caa a22 4500 475838351 CHVBK 20180406123854.0 cr unu---uuuuu 170329e20000401xx s 000 0 eng 10.1007/s101440050012 doi (NATIONALLICENCE)springer-10.1007/s101440050012 Response by coccinellids to spatial variation in cereal aphid density [Elektronische Daten] [N. Elliott, R. W. Kieckhefer] The objectives of this study were to determine if coccinellids adjusted their distribution within spring wheat fields in response to spatial variation cereal aphid density in the fields and to describe the patterns of cereal aphid population growth that resulted. Field experiments were completed in which the physical dimensions of patches infested with cereal aphids, cereal aphid density, and access to patches by coccinellids were varied. Aphid infestations consisted of naturally occurring densities (natural patches) and much greater densities created by supplementing patches with aphids (supplemented patches). Coccinellids were denied access to some supplemented patches (exclusion patches) but allowed unlimited access to others. Densities of adult Hippodamia convergens and Coccinella septempunctata were correlated with aphid density in patches whereas density of Coleomegilla maculata was not. Aggregation by coccinellids was independent of patch area. The realized aphid population growth rate (r) was lower in supplemented than natural patches in all four trials but was significantly lower in only one trial. The lower r in supplemented patches was not exclusively caused by coccinellid predation, and emigration of aphids from patches probably also contributed. r was significantly greater in exclusion patches than supplemented and natural patches, indicating that coccinellids markedly reduced aphid numbers in patches even when aphid density was extremely high. The Society of Population Ecology and Springer-Verlag Tokyo, 2000 Key words Aphididae nationallicence Biological control nationallicence Coccinellidae nationallicence Predation nationallicence Density dependence nationallicence Functional response nationallicence Elliott N. USDA, ARS Plant Science and Water Conservation Research Laboratory, 1301 N. Western St., Stillwater, OK 74075, USA e-mail: nelliott@pswcrl.ars.usda.gov Tel. +1-405-624-4141 (ext. 227); Fax +1-405-372-1398, US aut Kieckhefer R. W. USDA-ARS Northern Grain Insects Research Laboratory, Brookings, SD, USA, US aut https://doi.org/10.1007/s101440050012 text/html Onlinezugriff via DOI 1 research-article jats NATIONALLICENCE 856 40 https://doi.org/10.1007/s101440050012 text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Elliott N. USDA, ARS Plant Science and Water Conservation Research Laboratory, 1301 N. Western St., Stillwater, OK 74075, USA e-mail: nelliott@pswcrl.ars.usda.gov Tel. +1-405-624-4141 (ext. 227); Fax +1-405-372-1398, US aut NATIONALLICENCE 700 1- Kieckhefer R. W. USDA-ARS Northern Grain Insects Research Laboratory, Brookings, SD, USA, US aut Metadata rights reserved Springer special CC-BY-NC licence nationallicence BK010053 XK010053 XK010000 NATIONALLICENCE NATIONALLICENCE NL-springer