Interactions between weeds, arthropod pests, and their natural enemies in managed ecosystems

Interactions between weeds and arthropods occur frequently. This review cov ers the topic of weed/arthropod interactions, and provides the reader with access to literature in the subject area that is scattered in weed science, entomological, crop production, and ecological journals. We first analyze the current status of weed and arthropod management in the context of multi disciplinary integrated pest management (IPM). The remainder of the review is organized according to the mechanisms driving interactions. The first se ction deals with interactions driven by trophic relationships, and is subdi vided into direct and indirect trophic interactions. Direct trophic interac tions occur when pest or beneficial arthropods feed directly on weeds. Indi rect trophic interactions occur when arthropod feeding damage to crops impa cts weeds through alteration of ecosystem resource availability, or through weeds serving as hosts for alternate prey for beneficial arthropods, or vi a tritrophic interactions. The second mechanism driving interactions is con sidered in relation to alteration of the physical habitat by the presence o f weeds, such as alteration of temperature within the plant canopy. The thi rd major mechanism driving interactions is based on control tactics for the two types of pests. These are considered from the aspect of direct physica l effects, such as tillage, and from the aspect of interactions resulting f rom the use of pesticides. The latter is divided into direct effects of her bicides and insecticides on non-target pests and beneficials, and on intera ctions that result from alteration of host plant physiology by pesticides. A conclusion section attempts to place the impact of interactions into an I PM framework, and to indicate where multidisciplinary research involving we ed and arthropod management should be focused in the future.