Establishment and performance of the tobacco splitworm (Phthorimaea operculella) in the tobacco agroecosystem

The tobacco splitworm (Potato tuberworm, Phthorimaea operculella), a microlepidopteran with oligophagous larvae that feed on solanaceous plants, is a recent concern for tobacco growers. Tobacco (Nicotiana tabacum) is an infrequent host of this species and few studies are available on the biology and ecology of this pest in the tobacco agroecosystem. Potato (Solanum tuberosum) is the most common host of P. operculella on which larvae both mine leaves and bore in tubers. In tobacco, larvae primarily act as leaf-miners. As observed through correlation of pheromone trap captures with in-field damage in tobacco from 2008-10, splitworms are a multivoltine pest (2-3 generation per field/season) with potential to cause economic loss at a high rate of infestation during the late season. When feeding on tobacco, the chemical and physical differences within the plant as well as the cultural practice of priming in flue-cured varieties of tobacco may impact the establishment and performance of splitworm larvae. In 2009 and 2010, field trials using colony-reared neonate larvae were caged on leaves at upper, middle and lower stalk positions at three different stages of plant maturity and assessed for differences. When plants reached full maturity, plant architecture was altered to mimic flue-cured priming by removal of one-fourth to three-fourths of the leaves on a plant. Larvae were released at the base of the stalk where female moths oviposit. The results indicated plant age impacts development and increased removal of leaves decreases establishment which has both management and ecological implications for splitworms in the tobacco agroecosystem.