Journal of Invertebrate Pathology 87 (2004) 129–131 www.elsevier.com/locate/yjipa 0022-2011/$ - see front matter  2004 Elsevier Inc. All rights reserved. doi:10.1016/j.jip.2004.09.003 Short Communication The development of the endoparasitoid Venturia canescens in Bt-tolerant, immune induced larvae of the Xour moth Ephestia kuehniella M. Mahbubur Rahman, Harry L.S. Roberts ¤ , Otto Schmidt Insect Molecular Biology Laboratory, School of Agriculture and Wine, University of Adelaide, Glen Osmond, SA 5064, Australia Received 13 August 2004; accepted 29 September 2004 Abstract We examined the survival and development of the endoparasitoid Venturia canescens in a Bt-tolerant laboratory strain of the Xour moth Ephestia kuehniella, in which Bt-tolerance has been shown to be associated with an inducible elevation of the insect’s immune response. The results indicate the elevated immune status associated with Bt-tolerance does not confer cross-protection against parasitism by V. canescens. No signiWcant diVerence was observed in the rate of emergent wasps from parasitised Bt-tolerant and Bt-susceptible hosts. In addition, wasps from Bt-tolerant hosts had longer development times and were larger than wasps from Bt-susceptible hosts.  2004 Elsevier Inc. All rights reserved. Keywords: Integrated pest management; Venturia canescens; Ephestia kuehniella; Bacillus thuringiensis; Biological control 1. Introduction Parasitoids are eVective natural enemies of many pest species and are widely used in conjunction with biopesti- cides such as Bacillus thuringiensis (Bt) in integrated pest management (IPM) programmes. Previous research has found little evidence of direct negative eVects on parasi- toids of Bt-formulations or of Bt-transgenic plants, nor of Bt-resistant hosts acquiring cross-resistance to parasi- toids (Glare and O’Callaghan, 2000; Schuler et al., 2004), indicating that parasitoids can be employed in a compli- mentary fashion with the use of Bt-formulations. How- ever, while in previous studies host Bt-resistance has typically been due to alterations in gut protease activity or receptor insensitivity, recent research has shown that tolerance to Bt endotoxins in a laboratory strain of the Xour moth Ephestia kuehniella (Lepidoptera: Phycitidae), a common pest of stored food products, is associated with an inducible increase in the rate of the melanization reaction in haemolymph (Rahman et al., 2004), a hall- mark of an elevated immune response in insects (Soder- hall and Cerenius, 1998). Similar results have also been observed for the cotton bollworm Helicoverpa armigera (Ma et al., under review) and the diamondback moth Plu- tella xylostella (M. Sarjan, unpublished data), suggesting that the initial development of Bt-tolerance through immune-related processes may be a common phenome- non. Since the capacity of a host to overcome parasitiza- tion in large part depends on the eVectiveness of its immune response, this raises the question of whether the immune induction associated with Bt-tolerance results in cross-protection against parasitism. To answer this ques- tion we examined the survival and development of the endoparasitoid Venturia canescens Grav. (Hymenoptera: Ichneumonidae) in Bt-tolerant E. kuehniella. * Corresponding author. Fax: +61-83794095. E-mail address: harry.roberts@adelaide.edu.au (H.L.S. Roberts).