In the ongoing battle against mosquito-borne diseases, traditional chemical insecticides have long been the first line of defense. However, the relentless evolution of mosquito populations has led to widespread resistance, significantly diminishing the effectiveness of these chemical agents. This alarming trend has driven researchers to explore innovative alternatives capable of disrupting mosquito lifecycles without adversely impacting the environment or non-target species. Among the promising candidates emerging from recent scientific advances are entomopathogenic fungi of the genus Metarhizium. These fungi possess the remarkable ability to infect and kill mosquitoes using only a minimal number of spores, presenting a sustainable and biologically targeted approach to vector control.
The interaction between insects and pathogens is often complex, involving a combination of behavioral cues and biochemical signals. Fascinatingly, prior studies demonstrated that fungi-infected caterpillars emit certain volatiles that inadvertently attract mosquitoes, suggesting an intriguing ecological mechanism whereby infected cadavers could influence insect behavior and potentially aid fungal spore dissemination. Until now, however, the exact chemical signals involved and their underlying sensory detection pathways in mosquitoes remained largely unknown. Furthermore, the practical applications of such fungal-mediated attraction for controlling mosquito populations were unexplored.
In a groundbreaking study, Tang et al. have elucidated the volatile composition of Metarhizium-colonized insect cadavers and identified a key chemical compound responsible for attracting healthy insects: the sesquiterpene longifolene. This naturally occurring bicyclic hydrocarbon is released as the fungal infection progresses within the cadaver, effectively signaling mosquitoes to approach the source. The fungal pathogen thus capitalizes on this chemical lure to bring new host insects into contact with infectious spores, facilitating efficient dispersal and transmission. Importantly, the researchers did not stop at chemical identification but extended their inquiry into the neurobiological mechanisms underpinning this attraction.
Using genetic and electrophysiological approaches, the team pinpointed the odorant receptors (ORs) in Drosophila melanogaster and Aedes albopictus responsible for detecting longifolene. These receptors are embedded in the antennae of the insects, serving as the molecular interface between environmental odors and neural sensory pathways. Characterizing these receptors provided crucial insights into how mosquitoes perceive fungal volatiles and how this olfactory recognition drives their host-seeking behavior. This novel understanding of fungal-insect chemical ecology opens new avenues for the strategic manipulation of vector attraction.
Capitalizing on these findings, the researchers employed synthetic biology techniques to engineer the virulent mosquito pathogen Metarhizium pingshaense for enhanced longifolene production. By introducing and expressing the gene encoding pine longifolene synthase, the transgenic fungus synthesized substantially higher levels of this volatile compound directly on culture media. This bioengineering innovation transformed M. pingshaense into a potent dual-function agent: it could now both attract mosquitoes more effectively and infect them upon contact with infectious spores. This elegant biocontrol strategy leverages the pathogen’s natural biology while boosting its capacity to lure and kill multiple mosquito species.
Field and laboratory assays revealed that the longifolene-overproducing fungal strains strongly attracted male and female mosquitoes across several vector species, including Aedes albopictus, Anopheles sinensis, and Culex pipiens. This broad-spectrum efficacy highlights the transgenic fungus’s potential as a versatile tool in integrated vector management programs. Notably, the attraction was maintained even in the presence of human hosts, alleviating concerns about possibly diminished effectiveness in real-world settings where competing stimuli abound. Such robustness underscores the practical relevance of this engineered biocontrol agent.
While human presence did not significantly deter mosquito attraction to the transgenic fungi, the researchers observed competition from natural mosquito-attracting flowering plants. These botanical competitors reduced mosquitoes’ relative preference for the fungal spores, indicating that environmental context influences the efficacy of the lure. Despite this ecological complexity, mortality rates among target mosquito populations remained impressively high—exceeding 90% in tested scenarios—attesting to the lethal potency of the transgenic pathogen. These findings suggest that even in ecologically rich environments, the engineered M. pingshaense can achieve substantial population suppression.
The discovery that Metarhizium fungi actively produce and deploy volatile attractants represents a paradigm shift in understanding entomopathogenic spore dispersal mechanisms. Traditionally viewed as passive pathogens relying on chance encounters with insect hosts, Metarhizium species now emerge as sophisticated agents capable of manipulating host-seeking behaviors to their advantage. This active recruitment of new hosts not only accelerates the pathogen’s life cycle but also enhances its potential as a biocontrol tool, especially against medically significant mosquitoes that transmit malaria, dengue, Zika, and other diseases.
Beyond mosquito control, the mechanistic insights gleaned in this study bear broader implications for biological pest management and chemical ecology. The identification of specific odorant receptors linked to fungal volatiles provides molecular targets for synthetic repellents or attractants, enabling precision modulation of insect behaviors. Furthermore, genetic engineering of entomopathogens to produce species-specific volatiles could be extended to other insect pests, offering customizable approaches to sustainable agriculture and vector-borne disease mitigation.
The work of Tang and colleagues brilliantly exemplifies the power of interdisciplinary research, merging fungal biology, neuroethology, molecular genetics, and chemical ecology to devise innovative vector control solutions. By transforming a natural pathogen into an odor-emitting attract-and-kill agent, this study heralds a new wave of biotechnological strategies with the potential to circumvent the growing challenge of insecticide resistance. Future efforts optimizing spore dispersal methods, enhancing stability, and field-testing in diverse ecological contexts will be critical to translating these laboratory successes into widespread public health breakthroughs.
Moreover, the resilience of attraction in the presence of humans, coupled with the overwhelming mosquito mortality observed, promises practical deployment scenarios in urban and rural settings. However, the interaction between fungal volatiles and competing environmental odors such as those from plants underscores the necessity to consider ecological variables in biocontrol deployment strategies. Integrating this fungal attractant system with existing vector control interventions could create synergistic effects, maximizing the suppression of mosquito populations and the diseases they transmit.
In conclusion, this landmark study presents a compelling example of how nature’s intricacies can be harnessed and enhanced through genetic engineering to combat one of humanity’s most persistent public health threats. Metarhizium fungi, long recognized for their pathogenicity against insects, now reveal hidden facets of behavior-modulating capabilities that researchers can exploit for targeted pest control. As mosquito-borne diseases continue to pose immense global burdens, innovations like engineered Metarhizium fungi offer hope for more effective, environmentally sound, and sustainable solutions.
The journey from uncovering fungal volatile emissions to deploying transgenic fungal strains in vector control illustrates the profound impact of understanding insect-pathogen communication channels. It uncovers a sophisticated chemical dialogue exploited by pathogens to increase their own fitness, now repurposed to diminish mosquito populations. This research not only advances scientific knowledge but also opens pathways toward real-world applications that could reshape public health strategies worldwide, exemplifying how cutting-edge science drives societal benefits.
Subject of Research: Engineered entomopathogenic Metarhizium fungi producing longifolene to attract and kill mosquitoes through olfactory manipulation.
Article Title: Engineered Metarhizium fungi produce longifolene to attract and kill mosquitoes.
Article References:
Tang, D., Chen, J., Zhang, Y. et al. Engineered Metarhizium fungi produce longifolene to attract and kill mosquitoes. Nat Microbiol (2025). https://doi.org/10.1038/s41564-025-02155-9
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