Habitat Preference and Community Assemblages of Carabid Beetles (Coleoptera: Carabidae) in Wheat Fields
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Biocontrol is an important ecosystem service that is extremely beneficial in agricultural systems. Many studies have looked at the conservation of natural enemies via habitat management and have found that adjacent habitats as well as chemical inputs can greatly affect natural predator populations. Specifically, adjacent habitats have been shown to increase natural enemy populations by providing additional food, shelter and overwintering sites. In this specific study, we investigated the movement of carabid beetles (a known natural enemy of crop pests) between wheat fields and adjacent habitats to determine their relative contribution of carabids within wheat fields. To determine these relative contributions, we used bidirectional pitfall traps placed between wheat fields and the various adjacent habitats (i.e. corn, soy, roadside vegetation, forest) and quantified carabid abundances entering and leaving wheat fields from these different habitats. We found that corn provided greater carabid abundances into wheat fields than forest and soy habitats, but was not significantly different than roadside vegetation. In addition, corn was the preferred alternate habitat from wheat and significantly more carabids were captured moving into corn from wheat than any other habitat. Using carabid diversity and abundance captured in bidirectional traps at the borders of habitats, as well as with traps placed in the interior of wheat fields, we found that carabid community assemblages in the various habitats were significantly different from one another with few exceptions. These findings suggest it is important to manage agricultural ecosystems so that they are composed of a variety of both non-crop and crop habitats, in order to maintain carabid abundance and diversity. Future research investigating how diversity and abundance of natural enemies in general change over time in a landscape context may further highlight their important role in biocontrol.