Assessing ground predation by invertebrates in crops: camera observations clarify the relevance of aphid cards and coleopteran sentinel prey

Redesigning cropping systems to promote natural pest control requires a sound understanding of the regulation potential enemies. Sentinel preys are useful quantify biological control, but use aphid cards (aphids glued sandpaper card) is controversial for their lack realism. The objectives here were: (1) compare non-fixed beetle larvae resembling coleopteran pests, with respect consumers attracted; and (2) ascertain whether predation on prey responds different invertebrates communities. We used cameras identify two types sentinel ground, compared an original prey, bruchid larvae. Aphids attracted opportunistic scavengers very long handling times, even scavengers, including harvestmen (33% consumption events), spiders slugs, few carabid beetles. Unattached were consumed largely by carabids (64%), secondarily rove beetles, ants chilopods. As not same organisms, these findings demonstrate importance choice organisms exposed estimate predation. Knowing identity from images, we investigated assemblages epigeic arthropods could explain rates under contrasting field conditions. Accounting all expected consumers, disappearance be explained statistically satisfactory goodness-of-fit. Slugs contributed more strongly than carnivorous Finally, alternative (especially Collembola) reduced diverting usual prey. Camera observations valuable assess relevance involved. With this knowledge, it possible ground-dwelling communities present.