Arthropod Communities Associated with Darlingtonia californica

Abstract

Twenty-one species of arthropods were found associated with the pitchers of Darlingtonia californica Torrey 1853. D. californica pitchers were collected from three seeps located within a 3-km radius of each other, in the Klamath Mountains in northern California. Immature insect stages were reared in pitchers in the laboratory, and reared adults were collected and identified. New arthropod-plant associations were recorded for 15 arthropods, and an undescribed species was collected in each of the genera Corynoptera (Diptera: Sciaridae), Nartshukiella (Diptera: Chloropidae), Aspilota (Hymenoptera: Braconidae), and Macrosiphum (Homoptera: Aphididae). Host-parasite relationships were identified between Aspilota n. sp. and the larva of Megaselia orestes (Diptera: Phoridae), and between Orgilus strigosus Muesebeck (Hymenoptera: Braconidae) and the caterpillar of Udea (?) sp. (Pyrali-dae: Lepidoptera). Significant intersite differences were found in the arthropod communities of D. californica: species inhabiting as high as 69% of the pitchers at a site, were absent from a site 3 km away. The data in this study indicated that the composition of the arthropod communities associated with the pitchers of D. californica can vary significantly over both large and small geographical areas. Resource heterogeneity, island biogeography, and habitat factors were suggested as possible mechanisms for creating species variability in pitcher faunas. The data supported earlier suggestions that the geographic distribution of the host plant is an important factor in structuring phytotelm communities. It was suggested that additional sampling of the pitcher faunas at other locations throughout the range of D. californica is necessary before the number and nature of the plant-arthropod associations in this phytotelm community can be known.