Estudio morfológico del estado larval de seis especies de Phyllophaga (Coleoptera: melolonthidae) de la región de los Altos de Chiapas, México

También puede consultar el capítulo en el libro con la clasificación 632.6 M4, en SIBE-San Cristóbal

Considerando la necesidad de identificar con precisión las larvas de los Coleóptera Melolonthidae que causan daños en los cultivos, y distinguir las especies benéficas, se realizó un análisis morfológico comparativo basado en 12 caracteres de la cápsula cefálica, la epifaringe y el raster. Se estudiaron 132 larvas de Phyllophaga menetriesi, P. tenuipilis, P. ravida, P. testaceipennis, P. obsoleta y P. tumulosa, comunmente asociadas al cultivo de maíz en Los Altos de Chiapas. Los resultados obtenidos con las mediciones y conteos fueron procesados con análisis estadísticos paramétricos y no paramétricos, los cuales señalaron que los mejores caracteres taxonómicos para diferenciar las larvas de estas especies son la longitud y la anchura de las palidia, la longitud y la anchura de la epifaringe, el tamaño de la cápsula cefálica y el número de pali. spa

There have been more studies on adult morphology of Phyllophaga than those on larval stage morphology. There are few keys for identification through species level at larval stage. It is urgent to study the way to identify these larvae, as larval stages are the main responsible of economic damage caused by Phyllophaga in many agricultural crops and there are no descriptions for most of the 254 mexican species (Morón, 1986). This work aims to study some key morphological characterics at larval stage for the identification of six species of Phyllophaga commonly present in Highland Chiapas. This study was realized with larvae obtained during 1996 within the project “Knowledge on white grubs and alternatives for its control”. In order to know the biology of white grubs field samples were taken each month. Half of each sample was reared in the laboratory to obtain exhuvia, pupa and adults; the other half was put first into a panpel solution and then into alcohol (70 %) for its conservation. Third-stage larvae were taken from the sample and the following morphological attributes were considered for their characterization (following Morón, 1986, and King, 1984): shape, length and width of palidiae, number of pali, size of cephalic capsule, anterior frontal seta, dorsal- epicraneal setae, length and width of epipharinx, presence/absence of proplegmatium, number of plegmae and length of the larvae. Observations, measurements and photographs were made under a Carl Zeiss Stemi SV 6 stereomicroscope. Results obtained through parametric and non-parametric statistical analyses suggest that critical taxonomic characteristics to differentiate between species of Phyllophaga were length and width of palidiae; length and width of epipharinx; size of cephalic capsule and number of pali (right or left). In addition, shape of palidiae and presence/abscence of proplegmatium were also important. These characteristics would be useful for more precise future studies at species level. eng