Submitted to: Environmental Entomology
Publication Type: Peer reviewed journal
Publication Acceptance Date: 1/17/2008
Publication Date: 4/1/2008
Citation: Kim, K.S., Stolz, U., Miller, N.J., Waits, E., Guillemaud, T., Sumerford, D.V., Sappington, T.W. 2008. A core set of microsatellite markers for western corn rootworm (Coleoptera: Chrysomelidae) population genetics studies. Environmental Entomology. 37(2):293-300. Interpretive Summary: Corn rootworms are insects that attack corn, causing over $1-billion in losses each year in the U.S. They have developed resistance to crop rotation and to many insecticides, and it is feared they may become resistant to transgenic ("Bt") corn as well. They are now spreading in Europe as well after an accidental introduction about 15 years ago. Thus, it is important to understand the genetics of rootworm populations, and a number of laboratories in several countries are pursuing such research. DNA markers called "microsatellites" are particularly useful for studying the population genetics of insects, but they are time consuming and costly to develop. By agreeing on a core set of these markers that all labs are encouraged to use, it will be possible to directly compare and share data across different laboratories, saving time and expense in developing new markers, and speeding progress in our common goal of understanding this destructive pest. The standard set of markers reported here not only will accelerate research and promote collaboration among other scientists studying western corn rootworm, but it will also serve as a model of cooperation and marker development for other insect pests.
Technical Abstract: Corn rootworms, Diabrotica spp., represent the most destructive pest complex of continuous corn (Zea mays) in North America, and the western corn rootworm, Diabrotica virgifera virgifera LeConte, is posing a major and spreading risk to corn in Europe since its initial introduction over a decade ago. Knowledge of rootworm population genetics is crucial to understanding the evolution and spread of insecticide- and rotation resistance, the introduction and spread of the western corn rootworm in Europe, and the possible evolution of resistance to rootworm-active Bt (Bacillus thuringiensis) toxin in North America. One of the key components for successful population genetics studies is the availability of suitable molecular markers. Using a standard group of microsatellite markers enables researchers from different laboratories to directly compare and share their data, reducing duplication of effort and facilitating collaborative work across laboratories. We propose six criteria for a core set of microsatellite markers for rootworm population genetics studies: high polymorphism, readability and repeatability of marker, no evidence of null alleles, marker neutrality, no linkage between loci, and cross-species amplification ability. A total of 22 pre-screened corn rootworm microsatellites were tested for the six criteria. We suggest a core set of six microsatellite markers for western corn rootworm for use in future population genetics studies of this species. Because Diabrotica population genetics research is in its infancy, the criteria for the core set of microsatellites can be applied to any corn rootworm microsatellites developed in the future. We present this effort as a model for other insect systems.