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Multi-scale approach of crop microclimates in complex agro-ecological landscapes in Ecuador: towards new pest management strategies?

Faye E., Rebaudo F., Herrera M., Dangles O.. 2016. In : Plinio Sist (ed.), Stéphanie Carrière (ed.), Pia Parolin (ed.), Pierre-Michel Forget (ed.). Tropical ecology and society reconciliating conservation and sustainable use of biodiversity. Program and abstracts. Storrs : ATBC, p. 369. Annual Meeting of the Association for Tropical Biology and Conservation (ATBC 2016), 2016-06-19/2016-06-23, Montpellier (France).

Microclimates have long been recognized in controlling the physiology and ecology of species. However, in the context of global warming and increasing climatic variability, a major uncertainty that hampers effective pest management is related to the thermal characteristics of agricultural landscapes, which are known to have profound effects on insect pest dynamics. Here, we addressed the issue of considering microclimates experienced by crop pests in their environments to infer their distribution and develop innovative pest control strategies based on processes of thermal agro-ecology. We assessed the heterogeneity of microclimates experienced by pests and natural enemies in complex agricultural landscapes of Ecuador (from 2800 to 3600 m.a.s.l.), made of various crop types and natural habitats. The assessment of microclimates was performed at the agrosystem, crop field, and plant scales using a combination of UAVs, thermal cameras and temperature micro-loggers. Then, we determined the relationship between microclimates heterogeneity (characterized using spatial metrics) and pest occurrences (measured in the field with pheromone traps and local plant samplings). Results revealed that microclimates heterogeneity must be taken into consideration when estimating ectotherm occurrences. Indeed, at the landscape scale, microclimates of crops and natural habitats substantially affect pest dynamics. At the field scale, the spatial metrics shaping microclimatic conditions are significantly related to pest occurrences. And at the plant scale, we found that pests can access in their close vicinity (<1.2 m) most of the thermal micro-environments recorded at the field level. In complex agro-ecological landscapes, there is likely a wide range of microclimatic conditions resulting in the presence of locallysuitable and unfavourable conditions for ectotherms (crop pests but also natural enemies), the existence of which might not be apparent at a coarser resolution. Consequently, this work stresses the need of a better incorporation of microclimatic data into models of species distribution (and vulnerability to climate change) and evidences that microclimates might provide new leverage for innovative agro-ecological pest management. (Texte intégral)

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