Population dynamics and life-cycle of corn borers in south Atlantic European coast

Abstract

Sesamia nonagrioides Lei. and Ostrinia nubilalis Hbn, are the main pests of maize in the mediterranean countries. Population fluctuations of both species were studied in NW Spain through 1990-1996. The abundance of both species varied greatly between and within locations. Their attacks were very intense in 1995 and 1996, reaching 100% of damaged plants in two plots, 30-50% in a third one and 7% in a Fourth plot. In several plots and years are found more than one lan ae per plant at harvest. The captures of adult moths made with pheromone traps indicate the existence of two generations, the first one flying in May and the second one in July-August. The larvae of first generation of both species rarely attack maize, but by September, most plants have been colonized by S. nonagrioides and, in a lesser degree, by O. nubilalis larvae. Larvae of both species overwinter inside the dead plants of maize, that are usually left in the fields after harvesting by most farmers. Given the mild winter temperatures of the South Atlantic coast, most of them survive until the nest spring and produce the adults of first generation. Cultural methods (e.g. destruction of plant stems) and the use of resistant maize genotypes could improve the management of maize borers, diminishing their economic damages.