Limonoids from Citrus Reticulata and their Moult Inhibiting Activity in Mosquito Culex Quinquefascia Tus Larvae

Three limonoids, namely limonin, nomilin and obacunone, were isolated from the seeds of Citrus
reticulata [Blanco Coorg Mandarin]. Their structures were confirmed by spectroscopic studies. With 4th instar
larvae of mosquito Culex quinquefasciatus, the ECs0 for inhibition of adult emergence was 6.31, 26.61 and
59.57 ppm for obacunone, nomilin and limonin, respectively. The pattern of mortality at around the ECs0
levels was indicative of moult inhibiting activity. The efficacy of a limonoid enriched fraction was similar to
that of limonin, probably due to the high content (70%) of limonin.