Effect of prey stage on life-table attributes of a genetically manipulated strain of Metaseiulus occidentalis (Acari: Phytoseiidae)

Metaseiulus occidentalis females from the carbaryl-organophosphate-sulfur resistant strain (COS) lived longer (25.3 days versus 19.7 days), had a higher total fecundity (43.8 eggs female super(-1) versus 33.6 eggs female super(-1)) and a higher daily fecundity rate (2.4 eggs female super(-1) day super(-1) versus 2.0 eggs female super(-1) day super(-1)), and exhibited a higher intrinsic rate of increase (0.243 individuals female super(-1) day super(-1) versus 0.182 individuals female super(-1) day super(-1)) and shorter generation time (13.9 days versus 17.0 days), at 24-28 degree C, 47-56% RH under continuous fluorescent light, when reared on a diet of 0-48-h-old eggs rather than a diet of mixed actives of Tetranychus pacificus McGregor on bean leaf disks. The sex-ratio of the progeny was female-biased for both diets, 2.1 females to 1 male for M. occidentalis reared on eggs and 2.0:1 female:male for M. occidentalis reared on mixed actives, suggesting that diet influences sex-ratio in some unknown way.