Egg parasitoids of noctuid stemborers on maize in Kenya

The West African scelionid egg parasitoid Telenomus isis was released into Kenya in 2005 for control of the noctuid stemborer Busseola fusca. Pre- and post-release surveys were carried out between 2004 and 2006 to assess parasitism of eggs of noctuid stemborers in ecozones where B. fusca is the dominant pest, namely in the mid-altitude areas of Taveta and Kiboko, in the highlands along the Eldoret-Kitale transect, and in Wundanyi, which stretches from the mid-altitudes to the highlands. Apart from Eldoret, where surveys were carried out weekly during the cropping seasons of 2004-2005, the sites were visited once during the short and/or long rainy seasons. In addition, after release of T. isis in Wundanyi in October 2005, two post-release surveys were conducted in 2006. Busseola fusca was the dominant stemborer species at Eldoret and Wundanyi. At Taveta and Kiboko only eggs of the noctuid Sesamia calamistis were recovered. There was generally a high variation in the numbers of egg batches and eggs per batch among the sites surveyed. Most of the infested plants had one egg mass. Egg parasitism varied between 10% and 32% across the study sites. The predominant parasitoid species was the scelionid Telenomus busseolae while the trichogrammatids Trichogramma bournieri, Trichogrammatoidea nr. lutea. Trichogrammatoidea nr. cryptophlebiae and Trichogramma mwanzai were minor species. In 2006, T. isis was recovered in Wundanyi. This study showed that although egg parasitoid species diversity was higher, egg parasitism was considerably lower in Kenya than in western Africa.