Changes in meligethes aeneus (Coleoptera: Nitidulidae) susceptibility to lambda-cyhalothrin in the czech republic between 2009 and 2011

Abstract

Susceptibility of Meligethes sp. (mainly M. aeneus) from the Czech Republic was tested with lambda-cyhalothrin (111 samples in 2009, 125 in 2010, and 102 in 2011) through the use of IRAC method No. 011, Vers. 3 Resistant samples were the most frequent in all three years and their proportions increased from 33% to 62% between 2009 and 2011 The last samples classified as highly susceptible were recorded in 2010 The mean percentage mortalities for a common European field rate of 7.5 g a.i/ha were 82.2% in 2009, 78.92% in 2010, and 67.45% in 2011(according to Abbott’s formula). The values of LC50 ranged from 0.084 to 47.27 g a.i./ha in 2009, from 0.051 to 46.78 g a.i./ha in 2010, and from 0.238 to 19.92 g a.i./ha in 2011 Only in 17.65% of samples there were LC90 values below the European field rate in 2011.