Insect predators in northeast China and their impacts on Aphis glycines

Abstract

AbstractPredators of Aphis glycines Matsumura (Hemiptera: Aphididae) were surveyed and their ability to suppress A. glycines population growth was determined in Harbin, northeast China (45.4°N, 126.4°E). Field surveys were conducted on 21 fixed sampling sites in 2004 and 17 in 2005. Impacts of natural enemies of A. glycines were studied using exclosure experiments. Thirteen natural enemies were found, the most abundant of which was Propylaea japonica (Thunberg), Harmonia axyridis (Pallas) (Coleoptera: Coccinellidae), Chrysopa sinica Tjeder, Chrysopa phyllochroma Wesmael, Chrysopa formosa Brauer (Neuroptera: Chrysopidae), Hemerobius humuli Linnaeus (Neuroptera: Hemerobiidae), Orius Wolff sp. (Heteroptera: Anthocoridae), Nabis stenoferus Hsiao (Heteroptera: Reduviidae), Deraeocoris punctulatus (Fallén) (Heteroptera: Miridae), and Episyrphus balteata (De Geer) (Diptera: Syrphidae). Three exclosure treatment types were established, large-mesh cages, small-mesh cages, and no cages. In exclosures, A. glycines density in small-mesh cages peaked at numbers 3.75-fold higher than in large-mesh cages and 17.44-fold higher than on plants with no cages in 2004. In 2005, these numbers were 4.59-fold and 60.98-fold. Temperature was not a factor in exclosures, but relative humidity had significant effects. These results indicated that existing predator communities could partially suppress soybean aphid population density in soybean fields in northeast China.