Biology And Pollination Ecology Of Bombus Hypocrite Pérez(Hymenoptera, Apidae)

Bumblebee is a polyphagous social insect. It is an important pollinator for many entomophilous pollination plants, especially for Leguminosae, Solanaceae and endangerous plant pollination. Bumblebee and honeybee belong to the same family (Hymenoptera, Apidae), and both feed on neatar and pollen. However, Bumblebee has the advantage over honeybee with that it can pollinate flowers at lower temperature, lower light intensity, and higher humidity. More importantly, bumblebee can provide the buzz-pollination that is crucial for crops like tomatoes.In the end of 1980s, techiques for year-round rearing of bumblebee were successfully created, with which the use of bumblebee for greenhouse pollination comes true. In Europe Bombus terrestris has been imported by many countries for greenhouse crop pollination. It is an excellent pollinating species for many crops such as tomatoes, eggplants. Bumblebee pollination brings significant economic, social and ecological benefits.Bumblebee producers have developed their specific rearing systems, which are kept as primarily secrets. As a result, the cost to import bumblebee colonies for crop pollination is extremely high. What is more important is that the exotic species may lead to severe negative effects on native species. Therefore, the techniques for artificially rearing bumblebees and for their pollination application have been researched in China since the end of 1990s. Now, six species of bumblebees have been selected for pollination application from native species. B. hypocrita is one of the excellent species.In the present research, the distribution, morhpology, phylogeny, biology and pollination ecology of B. hypocrita were studied, with methods combing field survey, molecular biology, laboratory rearing, greenhouse experiments, etc.. The aim of the research was to provide a theoretical basis for protecting bumblebee resources as well as the application of bumblebee pollination. The main content and results are listed as follows.1. The distribution of B. hypocrita was studied by field survey, investigation on the specimens collected by Institute of Zoology, Chinese Academy of Sciences and on the data reported in references. The results showed that B. hypocrita belongs to the Oriental, Japanese, Palaearctic Regions species, distributed in China, Korea, Japan and Russia. In China, it was mainly distributed in the east of Tibetan Plateau, Northern China and Northeastern China, with elevation between 50 m to 3500 m above sea level, in which the elevation 1000 m to 2500 m above see level had more richful ditribution. B. hypocrita foraged on plants of 28 species, which were classified into 11 families, with preference on Composite, Rosaceae, Leguminosae and Labiatae family。2. The barcoding sequence of COI gene was used to analyse the phylogeny of 13 species bumblebees belonging to 9 subgenuses. The results showed that the sequence of COI gene can reflect evolution relations of species in the same subgenus. The subgenus of Bombus s. str is monophyletic, in which B. ignitus diverged earliest and B. hypocrita and B. patagiatus diverged latest.3. The annual activity of B. hypocrita in North China was studied by field survey. In the middle of March, queens emerge from their hibernacula and search for suitable nest sites. Once a suitable site is located, the queen constructs her brood nest and deposits eggs. The first worker emerges in the first ten-days period of May. The population of the colony reaches the peak in July, after which queens and males are produced. Young queens mate about one week after emergence. In the end of September and the first ten-days period of October, the colony dwindles and callapse; newly mated queens start to hibernate over the winter.4. The effects of different kinds of pollen on the development of B. hypocrita colonies were studied. The results showed that there was no significant difference on the effects of different kinds of pollen on the proportion of egg-laying queens, or on the timing of the first worker emergence. However, different pollen diets did have significantly different effects on the time that queens took to start to oviposit, the success rate for colony founding, and the number of young queens produced. All three diets consisted of apricot pollen were better than fresh rape pollen for colony initiation and queen production. Fresh and dried apricot pollen had similar effects on colony development rates, but fresh pollen was better for producing more young queens. Overall, the highest numbers of young queens were produced with the mixture of fresh apricot and rape pollens. Therefore, we recommended feeding queen bumble bees with fresh apricot pollen in the initial stage of colony founding and then changing diet to mixed pollen.5. The effect of the different diets on the reproductive success of B. hypocrita workers was investigated by feeding queenless micro-colonies workers with combination of sugar or honey with six kinds of pollen. The results showed that the workers just fed with sugar did not lay eggs and had significantly lower longevity. Feeding different kinds of pollen also caused significant difference on the longevity of workers. The longevity of workers fed on corn pollen was significantly lower than those of workers fed on other pollens. Feeding different kinds of pollen did not have significant difference on the effects on worker's pre-oviposition time and number of egg cups, but had significant difference on the effects on the numbers of eggs, larval ejection, duration of male development and the number of progeny. Among all the treatments, sucrose and apricot pollen treatment delivered the highest number of eggs, apricot and tea pollen treatments caused lower number of larval ejection, rape and apricot pollen treatments resulted in shorter male development time, and apricot pollen treatment contributed to higher number of progeny. It was concluded that the worker colony development was significant affected by different feeds. So, we should provide with different food for bumblebee colony at different development phases.6. The effects of four pesticides (Mosplian, Kingbo, Score and Lvrtong), applied commonly in greenhouses in China, on three bumblebee species (B. hypocrita, B. ignitus and B. patagiatus) were studied. The results showed that the mortality of B. hypocrita after contacting the four pesticides was significantly lower than that of B. patagiatus and B. ignitus, but there was no significant difference between the mortality of B. patagiatus and B. ignitus. The oral toxicity LD50 value of Mosplian to B. hypocrita (0.0028μg.a.i./bee) was significantly higher than that to B. ignitus (0.0023μg.a.i./bee) and B. patagiatus (0.0021μg.a.i./bee). As long as the three species were concerned, it can be concluded that B. hypocrita was least susceptible to the four pesticides. The mortality of each bumblebee species after contact with Mosplian was significantly higher than that for the other three pesticides and the control group. The mortality of bumblebee in Kingbo group was significantly higher than that of control group, but Score and Lvrtong exposed groups showed no significant increase in mortality when compared to the control group. It can therefore be concluded that the pesticides differ in their negative influences on bumblebees, and that Mosplian is the most harmful.7. Foraging activities of B. hypocrita and their influence factors were studied. The results showed that bumblebee foraging activity was lively during the all flowering period. The daily foraging activity of bumblebee appears two peaks. The first peak was at 9:30～11:00 and the second at 13:30～15:30. Foraging activities of B. hypocrita was negatively correlated with humidity and nectar concentration and positively with temperature, light intensity, nectar weight and pollen quantity. Only humidity, nectar weight and pollen quantity reached significant difference level. Multiple selection regression analysis revealed that humidity and pollen quantity were direct factors and others were indirect.8. Foraging behavior of B. hypocrita and Apis mellifera was significantly different. The foraging temperature of B. hypocrita was lower than that of A. mellifera. However, the foraging frequence of A. mellifera was faster than that of B. hypocrita. The amount of pollen grain on the stigma was significantly different among three pollination methods. The order of the amount of pollen grain was as follows:B. hypocrita> A. mellifera> manual pollintion. The pollen activity collected by B. hypocrita, A. mellifera and hand were 79.95%,53.25% and 33.30%, respectively. The activity of pollen collected by A. mellifera was higher than that collectey by B. hypocrita. The reason for this could be that honeybee was more advanced than bumblebee in the aspect of evolution thus was able to recognize pollen with higher activity.To sum up, a complete distribution map of B. hypocrita was drawn according to the data collected from field survey in the last 3 years, the analysis of the specimens stored in Institute of Zoology, Chinese Academy of Sciences and data reported in references. The geographical distribution, morhpology, distribution elevation, annual activity and kinds of foraging plant of B. hypocrita were also studied by field survey. The phylogeny of B. hypocrita was predicted by analysis on the sequence of COI gene, which showed the evolution position of B. hypocrita in Bombus s. str clearly. Moreover, the effects of diets on colony development and reproductive success of queenless workers were also studied, which provided important informations on artificial rearing of B. hypocrita in laboratory. At last, the sensitivity of B. hypocrite, B. patagiatus and B. pyrosoma to four pesticides commonly used in greenhouse was compared and the pollination ecology of B. hypocrita was studied. The results have provided a theoretical basis for protecting bumblebee resource and artificial pollination application.