1 The current trend toward simplification of agricultural landscapes, as well as the associated loss of perennial cover types, can decrease landscape heterogeneity and also natural enemy abundance and diversity, favouring exotic species. 2 We evaluated the effects of agricultural landscape composition and heterogeneity at two different spatial scales (radii of 250 and 1000 m), on the diversity and abundance of native and exotic coccinellids, associated with alfalfa fields located in two regions of Central Chile. Data were analyzed using partial least square regressions, considering the whole coccinellid assemblage and the three most abundant species. 3 In both regions, coccinellid diversity and the abundance and proportion of native coccinellids in alfalfa responded differentially from total abundance and the abundance of exotic coccinellids. The diversity and abundance of coccinellids in alfalfa increased with the compositional and configurational heterogeneity of the landscape. The abundance of both native and exotic coccinellids in alfalfa fields decreased as the area covered by cultivated lands, such as annual crops and orchards, increased. Nevertheless, the responses of native and exotic coccinellids were not consistent among regions, which may be explained by responses of the dominant species in each region. 4 The results of the present study suggest that variables related to a higher intensification of agricultural landscapes (lower compositional and configurational heterogeneity, as well as more annual crops) reduce coccinellid diversity and abundance in alfalfa fields.To maintain a higher abundance and diversity of these natural enemies in alfalfa, more heterogeneous landscapes with less annual crops should be promoted.

Emerging infectious diseases in wildlife are increasingly associated with animal mortality and species declines, but their source and genetic characterization often remains elusive. Amphibian chytridiomycosis, caused by the fungus Batrachochytrium dendrobatidis (Bd), has been associated with catastrophic and well-documented amphibian population declines and extinctions at the global scale. We used histology and whole-genome sequencing to describe the lesions caused by, and the genetic variability of, two Bd isolates obtained from a mass mortality event in a captive population of the threatened Chilean giant frog (Calyptocephalella gayi). This was the first time an association between Bd and high mortality had been detected in this charismatic and declining frog species. Pathological examinations revealed that 30 dead metamorphosed frogs presented agnathia or brachygnathia, a condition that is reported for the first time in association with chytridiomycosis. Phylogenomic analyses revealed that Bd isolates (PA1 and PA2) from captive C. gayi group with other Bd isolates (AVS2, AVS4, and AVS7) forming a single highly supported Chilean Bd clade within the global panzootic lineage of Bd (BdGPL). These findings are important to inform the strengthening of biosecurity measures to prevent the impacts of chytridiomycosis in captive breeding programs elsewhere.

Biological invasions are an important threat to biodiversity. We studied the effect of thermal acclimation on thermal tolerance and locomotor performance in the invasive Xenopus laevis and the Chilean native Calyptocephalella gayi. We show that X. laevis is a better performer than C. gayi. Furthermore, thermal tolerance did not differ between the species.