Population Dynamics of Scyphophorus acupunctatus (Coleoptera: Curculionidae) on Blue Agave
Keywords:
agave tequilero, agave weevil, population fluctuation, aggregation pheromone trapsAbstract
The agave weevil, Scyphophorus acupunctatus Gyllenhal, is considered the main pest of Agave tequilana Weber var. ‘Azul’ (Asparagales: Asparagaceae) in Mexico. In this study, we investigated the population fluctuations of S. acupunctatus for 19 months using 2 sampling methods in blue agave fields in Ahualulco and Amatitán, Jalisco, Mexico. We recorded the direct damage caused by weevils on the sampled agave plants and evaluated the correlation between the number of S. acupunctatus captured by pheromone traps and the density of weevils located on plants. In Ahualulco, the highest agave weevil population density (for all developmental stages) was detected in Mar 2008, although the peak of trap captures occurred in May 2009. In Amatitán, the highest agave weevil population density was observed in Apr 2009, and the highest number of insects was captured in May and Sep 2009. The mean fraction of necrotic bole tissue caused by the weevils per sampled plant was 75.4 ± 2.1% and 72.6 ± 2.0% in Ahualulco and Amatitán, respectively. In Ahualulco, there was a positive correlation between the number of weevils caught in the pheromone traps and the number of adult weevils on the plants, whereas the number of weevils caught by the pheromone traps at Amatitán was positively correlated with the total number of weevils on the plants. We found that the sex ratio of weevils recovered from agave plants was approximately 1:1 at both experimental sites, and this trend did not vary seasonally; conversely, the sex ratio of captured weevils in pheromone traps was female-biased year-round.
El picudo del agave, Scyphophorus acupunctatus Gyllenhal, es considerado la principal plaga en Agave tequilana Weber var. Azul en México. En esta investigación, se utilizaron dos métodos de muestreo para estudiar la dinámica poblacional de S. acupunctatus durante 19 meses en plantaciones comerciales de agave tequilero en Ahualulco y Amatitán, Jalisco. Así mismo, se registró el daño directo causado por larvas de picudo en las plantas muestreadas. Adicionalmente, se determinó la posible relación entre el número de picudos encontrados en plantas y el número de picudos capturados en trampas con feromona de agregación sintética. En Ahualulco la mayor densidad poblacional de picudo (todos los estadios de desarrollo) se detectó en marzo de 2008, mientras que la mayor cantidad de picudos capturados en trampas ocurrió en mayo de 2009. En Amatitán, la mayor densidad poblacional de picudo (todos los estadios de desarrollo) se detectó en abril de 2009, mientras que las mayores cantidades de picudos capturados en trampas se obtuvieron en mayo y septiembre de 2009. El daño promedio causado por picudo por planta de agave muestreada fue de 75.4 ± 2.1% y 72.6 ± 2.0% en Ahualulco y Amatitán, respectivamente. En Ahualulco el número de picudos capturados en trampas estuvo positivamente orrelacionado con el número de picudos adultos en plantas. En Amatitán el número de picudos capturados en trampas con feromona estuvo positivamente correlacionado con el número total de picudos en plantas. En ambos sitios experimentales la proporción sexual de los picudos adultos encontrados en plantas fue de aproximadamente 1:1 y esta tendencia no varió a lo largo del tiempo. Sin embargo, en el caso de los picudos capturados en trampas, la mayoría fueron hembras.
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