The identity of belowground herbivores, not herbivore diversity, mediates impacts on plant productivity

Abstract

Across many ecosystems, increases in species biodiversity generally results in greater resource acquisition by consumers. Few studies examining the impacts of consumer diversity on resource capture have focused on terrestrial herbivores, however, especially taxa that feed belowground. Here we conducted field mesocosm experiments to examine the effects of variation in species richness and composition within a community of wireworm herbivores on wheat plant productivity. Our experiments involved wireworm communities consisting of between one and three species, with all possible combinations of species represented. We found that the presence of wireworms reduced plant biomass and seed viability, but wireworm species richness did not impact these plant metrics. Species identity effects were strong, as two species, Limonius californicus and Selatosomus pruininus, had significantly stronger impacts on plants compared to L. infuscatus. Communities with either of the two most impactful species consistently had the greatest impact on wheat plants. The effects of wireworms were thus strongly dependent on the particular species present rather than the overall diversity of the wireworm community. More broadly, our study supports the general finding that the identity of particular consumer species within communities often has greater impacts on ecosystem functioning than species richness.

Assessing the performance of pea and lentil at different seeding densities as trap crops for the management of wireworms in spring wheat

“…In the present study, fewer wireworms were collected at baits more than 30 days after deployment, suggesting the phenomenon of reduced attraction level of CO 2 after a specific time. Wheat and barley are considered to be a preferred crop for L. californicus , H. bicolor and A. mellillus (Horton & Landolt, ; Morales‐Rodriguez et al, ), and specially, L. californicus spends its entire life primarily in wheat crops (Milosavljević, Esser, & Crowder, ); it feeds on wheat through the growing season (Milosavljević et al, ) and causes twice as much damage to wheat compared to some other wireworm species (Milosavljević, Esser, Bosque‐Pérez, et al, ). A study done in 2015–2016 (Adhikari & Reddy, ) and the present study supports the idea that both pea and lentil have the capacity to serve as potential trap crops to manage damage to wheat plants by wireworms, and probably a closer association of trap crop plants may also be able to retain the wireworms for longer period of time and can reduce the damage to associated wheat stand.…”

“…Although wheat and barley are the preferred crops of these species (Horton & Landolt, ; Morales‐Rodriguez et al, ), there is a variation in species behaviour and L. californicus persists in crop habitats throughout its life cycle and exerts stronger impacts on crops since its activity increases with the progressing crop season (Milosavljević, Esser, & Crowder, ). Also, more crop damage occurs when one damage exerting species is dominant compared to the field where a greater number of species of wireworms occurs (Milosavljević, Esser, Bosque‐Pérez, & Crowder, ). Landscape and soil characteristics play an important role, with studies showing that factors such as texture, moisture, pH, temperature, bulk density and organic matter impact abundance and damage caused by wireworms (Milosavljević et al, ; Staudacher et al, ; Hermann, Brunner, Hann, Wrbka, & Kromp, ).…”

“…Also, more crop damage occurs when one damage exerting species is dominant compared to the field where a greater number of species of wireworms occurs (Milosavljević, Esser, Bosque‐Pérez, & Crowder, ). Landscape and soil characteristics play an important role, with studies showing that factors such as texture, moisture, pH, temperature, bulk density and organic matter impact abundance and damage caused by wireworms (Milosavljević et al, ; Staudacher et al, ; Hermann, Brunner, Hann, Wrbka, & Kromp, ).…”