The Potential Risks To Chinese Bumblebees By The European Bumblebee Bombus Terrestris Study On Mating And Pollen Collecting

Bumblebees are very important pollinators for agricultural greenhouse crops.With the rapid development of Agriculture installation,European bumblebee Bombus terrestris was domesticated and commercialized for pollination services and exported in different parts of the world.However other than economic benefits,many reports indicated that this species has gained the status of biological invasion in many countries.China is the greatest hotspot of bumblebee diversity in the world,but the rearing of native bumblebees have been insufficient,and imported a large number of B.terrestris colonies recent two decades to meet the domestic pollination market demand.Although there is no report about the biological invasion of B.terrestris in our country at present,however,based on the reports from other countries,especially from neighboring countries,it is very important to evaluate the B.terrestris risk of biological invasion.In this study,the risk assessment of biological invasion caused by B.terrestris was carried out on the basis of aspects,1)mating disturbance and,2)pollen collection:(1)The similarity comparison of cephalic labial gland secretions from B.terrestris males and local Chinese bumblebees species.We compared the composition of male cephalic labial gland secretions between B.terrestris and nine native bumblebee species of China using gas chromatography quadrupole time of flight mass spectrometry(GC-Q-TOF/MS),and the data were analyzed by cluster analysis.The results showed the GC-MS chromatograms of male cephalic labial gland secretions are unanimous within the bumblebee species,however,there is a significant difference present between the different species.The composition of male cephalic labial gland secretions of both B.lantschouensis and B.ignitus were similar to that of B.terrestris with 49.23% and 58.49%,respectively.(2)The effect of male B.terrestris to the mating of B.lantschouensis.We studied the effect of male B.terrestris to the mating of the most important native bumblebee species under controlled environment.The mating of B.lantschouensis was set according to the ratio of 1:8 between the queen and males,on this basis,the male B.terrestris with the proportion of 1/4,1/2 and 1/1 of the male B.lantschouensis were respectively added.Statistical analysis was performed on to study the effect of male B.terrestris on the mating of B.lantschouensis.The results showed that the males of B.terrestris can mate with the queens of B.lantschouensis and significantly(P<0.01)decreased the mating success of the later.(3)Pollen collection comparison between the B.terrestris and native bumblebee species in China In this experiment,we placed the colonies of B.terrestris,without allowing the queens to exit and native bumblebee species,B.ignitus and B.lantschouensis within their natural distribution areas.We collected the pollens carried by the workers just before their entrance to their hives.For the identification of the pollens,meta-barcoding with adual-indexing approach was used.Our results showed that,on the basis of pollen types and pollen collection,there is 50 %-100 % overlap of pollen collection between B.terrestris and national bumblebees.It was also observed that the pollens which were visited by B.terrestris are most important food for the China's native bumblebee species.Finally,we conclude that the male cephalic labial gland secretions of both B.ignitus and B.lantschouensis were similar to that of B.terrestris.This means the male cephalic labial gland secretions of B.terrestris most likely contains the chemical composition that attracts the queens of B.ignitus or B.lantschouensis.Within artificial conditions it was proved that the B.terrestris males can hybridize with B.lantschouensis queens and the males of the former have ability to significantly reduce the success rate of the latter by disturbing the mating of native species.Similarly,in the same vegetation environment,B.terrestris and local bumblebee species,B.ignitus,B.lantschouensis and B.patagiatus also have a great overlap in pollen feeding.Once the B.terrestris become wild,they will compete for limited pollen plant resources in China,and thus native bumblebee resources pose a serious threat.These results indicate in China B.terrestris have the risk of biological invasion.We should strengthen the management of the use of B.terrestris for pollination of crops to prevent the B.terrestris from escaping the greenhouse to the nature.