The research focused on the yellow fever mosquito Aedes aegypti, the Asian tiger mosquito Aedes albopictus, and the house mosquito Culex pipiens, three species that together transmit dengue, Zika, chikungunya, yellow fever, West Nile virus, and lymphatic filariasis. Decades of reliance on a small arsenal of synthetic insecticides, including organophosphates and pyrethroids, has driven the evolution of resistant mosquito populations on multiple continents, prompting public health agencies to call for novel modes of action. Boron chemistry, until now largely absent from the vector-control literature, offers a genuinely fresh starting point.

Boron-based compounds have attracted growing attention in medicinal chemistry because of their antimicrobial, cytotoxic, and broadly bioactive properties. Naturally occurring boron macrolides such as aplasmomycin and boromycin demonstrated antibiotic and even anti-HIV activity, while synthetic boron clusters and boronate esters have found roles in drug design, diagnostics, and therapy. Yet the insecticidal potential of one particular structural class, the 1,2-diborane derivatives, had never been systematically tested against mosquito larvae. The new study set out to fill that gap, combining synthetic chemistry, crystallography, toxicology, and histopathology in a single investigation.

The team, led by Yüksel Şahin of Aydın Adnan Menderes University together with Fatma Bursalı, Yücel Basimoglu Koca, Muhittin Aygün, Hakan Can Söyleyici, Resul Sevincek, and Hüseyin Özgener, worked with five previously synthesized diborane and diborolane derivatives and added a brand-new molecule to the collection. This sixth compound, a 1,3,2-diazaborinane derivative designated compound 6, was synthesized and fully characterized, with its three-dimensional structure confirmed by single-crystal X-ray diffraction. The crystallographic data, deposited with the Cambridge Crystallographic Data Centre under accession number 2414655, allowed the researchers to relate the precise arrangement of substituents around the boron atoms to biological performance, a classic structure–activity analysis.

When the six compounds were tested against late third- and fourth-instar larvae of all three mosquito species, the results were strikingly consistent. Every compound displayed significant larvicidal activity. Probit analysis, a statistical method for quantifying dose–response relationships, yielded lethal concentration fifty values ranging from 16.712 to 30.087 micrograms per milliliter for Aedes aegypti, from 17.417 to 32.636 micrograms per milliliter for Aedes albopictus, and from 17.789 to 28.582 micrograms per milliliter for Culex pipiens. In practical terms, the most potent molecules killed half of the exposed larvae at concentrations in the tens of micrograms per milliliter range, a level of activity that places them firmly on the radar as candidate larvicides.

Not all of the molecules performed equally, however, and the differences proved chemically informative. Compounds 1 and 2 emerged as the most potent larvicides across all three species, while compounds 3, 4, and the newly synthesized diazaborinane compound 6 were comparatively less active. The authors attribute this gradient to the nature of the substituents attached to the boron atoms, suggesting that strongly donating groups on boron enhance biological activity. This kind of structure–activity relationship is the raw material of drug and pesticide discovery: it tells synthetic chemists which molecular features to keep and which to modify as they optimize potency, stability, and selectivity in future generations of compounds.

To understand how the compounds kill, the researchers turned to histopathology, examining stained tissue sections of larvae that had been exposed to the molecules and comparing them with untreated controls. The picture that emerged was unambiguous: the primary targets are the gastric caeca and the midgut epithelium, the tissues responsible for digestion and nutrient absorption in the larval gut. Exposed larvae showed epithelial disruption, cytoplasmic vacuolization, cellular swelling, degeneration of the microvilli that line the gut surface, and damage to the peritrophic membrane, the protective chitinous sleeve that shields the midgut from mechanical and chemical insult.

These lesions matter physiologically. The peritrophic matrix is a critical barrier in insect digestion and a first line of defense against pathogens and toxins, and its disruption exposes the underlying epithelium to direct chemical attack. Vacuolization and swelling of epithelial cells are hallmarks of cellular stress and impending cell death, while the loss of microvilli drastically reduces the absorptive surface of the gut. A larva whose midgut is compromised in this way effectively starves and loses fluid balance, a mode of action that is distinct from the neurotoxic mechanisms of pyrethroids and organophosphates, which is precisely what makes the finding valuable for resistance management.

Intriguingly, the severity of tissue injury varied among the three mosquito species. Aedes aegypti, the primary vector of dengue and yellow fever, suffered the most severe alterations, Culex pipiens showed moderate damage, and Aedes albopictus displayed relatively mild changes. This species-specific pattern of susceptibility hints at differences in gut physiology, cuticular penetration, or detoxification enzyme activity among the three vectors, and it underscores the need to evaluate any new larvicide against the full range of target species rather than extrapolating from a single laboratory model.

The authors are careful to frame the work as a foundation rather than a finished product. Their conclusion emphasizes that diborane derivatives, particularly those bearing specific substituents on the boron atoms, exhibit significant biological activity against mosquito larvae with toxic effects concentrated on the larval digestive system, and that the results support further investigation of these compounds as potential larvicidal candidates. At the same time, they stress that studies on selectivity toward non-target organisms, and on mechanisms of action under both laboratory and field-relevant conditions, are required before any practical application can be contemplated. The gap between a promising laboratory LC50 value and a deployable vector-control product is wide, encompassing environmental fate, effects on aquatic ecosystems, formulation, cost, and regulatory approval.

Even so, the study arrives at a moment of genuine urgency. Dengue incidence has surged globally, vaccine development has been slow and uneven, and the World Health Organization’s Global Vector Control Response 2017–2030 explicitly calls for new tools and new chemistries. Resistance to bacterial larvicidal toxins and to synthetic insecticides continues to erode the effectiveness of existing programs, and climate change is expanding the geographic range of Aedes and Culex vectors into temperate regions. Against that backdrop, a chemically novel class of compounds with a gut-targeted mode of action and clear structure–activity guidance for optimization represents exactly the kind of lead that vector biologists have been asking for. The next steps, testing non-target organisms such as aquatic invertebrates and fish, probing the molecular mechanism of boron toxicity in insect cells, and validating efficacy in semi-field and field trials, will determine whether these unusual molecules can graduate from the crystallography bench to the mosquito-control toolkit. For now, the humble boron atom, better known for its role in plant cell walls and cancer therapy, has earned a place in the conversation about the future of mosquito control.

Subject of Research: Larvicidal activity and histopathological effects of diborane derivatives against Aedes and Culex mosquito larvae

Article Title: Synthesis, Structure–Activity Considerations and Histopathological Effects of Diborane Derivatives as Mosquito Larvicides

Article References: Şahin, Y., Bursali, F., Koca, Y. B., Aygün, M., Söyleyici, H. C., Sevincek, R., & Özgener, H. (2026). Synthesis, Structure–Activity Considerations and Histopathological Effects of Diborane Derivatives as Mosquito Larvicides. Acta Parasitologica, 71(5), Article 221. https://doi.org/10.1007/s11686-026-01390-2

Image Credits: AI Generated

DOI: 10.1007/s11686-026-01390-2

Keywords: diborane derivatives, mosquito larvicides, Aedes aegypti, Aedes albopictus, Culex pipiens, boron chemistry, histopathology, midgut epithelium, structure–activity relationship, vector control, insecticide resistance, diazaborinane