Aggregation of potato leafhoppers, Empoasca fabae (Harris) (Homoptera: Cicadellidae), on a trap crop in an edible bean, Phaseolus vulgaris L., intercropping system

The potato leafhopper is a serious pest of edible beans, causing significant yield reductions in the absence of control measures. Control recommendations in edible beans involve the application of phorate at planting or the foliar application of dimethoate when thresholds are reached. As an alternative to broadcast insecticide applications, the use of a highly susceptible bean cultivar, Berna Dutch brown, as a trap-crop was tested by interplanting one, two and four rows of Berna among rows of Stingray white bean at two locations in Ontario, Canada, in 2001 and 2002. Transect sampling of adults and nymphs indicated that potato leafhopper populations in the crop were not affected by different numbers of rows of Berna, although there were many more potato leafhoppers in rows of the Berna trap crop compared with adjacent rows of the white bean crop. An insecticide seed treatment (thiamethoxam) applied to rows of Berna in treated plots effectively lowered insect populations early in the season, but this combination did not improve the effectiveness of Berna as a trap for migrating adults. Damage inflicted by potato leafhoppers was initially highest in untreated plots and in the arrangement containing four rows of Berna. Differences among yields for treated and untreated plots of white bean were not significant. If planted as early-sown border rows, combined with better leafhopper management in the trap crop, Berna may be used as a trap cultivar to attract leafhoppers and consequently protect an edible bean main crop. Key words: Empoasca fabae, trap-crop, edible beans