Incidence of potato tuber moth, Phthorimaea operculella (Zell.) (Gelechidae: Lepidoptera), at different locations of West Bengal.
The incidence of potato tuber moth (PTM; P. operculella) on potato in 3 districts (Kalyani in nadia, Bionchee in Hooghly, and Memari and Kalna in Burdwan) of West Bengal, India, was studied during the rabi season from 1989/90 to 1998/99. Larval population and percentage of leaf mines caused by PTM were evaluated in 100 plants at fortnight intervals after planting. At Bionchee, the larval population ranged from 1.4 to 9.0 per plant, the percentage of leaf mines varied from 0.8 to 2.9%, and damaged tubers ranged from 5.8 to 17.3%. At Memari, the number of larvae varied from 1.1 to 5.0, and the number of leaf mines and percentage of damaged tubers ranged from 0.7 to 3.0 and 3.1 to 10.0%, respectively; at Kalna, these parameters ranged from 1.0 to 6.0, 1.2 to 2.0, and 4.5 to 9.4%. In these districts, PTM was present in crops from late January until the dehaulming stage during early March. Peak infestation was recorded from mid-February to early March. PTM was absent in Kalyani. The total tuber yield from 100 plants was highest (22.6 kg) at Kalyani and lowest (16.2 kg) at Kalna.