Parasitoids to check Papaya mealybug

KOCHI: The State Agriculture Department will release parasitoids shortly in its attempt to curb the crop destruction caused by Papaya mealybug, an invasive pest.

The parasitoids, multiplied in the laboratories of the Department of Entomology, College of Horticulture, Kerala Agricultural University, will be released by Agriculture Minister Mullakkara Ratnakaran on December 9 at the Krishi Vigyan Kendra in Malappuram.

They will be released in areas where the infestation has been reported most. The department is also planning to hand over nucleus cultures to the principal agricultural officers in all the districts and heads of research organisations free of cost for release, according to a communication from the University.

The bug is an invasive insect pest infesting more than seventy species of host plants, including vegetables, fruits, ornamental plants, plantations, forest and other non crop plants in Kerala. Though the presence of the species was first recorded in early 2009 in Kerala, the State later witnessed a phenomenal spread in population.

The bugs had caused widespread destruction of crops in the State during the past few months. It was the heavy rain that the State received during this year that helped in controlling the infestation to a considerable extent. The agricultural experts fear that the invasion would reach alarming proportions once there is a let-up in rain. The symptoms of infestation include crinkling, cupping, drying and outright death of the infested plants. The affected plants and the ones in its surroundings will have sooty mould, scientists said.

Source: The Hindu, 9-12-2010

Imported parasites to save crops

KOCHI: Three parasitoids imported from Puerto Rico will be released in the State shortly for biologically controlling papaya mealybug infestation. In biological control, natural enemies of pests are introduced to destroy them.

The mealybug infestation has destroyed a wide variety of agriculture and horticulture crops in the country including tapioca, pigeon pea, cotton, okra, tomato, brinjal, teak, silk cotton, jatropha, mulberry and guava. It had also affected rubber and teak plantations in the State.

Last year, the widespread invasion had resulted in huge financial loss.

The infestation subsided this year due to the heavy rain in the State. Once there is a let-up in the rain, agriculture scientists expect a massive outbreak again, said P.V. Balachandran, Director Extension, of the Kerala Agriculture University.

How they thrive

The spread of the mealybug has been reported from Karnataka, Maharashtra and Tripura, presumably due to the movement of infested fruits. “Initially the mealybugs colonise along the veins on the lower side of the papaya leaves and later cover the fruits rendering them unmarketable. Due to the explosive growth of the mealybug populations and the toxins produced, the younger plants are killed outright,” according to a publication from the National Bureau of Agriculturally Important Insects, Bangalore.

The Bureau imported three species with the help of the United States Department of Agriculture-Animal and Plant Health Inspection Services.

The parasitoids were also found to be safe to honeybees, silk worms and a host of other predators. Once released and conserved, they will establish naturally and control the papaya mealybug on crops on a long-term basis. They are expected to significantly suppress the papaya mealybug populations within six months to one year.

The Kerala Agriculture University is in the process of multiplying the parasitoids, which will be released in infested sites when rain subsides. The possible areas of high influx are being identified by the experts.

Farmers and general public can also communicate the instances of infestation to the University, said Mr. Balachandran.

T.V. Sajeev, entomologist of the Kerala Forest research Institute, Thrissur, said that chemical pesticides should not be applied on plants to which the parasitoids are released since they will destroy them. The mealybugs have a wax coating which prevents the pesticide from coming into direct contact with its body. But that is not the case with parasitoids, Dr. Sajeev said.

Source: The Hindu, 27-11-2010