Multiparasitism by the pupal parasitoids, Xanthopimpla stemmator (Hymenoptera: Ichneumonidae) and Pediobius furvus (Hymenoptera: Eulophidae) on two African cereal stemborers, Chilo partellus (Lepidoptera: Crambidae) and Busseola fusca (Lepidoptera: Noctuidae)

Abstract

The outcome of multiparasitism by two pupal parasitoids, the exotic solitary ichneumonid Xanthopimpla stemmator and the indigenous gregarious eulophid Pediobius furvus, was studied using the invasive crambid stem borer Chilo partellus and the indigenous noctuid Busseola fusca as hosts. Two parasitism sequences were observed, where X. stemmator oviposited before P. furvus, and vice versa. In addition, the effect of time between first and second parasitism on parasitoid emergence, development, sex ratio, and number of offspring was assessed. For most treatments, time interval between parasitism had no significant effect on the percentage if pupae producing either P. furvus or X. stemmator. In general, X. stemmator outcompeted P. furvus irrespective of the order of oviposition, time interval between ovipositions and host species. Further studies, especially on host finding capacity of the two parasitoid species are required to determine the competitiveness of the two species under field conditions.

Keywords:

• Xanthopimpla stemmator
• Pediobius furvus
• Chilo partellus
• Busseola fusca
• pupal parasitoids
• multiparasitism

Published online 13 October 2005

Published online 13 October 2005

Acknowledgments

The authors thank Ochieng, J., Ogweno, P. and Okuku, G. for their technical assistance. We also thank Dr. Des Conlong from Plant Protection Research Institute (PPRI), South Africa for provision of X. stemmator. This work was supported by the Directorate General for International Cooperation, the Netherlands.

Notes

Published online 13 October 2005