Sugar beet wireworm Limonius californicus damage to wheat and barley: evaluations of plant damage with respect to soil media, seeding depth, and diatomaceous earth application

Abstract

Wireworms, the larval stage of click beetles (Coleoptera: Elateridae), continue to be one of the major concerns of cereal producers, primarily due to the lack of effective pesticides and species-specific management options. To have a better understanding of species-specific interactions of one of the most damaging wireworms in the Pacific Northwest and intermountain regions of the USA, a greenhouse study was set to evaluate the damage from the sugar beet wireworm Limonius californicus to wheat and barley planted at different depths and in soil media with varying levels of organic content and texture. Overall, the evaluated wheat appeared to be more susceptible than the barley, showing greater reductions in emergence success and foliar biomass. The greatest loss of foliar biomass was observed in peatmoss-dominated medium, as indicated by a significant host plant-by-soil media interaction. Percentage of plants fed upon by L. californicus was significantly higher in the sand-dominated medium than peatmoss-dominated and 1:1 mix media. Moreover, manipulation of soil media by the addition of diatomaceous earth showed no consistent effect in protecting the planted wheat. Our findings indicated that in addition to quantifying wireworm species-specific interactions, host plant interactions with the environment in the presence of wireworm infestation should also be further studied. These relationships could influence the outcome of integrated management approaches and future risk assessment models and recovery plans.