At the University of Araraquara in São Paulo, Brazil, researchers have cracked a problem that's been limiting the reach of one of agriculture's most promising natural weapons: a fungus that kills crop-destroying insects but leaves everything else alone.
The challenge has always been shelf life. Beauveria bassiana, a fungus widely used as a bioinsecticide, tends to lose potency quickly once harvested. That means farmers need frequent applications, which drives up costs and undermines the sustainability promise of biological pest control. But a team at the Center for Sustainable Management of Pests, Diseases, and Weeds (CEMASU) has found an elegant solution: wrap the fungus in biopolymer beads.
Working through a process called ionotropic gelation, Hernane da Silva Barud and his colleagues at UNIARA created tiny spheres with a protective polymer shell on the outside and the fungal microorganism tucked safely inside. The polymer is made from carboxymethylcellulose, a water-soluble material derived from cellulose, cross-linked with aluminum to give it a three-dimensional structure. The results, published in ACS Omega, are striking: the encapsulation method increased the viability of B. bassiana from 69% to 85% after five months of storage—a meaningful boost for a product that loses effectiveness over time.
What makes this work is the precision. When the researchers tested two different formulations—one with aluminum as a cross-linking agent and another with calcium—the differences were revealing. Both formed spheres initially, but after drying, the aluminum-based beads maintained their shape and showed high uniformity, while the calcium ones collapsed and clumped together into irregular aggregates. Under scanning electron microscopy, the aluminum beads displayed a slightly rough surface with minor cracks, whereas the calcium versions were chaotic and pitted. The aluminum beads also showed greater thermal stability and better water retention—crucial for keeping the fungus alive inside.
The fungus itself works through an elegant mechanism. B. bassiana produces blastospores, reproductive cells that germinate rapidly when they encounter insect pests. These spores colonize the insects and kill them, yet the fungus is harmless to mammals—a critical advantage over chemical insecticides, which can poison both target and nontarget species. Because encapsulation extends shelf life and slows the release of fungal spores, farmers need fewer applications, reducing both cost and environmental risk.
The breakthrough is practical as well as elegant. The encapsulation process is simple, fast, and efficient. Viable spores remained on the surface of the beads even after five months of storage at -18° C. The researchers are now testing whether the beads can maintain their cargo at warmer temperatures—in a conventional refrigerator at 4° C and at room temperature—which would make the product far easier to distribute and use.
The path forward is clear. Barud notes that if field trials confirm the method works as well outside the lab as it does inside, the production process is scalable. That scalability is key: it would dramatically reduce manufacturing costs and make the product commercially viable. Beyond B. bassiana, the encapsulation method could work with other fungi, potentially expanding the range of crops that benefit. There's even potential for livestock farming, where the beads could be used to combat ticks. A simple biopolymer innovation, born in a São Paulo laboratory, could reshape how farmers protect their crops.