Does Phenoloxidase Contributed to the Resistance? Selection with Butane-Fipronil Enhanced its Activities from Diamondback Moths
Shouzhu Liu1, 2, Hongtao Niu2, Ting Xiao3, Chaobin Xue2, Zhongde Liu4, Wanchun Luo*, 2
Identifiers and Pagination:Year: 2009
First Page: 9
Last Page: 13
Publisher ID: TOBIOCJ-3-9
Article History:Received Date: 12/12/2008
Revision Received Date: 25/12/2008
Acceptance Date: 28/12/2008
Electronic publication date: 26/1/2009
Collection year: 2009
open-access license: This is an open access article licensed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/3.0/) which permits unrestricted, non-commercial use, distribution and reproduction in any medium, provided the work is properly cited.
Using microtitration method, the relationship between Phenoloxidase activity and the resistance of the diamondback moth Plutella xylostella (Linnaeus) to the novel insecticide butane-fipronil was determined in vitro. After selection of the tenth-generation by butane-fipronil, the resistance of the fourth instar larvae was increased 83.80-fold as compared to the susceptible strain. Phenoloxidase activity of the resistant strain (POr) was 1.29-fold higher than the susceptible one (POs). However, the Km and optimum pH values were similar in resistant and susceptible strains, which were 1.11 mM and 6.5, respectively. Both POr and POs have maximum stability at pH values less than 7.0, although POs was less stable at lower pH values than POr. In addition, the thermal stabilities of the two phenoloxidase were very similar. It is suggested that PO may play an important role in the increasing resistance of pests to pesticides.