Effects of fertilization type on biocontrol of pests

 

Biological control of pests in arable land is an important ecosystem service provided by natural enemies such as predators and parasitoids. Plant fertilization has been shown to influence both pests and natural enemies and to induce strong bottom-up effects, leading to trophic cascades up to the fourth trophic level. There is increasing evidence that these bottom-up effects differ between fertilization types. Moreover, the type of fertilization may affect the efficacy of pest control by natural enemies. However, hardly anything is known on how fertilization type effects pest-natural enemy interactions and the efficacy of biocontrol.

The current Austrian Science Fund (FWF) project addresses this gap of knowledge by experimentally comparing how different fertilization types affect invertebrate assemblages in the field. As biological control is effectively the product of networks of interactions between the pest, its natural enemies and the non-pest food sources utilized by the latter, we will employ a food web approach to obtain a better mechanistic understanding of how fertilization type influences species interactions and biocontrol.

Aphids and cereal leaf beetles are major pests in cereals, causing significant economic losses. Here we will employ a molecular food web approach to measure the frequency of trophic interactions between these cereal pests and their parasitoids as well as between the pests, parasitoids, non-pest prey and ground- and foliage-dwelling predators under different fertilization regimes. Plots with organic and inorganic fertilization as well as unfertilized controls will be established in replicated wheat fields. The fertilisation effect on invertebrate densities and community composition as well as on food web interactions and the levels of pest control will be measured. This work will provide novel insights into how the type of fertilization, one of the major bottom-up measures in agricultural systems, effects trophic interactions and herbivore control in complex species assemblages.

  

ATE members involved in the fertilization biocontrol project:

• Daniela Sint (co-PI), Michael Traugott (PI)
• Oskar Rennstam Rubbmark (PhD student)
• Lena Manzl, Nina Egger, Sandra Cupic, Nina Horngacher, Romina Reinpold (MSc. students)
• Samuel Sieder, Regina Penz, Britta Frei, Markus Spielvogel, Athina Meindl (BSc. students)