Present address: Department of Entomology, Kansas State University, 123 W. Waters Hall, Manhattan, KS 66506, USA.
Alate immigration disrupts soybean aphid suppression by predators
Article first published online: 30 APR 2012
© 2012 Blackwell Verlag, GmbH
Journal of Applied Entomology
Volume 137, Issue 4, pages 317–320, May 2013
How to Cite
Costamagna, A. C., McCornack, B. P. and Ragsdale, D. W. (2013), Alate immigration disrupts soybean aphid suppression by predators. Journal of Applied Entomology, 137: 317–320. doi: 10.1111/j.1439-0418.2012.01730.x
- Issue published online: 8 APR 2013
- Article first published online: 30 APR 2012
- Received: 4 February 2012; accepted: 2 April 2012.
- Aphis glycines ;
- population outbreak;
- pest control;
- natural control;
- biological control
Natural enemies suppress many aphid populations, and yet, population outbreaks sometimes occur. The reasons predation fails to suppress such outbreaks are not clearly understood. While manipulating predators to examine their role in soybean aphid population growth, a natural immigration of soybean aphids occurred that enabled us to compare the roles immigration and predation played in population growth. Using predator exclusion cages, we found that predation on the top of the plant accounted for 42.3 ± 11.4% (mean ± SE) reduction in aphid population growth rates. When 90–100% of the canopy was exposed, predation failed to reduce aphid population growth because winged immigrants colonized plants, with an observed 6-fold increase in alates compared to plants completely covered or exposing only the top nodes (approximately 10% of the total canopy). We conclude that reproduction by immigrants contributed to population growth rates sufficiently to compensate for predation. These results demonstrate that immigration can counteract high levels of predation and lead to aphid population growth rates that could result in outbreak population densities.