By Dr. Fei Yang
Corn farmers in Minnesota continue to face significant challenges from the corn rootworm (CRW) complex, primarily the Northern Corn Rootworm (NCR) and Western Corn Rootworm (WCR). Crop rotation has traditionally been a reliable method for managing CRW, as adults predominantly lay eggs in corn fields and the larvae survive only on corn roots. Rotating corn to other crops will disrupt the CRW life cycle and eliminate local populations. While significant Minnesota WCR populations have been limited to continuous corn, a subset of NCR has adapted to crop rotation through an extended diapause trait, which allows eggs to remain dormant in the soil for two or more winters. This adaptation enables larval survival in rotated fields when corn is planted every other year.
In general, nearly all NCR eggs need to rest or diapause through the winters before hatching. However, a proportion of NCR eggs with extended diapause trait can delay hatching, with diapause spanning two or more winters (a small proportion of extended diapause eggs may delay hatching for up to four winters). This extended diapause trait is advantageous to larval survival in every-other-year rotated corn fields.
Source : umn.edu