Abstract
ABSTRACTThe fact that plant spatial aggregation patterns shape insect-herbivore communities in a variety of ways has resulted in a large body of literature on the subject. The landmark resource concentration hypothesis predicts that density of insect herbivores per plant will increase as host plant density increases. I examined this prediction across temporal samplings using Jatropha nana and the associated specialist insect herbivores as a system. Through 12 field samplings, I modelled the effect of host plant density on insect-herbivore loads. The initial samplings (2–3) provided evidence for the resource concentration hypothesis, with insect loads increasing with increasing host plant density, whereas the later samplings (4–5, 7–11) showed the opposite; a resource dilution pattern with a decline of insect loads with increasing host plant density. These patterns also depend on the biology of the herbivores and have important implications on J. nana population dynamics.This article has an associated First Person interview with the first author of the paper.
Highlights
Insect herbivory is one of the most important biotic drivers that maintains the structure and function of tropical plant communities (Weissflog et al, 2018)
Host plants and insect herbivores have been widely studied given the ecological importance of their relationships in understanding trophic interactions (Koricheva et al, 2000) and the economic importance of their relationships in crop production (Bukovinszky et al, 2005)
The present work provides only partial support for the resource concentration hypothesis’ (RCH) and the results support the predictions of the RCH for the initial stages of the host plant
Summary
Insect herbivory is one of the most important biotic drivers that maintains the structure and function of tropical plant communities (Weissflog et al, 2018). Host plant characteristics play an important role in driving patterns of insect-herbivore abundance and diversity, through a variety of mechanisms including chemical and physical defences, nutritional content of leaves, as well as spatial and temporal variation in resources (Neves et al, 2014). Host plants and insect herbivores have been widely studied given the ecological importance of their relationships in understanding trophic interactions (Koricheva et al, 2000) and the economic importance of their relationships in crop production (Bukovinszky et al, 2005)
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