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Using reverse transcription polymerase chain reaction and degenerate oligonucleotide primers, a partial para-homologous sodium channel cDNA was obtained from the southern cattle tick, Boophilus microplus (Canestrini). The cDNA sequence encoded the region in which knockdown resistance (kdr)-type mutations have been identified in numerous insect species. Comparison of deduced amino acids from the cDNA sequence showed high similarity with sodium channels from other species, particularly in highly conserved repeat domains of the sodium channel. Analysis of the kdr-homologous region of the genomic DNA sequences from several susceptible and pyrethroid-resistant tick strains did not detect mutations. The result suggests novel mutations in the sodium channel gene or metabolic detoxification may be involved in the resistance to pyrethroids in this tick.

Particulate fractions (10,OOOg) from pupae of Stomoxys calcitrans transfer[14C]-mannose from CDP-[14C]-mannose to dolichol monophosphate and proteins. production of the mannosyl lipid was inhibited by Mn2+, UDP, GMP, GDP, and EDTA. The insect growth regulator diflubenzuron had no effect on mannosyl transferase activity. Dolichol monophosphate and Mg2+ stimulated mannosyl transferase activity. The mannosyl lipid product was identified as mannosyl-phosphoryl-dolichol (Man-P-Dol)*. The apparent K , and V, , , values for the formation of Man-P-Do1 using GDP-[14C]-Man while holding dolichol phosphate constant were 2.4 k 0.9 p M and 9.4 k 2.3 pmol Man-P-Do1.min-l.mg-l protein, respectively. The apparent K , and V , , , values using dolichol phosphate while holding GDP-Man constant were 2.2 f 1.2 p M and 18.5 f 1.7 pmol Man-P-Dol.min-'.mg-' protein.

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