Trophic ecology of lizards in vineyards: Diet composition and implications for pest control

Promoting pest management strategies, based on pest consumption by natural enemies rather than pesticide applications, represents a promising and more sustainable pathway in agriculture. Despite being considered mid-level consumers, “farmers’ friends”, widely abundant in agroecosystems, lizards are still largely overlooked as potential biological control agents in agricultural landscapes. In this study, we combined DNA metabarcoding and stable isotopes approaches to assess the trophic role of the wall lizard Podarcis bocagei, and specifically their contribution to pest consumption. We sampled seven vineyards from NW Portugal, across a gradient of pesticide application regimes. Overall, 316 arthropod prey species, from 95 families, 25 orders and 7 classes were detected in the lizard pellets. Agrotis spp. (Lepidoptera) was the only vineyard pest identified, and it occurred at relatively low frequencies across populations. Both DNA metabarcoding and isotopic approaches recovered consistent patterns in trophic structure across lizard populations: generalist diets, high overlap on prey composition among populations, and only limited divergence in niche breadth, regardless of local differences in prey availability and pesticide exposure. Although pest consumption by P. bocagei was limited, our study highlights that wall lizards in agroenvironments remain flexible enough to consume a wide array of arthropod groups and, expectably, other eventual pests eventually emerging. The complexity of trophic interactions under agricultural intensification advise for an integrative, multi-seasonal, and multi-method approaches to fully understand reptile-mediated ecosystem services.