Statistical Model of Crop Losses Caused by Maize Stem Borers (Lepidoptera: Noctuidae, Pyralidae) in Côte d'Ivoire

Abstract

Six experiments were conducted in the savanna and forest areas of Côte d'Ivoire to study the influence of stem borers on maize crop yield components and production. Statistical models showed the effect of the oldest preimaginal instars of 2 stem borers, Elduna saccharina Walker (Pyralidae) and Busseola fusca (Fuller) (Noctuidae). Plant destruction was mainly caused by early attack of B. fusca Attack by both borers on or about the 60th d after emergence induced pIant sterility. Stem borers had no direct effect on number of grains per cob-carrying plant: the level of this yield component was set according to the level of the previously determined components through a compensation phenomenon. The last yield component, average weight of grain, decreased with attack by E. sacchadna occurring on or about the 80th d after emergence. Effects of borer aggregation, maize variety, and maize streak virus incidence were studied. The statistical model of crop loss, which explains 81.7% of the variation in yield, was validated from the results of 3 trials that were not included in the regression analysis. It enables one to estimate accurately crop losses in most of Côte d'Ivoire with only 2 samplings during the growing season, on the 40th and 80th d after emergence.

Biocontrol of the maize borer Sesamia cretica Led. (Lepidoptera: Noctuidae) in Egypt using a granulovirus

“…The experiments described here suggest that the influence of S. cretica on yield is higher when infestation occurs sooner. Such relationships have been observed for other borers that infest maize at the beginning of the cycle, such as B. fusca (Moyal 1996) or Papaipema nebris (Gue  ne  e) (Lepidoptera: Noctuidae) (Levine et al 1984). Further studies on this topic are needed to obtain a better understanding of the influence of the pink borer on yield.…”