page 148 The spiralling whitefly, Aleurodicus dispersus Russell (Homoptera: Aleyrodidae), native to the Caribbean Islands and Central America was first discovered in the city of Thiruvananthapuram, South India, in November 1993 (Palaniswami et al, 1995). The spiralling whitefly may have been introduced into India from neighbouring countries such as Maldives (Muniappan, 1993) and Sri Lanka (Ranjith et al, 1996) through plant material. Since then, it has been reported from other parts of Kerala, Karnataka, Andhra Pradesh, Tamil Nadu and Maharashtra (David and Regu, 1995; Prathapan, 1996; Mani and Krishnamoorthy, 1996; Sathe, 1999) and Lakshadweep islands (Ramani, 2000). The spiralling whitefly is a polyphagous pest known to attack about 500 plant species including several ornamentals (Srinivasa, 2000). Chemical control of A. dispersus is almost impossible owing to its wide host range and heavy wax coating (Kajita et al, 1991). However, the natural enemies, chiefly the aphelinid parasitoids Encarsia guadeloupae Viggiani and Encarsia (?) haitiensis Dozier, have proved useful in suppressing the spiralling whitefly in the Pacific Islands and African countries (Waterhouse and Norris, 1989; D’Almeida et al, 1998). The present study was conducted to colonise the parasitoid, E. guadeloupae, on spiralling whitefly infesting ornamentals like rose, poinsettia, hibiscus and acalypha. Cassia leaves containing parasitised nymphs (black) were kept in glass vials (15 cm x 2.5cm). Adult parasitoids that emerged were collected and the identity of E. guadeloupae was ascertained in the laboratory. These were fed on 50% honey in glass vials prior to release in the field. Field releases made on Hibiscus rosasinensis L. at U.A.S. farm, Hebbal, Acalypha hispida Burm.f and Euphorbia (= Poinsettia) pulcherrima Willd. at the IIHR Farm, Hessaraghatta and Rosa indica Lindl. at Hessaraghatta village, all located in Bangalore North. A Colonization of introduced parasitoid, Encarsia guadeloupae Viggiani, on the exotic spiralling whitefly, Aleurodicus dispersus Russell, infesting ornamentals M. Mani 1 and A. Krishnamoorthy Division of Entomology and Nematology Indian Institute of Horticultural Research Hessaraghatta Lake Post, Bangalore - 560 089, India E-mail : mmani1949@ yahoo.co.in ABSTRACT The exotic spiralling whitefly, Aleurodicus dispersus Russell, was observed to infest several ornamentals including rose, hibiscus, poinsettia and acalypha in and around Bangalore. Efforts were made to colonize the aphelinid parasitoid, Encarsia guadeloupae Viggiani, during 2002 - 2003 on the above ornamentals infested with the spiralling whitefly. A total of five predators, namely, Axinoscymnus puttarudriahi Kapur and Munshi, Cryptolaemus montrouzieri Muls., Anegleis cardoni (Weise), Mallada astur (Banks) and Cybocephalus sp. were observed on the spiralling whitefly on these ornamentals during the study but their impact on the spiralling whitefly was negligible. Inoculative releases of E. guadeloupae were made on rose (156 adults), hibiscus (179 adults), poinsettia (124 adults) and acalypha (247 adults). Encarsia guadeloupae was recovered within a month after its release with 3.43 - 32.94% parasitism. A steady decline in the population of spiralling whitefly was observed on these ornamentals. Encarsia guadeloupae was found to be the only parasitoid encountered throughout the study and the total parasitism steadily increased up to 96.00% on rose, 86.40% on hibiscus, 90.40% on poinsettia and 39.86% on acalypha at six months from release. Parasitism by E. guadeloupae was significant and negatively correlated with the population of spiralling whitefly on all the four ornamentals. Key words: Aleurodicus dispersus, Encarsia guadeloupae, biological control, spiralling whitefly, rose, hibiscus, poinsettia, acalypha J. Hort. Sci. Vol. 1 (2): 148-151, 2006 1 Present address : National Research Centre for Grapes, P.B. No. 3, Manjari Farm, Solapur Road, Pune - 412 307. Short communication page 149 total of 156 adults of E. guadeloupae on R. indica in August 2002, 179 adults on H. rosasinensis during May 2003, 124 adults on P. pulcherrima in July 1998, and 247 adults on A. hispida infested with spiralling whitefly in June 2003, were released. Sampling was done for six months on the ornamental plants from the month of release. Populations of the whitefly and its natural enemies were estimated at monthly intervals. Ten plants infested with spiralling whitefly were randomly chosen for recording observations. In each plant, four shoots were selected and in each shoot, ten leaves (beginning 6 th leaf from top) were collected and populations of adult whiteflies, healthy and parasitised nymphs and the predators if any were recorded on each leaf. The leaves were kept in plastic jars (16 cm x11 cm) and the emergence of natural enemies was recorded. Parasitoids emerged making an irregular hole, while, the whiteflies emerged through a ‘T’ shaped slit. Correlation analysis was carried out to determine relationship between parasitism and spiralling whitefly population. Although more than 40 indigenous predators were found to feed on spiralling whitefly in India (Ramani et al, 2002), a total of five species of predators, namely, Axinoscymnus puttarudriahi Kapur and Munishi, Cryptolaemus montrouzieri Muls., Anegleis cardoni (Weise), Cybocephalus sp. and Mallada astur Banks were recorded on the spiralling whitefly infesting rose, hibiscus, poinsettia and acalypha during the study period. Local predators, observed in negligible numbers did not have any impact on the population of spiralling whitefly as observed in Indonesia by Kajita et al (1991). Results on colonization of E.guadeloupae on the spiralling whitefly infesting different ornamentals are presented in figures 1- 4. Rose The population of spiralling whitefly declined from 30.50/ leaf in August 2002 to 2.57 / leaf in February 2003. Encarsia guadeloupae was first recovered in September 2002 and found to be causing 21.74% parasitism, which went up to 96.00% in February 2003 (Fig 1). Correlation analysis revealed that there was significant influence of parasitism (r = -0.943) on the population of spiralling whitefly. Fig 1. Parasitism by Encarsia guadeloupae on rose Hibiscus Spiralling whitefly incidence was observed in May 2003 on hibiscus at Hebbal. The population declined from 52.40 /leaf in May 2003 to 2.90 in November 2003 (Fig 2). Encarsia guadeloupae was first recovered in June 2003 causing 18.96 % parasitism, which later increased to 86.40% in November 2003. Correlation analysis revealed that there was significant influence of parasitism (r = -0.979) on the population of spiralling whitefly. Fig 2. Parasitism by Encarsia guadeloupae on hibiscus Poinsettia The spiralling whitefly was observed in severe form in June 2003 on poinsettia at the IIHR Farm. The parasitoid was recovered in July and recorded a parasitism of 32.94 %. The parasitism went up to 90.40 % in December 2003. The Colonization of parasitoid on spiralling whitefly 149J. Hort. Sci. Vol. 1 (2): 148-151, 2006 page 150 population of whitefly declined from 105.42/leaf in June 2003 to 1.52 / leaf in December 2003 (Fig 3). Correlation analysis revealed that there was significant influence of parasitism (r = -0.954) on the population of spiralling whitefly. Fig 3. Parasitism by Encarsia guadeloupae on poinsettia Acalypha On acalypha, the population of whitefly declined from 23.45/leaf in June 2003 to 9.66 / leaf in December 2003 following the release of E. guadeloupae in June 2003. Parasitism level increased gradually from 3.43% to 39.86% (Fig 4). Correlation analysis revealed that there was significant influence of parasitism (r = -0.948) on the population of spiralling whitefly. Fig 4. Parasitism by Encarsia guadeloupae on acalypha Very high level of parasitism of 86.40 - 96.00% by E. guadeloupae was observed on the above ornamental crops, except on acalypha, in the present study. Even in acalypha, if observations had been continued for some more months, higher level of parasitism could probably have been observed. Geetha (2000) and Mani et al (2004) reported 80 % parasitism by E. (?) haitiensis (Encarsia meritoria sp. nr.) on spiralling whitefly infesting guava. The activity of parasitoids was observed throughout the study period. Parasitism by E. guadeloupae was significant and negatively correlated with the population of whitefly (r = -0.943 to -0.979) in the present study. Similar significant correlations between abundance of spiralling whitefly and natural enemies, chiefly E. (?) haitiensis in Hawaii, was reported (Kumashiro et al, 1983). Similarly, Chandrasekar (1990) and D’Almeida et al (1998) reported that the decline in spiralling whitefly population was mainly due to the action of E. (?) haitiensis and E. guadeloupae in Sri Lanka and Benin, West Africa. According to Kumashiro et al (1983), a single release of E. (?) haitiensis in 1980 reduced the population of the spiralling whitefly by 78- 98% around Honolulu in Hawaii. The population of A dispersus in Malaysia remained low mainly due to the presence of E.guadeloupae (H.Kajita, pers. commun., 1996). The efficacy of E. guadeloupae in controlling spiralling whitefly (as observed in the present study on ornamental crops) in Hawaii, Malaysia, India, Philippines, Togo, Ghana, Nigeria, Tenerife (Canary Islands) and Taiwan (Waterhouse and Norris, 1989; Neuenschwander, 1994; Chien et al, 2000; Nijhof et al, 2000; Mani and Krishnamoorthy, 2002) has also been reported on other crops. ACKNOWLEDGEMENTS The authors acknowledge Director, IIHR, for providing facilities to conduct the study and Mr. G.L.Pattar for technical assistance in the present investigation. REFERENCES Chandrasekara, D.1990. Effect of weather and natural enemies on population variation of the spiralling whitefly (SWF), Aleurodicus dispersus Russell (Homoptera, Aleyrodidae). Research Report submitted to the Degree of B.Sc., University of Peradeniya, Sri Lanka, 26 p. J. Hort. Sci. Vol. 1 (2): 148-151, 2006 Mani & Krishnamoorthy 150 page 151 Chien, C. C., Chou, L.Y. and Chang, S.C. 2000. 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Vol. 1 (2): 148-151, 2006 Colonization of parasitoid on spiralling whitefly 151 (MS Received 26 June 2006, Revised 22 November 2006)