Tarnished plant bug and eastern bumble bee in strawberry

Land use change affects both pollinator and herbivore populations with
consequences for crop production. Recent evidence also shows that land use
change affects insect traits, with intraspecific body size of pollinators
changing across landscape gradients. However, the consequences on crop
production of trait changes in different plant interactors have not been
well-studied. We hypothesized that changes in the body size of key species
can be enough to affect crop productivity, and therefore looked at how the
field-realistic variation in body size of both an important
pollinator, Bombus impatiens (Cresson), and a key pest
herbivore, Lygus lineolaris (Palisot), can affect fruit size and
damage in strawberry. First, we determined if pests vary in body size
along land use gradients as prior studies have documented for pollinators;
and second, we tested under controlled conditions how the individual and
combined changes in the size of an important pollinator and a key
herbivore pest affect strawberry fruit production. The key herbivore pest
was smaller in landscapes with more natural and semi-natural habitats,
confirming that herbivore functional traits can vary along a land-use
gradient. Additionally, herbivore size, and not pollinator size,
marginally affected fruit production—with plants exposed to larger pests
producing smaller fruits. Our findings suggest that land use changes at
the landscape level affect crop production not just through changes in the
species diversity of insect communities that interact with the plant, but
also through changes in body size traits.