FORUM Insecticide Resistance and Dominance Levels

• Main Authors: D. Bourguet, A. Genissel, M. Raymond, J. Econ Entomol
• Other Authors: The Pennsylvania State University CiteSeerX Archives
• Format: Text
• Language: English
• Subjects: DML
• Online Access: http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.489.6446; http://www.evolutionhumaine.fr/michel/publis/pdf/Bourguet_2000_J_Eco_Entomol.pdf

ABSTRACT Dominancehas been assessed indifferentways in insecticide resistance studies, based on three phenotypic traits: the insecticide concentration required to give a particular mortality (DLC), mortality at a particular insecticide dose (DML), and Þtness in treated areas (DWT). We propose a general formula for estimating dominance on a scale of 0 to 1 (0 5 complete recessivity and 1 5 complete dominance). DLC, DML, and DWT are not directly related and their values depend ongeneticbackgroundandenvironmental conditions.Wealso showthatpestmanagement strategies can have the consequence to increase DWT via the selection of dominance modiÞers. Studies on resistance to Bacillus thuringiensis toxins provide the ultimate example of the complexity of the deÞnition of the concept of dominance. Almost all studies have focused on calculation ofDLC, which provides little information about the efÞciency of pest management programs. For instance, one assumption of the high dose/refuge strategy is that Bacillus thuringiensis resistance must be effec-tively recessive (i.e., DML must be close to zero). However, DWT, rather than DML, is relevant to the resistance management strategy. Therefore, we strongly suggest that the time has come to focus on Þtness dominance levels in the presence and absence of insecticide. KEY WORDS Bacillus thuringiensis, effective dominance, Þtness cost, balanced polymorphism