Meccanismi di resistenza ai piretroidi in popolazioni di Musca domestica L. (Diptera: Muscidae) dell’Italia settentrionale

[Autom. eng. transl.] In insects, the target site resistances against pyrethroid insecticides are caused by point mutations in the sequence encoding the sodium channel. These resistance mechanisms compromise the efficacy of this class of active ingredients which still have great importance to combat the infestations of Musca domestica L. in an urban or zootechnical environment. Combining in vitro molecular techniques and in vivo efficacy biosages, two populations collected in different environmental contexts of the province of Piacenza were examined, comparing them with a sensitive reference population. Specific allele PCRs showed the widespread presence of mutations at the kdr loci (L1014F and L1014H, the latter also known as kdr-his) and super-kdr (M918T). The bioassays have estimated very high resistance factors in the studied populations that can be correlated to the frequencies of the identified mutations. The data confirmed the presence of the M918T mutation only at the same time as the L1014F, as already highlighted in previous studies conducted in Europe, Asia and the United States. In contrast, the L1014H mutation (whether in heterozygosity or homozygosity) was never found in correlation with the super-kdr. The analysis of the intronic sequence in the vicinity of the kdr locus has also highlighted a remarkable variety of haplotypes in agreement with the literature data, confirming the probable multiple origin of the mutations responsible for resistance to pyrethroids in M. domestica.