Impact of alfalfa/cotton intercropping and management on some aphid predators in China

A short-term study was carried out to evaluate the influence of some predators on cotton aphid in Xinhe County of Xinjiang Uygur Autonomous Region, China, where cotton was mainly intercropped with alfalfa. In spring, alfalfa was cut at the size of 20 m x 10 m and some groups of predators were obliged to migrate into cotton fields. Cotton aphid and its predators including spiders and lacewings were surveyed on cotton plants before and after alfalfa-cutting. The result indicated that the increment of population of cotton aphids was significantly slower in cotton grown in plots which bordered the alfalfa-cutting areas than in the uncut control areas (CK), while the rate of increase of spiders and lacewings were significantly faster in cotton grown in plots bordering on the cut areas than CK.