Abundancia de chisas rizófagas (Coleoptera: Melolonthidae) en agroecosistemas de Caldono y Buenos Aires, Cauca, Colombia = Abundance of whitegrubs (Coleoptera: Melolonthidae) in two Colombian agroecosystems

Al examinar la composición y variación de la abundancia del problema de plagas subterráneas tipo chisa (larvas de Coleóptera Melolonthidae) en Caldono y Buenos Aires, dos localidades agrícolas del departamento del Cauca (altitud: 1.400 a 1.500 msnm; T°: 21,5°C (promedio); precipitación: 2.192 mm/año), se registró la presencia de varias especies, integrando un complejo de especies cuya abundancia es variable y depende del medio agrícola y el clima Con la finalidad de determinar si la cantidad de las chisas estrictamente rizófagas es una variable importante en el daño ocasionado, se desarrollaron muestreos en cuatro circunstancias agroecológicas en parcelas de media hectárea, así: cultivo de yuca, pastizal, cafetal (sombrío), bosque (área media Ha), que se visitaron cada 15 días (12 excursiones). Adicionalmente, durante un año, se colectaron adultos en trampas de luz para complementar el estudio. Se obtuvieron 12.512 adultos y 10.261 larvas representativas de 32 especies de la familia Melolonthidae. Los análisis estadísticos de cuatro muestreos simultáneos, revelan diferencias significativas en la abundancia de individuos entre las dos localidades (F= 248,83; p= 0.0), entre muestreos (F= 20,27; p= 6,02) y entre los cuatro tipos de habitat (parcela) combinando los dos sitios muestreados (F= 34,43; p = 4,7). Se concluye que existe semejanza entre las estructuras del complejo chisa de las dos localidades de estudio, aunque al analizar en detalle la abundancia se revelan diferencias significativas entre localidades, muestreos y tipos de habitat explicadas en términos de las variaciones climáticas, edáficas y sistemas de manejo agrícola existentes entre las localidades. La sola abundancia del complejo no permite determinar el efecto nocivo en cultivos, ya que ello está dado por la abundancia de las chisas estrictamente rizófagas. = The composition and variation in frequency of soil pests, especially the whitegrub (larvae of Coleoptera, family Melolonthidae) was studied in Caldono and Buenos Aires. These are two agricultural locations in the Department of Cauca (elevation ranges from 1.400-1.500 meters above sea level, temperature of 21.5°C and precipitation averaging 2.192 mm/year). This study showed that the whitegrub complex was composed of several species, in different stages of development. Samples were taken to determine the number and influence of root feeding whitegrubs on plant damage. This was done in four different agro-ecologies: cassava, pasture, coffee under shade, and forest fields. Each plot had an area half an hectare and samples were taken every 15 days, with 12 samples dates, from which four were used for the statistical analysis. A total of 12.512 adults and 10.261 larvae were collected, which represented 32 species within the family Melolonthidae. The statistical analysis of the selected data revealed significant differences in number of individuals from localities (f =248,83; p=O.0), between samples (f =20,27; p=6,02) and between the four types of habitat when the two localities were combined for analysis (f=34,43; p=4.7). In conclusion, there were similarities in the structure of the complex of whitegrubs in Caldono and Buenos Aires (Cauca), however when abundance of whitegrubs was analyzed in detail, statistical differences were noted between the four ecologies selected for the study, which are explained by variations in climate and soils between localities. The data obtained allow us to conclude that the damage caused by whitegrubs is more severe in Caldono than in Buenos Aires.