By excluding predators from certain plants researchers were able to study the ability of generalist predators to reduce establishment of aphid colonies and thus limit the spread of the virus. In field trials, a combination of predators, including soldier beetles and lady beetles, reduced aphid numbers by 80% in 24 hours. Over 90% of those aphids protected from predation survived during the same period. In a second study, it was shown that protecting aphids from ground dwelling predators (ground beetles, spiders, rove beetles, etc.) for four weeks early in the season, significantly increased the number of plants developing initial BYV infections. At season end, where predators had been excluded, the overall infection was about one-third greater.
These studies, conducted in the Netherlands, demonstrate the potential of naturally occurring predators to limit aphid populations in field crops and thus help in the management of virus diseases.
Presentation at the National Meeting of the Entomological Society of America, December 1996 by D. A.
Landis, Michigan State University and W. van der Werf, Department of Theoretical Production Ecology
Wageningen Agricultural University PO Box 430, 6700 AK Wageningen,The Netherlands.