Production of pyrethrins in cultured tissues of pyrethrum (Chrysanthemum cinerariaefolium Vis.).

Calluses were initiated from elite high-yielding (2.5% pyrethrins) lines of C. cinerariaefolium [Tanacetum cinerariifolium] on MS medium supplemented with 2,4-D at 2 mg and kinetin at 0.5 mg/litre. Callus growth was slow until the third week of culture; during this period the pyrethrins content rose rapidly to reach peak value (0.224%) in the third week. Exponential growth occurred, concurrently with a decline in pyrethrins, from week 3 to week 6. The callus extracts showed effective insecticidal activity in bioassays against mosquito larvae, when compared with authentic samples of pyrethrins.