In agroecosystems the population dynamics and trophic interactions operate at landscape scale. This dimension is determined because many insects are able to move and to search resources beyond the crop. However, crop management affect pests and antagonists. Insect abundance and is driven by the interaction between the crop management and landscape characteristics. In NE Spain is produced 60% of the country alfalfa yield and nearly 30% of maize.
Both crops are in landscapes where also other crops, uncultivated areas, forests, etc. are. Alfalfa and maize have specific pests but share a broad spectrum of natural enemies able to move between both crops. The hypothesis to be contrasted is that the crop management affect pest and natural enemy abundances but that its effects may be modulated by landscape characteristics. The aim is to identify the drivers of the abundance of three key pests and their natural enemies in the alfalfa-maize system: a) Hypera postica, alfalfa specific and with low mobility; b) aphids as virus vector in alfalfa and other crops around, and c) Helicoverpa armigera, a polyphagous pest with high mobility between alfalfa and maize.