{"id":40846,"date":"2026-01-29T00:01:45","date_gmt":"2026-01-29T05:01:45","guid":{"rendered":"https:\/\/beyondpesticides.org\/dailynewsblog\/?p=40846"},"modified":"2026-01-26T16:49:50","modified_gmt":"2026-01-26T21:49:50","slug":"neonicotinoid-insecticides-cause-deadly-overheating-behavior-in-honey-bees-study-finds","status":"publish","type":"post","link":"https:\/\/beyondpesticides.org\/dailynewsblog\/2026\/01\/neonicotinoid-insecticides-cause-deadly-overheating-behavior-in-honey-bees-study-finds\/","title":{"rendered":"Neonicotinoid Insecticides Cause Deadly Overheating Behavior in Honey Bees, Study Finds"},"content":{"rendered":"

(Beyond Pesticides<\/em>, January 29, 2026) A study of ecotoxicity risk from neonicotinoid insecticides, published in Environmental Chemistry and Ecotoxicology<\/em><\/a>, finds that chemicals in this class of pesticides, particularly dinotefuron<\/a>, increase the body temperature of Apis mellifera<\/em> (European honey bee) and subsequently accelerate the translocation (movement) of contaminants into hives by the honey bees. The research indicates that neonicotinoids affect acetylcholine receptors in the nervous system, leading to an “elevation in octopamine<\/a> titer [neurotransmitter\/hormone] and subsequent increase in the body temperature of honeybees,\u201d the authors report. They continue: \u201cFurthermore, we observed a considerable upregulation [of] the expression of a flight gene flightin<\/em> in honeybees. This gene accelerates the homing behavior of honeybees and facilitates the rapid and frequent transport of neonicotinoid pesticide-contaminated nectar to the hive.\u201d<\/p>\n

In describing their results, the researchers state: \u201cFor the first time, we propose that neonicotinoid pesticides accelerate the homing ability of honeybees by affecting their body temperature, which leads to more neonicotinoid pesticides entering the hive and explains the prevalence of neonicotinoids and at higher concentrations in terms of their effects on the honeybee body temperature that enhances homing.\u201d This accelerated movement of neonicotinoid pesticides into honey bee hives heightens the toxicity risks to honey bee populations.<\/p>\n

The study also analyzes the difference between S-dinotefuran and R-dinotefuran, which are enantiomers<\/a> (mirror images) of the same compound that can vary in their chemical properties due to different configurations. The results reveal that \u201cS-dinotefuran exhibited a markedly higher influence on the body temperature of honeybees and the expression of flight genes than R-dinotefuran,\u201d the authors state.<\/p>\n

Study Background<\/strong><\/p>\n

Neonicotinoids<\/a> (neonics) are a class of insecticides that share a common mode of action that affects the central nervous system of insects, resulting in paralysis and death. A multitude of studies show that neonicotinoid residues accumulate in the pollen and nectar of treated plants and represent a risk to pollinators and other nontarget insects. As a result of this and their pervasive use, there is a preponderance of evidence<\/a> that neonics play a major contributing role in pollinator and biodiversity decline. (See Beyond Pesticides\u2019 resource page here<\/a> for more information.)<\/p>\n

As the current study states: \u201cInsects possess a strong thermoregulatory capacity to maintain normal insect metabolism, which maximizes their adaptive capacity and ensures that they can survive normally. Honeybees can regulate their body temperature, which is essential for maintaining the health and stability of their colonies.\u201d Disruptions to these mechanisms adversely impact the health of individual honey bees, as well as the health of the colony. Not only does temperature regulation impact bees\u2019 foraging abilities under a range of weather conditions, but a bee\u2019s body temperature can directly impact flight capability. \u201cIn cold environments, foragers utilize flight muscles to maintain their thorax temperature above the ambient temperature during foraging activities,\u201d the authors note. \u201cThe regulation of the honeybee body temperature is paramount in their overall functionality and survival strategies.\u201d (See study here<\/a>.)<\/p>\n

Prior research<\/a> shows the importance of thermogenesis in honey bees, highlighting the role of octopamine signaling and octopamine receptors in this process. Octopamine, as a neurotransmitter, neurohormone, and neuromodulator in invertebrates (see more<\/a>), directly impacts the flight muscles of honey bees, allowing for the promotion of thermogenesis and maintenance of proper body temperature. While neonics have been previously recognized as neurotoxic agents<\/a>, their implications on body temperature in honey bees has not been fully evaluated.<\/p>\n

To address this gap in scientific knowledge, the researchers \u201cconducted a study on the effects of body temperature of the honeybees after subacute exposure, their returning ability to their hive, and the enrichment of pollutants they carry to their hive in the field.\u201d The authors continue, saying: \u201cOur results show for the first time neonicotinoid pesticides dinotefuran substantially increased the octopamine titer [concentration] and body temperature of the honeybees, thereby accelerating their homing and foraging behavior, and considerably expedited enrichment and transfer of contaminated nectar in the field to honeybee populations and hives. These findings may be the underlying reason neonicotinoid pesticide use poses a higher risk to honeybee populations than other pesticide types.\u201d<\/p>\n

Methodology and Results<\/strong><\/p>\n

Within the experiments, the effects of multiple neonicotinoid pesticides on thermoregulation in honey bees are analyzed. The body temperatures of the bees were recorded after exposure to the neonics S-dinotefuran<\/a>, R-dinotefuran, Rac-dinotefuran (a 50\/50 mixture of S- and R-dinotefuran), and thiamethoxam<\/a>, as well as pyriproxyfen<\/a>, an insecticide that is not in the neonicotinoid class, as a comparison. Additional analyses include the determination of octopamine content in honey bees and the effect of dinotefuran enantiomers on genes and the homing ability of honey bees. Both laboratory and field experiments are included, with additional RNA extraction and sequence analysis and statistical data analyses.<\/p>\n

The results reveal that Rac-dinotefuran-treated honey bees have the highest body temperatures when compared to untreated bees, while all bees treated with thiamethoxam and dinotefuran exhibit elevated body temperatures. \u201cWhen the honeybees were treated with dinotefuran enantiomers, a remarkable increase in the body temperature of those treated with S-dinotefuran than those treated with R-dinotefuran and the sucrose solution\u201d is noted.<\/p>\n

To elucidate the differences in the body temperature of bees treated with neonicotinoid pesticides and a non-neonicotinoid insecticide, bees were exposed to pyriproxyfen as a control agent. The authors report, \u201cAfter thiamethoxam and pyriproxyfen treatments, the thiamethoxam-treated honeybees exhibited a significantly higher body temperature (28.6\u00b0C) than those treated with pyriproxyfen (24.5\u00b0C) and sucrose solution (19.3\u00b0C).\u201d Most notably, the honey bees treated with Rac-dinotefuran have a significantly higher body temperature (30.4\u00b0C). These results highlight that neonicotinoids in comparison to other pesticides trigger a specific mechanism of dysfunction that threatens temperature regulation in honey bees.<\/p>\n

The data shows \u201ctremendous increases\u201d in the octopamine content in honey bees after treatments with S-dinotefuran, Rac-dinotefuran, and thiamethoxam, indicating that neonicotinoid pesticides influence octopamine concentration and thus the body temperature of honey bees. In terms of genetic implications, honey bees exposed to the dinotefuran enantiomers experience significant alterations in genes that are associated with flight muscles and thermoregulation.<\/p>\n

Additionally, the number of honey bees returning to their hive after treatment with the dinotefuran enantiomers was 3.9 times higher with treatment of S-dinotefuran than with R-dinotefuran. \u201cTherefore, compared to R-dinotefuran, honeybees transport significantly more S-dinotefuran into the hive,\u201d the researchers state. S-dinotefuran treatment also \u201cresulted in significant changes in 44 genes,\u201d many of which are related to thermogenesis.<\/p>\n

Overall, the results show that \u201cS-dinotefuran is more toxic than R-dinotefuran at the same concentration, and thus, it exhibits a stronger effect on insects.\u201d The authors continue: \u201cOur study indicated that the neonicotinoid insecticide dinotefuran acted on the insect acetylcholine receptor, which caused synaptic excitation and upregulation of the expression of flightin<\/em> in bees. This phenomenon may be the direct reason for the substantial promotion of the homing behavior of bees within a short period.\u201d \u00a0<\/p>\n

Previous Research<\/strong><\/p>\n

There is a wide body of science on the effects of neonicotinoids on nontarget organisms, particularly pollinators, as documented by Beyond Pesticides in Daily News<\/em><\/a> and on the What the Science Shows on Biodiversity<\/a> page. Recent research highlights the impacts of neonics on honey bee reproduction<\/a> and how safety reviews fail to capture the hazards associated with neonicotinoids and their transformation products<\/a>.<\/p>\n

Additional research on neonicotinoids is captured in the current study that supports the findings, including:<\/p>\n