(2aE,2'S,4E,5'S,6S,6'R,7S,8E,11R,15S,17aR,20Z,20aR,20bS)-6'- cyclohexyl-7-[(2,6-dideoxy-3-O-methyl-α-L-arabino- hexopyranosyl)oxy]-20b-hydroxy-20-(hydroxyimino)-5',6,8,19- tetramethyl-5',6,6',7,10,11,14,15,17a,20,20a,20b- dodecahydrospiro[2H,17H-11,15-methanofuro[4,3,2-pq] [2,6]benzodioxacyclooctadecine-13,2'-pyran]-17-one ((5Z,25R)-25- cyclohexyl-4'-O-de(2,6-dideoxy-3-O-methyl-α-L-arabino- hexopyranosyl)-5-demethoxy-25-de(1-methylpropyl)-5- (hydroxyimino)avermectin A1a)