field vole common microtus arvalis disaster extremely attacked alfalfa medicago sativa lucerne drone aerial plant violet

field vole common microtus arvalis disaster extremely attacked alfalfa medicago sativa lucerne drone aerial plant violet flowers infested shorttailed pest rodent agrestis greybrown overpopulation yield damage rapeseed intensive agricultural production compensation rodenticides poison feed mainly green plants pesticide pesticides inappropriate farming landscape unfriendly problem largescale agriculture europe czech european regime