Data from: Multiple factors, including arena size, influence the functional responses of ladybird beetles

1. Functional response studies are often used to determine the suitability
of predators as biocontrol agents. Ladybird beetles (Coleoptera:
Coccinellidae) often are used for the control of crop pests such as
aphids. However, most functional response studies on coccinellids compare
a limited number of species at different life stages, temperatures, or
sexes. A large-scale comparison of ladybird beetle functional responses is
needed to evaluate the utility of these species as potential biocontrol
predators and to understand the traits that influence the interaction
strength between ladybird beetles and their prey. 2. We compiled 158
ladybird beetle functional responses from 30 studies and tested for
effects of taxa, traits, temperature, and arena size on functional
response parameters using linear mixed-effects models. 3. Our results show
that functional response parameters (handling time and space clearance
rate) are affected by predator stage, predator mass, prey type,
temperature, and arena size. Although complicated by interaction terms,
space clearance rate generally increased with predator size, temperature,
and predator stage, while handling time decreased with predator size,
temperature, and predator stage. Coleopteran prey induced the highest
handling times. 4. Our results also show that experimental arena size has
a large, consistent effect on space clearance rate. Arena size is more
important in determining foraging rates at low prey densities than any
other factor considered here, including predator mass and temperature.
Efforts to use laboratory-based functional response experiments to
evaluate the efficacy of biocontrol predators are therefore confounded by
the choice of arena size. 5. Synthesis and applications. In addition to
confirming known body mass and temperature effects, our study reveals
previously unclear age-related effects and the importance of prey types,
which can be used to optimize biocontrol programs. The arena size effect
is unexpected and problematic because failure to account for arena size
precludes accurate comparison of biocontrol predator effectiveness. We
suggest managers and biocontrol practitioners re-evaluate the efficacy of
candidate biocontrol predators, perhaps by statistically controlling for
arena size to minimize the influence of this widely unconsidered factor on
functional response estimates.