Climate change drives reduced biocontrol of the invasive spongy moth

The effects of climate change on forest-defoliating insects are poorly understood, but could severely reduce forest productivity, biodiversity and timber production. For decades following its introduction in 1869, the spongy moth (Lymantria dispar) severely defoliated North American forests, but the introduction of the fungal pathogen Entomophaga maimaiga in 1989 suppressed spongy moth defoliation for 27 years. E. maimaiga, however, needs cool, moist conditions, whereas climate change is bringing hot, dry conditions to the range of the insect. Here we use an empirically verified eco-climate model to project that climate change will sharply reduce E. maimaiga infection rates, thereby increasing spongy moth defoliation. Recent rebounds in defoliation are consistent with our projections. Our work demonstrates that the effects of climate change on species interactions can have important consequences for natural ecosystems. The authors constructed an eco-climate model to project climate change impacts on populations of the spongy moth (Lymantria dispar) and its pathogen Entomophaga maimaiga. They show that climate change will sharply reduce E. maimaiga infection rates and subsequently increase spongy moth defoliation.