Routine alfalfa (Medicago sativa) cutting program and its influence on pea aphid (Acyrthosiphon pisum Harris) populations.

1. Cutting does not influence the general features of the pea aphid population trends on alfalfa. 2. Cutting significantly influences host plant conditions. 3. By affecting host-plant conditions, cutting may partially influence aphid population density on alfalfa. 4. The plant growth is not always coincident with the increase of aphid numbers. 5. Migration of aphids from alfalfa could have basic disruptive effects on the alfalfa field ecosystem in some years. 6. Routine alfalfa cutting may be partially responsible for a slight increase of the disruptive effect caused to the alfalfa ecosystem stability through mass-migration of aphids. 7. Mass-migration of aphids could possibly negatively influence even the strip-cutting program in certain years, if this program is applied under Central European conditions. 8. Multilateral control approach should be followed. Strip-farming or intercropping of perennial and annual crops should be studied.