Advances in Conventional Breeding for Insect Resistance in Tropical Maize

摘要

Insects attack maize throughout the cropping cycle and during storage, resulting in as little as 10% up to complete crop loss. To address this problem, the International Maize and Wheat Improvement Center (CIMMYT) has developed methodologies to facilitate breeding for host plant resistance (HPR) to the major insect pests attacking maize. The major field pests targeted for Asia include the spotted stem borer (Chilo partellus (Swinhoe)) and the pink stem borer (Sesamia inferens Walker). In collaboration with entomologists and breeders in India, Thailand and the Philippines, 15 tropical lines have been identified with a moderate level of resistance to the above stem borers while having good regional adaptation and agronomic performance. There was no correlation between downy mildew resistance and stem borer resistance. Tropical maize germplasm developed by CIMMYT programs in Asia and Mexico have been screened for their susceptibility to storage pests, using the maize weevil (MW), Sitophilus zeamais (Motsch.) and the larger grain borer, Prostephanus truncatus Horn. Several lines and hybrids have been identified with moderate levels of resistance to the MW, with several lines being identified from the Asian program. In addition to characterizing advanced lines and hybrids, CIMMYT has also developed source populations for storage pest resistance using intra-population improvement. This paper will also present CIMMYT's breeding strategy for developing HPR in maize and our current understanding of the biochemical basis for both stem borer and storage pest resistance.