نتایج جستجو برای: bumblebees
تعداد نتایج: 906 فیلتر نتایج به سال:
The species diversity of bumblebees was investigated in two provinces, Tehran (Fasham, Zayegan) and Qazvin (Alamut, Wikan) in central Alborz during 2005-2006. Three casts of queen, worker and male bumblebees were collected during spring and summer in six dates in the two mentioned regions. Sampling of adult bees in Wikan was done from 26 July 2006 until 19 September 2006, and in Zayegan from 24...
In a recent opinion article in TREE, Ghazoul [1] questions the existence of a global pollinator crisis and, in doing so, raises some important points about the uncertainty of human dependence upon pollination services. We agree with Ghazoul [1] that much uncertainty remains regarding pollinator–pollination declines. However, we think that his assessment draws biased conclusions for pollinator d...
Frequency response characteristics of bumblebees to vertical visual oscillations were measured and analyzed. We measured the vertical force of the bees at four oscillation frequencies (0.9, 1.8, 3.6 and 7.4 Hz), and summarized their response characteristics in terms of amplitude and phase differences. The amplitude was almost constant throughout the examined frequency domain, whereas the phase ...
16 For central place foragers, such as bumblebees, it is essential to return reliably to their nest. Instead of 17 just flying away to forage, bumblebees, leaving their inconspicuous nest hole for the first time, need to 18 gather and learn sufficient information about the surroundings to allow them to return to the nest at the 19 end of their trip. Therefore, we assume an intrinsic learning pr...
Floral color changes and retention of old flowers are frequently combined phenomena restricted to the floral guide or single flowers in few-flowered inflorescences. They are thought to increase the attractiveness over long distances and to direct nearby pollinators toward the rewarding flowers. In Tibouchina pulchra, a massively flowering tree, the whole flower changes its color during anthesis...
Correction: Virus Infection of Plants Alters Pollinator Preference: A Payback for Susceptible Hosts?
Plant volatiles play important roles in attraction of certain pollinators and in host location by herbivorous insects. Virus infection induces changes in plant volatile emission profiles, and this can make plants more attractive to insect herbivores, such as aphids, that act as viral vectors. However, it is unknown if virus-induced alterations in volatile production affect plant-pollinator inte...
Electrophoretic analysis of extracts of 12 bumblebee species revealed complex patterns of extramitochondrial diphosphopyridine nucleotide-dependent glycerol 3-phosphate dehydrogenase (EC 1.1.1.8) variants. Most Bombus species show one pattern, while Bombus nevadensis has a second and Bombus occidentalis a third pattern. All three Psithyrus (i.e. parasitic bumblebee) species tested have a fourth...
15 There is considerable and ongoing debate as to the harm inflicted on bees by exposure to 16 agricultural pesticides. In part, the lack of consensus reflects a shortage of information on field17 realistic levels of exposure. Here, we quantify concentrations of neonicotinoid insecticides and 18 fungicides in the pollen of oilseed rape, and in pollen of wildflowers growing near arable fields. W...
Insect pollinators are essential for both the production of a large proportion of world crops and the health of natural ecosystems. As important pollinators, bumblebees must learn to forage on flowers to feed both themselves and provision their colonies.Increased use of pesticides has caused concern over sublethal effects on bees, such as impacts on reproduction or learning ability. However, li...
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