Host Plants of Invasive Papaya Mealybug, Paracoccus marginatus (Williams and Granara de Willink) in Tamil Nadu

Invasive papaya mealybug, Paracoccus marginatus (Williams Granara de Willink) invaded Tamil Nadu, India in 2008 has attained the status of a serious pest on a wide range of host plants. An extensive survey conducted during 2009 - 2011 revealed the presence of this mealybug on 133 plant species belonging to 48 families including pulses, oilseeds, fibre crops, narcotics, green manures, vegetables, fruit trees, tuber crops, flower plants, ornamentals, plantation crops, medicinal and aromatic plants, biofuel crops, tree species and weeds. Plants from Malvaceae, Solanaceae, Asteraceae and Euphorbiaceae were generally found as preferred hosts of this mealybug species. High host preference was noticed on 33 hosts followed by medium damage in 31 hosts. Pest intensity and damage was found to be low in 56 host plants while there was incidental damage for shorter durations in 13 hosts.

About 5000 species of mealybugs (Pseudococcidae: Hemiptera) have been recorded from 246 families of plants throughout the world (Ben-Dov, 1994). Paracoccus marginatus (Williams and Granara de Willink) is a polyphagous pest that can damage a large number of economically important field crops, tropical and sub-tropical fruits, vegetables and ornamental plants (Ben-Dov, 2008). The papaya mealybug is believed to a native of Mexico or Central America and was first described in 1992 by Williams and Granara de Willink and re-described in 2002 by Miller and Miller. P. marginatus has established in the Caribbean since 1994 (Miller et al., 1999). P. marginatus was recorded in papaya for the first time in Tamil Nadu Agricultural University, Coimbatore, during July, 2008 (Muniappan, 2009).
It became a serious pest of papaya in Tamil Nadu and nearly 820 ha in Erode and 576 ha in Coimbatore districts had been affected (Revathy, 2010). The entire papain industry at Coimbatore district faced a dire threat due to the severity of this pest on papaya, apart from inflicting severe damage to tapioca and mulberry in the neighbouring districts of Tamil Nadu (Suresh et al., 2010). threatened the economical production of many crops. Keeping in view the prevailing situation, a field survey was conducted during 2009 -2011 to record the host range of P. marginatus in Tamil Nadu.

Materials and Methods
An extensive survey for papaya mealybug was conducted for consecutive years in Tamil Nadu during 2009-2011. Infestation of mealybug was categorized on the following parameters based on *Corresponding author email: sakthiento@yahoo.com visual observation. During survey, whole plants of the species were examined for occurrence and infestation levels as described by Arif et al. (2009

Results and Discussion
Paracoccus marginatus was recorded from 133 plant species belonging to 48 families including pulses, oilseeds, fibre crops, narcotics, green manures, vegetables, fruit trees, tuber crops, flower plants, ornamentals, plantation crops, medicinal and aromatic plants, biofuel crops, tree species and weeds (Table 1). Plants from Malvaceae, Solanaceae, Asteraceae and Euphorbiaceae were generally found as preferred hosts of this mealybug species. Among these, Parthenium hysterophorus (Asteraceae), Hibiscus rosa sinensis, Abutilon hirtum (Malvaceae), Jatropha curcas, Manihot esculenta (Euphorbiaceae) and Plumeria alba (Apocynaceae) harboured this pest round the year and acted as a persistent source for the spread of papaya mealybug. High host preference was noticed on 33 hosts followed by 31 hosts with medium damage while 56 hosts recorded low levels of damage and 13 with incidental damage. Physic nut Biofuel **** Jatropha glandulifera L.
Gout Earlier, Miller et al. (1999) reported the incidence of papaya mealybug on 60 host plants of about 25 genera including economically important crops. Meyerdirk and Kauffman (2001) reported a wider host range of about over 60 species and Walker et al. (2003) listed 55 host plants in 25 genera. Ben-Dov reported the presence of mealybug species in 22 plant families (Ben-Dov, 2008). Regupathy and Ayyasamy (2010) also made an extensive survey and reported about 50 hosts including field and horticultural crops, herbaceous perennials, climbers, trees, ornamentals and several weed hosts.
However, the present study revealed about 133 plant species from 47 plant families indicating the sheer invasiveness of this species. Diversified hosts coupled with absence of a native natural enemy complex are responsible for the invasiveness of papaya mealybug. Weed species like Parthenium, Abutilon, Sida sp. etc., also provide a green bridge for the successful perpetuation of this species throughout the year as opined by Regupathy and Ayyasamy (2010).
The extreme host range is an alarm cum awakening call that P. marginatus may attack many more plants in future. Therefore effective weed control, field sanitation, following proper crop rotation and quarantine measures will be of high significance while adopting management strategy of this papaya mealybug.