Exploring Biocontrol Strategies Against Asian Longhorned Beetles

In a significant push towards sustainable pest management, researchers are advocating for the use of microbial pathogens as a biocontrol strategy against the invasive Asian longhorned beetle (Anoplophora glabripennis), a notorious threat since its detection in New York in 1996. This beetle, identifiable by its striking black-and-white coloration, poses a severe risk to hardwood trees, including maple, birch, and elm, as its larvae burrow deep into tree trunks, leading to the trees' decline and death. Current management strategies primarily involve the removal and destruction of infested trees. However, a newly published review in the journal Environmental Entomology highlights a promising array of entomopathogens—fungi, bacteria, and nematodes—that could supplement existing management practices.

According to Dr. Ann Hajek, Professor Emerita at Cornell University and lead author of the review, the absence of a comprehensive study on this subject prior to their work was surprising. "I was stunned that we had never written a review about this," she stated, emphasizing the wealth of information available on these microbial agents. The review meticulously details various entomopathogens, particularly focusing on insect-killing fungi such as Beauveria and Metarhizium species. These fungi have demonstrated efficacy in laboratory settings, infecting and ultimately killing adult beetles when spores latch onto their bodies.

Despite the promising results of laboratory trials, the application of these biocontrol methods in the U.S. faces several challenges. The U.S. eradication strategy, characterized by rapid detection and removal of ALB-infested trees, leaves little room for field trials of biocontrol methods. Consequently, most research has occurred in China, the beetle's native habitat, where sustained beetle populations are more readily available for study. However, as Hajek notes, ecological differences, such as varying moisture levels, have complicated these trials.

In parallel, tiny parasitic nematodes, specifically Steinernema carpocapsae and S. feltiae, have shown potential in targeting ALB larvae. These nematodes can infiltrate beetle tunnels and are attracted to beetle droppings, effectively killing ALB larvae. Additionally, the bacterium Bacillus thuringiensis (Bt), commonly used in biopesticides, has been considered, but its practical application is hindered by the larvae's deep nesting habits within trees.

Despite their potential, the broader application of these biological control methods in the U.S. remains limited. The aggressive eradication approach, which has been largely successful in controlling outbreaks, has resulted in a reluctance to adopt biocontrols that are better suited for population suppression rather than complete eradication. Hajek advocates for a shift in perspective, suggesting that the U.S. could benefit from a strategy similar to that of Japan, where fungal bands are currently in use as a management tool.

The role of citizen scientists has been invaluable in the ongoing efforts to combat the ALB. According to Hajek, all known ALB infestations in the U.S. have been initially reported by the public, highlighting the importance of community engagement in detecting and managing invasive species.

In conclusion, while microbial pathogens may not provide a magic bullet for ALB control, they represent a powerful arsenal of tools that could become increasingly vital as the invasive species continues to spread. The integration of these biocontrol methods with existing strategies could enhance management efforts and ultimately protect valuable hardwood ecosystems across the United States. As researchers explore these avenues, the potential for a more nuanced and effective approach to pest management looks promising.

For further reading, please refer to the study titled 'Entomopathogens for control of Asian longhorned beetles (Coleoptera: Cerambycidae)' published in Environmental Entomology in June 2025.