Presented at the National Meeting of the Entomological Society of America, Fort Lauderdale, Florida, November 2002.
Colorado potato beetles compensate for tomato cathepsin D inhibitor expressed in transgenic potato †
Version of Record online: 17 FEB 2004
Copyright © 2004 Wiley-Liss, Inc.
Archives of Insect Biochemistry and Physiology
Special Issue: Insect Digestion: Potential Applications in Insect Management
Volume 55, Issue 3, pages 103–113, March 2004
How to Cite
Brunelle, F., Cloutier, C. and Michaud, D. (2004), Colorado potato beetles compensate for tomato cathepsin D inhibitor expressed in transgenic potato . Arch. Insect Biochem. Physiol., 55: 103–113. doi: 10.1002/arch.10135
- Issue online: 17 FEB 2004
- Version of Record online: 17 FEB 2004
- Natural Science and Engineering Research Council of Canada
- insect digestive proteases;
- cathepsin D inhibitor;
- potato (Solanum tuberosum L.);
- Colorado potato beetle (Leptinotarsa decemlineata Say);
We reported earlier the importance of digestive cathepsin D-like activity for initiating dietary protein hydrolysis in Colorado potato beetle, Leptinotarsa decemlineata Say [Brunelle et al. (1999) Arch. Insect Biochem. Physiol. 42:88–98]. We assessed here whether transgenic lines of potato (Solanum tuberosum L.) expressing a cathepsin D inhibitor (CDI) from tomato would show resistance to the beetle, or if the insect would compensate for the loss of cathepsin D activity after ingesting the recombinant inhibitor. Transgenic potato lines expressing tomato CDI were developed by Agrobacterium tumefaciens genetic transformation, and selected based on their relative amount of CDI. After confirming the absence of detectable visible effects of CDI on the plant's phenotype, diet assays with control and transgenic lines were carried out to assess the impact of the inhibitor on growth and development of the insect. Leaf consumption, relative growth rate, molting incidence, and digestive protease activity were monitored at 12-h intervals over 132 h for 3rd-instar larvae provided with transgenic potato foliage. Leaf consumption and relative growth rate were slightly reduced during the first 12 h for larvae fed CDI, but no significant differences were observed thereafter. In contrast, time for molting to the 4th larval stage was significantly longer for larvae fed modified plants, with developmental delays of ˜10 h (0.5 day) compared to control larvae. Recombinant CDI also had an impact on the insect's digestive physiology, readily inducing overproduction of digestive proteases (rubiscases), followed by a gradual decrease of total and pepstatin-sensitive activity. Overall, these observations show the ability of Colorado potato beetle to compensate for the loss of cathepsin D activity by modulating its digestive protease complement in response to aspartate-type inhibitors in the diet. From a practical viewpoint, these data stress the importance of devising improved strategies for the effective inhibition of insect digestive proteinases in vivo, based on the use of hybrid inhibitors active against different protease classes. Arch. Insect Biochem. Physiol. 55:103–113, 2004. © 2004 Wiley-Liss, Inc.