29
Jan
Neonicotinoid Insecticides Cause Deadly Overheating Behavior in Honey Bees, Study Finds
(Beyond Pesticides, January 29, 2026) A study of ecotoxicity risk from neonicotinoid insecticides, published in Environmental Chemistry and Ecotoxicology, finds that chemicals in this class of pesticides, particularly dinotefuron, increase the body temperature of Apis mellifera (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 titer [neurotransmitter/hormone] and subsequent increase in the body temperature of honeybees,†the authors report. They continue: “Furthermore, we observed a considerable upregulation [of] the expression of a flight gene flightin 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.â€
In describing their results, the researchers state: “For 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.†This accelerated movement of neonicotinoid pesticides into honey bee hives heightens the toxicity risks to honey bee populations.
The study also analyzes the difference between S-dinotefuran and R-dinotefuran, which are enantiomers (mirror images) of the same compound that can vary in their chemical properties due to different configurations. The results reveal that “S-dinotefuran exhibited a markedly higher influence on the body temperature of honeybees and the expression of flight genes than R-dinotefuran,†the authors state.
Study Background
Neonicotinoids (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 that neonics play a major contributing role in pollinator and biodiversity decline. (See Beyond Pesticides’ resource page here for more information.)
As the current study states: “Insects 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.†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’ foraging abilities under a range of weather conditions, but a bee’s body temperature can directly impact flight capability. “In cold environments, foragers utilize flight muscles to maintain their thorax temperature above the ambient temperature during foraging activities,†the authors note. “The regulation of the honeybee body temperature is paramount in their overall functionality and survival strategies.†(See study here.)
Prior research 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), 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, their implications on body temperature in honey bees has not been fully evaluated.
To address this gap in scientific knowledge, the researchers “conducted 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.†The authors continue, saying: “Our 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.â€
Methodology and Results
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, R-dinotefuran, Rac-dinotefuran (a 50/50 mixture of S- and R-dinotefuran), and thiamethoxam, as well as pyriproxyfen, 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.
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. “When 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†is noted.
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, “After thiamethoxam and pyriproxyfen treatments, the thiamethoxam-treated honeybees exhibited a significantly higher body temperature (28.6°C) than those treated with pyriproxyfen (24.5°C) and sucrose solution (19.3°C).†Most notably, the honey bees treated with Rac-dinotefuran have a significantly higher body temperature (30.4°C). These results highlight that neonicotinoids in comparison to other pesticides trigger a specific mechanism of dysfunction that threatens temperature regulation in honey bees.
The data shows “tremendous increases†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.
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. “Therefore, compared to R-dinotefuran, honeybees transport significantly more S-dinotefuran into the hive,†the researchers state. S-dinotefuran treatment also “resulted in significant changes in 44 genes,†many of which are related to thermogenesis.
Overall, the results show that “S-dinotefuran is more toxic than R-dinotefuran at the same concentration, and thus, it exhibits a stronger effect on insects.†The authors continue: “Our study indicated that the neonicotinoid insecticide dinotefuran acted on the insect acetylcholine receptor, which caused synaptic excitation and upregulation of the expression of flightin in bees. This phenomenon may be the direct reason for the substantial promotion of the homing behavior of bees within a short period.†Â
Previous Research
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 and on the What the Science Shows on Biodiversity page. Recent research highlights the impacts of neonics on honey bee reproduction and how safety reviews fail to capture the hazards associated with neonicotinoids and their transformation products.
Additional research on neonicotinoids is captured in the current study that supports the findings, including:
- A study of brief acute exposure to dinotefuran shows enhanced flight capacity in honey bees, as does short-term treatment with thiamethoxam in additional research. (See here and here.)
- “[S]ublethal acute exposure to the neonicotinoid insecticide thiamethoxam increased the flight time and distance of bees and demonstrated that thiamethoxam had short-term excitatory and long-term inhibitory effects.â€
- Apis cerana (honey bee specific to Asia) experience “a significantly higher average homing time, mean flight velocity, flying distance, and flying duration than the control with a short period after acute oral treatment with 20 μL thiamethoxam.†(See study here.)
- As reported by Chen et al., “S-dinotefuran is 41.1–128.4 times more toxic to honeybees than R-dinotefuran.â€
- Neonicotinoid insecticides, even in trace amounts, can reduce the foraging performance and success of honey bees. (See research here, here, and here.)
The Organic Solution
To safeguard honey bees, other pollinators, and all insects throughout the environment, neonicotinoid insecticides and all other petrochemical pesticides and synthetic fertilizers need to be phased out of use. Protecting the health of all wildlife within the ecosystems we depend upon also directly protects human health. As Beyond Pesticides and organic advocates affirm, this is only possible through the wide-scale transition to organic land management practices.
Currently, the pesticide treadmill is perpetuated within our chemical-intensive society, where one pesticide could be removed from use but another, potentially more toxic compound, immediately fills its place. Organic agriculture and land management offers a holistic approach in which alternative practices can be implemented that eliminate the need for the input of toxic chemicals. In prioritizing soil health, healthy systems are built and maintained that do not need harmful compounds such as neonicotinoids for pest management.
To support the organic movement, start by buying or growing organic products and get involved in your local community by advocating for Sustainable Parks for the New Year. To learn more, sign up to get our Action of the Week and Weekly News Updates delivered right to your inbox and email our team at [email protected] to learn about the Parks for a Sustainable Future program.
All unattributed positions and opinions in this piece are those of Beyond Pesticides.
Source:
Zhang, F. et al. (2025) Neonicotinoid pesticides dinotefuran increase honeybee body temperature and accelerate honeybee (Apis mellifera) translocation of contaminants into hives to enhance ecotoxicity risk, Environmental Chemistry and Ecotoxicology. Available at: https://www.sciencedirect.com/science/article/pii/S2590182625002590.
