Low-temperature Biology And Pollination Value Evaluation Of Osmia Excavata Alfken

Osmia excavata Alfken belongs to the genus Osmia of the family Apoidea Megachilidae.O.excavata is a pollinating insect that has been rapidly promoted and applied in agricultural production in recent years,and plays an important pollination-increasing service function.In recent years,problems such as high population mortality and reduced pollination function have been gradually exposed in production.We focused on the low-temperature biological characteristics of O.excavata,in order to clarify the low-temperature adaptability and the effect of low-temperature storage on the population and pollination function of O.excavata,to provide a basis for scientific use of O.excavata.At the same time,we borrowed the latest evaluation methods of pollination function of pollinating insects,and evaluated the pollination value of O.excavata on apples,pears,cherries and rape by field test.The findings are as follows:1.Low-temperature biology research on O.excavata.The supercooling point,freezing point,changes in body substance,and protective enzyme activity were measured at different times in the post-diapause stage at room temperature.The results showed that there was not much difference in cold resistance between females and drones,and the supercooling point and freezing point in the postdiapause stage gradually increased before cocoon emergence and decreased after cocoon emergence.The super-cooling point and freezing point of females and drones of O.excavata were-12.35°C,-9.98°C,-12.63°C,-8.91°C in cocoon emergence,respectively.In the postdiapause stage,the fat content of the male was significantly higher than that of the female,and the protein content of the female was significantly higher than that of the female.After the cocoon emerged,the fat content of the male decreased rapidly,and the protein content of the female was rapidly decreased.Before cocoon emergence,the activities of superoxide dismutase,catalase,and acetylcholinesterase in male drones were higher than those in female bees.After cocoon emergence,the enzyme activity of female bees increased significantly.In the post-diapause stage,the trehalose in females and drones of O.excavata significantly decreased,and the trehalose content of the females on the cocoon emerged day decreased by64.5% compared with 190 days after cocoon.In short,O.excavata has strong cold resistancein the post-diapause stage.The cold resistance gradually decreases with time,and the cold resistance increases after cocoon emerges.Trehalose metabolism may be an important way of energy consumption in the post-diapause stage of O.excavata.There is a significant difference in the material changes and enzyme activities of female and drones in the postdiapause stage.The male individuals are small and have strong antioxidant systems,while females are large and have high protein content,indicating that there may be different low temperature adaptation strategies between the two.The body weight,mortality,flight behavior,changes in the body substance,and protective enzyme activity of O.excavata were measured under low temperature storage environment.In the process of low temperature storage,the weight,mortality and flight ability of O.excavata showed a gradual decline,which is basically divided into four stages.During storage,the water and protein content showed an upward trend,while the fat content first increased and then decreased,while the trehalose content kept decreasing;the activities of superoxide dismutase and catalase showed fluctuations over time.In short,as the storage time prolonged,the weight of O.excavata slowly decreased,and the mortality rate gradually increased.Although more than 70% of the individuals survived after 170 days of storage,their flight capacity decreased by more than 50% during the first month of storage.After two months of storage,its flight capability has decreased by more than 95%.It means that the pollination service function of O.excavata is greatly reduced after long-term storage,which is related to the consumption of energy metabolites such as trehalose.2.Observation of pollination behavior and evaluation of pollination value of O.excavata.The camera was used to record the visits and activities of O.excavata in the rape field.It was found that more than 60% of O.excavata came out of the nest from 7 to 8 am,and returned home from 16:30 to 17:30 pm every day.The average activity time after leaving the nest every day was 9.58 h,and the average time spent on visiting each flower was 10.89 s.The net cover method was used to determine the pollination effect of O.excavata on rapeseed,apple,pear and cherry.It was found that the fresh weight of rape weight,silique ratio,the grain number in rapeseed increased by 2.74%,4.81%,and 11.48%,respectively;The inflorescence fruit setting rate of apples,pears,and cherries increased by 9.55 times,12.58 times,and 6.87 times,and the flower fruit setting rates increased by 11.82 times,3.61 times,and 3.06 times,respectively.Using the bee dependence market valuation method to evaluate the potential pollination value of O.excavata for the above 4 crops in China,the results showed that the pollination function of rapeseed was about 3.733 million tons,and the total value of pollination service was about 19.421 billion yuan;The pollination functions ofapples,pears,and cherries were about 8.5 million tons,1 million tons,and 300,000 tons,respectively.The value of pollination services was about 60 billion yuan,5 billion yuan,and18 billion yuan.