Individual study: Within-field manipulation of potato leafhopper (Homoptera: Cicadellidae) and insect predator populations using an uncut alfalfa strip
Weiser L.A., Obrycki J.J. & Giles K.L. (2003) Within-field manipulation of potato leafhopper (Homoptera: Cicadellidae) and insect predator populations using an uncut alfalfa strip. Journal of Economic Entomology, 96, 1184-1192
This study is summarised as evidence for the intervention(s) shown on the right. The icon shows which synopsis it is relevant to.
Leave part of the crop or pasture unharvested or uncut
Two replicated, controlled trials from 1998-2000 in twelve 7.5-17 ha alfalfa Medicago sativa fields at 3-4 sites in Iowa, USA (Weiser et al. 2003) found that in more than 50% of whole fields surveyed there were more predatory insects (net-winged insects (Neuroptera), minute pirate bugs (Anthocoridae), and ladybirds (Coccinellidae)) captured by sweep-netting in 3 m-wide uncut strips than cut areas, 1-3 weeks after hay had been collected (numbers not given). Numbers from sticky traps were similar between treatments. The proportion of insect predators to prey was higher in uncut than cut alfalfa in one field in 1998 and four in 1999, 1-4 weeks after cuttings were collected (uncut strips: 0.28-8.65 predators/prey, cut alfalfa: 0.06-0.94). In the plot-scale trial, predator numbers were similar between treatments and sampling periods in 1999. In 2000, uncut strips attracted insect predators in sweep net samples in weeks 1, 3 and 4, however ladybirds caught in sticky traps were more abundant in controls in one plot in week 1. Potato leafhopper Empoasca fabae (pest) numbers were higher in 73% of uncut strips surveyed for 2-3 weeks after harvest in 1998 and 2000. In 1999, leafhopper numbers were generally not higher in uncut than cut strips.