Pyrethroid target site resistance in Greek populations of the honey bee parasite Varroa destructor (Acari: Varroidae) | Resistencia diana al piretroide en poblaciones griegas del parásito de la miel de abeja Varroa destructor (Acari: Varroidae)
2017
Alissandrakis, Eleftherios | Ilias, Aris | Tsagkarakou, Anastasia
The mite Varroa destructor is the most serious pest of honey bees worldwide and its control is mainly based on the use of synthetic acaricides, which, in many cases, has led to the development of resistance. In Greece, evidence of resistance to the pyrethroid tau-fluvalinate goes back to the early 1990s. In the present study we examined the presence of resistance mutations at the voltage gated sodium channel (VGSC) gene, encoding the target of pyrethroids. The frequency of resistance mutations was examined by genotyping 113 V. destructor individuals from seven localities in Greece The nucleotide sequencing of the IIS4-IIS5 region of the VGSC gene revealed two amino acid replacements at position 925: a leucine to valine substitution (L925 V) and a leucine to isoleucine substitution (L925I). This is the first report of L925I mutation in European populations of V. destructor that has so far been identified only in USA. No mutations at two other “hot spot” resistance positions, 918 and 929 of the VGSC gene encompassing position 925 were identified. Resistant alleles were predominant (53%) and most of them (83%) corresponded to the L925I substitution. Genotyping results showed the presence of homozygous wild type 925L (44.2%) individuals as well as homozygous resistant 925I (39.8%) and 925 V (7.1%), while heterozygous individuals (925I/L, 925I/V, 925 V/L) were present at low frequency (5.3, 2.7 and 0.9 respectively). Our results clearly show the presence of pyrethroid resistant mutations in high frequency in Greek Varroa populations.
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