Phylogeography Approach of Diloboderus abderus (Coleoptera: Melolonthidae) in the Southern Cone of America.

Diloboderus abderus (Sturm, 1826) (Coleoptera: Melolonthidae) is a serious soil pest of corn, wheat, oat, and natural and cultivated pastures in Argentina, Paraguay, Uruguay, and southern Brazil. Despite its economic importance, the genetic diversity and population structure of D. abderus remain unknown. We sequenced a fragment of the mitochondrial gene cytochrome oxidase I region (COI), of six populations of D. abderus from the Southern Cone of America. The mtDNA marker revealed a high haplotype diversity, high pairwise FST values, and significant genetic variations among populations. No correlation was found between genetic and geographical distances, yet the most common haplotype (Dab01) was present in four out of the six populations. Analysis of molecular variance showed that most of the variation was within populations of D. abderus. Tajima's D and Fu's FS tests indicated no evidence that D. abderus populations are under recent expansion. Our results indicate that genetic-based traits will likely remain localized or spread slowly, and management strategies need to be undertaken on a small scale.

Ecological Characterization of White Grubs (Coleoptera: Melolonthidae) Community in Cultivated and Noncultivated Fields.

Comparative studies on the density and diversity of white grubs community (Coleoptera: Melolonthidae) occurring in cultivated and noncultivated fields of the Planalto region of the state of Rio Grande do Sul, Brazil, are presented. Sampling was carried out in 23 municipalities during the 2009 and 2010 winter seasons. Cultivated and noncultivated fields were chosen in each locality. Melolontid larvae were collected for identification and counted to determine the population density. A mean of 12.9 larvae m(-2) were collected in cultivated areas against 10.5 larvae m(-2) in noncultivated areas. The latter were more diverse (H' = 2.52) than cultivated areas (H' = 2.26). Despite the high evenness index (J = 0.75 noncultivated and J = 0.74 cultivated), faunistic parameters indicated Cyclocephala flavipennis Arrow and Diloboderus abderus Sturm as an extremely dominant species in cultivated areas. These results showed that the population density of white grubs increases, and their community composition is affected in cultivated areas.