The infestation has been fully controlled using a parasitoid released/ by Kerala Agricultural University (KAU) as part of a biological control drive, said P.V. Balachandran, Director of Extension of the University. (A parasitoid is an organism that lives attached to a host ultimately sterilising or killing the host). The use of parasitoid combined with the good rain that the State received has fully washed out the disease. In case of recurrence of the disease, the control measures could be successfully used again, he said.
PMB, an invasive insect pest, had wreaked havoc in the agriculture sector of the State and brought down fruit and vegetable production in 2009 and 2010. It had infested more than 70 species of plants, including vegetables like amaranthus and brinjal and fruit trees like papaya, guava, sapota, mango, jack, and amla. It had also affected ornamental plants like hibiscus and plantations of teak and rubber. It was the papaya plant that came under severe attack.
Widespread agriculture and horticulture crop loss was reported in other parts of the country, including Karnataka, Maharashtra, and Tripura. There were reports of the pest attacking tapioca, pigeon pea, cotton, okra, tomato, silk cotton, jatropha, and mulberry. The attack had resulted in huge financial loss to farmers
The affected plants developed chlorosis (discolouration of leaves due to insufficient production of chlorophyll which led to the eventual death of the plant), crinkling, and drying. Sooty mould was found on affected plants and those in its surroundings. The pest, which remains slightly withdrawn during the rainy season, resurface as the rain recedes.
The parasitoid Acerophagous papayae, imported from Puerto Rico, was mass-reared and acclimatised in the laboratories of the College of Horticulture and released, said Mani Chellappan, officer in charge of the All India Network Project on Agricultural Ornithology of Kerala Agricultural University, Thrissur.
Evaluations carried out in Thrissur, Palakkad, Ernakulam, and Malappuram districts, where severe attack of the pest was reported, indicated that the pest was reduced to insignificant levels. There was not even 10 per cent possibility of the recurrence of the attack, Dr. Chellappan said. The papaya plants had recovered from the onslaught of the bug and were bearing fruits. The leaves of papaya were found free from any damage, he said.