Data from: The relative importance of plant intraspecific diversity in structuring arthropod communities: a meta-analysis

1. Understanding how plant diversity influences higher trophic levels is
important for predicting the consequences of global biodiversity loss.
While early studies have focused on the effects of plant species richness,
more recently a growing number of experiments have explored the effects of
plant intraspecific diversity by manipulating the genotypic richness of
plant communities. 2. By combining 162 estimates of effect size from 60
experimental studies, we examined the effects of plant genotypic richness
on arthropods, one of the most diverse and abundant taxa which play a
crucial role in many ecosystem processes and services. We have also
compared the effects of plant genetic and species diversity on arthropods
when both were manipulated within the same study. 3. Species richness and
abundance of most trophic groups of arthropods was higher in genetically
diverse plant stands. Interestingly, the effects of plant genetic
diversity on natural enemies of herbivores were stronger than the effects
of plant genetic diversity on herbivores, suggesting that plant genetic
diversity effects on predators might be driven by mechanisms independent
of herbivores. 4. Herbivore and predator abundance increased with plant
genetic diversity in studies using wild plants whereas predator abundance
was unaffected and herbivore abundance was reduced by crop genetic
diversity. Damage by generalist herbivores was reduced by plant genetic
diversity whereas damage by specialist herbivores was not affected. 5.
When the effects of plant genetic and species diversity on arthropods were
compared within the same study, the magnitude of plant genetic diversity
effects was comparable to that of plant species diversity. 6. Our results
suggest that plant genetic diversity has significant effects on the
diversity of arthropods across several trophic levels, thus highlighting
the importance of maintaining high levels of both plant species and
genetic diversity for arthropod conservation. However, the potential of
using crop genetic mixtures in agriculture for pest control appears to be
limited as even though herbivore abundance was reduced in genetically
diverse plots, herbivore damage and predator abundance were not affected
by crop genotypic richness.