Abstract
Herbivory is a major fitness pressure for plants and a key driver of crop losses in agroecosystems. Dense monocultures are expected to favor specialist herbivorous insects, particularly those who primarily consume crop species; yet, levels and types of herbivory are not uniform within regional cropping systems. It is essential to determine which local and regional ecological factors drive variation in herbivory in order to support functional agroecosystems that rely less on chemical inputs. Crops in the genus Cucurbita host a suite of both generalist and specialist herbivores that inflict significant damage, yet little is known about the relative contribution of these herbivores to variation in herbivory and how local- and landscape-scale Cucurbita resource concentrations, management practices, and natural enemies mediate this relationship. In this study, we tested whether three foundational ecological hypotheses influenced Cucurbita herbivory across 20 pumpkin fields in the semi-arid Southern High Plains Region of Texas. We used generalized linear mixed models and confirmatory path analysis to assess whether the Density-dependent Herbivory Hypothesis, Resource Concentration Hypothesis, or the Natural Enemies Hypothesis, could explain variation in Cucurbita herbivory and insect dynamics in the context of conventional agronomic practices. We found that herbivory increased over time, indicating that herbivores were causing sustained damage throughout the growing season. We also found that fields with higher local Cucurbita resources had lower herbivory, suggesting a resource dilution effect. Natural enemy communities were more abundant and taxonomically rich in sites with greater generalist herbivore abundance, though predator abundance declined over time, indicating that late-season crop fields are most at risk given high herbivory and low natural enemy-based control. Our findings also suggest that while local resource availability may drive the abundance and richness of arthropod communities, additional agronomic and phenological information is needed to anticipate herbivory risk in an agriculturally dominated landscape.
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The text the model read, with the source record’s inline markup (italics, sub- and superscripts) rendered and its character entities decoded; quote offsets refer to the raw text.
Claims 5
Claim · model-written summary
Cucurbita herbivory increased over the growing season.
CucurbitaNot reportedInteractor
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“herbivory increased over time”
e1“Cucurbita herbivory across 20 pumpkin fields”
Claim · model-written summary
Fields with more local Cucurbita resources had lower herbivory.
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“fields with higher local Cucurbita resources had lower herbivory”
Claim · model-written summary
Natural enemy communities were more abundant where generalist herbivores were more abundant.
- Interactor
- generalist herbivoree0herbivore
- Outcome
- Natural enemy communities were more abundante0
- Direction
- more abundante0
- Setting
- sitese0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Natural enemy communities were more abundant and taxonomically rich in sites with greater generalist herbivore abundance”
e1“local- and landscape-scale Cucurbita resource concentrations”
Claim · model-written summary
Natural enemy communities were richer where generalist herbivores were more abundant.
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Natural enemy communities were more abundant and taxonomically rich in sites with greater generalist herbivore abundance”
e1“local- and landscape-scale Cucurbita resource concentrations”
Claim · model-written summary
Predator abundance declined over time.
Not reportedSetting
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“predator abundance declined over time”
e1“local- and landscape-scale Cucurbita resource concentrations”