Submitted to: American Entomologist
Publication Type: Peer reviewed journal
Publication Acceptance Date: 8/29/2005
Publication Date: 1/3/2006
Citation: O'Neal, M.E., Prasifka, J.R., Schmidt, N.P., Singer, J.W., Hellmich II, R.L., Kohler, K.A. 2006. Assessing carabids contribution to ecosystem services: Does it matter if there are more beetles? American Entomologist. 51:231-233. Interpretive Summary: Within a more profitable main crop, other plants may be used to control weeds or erosion. When such plants are not killed, but allowed to grow along with the main crop, they are called living mulches. The number or effectiveness of beneficial insects, including predators such as ground beetles, may be increased by living mulches. Alfalfa and kura clover living mulches were tested as part of a rotation with corn and soybean to examine their possible benefits to pest management. When corn and soybean were grown with living mulches, more ground beetles were collected, and more artificially-introduced pests (European corn borer pupae) were fed upon. However, overall corn and soybean yields were reduced by the mulches. This information is relevant to researchers in crop production or growers considering adding living mulches or other cover crops to the production of their main crops. The results suggest that it is important to consider improved control of some pests as one of the possible benefits to growing crops with living mulches. However, the potential benefits of living mulches to pest control are not considered a stand-alone solution to pest control needs. This information is useful for all stakeholders interested in developing methods for sustainable agriculture.
Technical Abstract: Planting living mulches, cover crops grown concurrently with a main crop on the same parcel of land, has established benefits to nutrient recycling and weed control. However, additional benefits of living mulches may include increases in the abundance of predatory arthropods. Effects on many arthropod taxa have been observed from the use of living mulches, but we emphasize the impact of living mulches on communities of ground beetles (Carabidae) in plots of corn and soybean and explore whether living mulches enhance predation within the main crops. Perennial alfalfa or kura clover mulches incorporated into a three year rotation with corn, soybean, and forage (mulches grown alone) increased the overall abundance of ground beetles collected in pitfall traps during June through September, showing significant positive effects for four of the most common carabid species. Over the same period, predation on European corn borer pupae used as sentinel prey was shown to be greater in corn and soybean with living mulch than in the annual crops grown without a mulch. However, living mulches also competed with corn and soybean, leading to yield reductions. This adverse effect on yield may diminish over time, but all of the positive aspects of living mulches, including benefits to pest management, should be considered against the possible costs to determine the value of living mulches as a farm management practice.