Subterranean termites in urban forestry: tree preference and management

Area of Science:

• Urban Forestry
• Entomology
• Plant Pathology

Background:

• Urban tree deterioration is a global issue, often exacerbated by pest and disease attacks.
• Subterranean termites pose a significant threat to urban trees, potentially leading to structural failure and falls.

Purpose of the Study:

• To investigate subterranean termite damage in street trees in São Paulo, Brazil.
• To assess the relationship between tree size, plant group (native, exotic, palm), and termite infestation.
• To identify key termite species and susceptible tree species for improved urban forestry planning.

Main Methods:

• A 9-year study monitored 1477 street trees, identifying species and measuring circumference at breast height (CBH).
• Trees were categorized into native, exotic, and palm groups.
• Termite species were identified, and infestation levels were recorded.

Main Results:

• Four subterranean termite species were identified, with Coptotermes gestroi being the most prevalent, affecting up to 27% of trees.
• Palm trees showed no termite damage. Native plants, particularly Caesalpinia pluviosa var. peltophoroides, were most susceptible.
• Larger trees (higher CBH) exhibited a greater percentage of internal damage from C. gestroi. Exotic plants were generally susceptible, with exceptions like Lagerstroemia indica and Platanus acerifolia.

Conclusions:

• Plant species selection is crucial for urban forestry to mitigate termite damage, with native species often being more vulnerable.
• Tree size is correlated with the extent of internal termite damage.
• Chemical treatments using imidacloprid and thiamethoxam proved effective in controlling subterranean termites over the study period.