Biological Control beneath the Feet: A Review of Crop Protection against Insect Root Herbivores

Abstract

Sustainable agriculture is certainly one of the most important challenges at present, considering both human population demography and evidence showing that crop productivity based on chemical control is plateauing. While the environmental and health threats of conventional agriculture are increasing, ecological research is offering promising solutions for crop protection against herbivore pests. While most research has focused on aboveground systems, several major crop pests are uniquely feeding on roots. We here aim at documenting the current and potential use of several biological control agents, including micro-organisms (viruses, bacteria, fungi, and nematodes) and invertebrates included among the macrofauna of soils (arthropods and annelids) that are used against root herbivores. In addition, we discuss the synergistic action of different bio-control agents when co-inoculated in soil and how the induction and priming of plant chemical defense could be synergized with the use of the bio-control agents described above to optimize root pest control. Finally, we highlight the gaps in the research for optimizing a more sustainable management of root pests.

Pressures on soil functions from soil management in Germany. A foresight review

“…The Research bringing new insights into how to generate positive effects on plant production through microbial inoculation Johnson et al 2016;Saia et al 2015a;Saia et al 2015b;Zhang et al 2014;Verbruggen et al 2012;El-Sirafy et al 2006;Rasmann et al 2017;Kergunteuil et al 2016;Larkin 2015 Research, soil threats: generally positive effects on soil habitat function if pesticides can be avoided because of inoculation with natural enemies Kergunteuil et al 2016 Policies: If not studied and regulated enough, inoculants could reach the market that may affect non-targeted organisms negatively Kergunteuil et al 2016 Research bringing new insights on promoting local mutualists of crops and natural enemies of pests Johnson et al 2016;Rasmann et al 2017;Larkin 2015 Technology: improved methods to assess soil biota and derive management options expected ↑ Teagasc 2016…”

“…The necessity for efficient P use is a topic at the interface of research and the political agenda in Germany Thus, there is a clear trend towards recycling nutrients for fertilizers while it is still unsure when and what kind of change exactly will occur. 4.5.5 Inoculation of soil and seeds with, and management of, mutualists of crops and natural enemies of pests Biotic inoculation of soils and seeds is seen by some authors (Johnson et al 2016, Kergunteuil et al 2016 as an evolving, promising method for plant performance and protection.…”

“…They include viruses, bacteria, fungi, nematodes, and arthropods (Kergunteuil et al 2016). High potential for inoculation with such organisms is seen for several types of natural enemies, such as entomopathogenic nematodes (EPNs) (Johnson et al 2016 andKergunteuil et al 2016) and mixes, such as EPNs with Bacillus thuringiensis (Kergunteuil et al 2016).…”

“…For some organisms, effects on non-targeted organisms are not sufficiently studied yet. But in general, negative effects are much less expected than from chemical pesticides (Kergunteuil et al 2016). Wide application of inoculation with natural enemies is still hindered by technical and economic obstacles, including factor costs (Johnson et al 2016 andKergunteuil et al 2016), so that currently, research, including industrial research, seems to be the decisive driver towards inoculation of soil with natural enemies.…”

Managing soil functions for a sustainable bioeconomy—Assessment framework and state of the art

“…Pesticide application can also be reduced by promoting antagonists of pests, for example, by adding organic amendments or inoculating soil or seeds with beneficial organisms. The latter is still rare, but researchers see significant advances and potential for this technology (Johnson et al, 2016;Kergunteuil et al, 2016).…”