In the subtropical soils of Cuba and Florida, an invisible revolution is unfolding—one that promises to shift the balance in the long battle against weevils devastating coffee and other key crops. At the heart of this change lies an unlikely hero: a newly identified fungal species, Metarhizium caribense, emerging from the tangled phylogeny of its more famous cousins to become a potent force in the fight for sustainable agriculture.

For decades, the genus Metarhizium has intrigued scientists and agriculturalists alike. These entomopathogenic fungi naturally prey on insects, penetrating their exoskeletons and consuming them from the inside out. Harnessing their lethal precision as a biocontrol agent has made them a key alternative to synthetic pesticides—especially in regions where pests have become resistant or where chemical use poses ecological risks.

But until recently, species identification within the genus was a complex and imprecise task. The Metarhizium anisopliaespecies complex, in particular, held a host of cryptic species whose morphological similarities made accurate classification nearly impossible using traditional microscopy. Only with the advent of multilocus sequence analysis (MLSA) and advanced genetic marker systems has the true diversity within this genus begun to emerge.

This is where M. caribense steps into the frame.

Discovered in coffee-growing soils and in association with the notorious coffee berry borer (Hypothenemus hampei)—the most destructive insect pest in global coffee production—M. caribense was initially mistaken for M. pinghaense, a known agent in the PARB clade of Metarhizium species. Yet closer analysis of three Cuban strains (LBM-30, LBM-41, and LBM-42) revealed that something did not quite add up.

Through a combination of protein-coding and non-coding genetic markers—5TEF, MzIGS3, and ribosomal intergenic spacer (rIGS)—researchers uncovered compelling evidence that these fungi formed a distinct, genetically isolated lineage. Further differentiation was confirmed through the detection of a rare, unusually long group-I intron in their 28S ribosomal RNA gene—an evolutionary fingerprint absent from other known PARB species. The result: the formal description of Metarhizium caribense as a new species, with strain ARSEF 5197 designated as its nomenclatural type.

Why does this matter for coffee professionals?

First, because the discovery of M. caribense offers a new biological tool in our pest management arsenal. This species has demonstrated natural pathogenicity against key pests like the coffee berry borer and the sweet potato weevil—both of which not only destroy crops but also force farmers into reliance on expensive, often environmentally damaging chemical pesticides.