Hallucinations represent a transdiagnostic phenomenon observed in multiple neuropsychiatric disorders, including schizophrenia, substance use disorder and substance-induced psychotic conditions. Despite their clinical prevalence, objective assessment remains challenging due to its subjective nature, underscoring the critical need for validated translational models. The present study explores the biological mechanisms underlying hallucinations, evaluates the animal models developed to date, and discusses methods for analyzing these models along specific pathways. Hallucinations are primarily mediated through glutamatergic and/or serotonergic pathways. Numerous animal models for assessing hallucinations have been extensively reported; however, these models have mainly been designed to investigate specific neurotransmitter mechanisms, rather than encompassing all relevant pathways. Therefore, this study systematically examines currently established animal models based on the aforementioned neurotransmitter mechanisms and proposes future directions for developing universal animal models capable of comprehensively evaluating hallucinatory phenomena. The present study aims to provide deeper insights for future research involving animal models of hallucination.

Bumblebees are widely used to pollinate various greenhouse crops. Among the different bumblebee species, Bombus ignitus is indigenous to Korea, China, Japan and Russia. B. ignitus undergoes one generation per year, and artificial hibernation is essential for year-round rearing of the bumblebee. Keeping the queens under low-temperature conditions for several months is an effective method for terminating their diapause and promoting colony development. In the present study, we investigated how cold temperature affects the artificial hibernation of B. ignitus queens. Under chilling temperatures of -2.5°C, 0°C, 2.5°C and 5°C with constant humidity >80%, the queens stored at 2.5°C exhibited the highest survival rates, which were 74.0% at one month, 67.0% at two months, 60.0% at three months, 46.0% at 4 months, 33.0% at 5 months and 24.0% at 6 months. Lower survival rates were observed at 0°C, 5°C, 7.5°C and 12.5°C. At 2.5°C the colony developmental characteristics after diapause were 1.2- to 1.5-fold greater than those when queens were stored at 5°C. Thus, 2.5°C and 70% R.H. were the most favorable chilling temperature and humidity conditions for terminating the diapause of B. ignitus queens.

Bumblebees are important pollinators of crops and wildflowers in northern temperate regions. The number of bumblebee species has declined in recent decades, particularly, in developing regions. Here, we investigated the distribution and floral preferences of founder bumblebee queens that were collected between 2000 and 2012 in Korea with the intention of gathering information useful in the conservation of native bumblebee populations. A total of 13,130 overwintered bumblebee queens were collected at 63 locations from 8 provinces; the collected bumblebees consisted of five species of native bumblebees (Bombus ardens, B. ignitus, B. hypocrita spporoensis, B. ussurensis and B. consobrinus wittenburgi) and one species of exotic bumblebee (B. terrestris). The dominant species were Bombus ardens Smith and Bombus ignitus Smith, which accounted for 7,462 (56.8%) and 3,725 (28.4%) of the collected bumblebees, respectively. As a proportional distribution of the founder bumblebee queens that were collected, B. ignitus was the most common (9.8%-78.5%), followed by B. ardens (9.8%-66.1%), B. hypocrita spporoensis (0.9%-31.4%), B. ussurensis (0.8%-22.2%), B. consobrinus wittenburgi (0.1%-3.8%) and B. terrestris (0.0%-1.1%). The bumblebee queens foraged from 7 families of plants and 18 plant species. B. ignitus bumblebees were primarily collected from Prunus serrulata Matsumura and Corydalis speciosa Max, and B. ardens bumblebees were primarily collected from Rhodldendron mucronulatum Turcz and Prunus yedoensis.

Many bumblebee species have declined in number in recent decades, particularly in developing regions. Widespread declines of bumblebee species threaten the pollination levels of both wildflowers and crops. Here, we investigated the body weight and colony-developmental characteristics of Korean native bumblebee (B. ignitus) queens collected from 2000 to 2010 for conservation of native bumblebees for breeding. The average weight of 6,852 queens was 0.77 ± 0.44 g. The weight of B. ignitus queens collected in 2005 was the greatest, 0.87 ± 0.12 g, which was 1.0–1.3-fold heavier than any other year. The average oviposition rate was 81.6 ± 10.7%, and 2004 showed the highest rate, 95.0%. This value corresponded to 1.1-1.6-fold increases over the queens collected in the other years. The average rate of colony foundation was 60.9 ± 11.0%. Queens in 2008 exhibited the best performance, 75.4%, which was 1.0-1.9-fold higher than the other years. The rate of progeny-queen production averaged 27.0 ± 9.4% (Fig. 5) and peaked in 2001 at 43.2%; this value was 1.1–4.7-fold higher than other years. The average number of queens produced and number of generations begotten by queens was 27.6 ± 10.1% and 4.8 ± 2.0, respectively. Queens in 2000 averaged 9 generations of offspring, which was 1.1-3.1-fold greater than other years. These results indicate that the colony-developmental characteristics of the collected queens changed significantly between 2000 and 2010. In addition, there was no correlation between body weight and number of queens collected, although body weight was affected by collection year. Since 2008, the colony- developmental characteristics of queens have worsened.

Bumblebees are widely used to pollinate various crops, especially tomato, in greenhouses and fields. Here, we investigated whether different sugar solutions have any effects on the oviposition and colony development of Bombus terrestris queens. The types of sugar solution used were a white sugar solution, brown sugar solution, dark brown sugar solution, and prepared sugar solution; all solution contained with a 40% sugar concentration and 0.3% sorbic acid. Among these sugar solutions, B. terrestris queens reared on the white sugar solution exhibited the best results; the rates of oviposition, colony foundation and progeny-queen production were75.0± 11.0, 33.0 ± 9.6 and 21.7 ± 7.3, respectively, which corresponded to 1.1-33.0-fold increases over the results of other sugar solutions. Queens reared on the prepared sugar solution did not found any colonies. The death rate within one month was lowest for the queens reared on the white sugar solution at 26.1 ± 10.9%, which was 1.2–2.0-fold lower than the rate for the other sugar solutions. Furthermore, the numbers of progeny produced by queens reared on the white sugar solution, 131.4 ± 38.8 workers and 51.0 ± 40.6 queens, were also higher, corresponding to 1.1-1.2-fol d increases compared to queens raised on the other sugar solutions. Therefore, the white sugar solution was the favorable sugar solution for the egg-laying and colony developmental characteristics of B. terrestris queens.

Bumblebees are widely used to pollinate various crops, especially tomato, in greenhouses and fields. An artificial hibernation is essential for year-round rearing of the bumblebee that undergoes one generation per year. Here, we investigated whether a cold temperature and humidity affect artificial hibernation of the bumblebee queen Bombus terrestris. In cold temperature regimes of 0℃, 2.5℃, 5℃, 7.5℃ or 12.5℃ under a constant humidity 70% over, the queens stored at 2.5℃ was the best performance in survival rate, which was 74.0% in one month, 67.0% in two months, 60.0% in three months, 46.0% in 4 months, 33.0% in 5 months, and 24.0% in 6 months and lowed in the order of 0℃, 5℃, 7.5℃ and 12.5℃. And also, the colony developmental characteristics after diapause was 1.2-1.5 fold higher than those at queens stored at 5℃. In terms of cold humidity, the queens hibernated at 70% under 2.5℃ was the best performance in survival rate, which was 93.3±3.4% in one month, 83.3±0.0% in two months, 76.7±0.0% in 3 months and 36.7±12.1% in 5 months and lowed in the order of 50% and 90%. The rates of oviposition, colony foundation and progeny-queen production of queens hibernated at 70% were 80.8%, 30.8% and 30.8%, respectively. These values correspond to 1.7-3.3 fold that at queens stored at 50%. Therefore, 2.5℃ and 70% R.H. were the favorable cold temperature and humidity conditions for diapauses-break of B. terrestirs queen.

Bumblebees are widely used to pollinate crops in greenhouses and fields. Here, we investigated whether different wake-up treatments during a short period of 1-3 days just before indoor rearing has any effects on oviposition and colony development of CO2-treated Bombus ignitus queens and artificially hibernated B. terrestris queens The wake-up regimes were defined as 16L for 1 day (16L-1), 16L per day for 3 days (16L-3), 24L for 1 day (24L-1), or 24D for 1 day (24D-1). Among these wake-up treatments, the oviposition rate and preoviposition period of B. ignitus queens reared at 24L-1 were 16.7-25.1% higher and 1.0-3.5 days shorter than other wake-up treatments. B. terrestris queens reared at 24L-1 also showed the best results for egg-laying characteristics, which were 8.9-18.8% higher for oviposition and 0.6-3.5 days shorter for preovipostion period than other wake-up treatments. Furthermore, B. terrestris queens reared at 24L-1 were 17.5% and 13.8% higher in rate of colony foundation and queen production, respectively, than other wake-up treatments. These results show that the most favorable wake-up treatment just before rearing for egg-laying and colony developmental characteristics of B. ignitus and B. terrestris queens was 24L-1. Overall, our findings indicate that a wake-up treatment just before rearing was effective for colony initiation and colony development of bumblebee queens.

We investigated the mating age for sexual maturity and sperm quality of the bumblebee Bombus terrestris queens and males. In the mating age of sexual maturity of queen, mating rate was 6.7% at just emergence, 85.0% at 10 days of emergence, and decreased thereafter. In case of mating age of sexual maturity of male, mating rate was 38.3% at just emergence and 62.5% to 75.0% at 7 days to 20 days of emergence. The colony development at aging of B. terrestris queen and male was a similar tendency to the mating age of sexual maturity. In case of multiple mating, B. terrestris male was mated by 4 times, which was 74.3% for one time, 50.0% for two times, 22.9% for three times and 8.6% for four times. The number of spermatozoa was increased as the age of male was older until 25days after emergence. The number of spermatozoa of non-mated males of one day and 3 days after emergence was higher at 1.2 and 1.7 times than that of mated males and 18.9 and 36.6 times than that in spermatheca of mated queen. Our results indicate that period favorable for artificial insemination of B. terrestris was from 6 days after emergence for queen and 7 days after emergence for male.

We investigated mating conditions about care temperature of queen before mating, mating period, and number of queen per mating cage to improve mating rate of Bombus terrestris. Among 19℃, 22℃ and 25℃, care temperatures of queen before mating, queen cared at 19℃ was more effective than those at 22℃ and 25℃ in death rate during care and mating periods, and colony development. In case of mating period, oviposition rate and preoviposition periods at queen mated during 3 days were 89.3% and 11.4 days, respectively, which was higher and earlier than those of queen mated during 5 days and 7 days. The rate of worker emergence, colony foundation and progeny-queen production at 3 daysmated queen were also 2.0-11.6% higher than those at queen mated during 5 days and 7 days. In number of queen per mating cage, the rate of worker emergence, colony foundation and progeny-queen production queen mated at mating cage with 10 queens and 30 males were 41.5%, 25.9% and 23.2%, respectively. These values correspond to 1.5-6.8 folds those queen mated at cage with 20 queens and 30 queens. Therefore, we supposed that care temperature favorable for B. terrestris queen was 19℃ and the period need to mating was 3 days, and the number of queen per mating cage (55× 45× 65㎝) was 10.