9410872 KAREIVA The ecological landscape in today's world is becoming increasingly characterized by a checkerboard-like mosaic of diverse habitats encompassing urban, agricultural, and natural environments. Ecologists have yet to devise a general theory pinpointing the effects, and more importantly, the mechanisms behind the effects that mixed landscapes may have upon resident populations. The investigators have chosen to conduct a field experiment in which non-crop vegetation (e.g. weeds) is incorporated into a crop field. The experimental design includes varying mixtures of crop and weed at different scales as well, so that investigators can determine the usefulness of such mixtures in a variety of general farmland scenarios. The data from these experimental field tests will be incorporated into different mathematical models, in the hopes of elucidating the mechanisms operating in the field. This mix of empiricism and theory will lead to a protocol for determining, in any given setting, how and at what scale mixing landscape types may affect insect populations. Incorporating data obtained in field experiments into mathematical models will generalize to many different real-life scenarios in which organisms move through combinations of diverse landscapes. Any such general guidelines combining agricultural production and natural vegetation should be an important contribution ln light of the current trend towards increasing landscape fragmentation as well as increasing population pressure.
