BANGALORE: Every year huge loss of plants and fruits is witnessed due to the harmful and dangerous mealy bugs. The mealy bugs are small, soft-bodied insects that secrete white, powdery or mealy wax secretion that covers the body of most species. Recently NBAII (National Bureau of Agricultural Important Insects), national bureau ICAR noticed extremely dangerous papaya mealy bug — native of Mexico — with a wide range of hosts of over 60 species of plants including pigeon pea, tapioca, okra, tomato, brinjal, cocoa, cotton, mulberry and rubber etc.
Last year NBAII, introduced CBC — Classical Biological Control system to control the Mealy bugs through involving co- evolved natural enemies from native home range of the pest. After a year of observation from July 2010 of parasitoid on papaya mealy bug the population has drastically come down. This is safe to honey bees, lac insects, silk worms and other useful parasitoids and predators.
Says Dr A N Shylesha, P r i n c i p a l S c i e n t i s t Entomology, NBAII, Bangalore, “Classical biological control is the introduction of natural enemies (parasitoids or predators) to a new locale where they did not originate or do not occur naturally. This is generally adopted when an insect pest is accidentally introduced into a new geographic area without its associated natural enemies. In India, around 16 species of introduced bioagents have established in field conditions and some of them have provided recurring economic benefits.
One of the recent classic examples of classical biological control is the establishment of the introduced parasitoid Acerophagus papayae, which could successfully control the papaya mealybug, Paracoccus marginatus.” He further adds, “The pest was first observed by entomologists of Tamil Nadu Agricultural University during June 2008. On their alerting, the then director of NBAII and I visited the site along with scientists from TNAU Coimbatore and assessed the damage and from that day efforts were made to procure natural enemies of the same from the previous releases of parasitoids for CBC.” India leads the world in papaya production with an annual output of about three million tons compared to the estimated annual world production of six million tones of fruits. To control the economic loss and minimise the damage of plants and fruits, NBAII imported the three species of parasitoids last year from Puerto Rico with the help of USDAAPHIS (US Department of Agriculture — Animal and Plant Health Inspection Services) and completed all mandatory safety and specificity tests in the quarantine facility at Bangalore and introduced CBC system.
Surprisingly the parasitoids were observed to be specific to the papaya Mealy bug and did not allow parasitising seven other species of mealy bugs.
“The papaya Mealy bug is an invasive pest and it starts moving from one place to another attacking all the hosts. The more vulnerable crops are papaya, mulberry, cotton, plumeria, (temple tree or deva kanagale), parthenium, hibiscus rosa chinensis, butter fruit, tapioca, rubber, coffee etc. More than 500 ha of papaya and other fruit crops and 1,200 ha of mulberry had been affected in Karnataka and still more damage was observed in Maharashtra and Tamil Nadu during 2008-2009 which they have overcome now by practicing the CBC,” says Dr AN Shylesha.
