Deconstructing the control of the spotted alfalfa aphid

Control of insect pests and other taxa may be due to many factors that are difficult to separate and quantify as was the case for the control of the spotted alfalfa aphid (SAA, Therioaphis maculata Monell) in California and elsewhere. Introduced parasitoids, host plant resistance, pathogens and native predators led to its successful control, but the relative contribution of each factor remained largely unknown. The relative contribution of each control factor was estimated using a weather-driven physiologically-based demographic system model consisting of alfalfa, SAA (a), its three exotic parasitoids [Trioxys complanatus (Quilis) (b), Praon palitans Muesebeck (c), and Aphelinus semiflavus Howard (d)], a native coccinellid beetle [Hippodamia convergens (Guérin-Menéville)], a fungal pathogen [Erynia neoaphidis Remaudière & Hennebert (Zygomycetes: Entomophthorales) (g)], and host plant resistance (HPR) (h). Alone, each factor failed to control SAA, as did combinations of the parasitoids and coccinellid predation (f). Control was predicted across all ecological zones only when all mortality factors were included (i).

Gutierrez A.P., Ponti L., 2013. Deconstructing the control of the spotted alfalfa aphid Therioaphis maculata. Agricultural and Forest Entomology, 15: 272-284.
http://dx.doi.org/10.1111/afe.12015

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