Data from: Plant defences limit herbivore population growth by changing predator–prey interactions

Plant quality and predators are important factors affecting herbivore
population growth, but how they interact to regulate herbivore populations
is not well understood. We manipulated jasmonate-induced plant resistance,
exposure to the natural predator community and herbivore density to test
how these factors jointly and independently affect herbivore population
growth. On low-resistance plants, the predator community was diverse and
abundant, promoting high predator consumption rates. On high-resistance
plants, the predator community was less diverse and abundant, resulting in
low predator consumption rate. Plant resistance only directly regulated
aphid population growth on predator-excluded plants. When predators were
present, plant resistance indirectly regulated herbivore population growth
by changing the impact of predators on the herbivorous prey. A possible
mechanism for the interaction between plant resistance and predation is
that methyl salicylate, a herbivore-induced plant volatile attractive to
predators, was more strongly induced in low-resistance plants. Increased
plant resistance reduced predator attractant lures, preventing predators
from locating their prey. Low-resistance plants may regulate herbivore
populations via predators by providing reliable information on prey
availability and increasing the effectiveness of predators.