Identification of pyrethroid resistance associated mutations in the para sodium channel of the two‐spotted spider mite Tetranychus urticae (Acari: Tetranychidae)

Abstract

We investigated pyrethroid resistance mechanisms in Tetranychus urticae strains from Greece. Combined bioassay, biochemical and synergistic data indicated that although P450 mono-oxygenase activities were associated with the trait, target site insensitivity was the major resistance component. A 3.3 kb cDNA fragment of the T. urticae para sodium channel gene encompassing segment 4 of domain II to segment 6 of domain IV was obtained by a degenerate PCR strategy. The T. urticae sequence showed highest identity (56%) to the scabies mite, Sarcoptes scabiei, and was phylogenetically classified within the divergent group of Arachnida. Comparison of resistant and susceptible strains identified the point mutation F1538I in segment 6 of domain III, which is known to confer strong resistance to pyrethroids, along with a second mutation (A1215D) in the intracellular linker connecting domains II and III with an unknown role. Three transcripts were identified corresponding to the k and l alternative exons. The mode of inheritance of resistance was confirmed as incompletely recessive, which is consistent with a target site mechanism for pyrethroids.

Control of Tetranychus urticae Koch by extracts of three essential oils of chamomile, marjoram and Eucalyptus

“…Leaf discs (3 cm in diameter) of beef steak leaves were used as substrate to ovipositor. Four leaf discs were used for each treatment and five mite females were transferred to each disc and left 24 h to lay eggs, then females were removed.…”

“…urticae females, 3 days old, were obtained by placing 100 nymphs onto the culture, and wet cotton pads in Petri dishes were placed on excised beef steak leaves. The emerged females and males were transferred to new beef steak leaves for 2-3 days and allowed to mate.…”

“…The emerged females and males were transferred to new beef steak leaves for 2-3 days and allowed to mate. Afterwards, forty females were transferred equally to four discs (3 cm in diameter), and then treated with one of the previous treatments. Control treatment was operated by Triton X-100 at a rate of 0.1%.…”

“…A major problem in the control of T. urticae is the response to develop resistance to many acaricides due to an approximate 5-fold increase in the mixed function of oxidase activity [1] . For several years, chemical control of mites has been extensively practiced [2][3][4] . In Egypt, different extracts from Syzygium cumini (S. cumini) L. Skeels (Pomposia) against T. urticae Koch were used to control mite population and ethanol extract showed the most potent acaricidal activity [5] .…”

The Pyrethroid Knockdown Resistance

“…aegypti populations from Latin America and Southeast Asia, but at least two sites seem to be indeed related to pyrethroid resistance: 1016 (Val to Ile or Gly) and 1534 (Phe to Cys), respectively in the IIS6 and IIIS6 segments (Brengues et al, 2003;Harris et al, 2010;Martins et al, 2009a, b;Saavedra-Rodriguez et al, 2007). Mutations in the vicinity of this site in the IIIS6 segment were also encountered in the southern cattle tick Rhipicephalus microplus (He et al, 1999) and in the two-spotted spider mite Tetranychus urticae (Tsagkarakou et al, 2009). Although different Na V site mutations are known to confer resistance to pyrethroids, their number is quite restricted; additionally, far related taxa present alterations in the same homologous sites.…”