Habitat manipulation in potato affects colorado potato beetle dispersal

Authors: Szendrei, Zsofia; Kramer, Matthew; Weber, Donald

Submitted to: Journal of Applied Entomology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/26/2009
Publication Date: 11/16/2009
Citation: Szendrei, Z., Kramer, M.H., Weber, D.C. 2009. Habitat manipulation in potato affects Colorado potato beetle dispersal. Journal of Applied Entomology. 133:711-719.

Interpretive Summary: Colorado potato beetle is a major pest of potatoes that, in the absense of controls, can cause major to complete crop loss. Its resistance to insecticides calls for the need to develop alternative, non-chemical methods of control. This study investigated the potential for reducing Colorado potato beetle pest pressure in potato fields through the use of cover crop mulches between the rows. We investigated two types of mulches for their effect on the movement of marked beetles into and within experimental plots, compared with the conventional practice in potatoes, which is clean-tillage (no mulch). Additionally we recorded the number of naturally occurring Colorado potato beetles in the same plots. Colorado potato beetle immigration from the field border was reduced into potato fields with rye cover crop compared to vetch cover cropped or tilled fields. Naturally occurring beetles were also reduced in potato fields with rye cover compared to the other two treatments. Marked beetles did move within the fields differently based on the mulch type, but we could not see a consistent pattern through the season. These results are of interest to growers and pest managers interested in using cultural techniques such as cover cropping to manage insect pests. The clearest effect was that the rye cover crop mulch discourages immigration into the potato field.

Technical Abstract: Increased vegetational diversity in agricultural fields may alter the movement of pests into or within a field. Colorado potato beetle (Leptinotarsa decemlienata) is a devastating pest of potatoes world-wide that has developed resistance to insecticides, creating a need for alternate management strategies. Using a mark-release-recapture method, we compared the tenure time and dispersal of marked insects released from within experimental potato fields to those released at the field borders in three releases in summer 2006. Plots within fields had rye, vetch or no plant residues. Marked Colorado potato beetle immigration into the tilled plots was significantly higher than into vetch or rye cover treatments. The abundance of naturally occurring beetles in the three cover treatments followed the general patterns of the number of marked immigrants over all releases. Both beetle groups were found in higher numbers in tilled plots than in those with plant residues. More marked beetles released inside the potato field moved along the release row in tilled treatment than in the two mulch cover treatments. Marked beetles released in the three cover treatments disappeared within the potato field differently, but the patterns were not consistent over the season. Dispersal patterns suggested that two classes of beetles were present: “slow” and “fast” walkers. The dispersal of slow walkers was greater in plots with rye cover crop than in the other two treatments. Rye cover crop had proportionally more slow walkers than the other two cover treatments. A meaningful incorporation of dispersal into pest management strategies is expected to improve methods of pest population regulation.