Tipula larval populations affected by soil edaphic and microbiological properties: Insights from Ireland and Scotland
Herbivorous soil-dwelling pests cause damage in agriculture through decreases in root and shoot biomass, which can affect both plant and economic yield. Having a greater understanding of the soil environment of these pests could identify potential avenues for mitigation/control strategies. Leatherjackets (Tipula larvae) are pests of grasslands and cereals across Europe and North America, for which there are no known effective or economical non-chemical control options. Within this study, the soil habitats of Tipula paludosa in grassland and cereal sites were examined across Ireland and Scotland, to assess the impact of edaphic properties on their occurrence. Significant correlations were observed between leatherjacket populations and silt content, positively in cereal sites and negatively in grasslands. Larval populations were positively correlated with Na, Al, and Zn, and negatively correlated with Fe, Mn, and K. As grasslands were more vulnerable to high T. paludosa infestations, their soil microbiomes were also examined from a prokaryotic and fungal community structure context. Microbial community structure was linked to leatherjacket occurrence and abundance, and specific microbial genera were associated with the absence or high prevalence of larvae. Plant growth promoting bacteria (Flavobacterium) and fungi (Mortierellaceae) were significantly more abundant in soils where larvae were absent. Where there were larval populations above the economic threshold for crop damage, significantly higher abundances of anaerobic bacteria (Anaerolineaceae) were present. Studies of pest related soil microbiomes and environments could hold promise for future pest suppression strategies via management and biocontrol opportunities.