Document Type

Article

Publication Date

5-2008

Journal or Book Title

Journal of Insect Physiology

Volume

54

Issue

5

First Page

777

Last Page

789

DOI

10.1016/j.jinsphys.2008.02.008

Abstract

ScathL is a cathepsin L-like cysteine protease derived from the flesh fly Sarcophaga peregrina that functions in basement membrane (BM) remodeling during insect development. A recombinant baculovirus expressing ScathL (AcMLF9.ScathL) kills larvae of the tobacco budworm, Heliothis virescens, significantly faster than the wild-type virus. Here, we show that the occurrence of larval melanization prior to death was closely associated with the onset of high cysteine protease activity of ScathL in the hemolymph of fifth instars infected with AcMLF9.ScathL, but not with AcMLF9.ScathL.C146A, a recombinant baculovirus expressing a catalytic site mutant of ScathL. Fragmented fat body, ruptured gut and malpighian tubules, and melanized tracheae were observed in AcMLF9.ScathL-infected larvae. Phenoloxidase activity in hemolymph was unchanged, but the pool of prophenoloxidase was significantly reduced in virus-infected larvae and further reduced in AcMLF9.ScathL-infected larvae. The median lethal dose (LD50) for purified ScathL injected into fifth-instar H. virescens was 11.0 μg/larva. ScathL was also lethal to adult pea aphids, Acyrthosiphon pisumwith a similar loss of integrity of the gut and fat body. Injection with purified ScathL.C146A or bovine trypsin at 20 μg/larva did not produce any effect in either insect. These results illustrate the potent insecticidal effects of ScathL cysteine protease activity and the potential for use of ScathL in development of insect resistant transgenic plants when combined with an appropriate delivery system.

Comments

This article is from Journal of Insect Physiology 54, no. 5 (May 2008): 777–789, doi:10.1016/j.jinsphys.2008.02.008.

Rights

Works produced by employees of the U.S. Government as part of their official duties are not copyrighted within the U.S. The content of this document is not copyrighted.

Language

en

File Format

application/pdf

Included in

Entomology Commons

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