Flow of predatory insects in an agricultural landscape: a14-year synthesis

Gage, S.H., M. Colunga-Garcia, and C.H. McKeown

Presented at the All Scientist Meeting (2004-10-08 )

This research synthesizes patterns of response of eight species of Coccinellidae, generalist insect predators of plant inhabiting herbivores, to an array of management regimes in a variety of plant communities and cropping systems implemented at the KBS LTER. The work is based on a 14-year project aimed to examine ecological principles as substitutes for chemical subsidies in agricultural ecosystems. This project also relates to the LTER Network theme of trophic dynamics in space and time. Weekly species counts of adult beetles have been made from May through August at 210 permanent locations. The sample array covers all seven KBS LTER treatments, cropping rotations and plant communities. The resulting 444,000 observations of insect abundance have been stored in a relational > >database, and linked to 14 years of daily weather observations to provide a spatial-temporal landscape scale response to treatment and plant community regimes. In addition, a system has been developed to automate the production of distribution maps for 8 species of insect predators at intervals of 100, 200, 400 and 1200 degree days over the 14 year time span resulting in 2600 distribution maps. This spatial-temporal database is being analyzed to model the numerical response of these species to changing plant communities, cropping patterns, treatment manipulation and meteorological conditions. During the observation period we have quantified natural biological regulation of a plant herbivore, documented the outbreak of two exotic species, examined the interaction of exotic and native predators, quantified the response of species to changing plant growth and characterized long term population trends in predators.

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