| The honeybee is one of most important natural pollinators for crops.It can also provide humans with nutritious honeybee products.In recent years,the global beekeeping industry is facing many stresses,resulting in massive colony collapse.Previous evidence indicated that poor queens are one of the main factors for this massive colony collapse.Besides,queen quality is also the main factor for colony productivity.Therefore,improving the quality of queens is extremely important in beekeeping industry.This study developed a new queen-cell egg laying device based on the biological principles of honey bees.This device includes,we have designed and developed techniques and equipment for rearing high quality queens from honey bee queen platforms.The queen rearing equipment includes queen-cell ovipositor,queen excluder,ovipositor frame,queen cells,queen rearing frame,baffle and rotating queen rearing bars.Queens reared from this queen-cell egg laying device(QC),and the the control queens were reared from domestic queen rearing technology by using 2-day worker larvae(2WL).The newborn weight,morphological indexes,number of ovarioles and the expression of four key genes(Jhamt,Hex110,Defensin1 and CYP9Q1)of these two queen groups were measured and compared.Our results showed that the larval acceptance rate of QC decreased with the increase of their age,but significantly lower than that of 2WL.However,the newborn weight,front wing length and width of QC were significantly higher compared to the 2WL;The QC group had significantly more ovarioles from the right side of ovary than that of 2WL;the expressions of three key genes(Jhamt,Hex110 and Defensin1)were also higher in QC compared to 2WL.These findings revealed that the queen-cell egg laying technology can dramatically improve honeybee queen quality.Due to the low queen-cell acceptance rate in QC group,this study explored the egg-lay traits of honeybee queen in different shapes of plastic worker cells and queen cells.Four plastic frames with different shapes of worker cells(round,square,triangle and hexagon;diameter: 5.2 mm)were designed,and queens were caged on these frames for 24 hrs.The results showed that the hexagon cells had the higher egg-laying rate(59.9 ± 2.03%),followed by square(47.85% ± 4.79%),round(37.04 ± 7.23%)and triangle(9.24 ± 3.06%)cells.The survival rates of four groups were all quite low.In details,the hexagon cells had the highest rate at 11.5 ± 1.2%,which was significantly higher than the round(0.4 ± 0.1%;P < 0.05)and triangle(0%)cells but not differed with square cells(4.10 ± 0.8%;P ≥ 0.05).Caged queens on a plastic queen-cell frame to lay eggs for 24 hrs,and the eggs were placed into an incubator for 55-70 hrs.Afterward,the total RNA of each egg was extracted individually using an Omega RNA extract kit(R6734).Two primers of the male transcript and female transcript of the honeybee fem gene were designed.The expression of these male transcript and female transcript were tested using RT-q PCR.The results showed that 23.01 ± 4.55 eggs were collected from the queen-cell frames after egg-laying for 24 hrs,however,only 3.02 ±2.05% eggs were fertilized eggs which was significantly lower than the unfertilized eggs(96.97 ± 2.05%).These findings clearly demonstrated that honeybee queens have an ability of control in fertilized and unfertilized egg laying in a same type of cells.They laid only a low proportion of fertilized eggs in plastic queen cells.In summary,this study developed a queen-cell egg laying technology which could dramatically improve the quality of honeybee queens.However,the honeybee queen has an ability of control in fertilized and unfertilized egg laying in queen cells,leading to a low proportion of fertilized eggs in plastic queen cells.Further studies should focus on the improvement of the rate of fertilized egg in queen cells. |
