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Simple Summary: Honeybees are known for their ability to communicate about resources in their environment. They inform the other foragers by performing specific dance sequences according to the spatial characteristics of the resource. The purpose of our study is to provide a new tool for honeybees dances recording, usable in the field, in a practical and fully automated way, without condemning the harvest of honey. We designed and equipped an outdoor prototype hive, later called "GeoDanceHive", allowing the continuous recording of honeybees' dances and their analysis. The use of the GeoDanceHive is designed for a wide range of users, who can meet different objectives, such as researchers or professional beekeepers. Thus, our hive is a powerful tool for honeybees studies in the field and could highly contribute to facilitating new research approaches and better understanding landscape ecology of key pollinators. Honeybees are known for their ability to communicate about resources in their environment. They inform the other foragers by performing specific dance sequences according to the spatial characteristics of the resource. The purpose of our study is to provide a new tool for honeybees dances recording, usable in the field, in a practical and fully automated way, without condemning the harvest of honey. We designed and equipped an outdoor prototype of a production hive, later called "GeoDanceHive", allowing the continuous recording of honeybees' behavior such as dances and their analysis. The GeoDanceHive is divided into two sections, one for the colony and the other serving as a recording studio. The time record of dances can be set up from minutes to several months. To validate the encoding and sampling quality, we used an artificial feeder and visual decoding to generate maps with the vector endpoints deduced from the dance information. The use of the GeoDanceHive is designed for a wide range of users, who can meet different objectives, such as researchers or professional beekeepers. Thus, our hive is a powerful tool for honeybees studies in the field and could highly contribute to facilitating new research approaches and a better understanding landscape ecology of key pollinators. [ABSTRACT FROM AUTHOR]

Apis mellifera often encounters the fungicide boscalid in agricultural landscape. In this study, we assessed the impacts of ingesting boscalid and Pictor Pro® (a commercial formulation of boscalid) at environmentally relevant doses during the larval development phase. Following chronic exposure, we measured survival, development time, and gene expression in both larvae and in 10-day-old workers. The genes analyzed were involved in immunity, detoxification, development, and mitochondrial activity pathways. We found no significant impact of boscalid in larval survival and emergence. However, genes related to cytochrome b, succinate dehydrogenase, and catalase were downregulated in larvae and adult workers exposed to boscalid, though the differences were not significant when compared to the solvent control. Late variation was observed in 10 days adult bees’ overexpression of the vitellogenin gene, which is linked to development. The effects observed with boscalid molecule were not seen with the commercially formulated product, Pictor Pro®. [ABSTRACT FROM AUTHOR]

Artificially reared larvae are an ideal model for experiments involving brood diseases or testing pesticides. Larvae development condition can influence the general performance of adult honey bees but little is known about queen larvae. We first performed a review of existing protocols. Based on existing protocols we tested and changed parameters linked to breeding conditions. The aims of this study were to compare and determine the best protocol for in vitro queen larvae rearing. For this purpose, we tested 57 sub-protocols both available in the literature and new protocols to compare their effectiveness and to identify potential improvement. As a major result of this study we found low queen emerging rate in most of the sub-protocols. The size and the type of rearing cup, diet quantity (food can be done ad-libitum but a lower volume (i.e., 270 µl) is also highly suitable) and quality including freshness of the royal jelly among other variables contribute to the conjunction of numerous parameters that makes queen in vitro rearing complex. The high number of rearing conditions tested here facilitates emerging rate comparison. The available literature and the current study highlight the complexity of searching for the best protocol and necessitate further investigation to provide a suitable protocol for in vitro queen rearing. Such protocol will be very needed to facilitate larvae development of future queens and evaluate the consequences of other stressors (parasites, pollutants ...) in control condition on queen health. [ABSTRACT FROM AUTHOR]

Apis mellifera was used as a model species for ecotoxicological testing. In the present study, we tested the effects of acetone (0.1% in feed), a solvent commonly used to dissolve pesticides, on bees exposed at different developmental stages (larval and/or adult). Moreover, we explored the potential effect of in vitro larval rearing, a commonly used technique for accurately monitoring worker exposure at the larval stage, by combining acetone exposure and treatment conditions (in vitro larval rearing vs. in vivo larval rearing). We then analyzed the life‐history traits of the experimental bees using radio frequency identification technology over three sessions (May, June, and August) to assess the potential seasonal dependence of the solvent effects. Our results highlight the substantial influence of in vitro larval rearing on the life cycle of bees, with a 47.7% decrease in life span, a decrease of 0.9 days in the age at first exit, an increase of 57.3% in the loss rate at first exit, and a decrease of 40.6% in foraging tenure. We did not observe any effect of exposure to acetone at the larval stage on the capacities of bees reared in vitro. Conversely, acetone exposure at the adult stage reduced the bee life span by 21.8% to 60%, decreased the age at first exit by 1.12 to 4.34 days, and reduced the foraging tenure by 30% to 37.7%. Interestingly, we found a significant effect of season on acetone exposure, suggesting that interference with the life‐history traits of honey bees is dependent on season. These findings suggest improved integration of long‐term monitoring for assessing sublethal responses in bees following exposure to chemicals during both the larval and adult stages. Environ Toxicol Chem 2024;43:1320–1331. © 2024 The Authors. Environmental Toxicology and Chemistry published by Wiley Periodicals LLC on behalf of SETAC. [ABSTRACT FROM AUTHOR]

Measuring time–activity budgets over the complete individual life span is now possible for many animals with the recent advances of life‐long individual monitoring devices. Although analyses of changes in the patterns of time–activity budgets have revealed ontogenetic shifts in birds or mammals, no such technique has been applied to date on insects.We tested an automated breakpoint‐based procedure to detect, assess and quantify shifts in the temporal pattern of the flight activities in honeybees. We assumed that the learning and foraging stages of honeybees will differ in several respects, to detect the age at onset of foraging (AOF).Using an extensive dataset covering the life‐long monitoring of 1,167 individuals, we compared the AOF outputs with the more conventional approaches based on arbitrary thresholds. We further evaluated the robustness of the different methods comparing the foraging time–activity budget allocations between the presumed foragers and confirmed foragers.We revealed a clear‐cut learning–foraging ontogenetic shift that differs in duration, frequency and time of occurrence of flights. Although AOF appeared to be highly plastic among bees, the breakpoint‐based procedure seems better capable to detect it than arbitrary threshold‐based methods that are unable to deal with inter‐individual variation.We developed the aofr‐package including a broad range of examples with both simulated and empirical datasets to illustrate the simplicity of use of the procedure. This simple procedure is generic enough to be derived from any individual life‐long monitoring devices recording the time–activity budgets, and could propose new ecological applications of bio‐logging to detect ontogenetic shifts in the behaviour of central‐place foragers. [ABSTRACT FROM AUTHOR]

Abstract The paradigm for all toxicological bioassays in the risk assessment of pesticide registration reflects the principle that experimental conditions should be controlled to avoid any other factors that may affect the endpoint measures. As honeybee colonies can be frequently exposed to bio-aggressors in real conditions, often concomitantly with pesticides, co-exposure to pesticide/bio-aggressors is becoming a concern for regulatory authorities. We investigated the effects of the neonicotinoid insecticide thiamethoxam on the homing performances of foragers emerging from colonies differentiated by health status (infestation with Varroa destructor mites, microsporidian parasite Nosema spp. and Deformed Wing Virus). We designed a homing test that has been recently identified to fill a regulatory gap in the field evaluations of sublethal doses of pesticides before their registration. We also assessed the effect of temperature as an environmental factor. Our results showed that the Varroa mite exacerbates homing failure (HF) caused by the insecticide, whereas high temperatures reduce insecticide-induced HF. Through an analytical Effective Dose (ED) approach, predictive modeling results showed that, for instance, ED level of an uninfested colony, can be divided by 3.3 when the colony is infested by 5 Varroa mites per 100 bees and at a temperature of 24 °C. Our results suggest that the health status of honeybee colonies and climatic context should be targeted for a thorough risk assessment. Graphical abstract Image 1 Highlights • Temperature and colony health modulate insecticide-induced homing failure in honeybee. • Varroa mites exacerbate homing failure caused by the insecticide thiamethoxam. • Low temperatures aggravate insecticide-induced homing failure. • Pesticide risk assessment should include temperature and Varroa mites as covariates. [ABSTRACT FROM AUTHOR]

Honeybees, major providers of pollination, are endangered in many areas. Embryo cryopreservation may be a very useful tool to maintain their genetic diversity. However, it is complex in insects, because embryos are chill sensitive and are surrounded by two protectant membranes, the chorion and vitelline. These membranes prevent penetration of cryoprotectant in the embryos. This study aimed to test different conditions of embryo preparation before cryopreservation, including low-frequency sonophoresis, a physical method of permeabilization, and passages through cryoprotectant solutions. Apis mellifera ligustica embryos were collected in artificial cell plugs 7.5 h after queens had been caged, in two different seasons (winter, spring) and were then incubated in vitro overnight (16.5 h). Embryos were individually sonicated and then incubated in three cryoprotectant baths (B1 = 10%, B2 = 20% and B3 = 40% of cryoprotectant) and quenched in liquid nitrogen. Artificial cell plugs and in vitro incubation device were efficient in producing future embryos hatching. Embryos stained ruby red with rhodamine B after sonophoresis treatment indicated that low-frequency ultrasound had permeabilized embryos. According to the treatment, different significant hatching rates were obtained after sonophoresis (up to 25%). After three cryoprotectant incubations, best hatching rates were obtained after 10 min in B1 and B2, and 40 s in B3. These results show that sonophoresis is an efficient tool to permeabilize the chorion and vitelline membrane of the day one honeybee embryo allowing a hatching rate of more than 20%. They also show that the season is an important variability factor. [ABSTRACT FROM AUTHOR]

Bee declines are driven by multiple combined stresses, making it exceedingly difficult to identify experimentally the most critical threats to bees and their pollination services. We highlight here the too often ignored potential of mechanistic models in identifying critical stress combinations. Advanced bee models are now available as open access tools and offer an unprecedented opportunity for bee biologists to explore bee resilience tipping points in a variety of environmental contexts. We provide general guidelines on how to run bee models to help detect a priori critical stress combinations to be targeted in the field. This so-called funnel analysis should be performed in tight conjunction with the recent development of large-scale field monitoring programs for bee health surveillance. [ABSTRACT FROM AUTHOR]

Recent studies succeeded in developing a method to automatically record honeybees going in and out of the hive. Honeybees were individualized with radio frequency identification (RFID) tags glued onto their dorsal surface and detected at the hive entrance by readers emitting high-frequency (HF) radio waves. In this work we search for a possible adverse effect of HF on honeybees' survival. Eight-day-old honeybees were exposed to HF (13.56 MHz) or ultra-high-frequency (UHF, 868 MHz) radio waves for 2 h split into ON and OFF periods. The ON/OFF ratio was 1:3 (OFF duration 3, 90, 180, 370 and 360 s) or 1:5 (OFF duration 300 s). Dead individuals were counted every day, and the cumulative mortality rates of exposed and non-exposed honeybees were compared 7 days after exposure. Out of the five experimental conditions, we observed an increase in mortality in two conditions, once after HF and once after UHF exposure, with OFF duration of 5 min or more. We then recommend limiting exposure of honeybees to radio waves to less than 2 h per day, and we conclude that the RFID parameters, like those we used in the field for monitoring hive activity, present no adverse effects for honeybees. [ABSTRACT FROM AUTHOR]

Background: Juvenile hormone (JH) plays an important role in honeybee development and the regulation of age-related division of labor. However, honeybees can be exposed to insect growth regulators (IGRs), such as JH analogs developed for insect pest and vector control. Although their side effects as endocrine disruptors on honeybee larval or adult stages have been studied, little is known about the subsequent effects on adults of a sublethal larval exposure. We therefore studied the impact of the JH analog pyriproxyfen on larvae and resulting adults within a colony under semi-field conditions by combining recent laboratory larval tests with chemical analysis and behavioral observations. Oral and chronic larval exposure at cumulative doses of 23 or 57 ng per larva were tested. Results: Pyriproxyfen-treated bees emerged earlier than control bees and the highest dose led to a significant rate of malformed adults (atrophied wings). Young pyriproxyfen-treated bees were more frequently rejected by nestmates from the colony, inducing a shorter life span. This could be linked to differences in cuticular hydrocarbon (CHC) profiles between control and pyriproxyfen-treated bees. Finally, pyriproxyfen-treated bees exhibited fewer social behaviors (ventilation, brood care, contacts with nestmates or food stocks) than control bees. Conclusion: Larval exposure to sublethal doses of pyriproxyfen affected several life history traits of the honeybees. Our results especially showed changes in social integration (acceptance by nestmates and social behaviors performance) that could potentially affect population growth and balance of the colony. [ABSTRACT FROM AUTHOR]

The article discusses research investigating the physiological impact of nonlethal exposure of thiamethoxam (neonicotinoid systemic pesticide) on honey bees. The results from the authors’ study suggest that the use of neonicotinoid pesticides causes high mortality due to homing failure. They note that results indicate the potential for colony collapse from thiamethoxam intoxication. The team’s use of simulated exposure events on free-ranging foragers labeled with a radio-frequency identification tags and insights into the consequence of common neonicotinoid pesticides used worldwide are discussed.