title: Resistance to hexythiazox in Brevipalpus phoenicis (Acari: Tenuipalpidae) from Brazilian citrus.
abstract: The objective of this study was to collect baseline information for implementing an acaricide resistance management program of Brevipalpus phoenicis (Geijskes) to hexythiazox in Brazilian citrus groves. The egg susceptibility of B. phoenicis to hexythiazox was measured by a direct contact bioassay. The estimated LC50 for the S strain was 0.89 mg hexythiazox L(-1) of water (95% FL 0.75-1.03). After hexythiazox selection of a field-collected population associated with intense hexythiazox use, a resistance ratio greater than 10,000-fold was detected. Results from a survey revealed a great variability in the frequency of resistance in populations of B. phoenicis collected from citrus groves located in the State of São Paulo. No relationship was observed between the intensity of hexythiazox use and the frequency of resistance. Studies on dynamics of resistance showed that the resistance of B. phoenicis to hexythiazox is stable under laboratory conditions. Therefore, there is an urgent need to implement resistance management of B. phoenicis to hexythiazox in order to prolong its effective use in Brazilian citrus groves.
authors.affiliation: Departamento de Entomologia, Fitopatologia e Zoologia Agricola, Escola Superior de Agricultura Luiz de Queiroz, Universidade de São Paulo, 13418-900 Piracicaba, SP, Brazil.
authors.forename: Fernando Joly
authors.initials: FJ
authors.lastname: Campos
authors.forename: Celso
authors.initials: C
authors.lastname: Omoto
mesh_terms: D000818:Animals; D001681:Biological Assay; D001938:Brazil; D002957:Citrus / Q000469:parasitology*; D005260:Female; D007305:Insecticide Resistance; D007306:Insecticides; D008925:Mites / Q000254:growth & development* / Q000378:metabolism
chemical_list: D007306:Insecticides