Stage-dependent tolerance of the German cockroach, Blattella germanica for dichlorvos and propoxur
1Department of Entomology, China Agricultural University, Beijing, 100193, China
2Beijing Center for Disease Prevention and Control, Beijing, 100013,China
Abstract
Stage-dependent dichlorvos and propoxur tolerance in a field population of the German cockroach, Blattella germanica Linnaeus (Blatodea: Blattellidae), was investigated in the laboratory using a topical application bioassay. The results showed the 6 week-old nymphs were more tolerant to dichlorvos and propoxur than the other ages tested. LD50 values of dichlorvos and propoxur for the 6 week-old nymphs were 2.003 μg per insect and 5.296 μg per insect, respectively. Tolerance ratios of 18.55-fold and 4.98-fold for LD50 were obtained from 6-weekold nymphs compared to 4 week-old nymphs. The specific activity of acetylcholinesterase (AChE) from 1 week-old nymphs was the highest among all tested developmental stages of nymphs and adult males and females. The specific activity of AChE decreased significantly with increasing age. The sensitivity of AChE to dichlorvos was the highest with a ki value of 3.12×104 mol-1min-1 in the last nymphal stage of B. germanica (about 6 weeks-old). The AChE from 4 week-old nymphs was the most sensitive to propoxur, with the highest ki value being 2.63×105 mol-1min-1. These results indicated that the different developmental stages and sexes of B. germanica affected the inhibition of AChE by dichlorvos and propoxur.
Keywords: acetylcholinesterase, insecticide tolerance, stage-dependent susceptibility
Abbreviations: AChE, acetylcholinesterase; dichlorvos, the insecticide 2, 2-dichlorovinyl dimethyl phosphate;
DTNB, Ellman’reagent 5, 5’-dithiobis-(2-nitrobenzoic acid)
Correspondence:
a*qkcandy@126.com,
bnoble1211222@163.com,
cxpzeng@yahoo.com.cn,
delfting@126.com,
egaoxiwu@263.net.cn, *Corresponding author
Editor: James Ottea was editor of this paper.
Received: 23 June 2008 | Accepted: 7 October 2010 | Published: 3 December 2010
Copyright: This is an open access paper. We use the Creative Commons Attribution 3.0 license that permits unrestricted use, provided that the paper is properly attributed.
ISSN: 1536-2442 | Volume 10, Number 201
Qian K, Wei XQ, Zeng XP, Liu T, Gao XW. 2010. Stage-dependent tolerance of the German cockroach, Blattella germanica for dichlorvos and propoxur. Journal of Insect Science 10:201, available online: insectscience.org/10.201
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