Touching the Sky: Coccinellids (Coleoptera: Coccinellidae) at High Altitudes in South America.

Records of extreme altitudes where several coccinellid species from South America inhabit the Andes of Argentina, Bolivia, Chile, Colombia, Ecuador, and Peru are provided. After an intensive review of several entomological collections and literature, records for 35 species with at least one location over 3500-m elevation were obtained, including the genera Cycloneda (ten species), Eriopis (15 species and one subspecies), Harmonia (one species), Hippodamia (two species), Mimoscymnus (two species), Psyllobora (one species), and Stenadalia (four species). In total, 184 location records are listed, of which 119 were from between 3000 and 4000 m, 57 between 4000 and 4900 m and eight above 4900 m, with the highest altitude record at 5250 m for Eriopis minima Hofmann. All records above 4000 m were obtained in the Puna biogeographic province within the Paramo Puneña biogeographic subregion. These records are the highest altitudes observed for the American continent and by far surpass others known for coccinellids worldwide. Several species of coccinellids living in sympatry at these high altitudes were verified, and in some cases, in situ development was inferred by the presence of immature stages. These findings are important to foresee the future effects of global warming that will affect especially the biological communities of extreme altitudes.

Resource concentration hypothesis: effect of host plant patch size on density of herbivorous insects.

The resource concentration hypothesis (Root 1973) predicts that specialist herbivorous insects should be more abundant in large patches of host plants, because the insects are more likely to find and stay longer in those patches. Between August 1989 and January 1990 we experimentally tested Root's hypothesis by analyzing the numerical response of four species of herbivorous insects associated with patches of 4, 16, 64 and 225 cabbage plants, Brassica oleracea var. capitata. In addition, we studied the colonization of patches by adults of Plutella xylostella (L.) (Lepidoptera: Plutellidae), and the migration of their larvae in patches of different sizes. No herbivorous insect densities differed significantly with patch size. Adults of P. xylostella colonized all kind of patches equally. Larvae did not migrate between patches, and their disappearance rate did not differ between patches. The resource concentration hypothesis is organism-dependent, being a function of the adult and juvenile herbivore dispersal behavior in relation to the spatial scale of patchiness.