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Sex-specific expression of detoxification proteins contributes to differential metabolic detoxification capacity and acaricide sensitivity in female and male Tetranychus cinnabarinus (Boisduval).

Pronounced sex-specific differences exist in the toxicological traits of spider mite species. Our previous work showed that female Tetranychus cinnabarinus exhibit significantly higher tolerance to acaricides than males, primarily driven by elevated detoxification enzyme activity. However, the molecular basis underlying this sex-specific difference remains unclear. Here, we used pyridaben and cyflumetofen as representative acaricides to dissect the molecular mechanisms underlying sex-specific differences in detoxification metabolism between female and male mites. After 48 h of cyflumetofen exposure, GST activity increased significantly in female mites. Following pyridaben exposure, the activities of both P450 (24 h and 48 h) and CCE (48 h) increased significantly in female mites. Under the same conditions, only P450 activity increased significantly in male mites after 48 h of pyridaben exposure. Proteomic profiling identified 33 differentially expressed detoxification enzymes, predominantly from the major detoxification families P450, GST, and CCE; among them, 26 were significantly upregulated in females relative to males. Six detoxification enzymes, including CYP392A3, CYP389C5, TcGSTd02, TcGSTd13, TcCCE39, and TcCCE52, were selected for functional characterization. We successfully obtained six active recombinant detoxification enzymes through heterologous expression. IC50 and in vitro metabolism assays showed that these recombinant proteins display both shared and distinct capacities for metabolizing or sequestering cyflumetofen and pyridaben. RNAi and bioassay results demonstrated that silencing CYP389C5, TcGSTd02, and TcCCE52 resulted in more pronounced changes in acaricide susceptibility in female than in male mites. Collectively, this study demonstrates that the sex-biased protein abundance identifies candidate biochemical contributors to differential susceptibility in female and male mites.

Animals

Biochemical mechanisms causing tick resistance.

Three general biochemical mechanisms can cause ticks to be resistant to acaricides: an alteration in the properties of the site of action, a change in the rate of transportation and a change in the rate of metabolism. The first mechanism enables increased concentrations of acaricide at the site of action to be tolerated, while the last two mechanisms result in a decreased concentration and/or persistence of the acaricide at the site of action. These mechanisms are discussed in detail with reference to a range or acaricides, particular emphasis being given to blue tick strains occurring in Southern Africa.

Animals

Can host genetics transform the sustainable control of tropical theileriosis? Insights from the Tick-Theileria interface.

Tropical theileriosis, caused by the tick-transmitted apicomplexan parasite Theileria annulata, remains a major constraint on cattle production across North Africa, the Mediterranean basin, the Middle East and South Asia. Current control depends on acaricides, the theilericidal drug buparvaquone and live attenuated schizont vaccines, but acaricide resistance, buparvaquone-resistance mutations and the logistical demands of vaccination are eroding the sustainability of these tools. Host genetics offers a complementary and durable alternative. Indigenous Bos indicus breeds are consistently more resistant to ticks and tolerate T. annulata infection better than exotic Bos taurus cattle, and this advantage has a measurable heritable component. Unlike previous reviews, which treat tick resistance, T. annulata immunobiology and livestock genomic selection as separate subjects, we integrate all three and assess host genetics specifically against the failure modes of current control. We review the tick, parasite and host interface, the evidence for natural resistance, and the genetic and immunological mechanisms involved, including signal-regulatory protein, bovine major histocompatibility complex class II and inflammatory pathway genes. We then assess whether genomic selection, multi-omics, machine learning and gene editing can translate these mechanisms into resistant cattle, and we weigh the biological, economic and infrastructural barriers to implementation. The evidence indicates that host genetics will not replace existing control but could reduce reliance on acaricides and chemotherapy. That contribution remains prospective rather than demonstrated: no resistance marker for T. annulata has yet been validated, prediction accuracies are moderate and transfer poorly between breeds, and no endemic production system has implemented selection for resistance.

Animals

The potential of some synthetic pyrethroids for control of the cattle tick (Boophilus microplus).

As part of a continuing programme to aid in the development of new acaricides, the potentials of three synthetic pyrethroids, permethrin, cypermethrin and decamethrin, were assessed against a range of resistant strains of the cattle tick (Boophilus microplus). The compounds were shown to be acaricidal, with decamethrin the most effective, giving efficient control of susceptible and organo-phosphorus resistant strains of the cattle tick at concentrations as low as one fifth of those previously used for any commercial acaricide. However higher concentrations were required for satisfactory control of the DDT-resistant strain. Permethrin-selection of a field strain containing a low percentage of DDT-resistant ticks led to rapid development of resistance to a level equivalent to that of the DDT-resistant strain. Further selection increased resistance to permethrin to a higher level than that shown in the DDT-resistant strain. This increased resistance to permethrin appears to be restricted mainly to this compound and is not associated with a marked increase in resistance to cypermethrin, decamethrin or DDT. The potential of organo-phosphorus compounds to potentiate the pyrethroids when the two classes of compounds are used as mixtures against the pyrethroid-resistant and susceptible strains was confirmed.

Animals

Molecular basis of Fenazaquin resistance in Polyphagotarsonemus latus revealed by transcriptome profiling and real-time validation.

The broad mite, Polyphagotarsonemus latus (Banks), is a highly polyphagous tarsonemid pest that causes severe damage to a wide range of agricultural and horticultural crops. The excessive and indiscriminate use of Fenazaquin, a mitochondrial electron transport inhibitor, resulted in the rapid development of resistance in P. latus. To elucidate the molecular mechanisms underlying acaricide resistance, a transcriptomic investigation was conducted on Fenazaquin-resistant (FEN-SEL) and susceptible (NBAIR-GR-TAR-01a) populations. The analysis identified putative genes involved in detoxification, including cytochrome P450 monooxygenases (CYPs), glutathione S-transferases (GSTs), choline and carboxyl esterases (CCEs), and ATP-binding cassette (ABC) transporters. Phylogenetic analysis revealed lineage-specific expansions of clan 3 CYPs, delta and acari-specific mu classes of GSTs, and ABCC, ABCG, and ABCH subfamilies of ABC transporters. Ten resistance-associated unigenes were validated using quantitative real-time PCR to assess gene expression patterns. The results showed significant upregulation of CYP4CL3, CYP4CF4, two delta-class GSTs, two CCEs belonging to clade J″, and two ABC transporters from subfamily C. However, CYP4725A2 and CYP4726A1 showed downregulation. These findings highlight the potential association of multiple metabolism-related gene families with Fenazaquin resistance and their possible contribution to the resistant phenotype. Overall, this study provides molecular insights into Fenazaquin resistance in P. latus, supporting the need for targeted resistance management strategies. Further research is warranted to evaluate the potential of these genes as molecular targets for sustainable broad mite management.

Acaricide