Rica]. / Distribución espacio-temporal de hormigas en un gradiente de luz, dentro de un sistema agroforestal de café, en Turrialba, Costa Rica.

Shade trees are frequently present in coffee (Coffea arabica L.) agroforestry systems of Mesoamerica. These systems can harbor a rich entomofauna, including ants, which could be predators of key pests in these systems. However, the role of shade on the distribution and abundance of these ants is unknown, yet such knowledge could suggest guidelines for manipulating certain environmental conditions of their habitat, thereby achieving their conservation and increase. Therefore, we studied the effect of shade on the spatial and temporal distribution of three ant species (Solenopsis geminata, Pheidole radoszkowskii and Crematogaster curvispinosa) that may prey on the coffee berry borer, Hypothenemus hampei (Coleoptera: Scolytidae), and the mahogany shootborer, Hypsipyla grandella (Lepidoptera: Pyralidae). To do this, abundance was evaluated across a sun-shade gradient in a coffee plantation with four alternate plots (from pure sun to total shade) in Turrialba, Costa Rica. In the community that was studied 28 species of ants were collected, of which S. geminata was the dominant species (79% of the total individuals), followed by P. radoszkowskii (16 %). S. geminata and C. curvispinosa preferred sunny areas, while P. radoszkowskii showed no defined preference. Likewise, with respect to location, S. geminata predominated in the soil, while P. radoszkowskii and C. curvispinosa predominated in coffee bushes.

Development of Hypsipyla grandella (Zeller) (Lepidoptera: Pyralidae) in response to constant temperatures / Desenvolvimento de Hypsipyla grandella (Zeller) (Lepidoptera: Pyralidae) em diferentes temperaturas constantes

O efeito da temperatura sobre o desenvolvimento da broca do broto do mogno, Hypsipyla grandella (Zeller), foi determinado em laboratório, em Turrialba, Costa Rica. Para tanto, duzentos ovos com menos de 24h foram colocados individualmente em frascos de vidro e expostos às temperaturas de 10; 12,5; 15; 20; 25; 30 e 35oC. O estudo foi realizado em câmaras climáticas, com umidade de 80-90% e fotoperíodo de 8L:16D. Após a eclosão, as larvas foram alimentadas com folhas tenras de cedro (Cedrela odorata) einspecionados a cada 24h para determinar a duração das fases larval e de pupa, e a emergência dos adultosem cada temperatura. As relações entre essas variáveis e a temperatura foram analisadas através de ANOVA, regressão e correlação. A temperatura teve grande influência no desenvolvimento das fases imaturas e naemergência dos adultos de H. grandella. A duração do ciclo biológico (ovo-adulto) variou de 30 dias (30ºC) a 104 dias (15ºC). A mortalidade do estágio larval foi alta nessas temperaturas, alcançando taxas de 90% (15°C) e 45% (30ºC). A mortalidade de larvas de primeiro instar foi também relativamente alta (51-75%) nastemperaturas dentro do intervalo de 15ºC a 30ºC, com exceção daquelas que se desenvolveram a 25ºC (14%). O peso das pupas foi menor em temperaturas extremas (15ºC e 30ºC). A estimativa da temperatura base dedesenvolvimento para todos os estágios imaturos (8,5ºC) permitiu calcular a constante térmica (1320 graus dias), a qual possibilitará a previsão de picos populacionais no campo.

Developmental response of the mahogany shootborer, Hypsipyla grandella (Zeller), to temperature was determined in laboratory trials in Turrialba, Costa Rica. Two hundred fresh eggs (less than 24h old) were placed individually inside glass flasks, and exposed to seven constant temperatures (10, 12.5, 15, 20, 25, 30 and 35°C), in separate experiments. These were carried out in environmental chambers, at 80-90% relative humidity and 8L:16D photoperiod. After hatch, larvae were fed tender foliage of Spanish cedar (Cedrela odorata) and were inspected every 24h to determine larval and pupal duration, and adult emergence, at each temperature. Relationships between these variables and temperature were analyzed by means of ANOVA, regression and correlation procedures. Temperature greatly influenced development of H. grandella immature stages and adult emergence; development time varied between 30 days (30ºC) and 104 days (15°C). Larval mortality was high at those temperatures, reaching values of 90% (15°C) and 45% (30ºC). Also, mortality of the first larval instar was relatively high (51-75%) at all temperaturesin the range 15-30°C, except at 25ºC (14%). Pupal weight was lower at extreme temperatures (15ºC and 30ºC).Estimation of a common lower thermal threshold for all immature stages (8.5ºC) allowed calculation of a general thermal constant (1320 degree-days), which could be used to predict population peaks in the field.