A Promising Predator-In-First Strategy to Control Western Corn Rootworm Population in Maize Fields

Abstract

Western Corn Rootworm is a pest of maize that mostly damages roots. Many alternative strategies have been explored to control this species, with little or non-lasting success, and it remains a threat to maize production worldwide. Gaeolaelaps aculeifer, a soil-dwelling predatory mite that inhabits the first few centimeters of the soil, showed high predatory potential against WCR larvae in the laboratory. In this study, we explored the efficiency of G. aculeifer against WCR in more realistic contexts. First, we infested maize plants isolated in pots in a greenhouse with WCR, and tested the impact of different densities of mites on plant protection. Using standard indicators of WCR population presence and impact, we confirmed that G. aculeifer has the potential to control WCR at densities starting from 100 mites/plant. Then, considering that the release of a large amount of biocontrol agents at WCR emergence might be too costly and constraining for large-scale implementation, we tested the efficiency of a predator-in-first strategy in a maize field infested by WCR. The goal was to introduce fewer G. aculeifer combined with Aleuroglyphus ovatus eggs as an alternative food source in order to let the mite population grow in the field and reach sufficient density at the critical stage for protection. This strategy gave comparable results to pesticide on all indicators examined in our field trial, highlighting the potential to sustainably manage this pest.

Review: predatory soil mites as biocontrol agents of above- and below-ground plant pests

“…This creates direct damage leading to yield loss (Riedell 1990 ; Sutter et al 1990 ; Spike and Tollefson 1991 ; Godfrey et al 1993 ; Gray et al 2009 ). Laboratory studies showed promising results when testing predatory soil mites against this pest; field experiments, however, gave mixed results (Prischmann-Voldseth et al 2011 ; Prischmann-Voldseth and Dashiell 2013 ; Pasquier et al 2021a , b ).…”