In recent years, the green shield scale Chloropulvinaria psidii (Green), has become a serious pest of several medicinal plants in India. Severe infestation of C. psidii was observed in June 2003 on Withania somnifera and in February 2004 on Madhuca longifolia, Mimusops elengi and Wrightia tinctoria at the IIHR farm. The scale insects suck cell sap resulting in loss of vigour in medicinal plants. Nymphs and adults excrete ‘honeydew’ resulting in development of sooty mold, thereby hindering photosynthetic activity of the scale-infested plants. Although some insecticides have been recommended for control of C. psidii (Pawar et al, 1981; Visalakshi et al, 1981), it is difficult to achieve perfect control of the green shield scales with conventional insecticides, mainly due to the mealy covering over their bodies (Chatterji and Datta, 1974). Eggs of the scales, protected by a waxy filamentous secretion of the ovisac, are almost impossible to reach with insecticides. On the other hand, scale insects (being sessile in nature) are more amenable to biological control. The Australian ladybird beetle, Cryptolaemus montrouzieri Mulsant, has been reported to the effective against various species of green shield scales (Mani and Krishnamoorthy, 1997a). The present study was conducted to evaluate the impact of C. montrouzieri in suppression of C. psidii on Evaluation of Australian ladybird beetle Cryptolaemus montrouzieri Mulsant against green shield scale Chloropulvinaria psidii (Maskell) on some medicinal plants M. Mani* and A. Krishnamoorthy Division of Entomology and Nematology Indian Institute of Horticultural Research, Bangalore -560 089, India E-mail: mmani1949@yahoo.co.in ABSTRACT 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. Key words: Chloropulvinaria psidii, Cryptolaemus montrouzieri, Withania somnifera, Madhuca longifolia, Mimusops elengi, Wrightia tinctoria the above mentioned four medicinal plants. Culture of Cryptolaemus montrouzieri Cryptolaemus montrouzieri was multiplied on mealy bug infested pumpkin fruits (Cucurbita moschata Linn.) as described by Chacko et al (1978) at 26+2oC and 60-70% RH in the laboratory. Selection of experimental area The study was conducted at the IIHR farm, Bangalore Rural District, on four medicinal plants during 2003-04. Only plants infested with the green shield scale were selected for the study. Field release of C. montrouzieri Ants afforded protection to the green shield scale from natural enemies, resulting in increase in the scale population (Briese, 1982). In the present study, ants were controlled by applying chlorpyriphos @ 0.05% in the ant holes, as suggested by Tumminelli et al (1997). Application of insecticides on the medicinal plants was arrested a fortnight prior to the release of C. montrouzieri. Larvae of C. montrouzieri @ 20 /plant were released on scale- infested plants. *Present address: National Research Centre for Grapes, Pune-412307. Short communication J. Hortl. Sci. Vol. 3 (2): 176-179, 2008 177 Sampling and evaluation Scale population was recorded at fortnightly intervals on 10 randomly selected plants infested with scales during the study. In each plant, five shoots were selected for counting the green shield scales. Activity of locally occurring natural enemies, if any, was studied by collecting the scale - infested shoots and keeping the same in cages for emergence. Data on weather parameters, viz., maximum and minimum temperature (oC), relative humidity (%) and rainfall (mm) were collected during the period of study. Correlation between the green shield scale and weather factors was worked out to determine influence of weather on green shield scale population present on these medicinal plants. Results on population trend in green shield scale C. psidii on W. somnifera are presented in Table1. Pre- release count of 173.48 scales / plant was observed on 22nd June, 2003. The scale population declined to 110.50/plant one month after the release of C. montrouzieri. The population of C. montrouzieri ranged from 4.68 to 9.46 per plant during the study period. Plants released with the predator had 4.35 scale insects in the last week of August 2003 as compared to 214.66 on check plants. The coccinellid predator C. montrouzieri was found preying on C. psidii on W. somnifera plants throughout the study period. The trend of scale population on M. longifolia is presented in Table 2. Pre-release count of 30.49 scales/ plant was observed on 12th February, 2004. The scale population declined to 10.40/plant one month after the release of C.montrouzieri. The population of C. montrouzieri ranged from 2.46 to 6.89 /plant during the study period. Plants released with the predator had 1.20 scale insects in the third week of March 2004 as compared to 80.69 on check plants. Similar results were obtained on M. elengi. Plants released with the predator had 3.57 scales as compared to 172.64 on check plants, two months from release of Cryptolaemus (Table 3). On W. tinctoria also, the scale population was effectively reduced to 4.92 as compared to 265.40 scales on check plants (Table 4). Table 1. Population of Chloropulvinaria psidii and Cryptolaemus montrouzieri on W. somnifera Date Mean population/plant ± S.D. % reduction Check Biocontrol in scale population C. psidii C. psidii C. montrouzieri in biocontrol 22-06-2003 150.48 ±6.56 173.48±10.24 —— —— 08-07-2003 164.16 ±5.96 162.84±8.64 4.68±3.40 6.16 23-07-2003 185.74± 9.82 110.50±7.80 6.62±2.02 36.30 07-08-2003 180.88 ± 6.43 60.25± 5.94 9.46±5.60 65.27 22-08-2003 214.66±12.38 4.35±2.87 4.28±2.65 97.49 S.D = Standard deviation Table 3. Population of Chloropulvinaria psidii and Cryptolaemus montrouzieri on Mimusops elengi Date Mean population/plant ± S.D. % reduction Check Biocontrol in scale population C. psidii C. psidii C. montrouzieri in biocontrol 12-02-2004 80.45 ± 6.24 90.20 ± 10.42 —— —— 27-02-2004 96.17 ± 7.94 86.83 ± 8.45 3.58±2.40 3.74 11-03- 2004 125.65 ± 10.42 65.32 ± 5.28 6.82±3.80 27.58 22-03-2004 158.90 ± 12.94 30.54 ± 4.82 5.50±3.50 66.14 12-04-2004 172.64 ± 10.68 3.57 ± 0.94 4.78±0.95 89.13 S.D = Standard deviation Table 2. Population of Chloropulvinaria psidii and Cryptolaemus montrouzieri on Madhuca longifolia Date Mean population/plant ± S.D. % reduction Check Biocontrol in scale population C. psidii C. psidii C. montrouzieri in biocontrol 12-02-2004 42.14 ± 6.36 30.49 ± 6.32 —— —— 27-02-2004 53.85 ± 7.28 26.64 ± 4.64 2.46±1.84 12.62 11-03- 2004 65.27 ± 5.83 10. 40 ± 3.80 6.89±2.85 65.89 22-03-2004 80.69 ± 6.28 1.20 ± 0.68 4.64±1.96 96.06 S.D = Standard deviation J. Hortl. Sci. Vol. 3 (2): 176-179, 2008 Australian ladybird beetle against green shield scale 178 In the present investigation, there was a reduction of 97.49%, 96.06%, 89.13% and 97.96% in the green shield scale population after 60, 45, 60 and 75 days of Cryptolaemus release on W. somnifera, M. longifolia, M. elengi and W. tinctoria, respectively. There was no correlation between weather factors like temperature, humidity and rainfall and population of the green shield scale. No other natural enemy, except C. montrouzieri was recorded on C. psidiii during the study period and reduction in the population of green shield scale was attributed mainly to action of the predator C. montrouzieri on all the four medicinal plants studied. Cryptolaemus montrouzieri gave control of several species of Chloropulvinaria on many crops. Cryptolaemus montrouzieri was found to be effective in suppressing Chloropulvinaria aurantii (Ckll.) and Chloropulvinaria floccifera (Westw.) (Kolotov, 1939), Chloropulvinaria polygonata (Ckll.) on mango (Mani and Krishnamoorthy, 1998) and C. psidii on lemon, guava, sapota and fig (Mani and Krishnamoorthy, 1999; Mani and Krishnamoorthy, 1990; Mani and Krishnamoorthy, 1997b; Kumar and Prakasam, 1984) and Chloropulvinaria maxima (Valt.) on neem (Tirumala Rao and David, 1958). ACKNOWLEDGEMENT The authors are grateful to Director, IIHR, for providing facilities to conduct the study. Technical help rendered by Mr. G.L. Pattar is also gratefully acknowledged. REFERENCES Briese, D.T. 1982. Damage to saltbush by the coccid Pulvinaria maskelli Olliff and the role played by an attendant. J. Austr. Entomol. Soc., 21:293-294 Chacko, M.J., Bhat, P.K., Rao, L.V.A., Deepak Singh, M.B., Ramanarayan, E.P. and Sreedharan, K. 1978. The use of the ladybird beetle Cryptolaemus montrouzieri for the control of coffee mealybugs. J. Coffee Res., 88:14-19 Chatterji, A. and Datta, A.D. 1974. Bionomics and control of mango mealy scale, Chloropulvinaria (Pulvinaria) polygonata (Cockerell) (Hemiptera: Coccidae) Ind. J. Agril. Sci., 44:791-795 Kolotov, D.G. 1939. Results of the experiment with the application of Cryptolaemus for the control of the mealybug in Abkhazia. Rept. Sci. Meet. Leningrade Institute of Agriculture, Cf RAE (1939) p. 454 Kumar, M.G. and Prakasam, C.B. 1984. The recovery of Cryptolaemus montrouzieri Muls. on the coffee green scale, Coccus viridis (Green), on the Shevroy Hills. Ind. J. Agril. Sci., 14:34-35 Mani, M. and Krishnamoorthy, A. 1990. Evaluation of the exotic predator Cryptolaemus montrouzieri Muls. (Coccinellidae, Coleoptera) in the suppression of green shield scale Chloropulvinaria psidii (Maskell) (Coccidae, Homoptera) on guava. Entomon, 15:45-48 Mani, M. and Krishnamoorthy, A. 1997a. Australian ladybird beetle, Cryptolaemus montrouzieri. Madras Agri. J., 84:237-249 Mani, M. and Krishnamoorthy, A. 1997b. Biological suppression of the soft green scale, Coccus viridis (Green), and the green shield scale, Chloropulvinaria psidii (Maskell), on sapota. Pest Mgt. Hortl. Ecosyst., 3:114-116 Mani, M. and Krishnamoorthy, A. 1998. Biological control studies on the mango green shield scale, Chloropulvinaria polygonata (Ckll.) (Homoptera: Coccidae), in India. Entomon, 23:105-110 Mani, M. and Krishnamoorthy, A. 1999. Suppression of green shield scale, Chloropulvinaria psidii (Maskell), with Australian ladybird beetle on lemon. Insect Envir. 4:116-117 Pawar, M.B., Teli, U.S. Ambekar, J.S. and Kalbhoor, S.E. Table 4. Population of Chloropulvinaria psidii and Cryptolaemus montrouzieri on Wrightia tinctoria Date Mean population/plant ± S.D. % reduction Check Biocontrol in scale population C. psidii C. psidii C. montrouzieri in biocontrol 12-02-2004 194.27 ± 8.56 240.86 ± 14.57 —— —— 27-02-2004 210.86 ± 9.46 154.25 ± 7.64 5.00±3.40 35.96 11-03- 2004 234.84 ± 12.60 124.63 ± 8.0 9.40±4.80 48.26 22-03-2004 256.80 ± 10.58 73.24 ± 6.94 8.40±3.86 69.59 12-04-2004 248.95 ± 9.80 43.64 ± 4.26 8.62±3.02 81.88 27-04-2004 265.40 ± 14.40 4.92 ± 1.46 3.68±0.86 97.96 S.D = Standard deviation J. Hortl. Sci. Vol. 3 (2): 176-179, 2008 Mani and Krishnamoorthy 179 1981. Efficacy of some o r g a n o p h o s p h o r u s insecticides of guava scale Pulvinaria psidii Maskell on guava. Pestology, 5:21-29 Tirumala Rao, V. and David, L.A. 1958. The biological control of a coccid pest in South India by the use of beetle, Cryptolaemus montrouzieri Muls. Ind. J. Agril. Sci., 28:545-552 Tumminelli, R., Saraceno, F. and Conti, D. 1997. Ants in citrus groves. Inform. Agrar., 53:57-60 Visalakshi, A., Beevi, S.N., Mathai, S. and Nair, M.R.G.K. 1981. On the occurrence of Pulvinaria psidii Maskell (Coccidae: Hemiptera) as pest of clove. Entomon, 6:180 (MS Received 16 June 2008, Revised 6 November 2008) Australian ladybird beetle against green shield scale J. Hortl. Sci. Vol. 3 (2): 176-179, 2008