Artificial sentinel prey models (e.g., clay caterpillars) evaluated for
removal or marks of attack |
mostly predators |
✓ |
✗ |
Live tethered or outplanted sentinel prey/hosts (usually immobile
stages, like eggs or pupae; but also confined larval stages) |
both |
✓ |
✗ |
Post-hoc assessment of natural enemy impact via detection of bite-marks
or other physical damage to prey |
predators |
✓ |
✗ |
Post-hoc assessment of natural enemy impact via detection of distinctive
host remains, host-feeding tubes or damage, remains of developing
parasitoids (egg chorions, larval or pupal exuvia, meconia, cocoons), or
distinctive parasitoid or host emergence holes |
parasitoids |
✓ |
✗ |
Dissection of hosts to record parasitoid eggs, larvae, or pupae; or
rearing of hosts |
parasitoids |
✓ |
✗ |
Monoclonal antibody-ELISA or DNA-based assays of hosts to detect
internally developing parasitoids |
parasitoids |
✓ |
✗ |
Gut content analyses – detection of prey remains using simple
dissections and visual inspection |
predators |
✓ |
✗ |
Monoclonal antibody-ELISA, immunomarking, or DNA-based assays of
consumer gut contents |
predators and host-feeding parasitoids |
✓ |
✗ |
Focal observations of prey/hosts, using human observers or video cameras |
both |
✓ |
Partially* |
Field life table construction by repeated sampling of a cohort of
developing hosts/prey to quantify survival and rate of development from
eggs to adults; often used with immobile hosts/prey |
both |
✓ |
Partially† |
Short-term (i.e., too short for prey reproduction) mesocosm assays using
hand removal or caging treatments to contrast the effects of natural
enemy presence/absence; response variable = prey survival |
both |
✓ |
Partially† |
Long-term (i.e., long enough to permit substantial prey reproduction)
mesocosm assays using hand removal or caging treatments to contrast the
effects of natural enemy presence/absence; response variable = prey
population size or growth rate |
both |
✓ |
✓ |
Experimental removal of natural enemy populations using selective
insecticides; response variable = prey/host population size or growth
rate |
both |
✓ |
✓ |
Experimental addition of natural enemy populations by controlling ants
that otherwise exclude the nature enemy; response variable = prey/host
population size or growth rate |
both |
✓ |
✓ |
Observational field methods comparing natural enemy present vs. absent
(e.g., in classical biocontrol settings: pre- vs. post-release, or
release site vs. non-release site); response variable = prey/host
population size or growth rate‡ |
both |
✓ |
✓ |