Thaumastocoris peregrinusCarpintero & Dellapé (Heteroptera: Thaumastocoridae) is a sap‐sucking insect that feeds on leaves ofEucalyptus.In Uruguay, it was detected in 2008 causing significant economic losses inEucalyptusplantations. At present, there is no efficient control for this pest; thus, the use of biological control agents seems to be an environmentally friendly alternative to reduce the damage caused by this insect. The aims of this study were to isolate and identify the species of entomopathogenic fungi that naturally infectT. peregrinusin Uruguay and to characterize and select the most virulent isolates towards this pest.Individuals ofT. peregrinuswere collected in eightEucalyptusplantations infested by the pest. The entomopathogenic fungi were isolated and identified by observation of their micromorphological characteristics, and their identity was confirmed by molecular methods. The pathogenicity and virulence againstT. peregrinusof the isolated entomopathogenic fungi were evaluated. Isolates causing the highest insect mortality were selected to evaluate the effect of temperature and water activity on conidial viability. Entomopathogenic fungi were found in very low number with the prevalence of less than 3%. Isolates corresponded toBeauveria,Fusarium,Isaria,Lecanicillium,Paecilomyces,Pochonia,PurpureocilliumandSimplicilliumgenera. Two species,B. pseudobassianaandL. muscarium,were first recorded in Uruguay. Among all the tested species, an isolate ofB. bassiana(FI 2403) showed the highest virulence followed by an isolate ofB. pseudobassiana. The isolate ofB. bassianapresented the highest percentage of spore germination at the three temperatures and the highest viability at low water activities. Isolate FI 2403 was selected as a promissory candidate for the development of a commercial formulation againstT. peregrinus.

The Australian psyllid, Blastopsylla occidentalis Taylor (Hemiptera, Aphalaridae) is here recorded in Eucalyptus tree plantations in Uruguay. It was first detected in 2010, but may have remained undetected for at least the five preceding years. This is the first record of this species in Uruguay, together with a new host record on Eucalyptus maidenii Muell. It is the fourth species of Australian psylloids, behind Ctenarytaina spatulata Taylor (first detected in 1994), C. eucalypti (Maskell) (in 1998), and Glycaspis brimblecombei Moore (in 2006) to become naturalised in Uruguay. Extralimital distribution and host data are summarised. No economic damage was associated with this species in the field.

The plantation and natural forests of South America have been highly impacted by native and exotic pests in recent decades. The interaction of emerging invasive pests, climate change, and timber markets will define the region’s forests, with significant but uncertain ecological changes and economic losses expected. The Southern Cone Forest Health Group (SCFHG), a joint ad hoc initiative run by forest health professionals from Argentina, Brazil, Chile, and Uruguay, aims to strengthen relationships between the forestry industry, stakeholders, academia, and government agencies across the region. Here, we highlight regional strengths, weaknesses, threats, and opportunities to address forest health issues in the region. A regional approach with a strong communication network is relevant for future actions. In the current global scenario of invasive species and climate change, the implementation of practices that incorporate the resilience of forest ecosystems and sustainable management needs to be prioritized in forest policy across the region. Understanding that pests and pathogens do not recognize borders, we call on governments and organizations to support joint actions with agreements and adequate resources to enhance our regional capabilities.