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Ecology and Epidemiology

Aphid Vector Population Dynamics and Movement Relative to Field Transmission of Blueberry Shoestring Virus. K. M. Morimoto, Department of Botany and Plant Pathology, Michigan State University, East Lansing 48824; D. C. Ramsdell, Department of Botany and Plant Pathology, Michigan State University, East Lansing 48824. Phytopathology 75:1217-1222. Accepted for publication 18 June 1985. Copyright 1985 The American Phytopathological Society. DOI: 10.1094/Phyto-75-1217.

Illinoia pepperi, the aphid vector of blueberry shoestring virus (BBSSV) has been shown to overwinter on highbush blueberry (Vaccinium corymbosum) and to complete its life cycle on that host in caged-bush experiments. Although within-field movement of alatae and apterae occurred, aphid movement out of the isolated field research site was rare. Field populations of I. pepperi were monitored weekly in yellow-pan water traps, on infected field source plants, and on 2-yr-old blueberry trap plants from early May through September. Populations of alatae and apterae were greatest in June. Apterae were found throughout the growing season; few alatae were found after mid-July. Individual I. pepperi were tested for presence of BBSSV by radioimmunosorbent assay. Percentages of virus-positive aphids ranged between 0 and 30% on uncaged source or trap plants throughout the season. There was wide variability in the quantity of virus detected in field-trapped individual aphids. Amounts of BBSSV ranged from 0.5 to 100 ng per aphid. Field transmission of BBSSV occurred from infected source plants to 2-yr-old healthy trap plants surrounding the infected source bushes. The incidence of trap plant infection was highest in May and June when the populations of I. pepperi were greatest.