Ho, C.-K., S. C. Pennings and T. H. Carefoot. 2010. Is diet quality an overlooked mechanism for Bergmann's rule? American Naturalist 175:269-276.
Pennings, S. C., C.-K. Ho, C. S. Salgado, K. Wieski, N. Davé, A. E. Kunza, E. L. Wason. 2009. Latitudinal variation in herbivore pressure in Atlantic Coast salt marshes. Ecology 90:183-195.
Pennings, S. C., Zimmer, M., Dias, N., Sprung, M., Davé, N., Ho, C.-K., Kunza, A., McFarlin, C., Mews, M., Pfauder, A., Salgado, C. 2007. Latitudinal variation in plant-herbivore interactions in European salt marshes. Oikos 116:543-549.
The leaf beetle Ophraella notulata eats the salt marsh shrub Iva frutescens. Beetles are several times more abundant, and do several times more damage to shrubs, at low versus high latitudes.
Variation between high and low latitudes in the densities of herbivores and in herbivore damage to the salt marsh shrub Iva frutescens. GCE-LTER scientists found that herbivores that eat leaves by chewing them (acridid grasshoppers, measured using two different methods; beetles; the omnivorous crab Armases) and herbivores that feed inside galls (a fly and a mite) were consistently more abundant at low versus high latitudes. In contrast, herbivores that feed by sucking plant juices (aphids) showed no pattern across latitude. Damage to leaves from chewing and gall-making herbivores was several times greater at low versus high latitudes. Similar results were found with other plant species studied.