Evaluation of Australian Ladybird Beetle Cryptolaemus montrouzieri Mulsant against Green Shield Scale Chloropulvinaria psidii (Maskell) on some Medicinal Plants

Severe infestation of green shield scale Chloropulvinaria psidii (Green) was observed during 2003-04 on the medicinal plants namely Withania somnifera, Madhuca longifolia, Mimusops elengi and Wrightia tinctoria. The Australian ladybird beetle Cryptolaemus montrouzieri Mulsant was released @ 20 larvae/plant. Following the release of C. montrouzieri , the scale population declined from 173.48 to 4.35/plant on W. somnifera, 30.49 to 1.20/plant on M. longifolia, 90.20 to 3.57/plant on M. elengi and 240.86 to 4.92/plant on W. tinctoria. There was 89.13 to 97.96% reduction in scale population 45-75 days after release of C. montrouzieri on the above medicinal plants. No other natural enemy, except C. montrouzieri, was recorded on C. psidii. There was no correlation between temperature, relative humidity or rainfall and scale population. Hence, the reduction in population of green shield scale was attributed mainly to the action of C. montrouzieri.