Modelagem de adequabilidade ambiental para Zagreus bimaculosus (Mulsant, 1850) sob mudanças climáticas no Nordeste brasileiro.

Abstract

The ladybug species Zagreus bimaculosus (Mulsant, 1850) stands out as a relevant biological control agent of scale insects in forage cactus crops within the Brazilian semi-arid region. Considering the rise in global average temperatures linked to climate change and the species' thermal requirements, this study aimed to model the environmental suitability for Z. bimaculosus in Northeastern Brazil for the 2021–2040 and 2041–2060 periods under the SSP2-4.5 and SSP3-7.0 climate scenarios. Model calibration utilized 38 occurrence records obtained from GBIF and variables bio_5, bio_11, and bio_17, selected from WorldClim’s 19 bioclimatic variables through Principal Component Analysis and biological criteria. Modeling was performed using the biomod2 package in R software, integrating GLM, GAM, MaxEnt, and Random Forest algorithms trained via K-fold cross-validation, with performance validated by AUC and TSS metrics. Only models with TSS ≥ 0.4 were included in the two ensemble models used for projections. The results indicate that the species' distribution is strongly influenced by thermal conditions, with a clear preference for mild climates. Future projections highlight that, in both analyzed scenarios, the increase in global average temperature will cause a progressive retraction of suitable areas. Consequently, the species' occurrence will be restricted to the coastal strip and higher altitude locations, where the effects of maritime influence and the altitudinal thermal gradient, respectively, provide lower temperature conditions favorable to the species' survival.