Carabids & Weed seed biocontrol
Date
2022-06-16
Authors
Journal Title
Journal ISSN
Volume Title
Publisher
ORCID
0000-0001-6718-966X
Type
Thesis
Degree Level
Doctoral
Abstract
Carabids are common inhabitants of crop fields and many species have been found to include seeds in
their diet. However, a simple relationship in the field between carabid activity-density and weed seed
predation is not always found. This may not be surprising, as carabids in a crop field are part of a wide
web of interactions which can influence both their activity-density and feeding choices. Furthermore, the
structural environment of a habitat influences the community in it and the strength of their interactions.
Hence, aspects that affect carabid weed seed biocontrol need to be further investigated to build more
robust and sustainable agricultural systems. In this work, I studied the relationship between carabid
activity-density and weed seed predation in pulse crops in Saskatchewan, Canada. Both pulse crops and
Saskatchewan are relatively understudied areas in carabid weed seed biocontrol research. The type of
pulse crop was expected to be an important factor determining carabid activity-density and community,
but carabid activity-density was highly variable between fields and previous crop type was a stronger
factor than pulse crop type in shaping the community. The granivorous genus Amara was positively
associated with canola seed predation and soil temperature. The relationships between carabids and
crickets (another common granivorous taxa) and seed predation were never simple linear relationships,
though. Indirect intraguild interactions may play a role herein. In the lab, granivorous carabids were found
to change their feeding and foraging behaviour when exposed to cues from a larger omnivorous species.
In agroecosystems, carabids occupy both crop fields and semi-natural areas. The latter are thought to
benefit carabids by providing overwintering habitats. Semi-natural habitats may also provide a refuge for
carabids associated with the original habitat of an area, and thus serve a biodiversity and conservation
role. I compared the community in Kernen prairie, a remnant native prairie patch, with that of the pulse
crop fields and found a very different community, suggesting it contributes to the carabid biodiversity of
the agroecosystem around Saskatoon.
Description
Keywords
Carabids, Ground beetles, Coleoptera, Carabidae, weed, biocontrol
Citation
Degree
Doctor of Philosophy (Ph.D.)
Department
Plant Sciences
Program
Agriculture and Bioresource