In recent years, across the world, the number of honeybee colonies has decreased considerably. For example, in the UK, the honeybee population decreased between 15 and 30% between 2007 and 2009. In other countries the decrease has been even more dramatic.
This is of great concern to anyone responsible for producing food because honeybees, as well as wild bees, are essential for good pollination of many crop plants. Over the past few years a lot of money has been put into researching why bee numbers have fallen, because of the potentially disastrous effect that loss of bees may have on food production.
Many reasons have been put forward for the decrease, including infection particularly by varroa mite, poor weather in recent summers, and agricultural chemicals such as nicotine-based pesticides. Some scientists suggest climate change may be an underlying cause, but others blame the way we change the land when we use it to grow our food.
Carry out research to find the most likely cause or causes of bee decline. The following questions might help you find some of the answers.
1a What is Colony Collapse Disorder (CCD)? (1 mark) a phenomenon in which worker bees from a beehive colony abruptly disappear
b Is CCD the cause of all bee decline or is it not found in some countries? (2 marks) Most occurances are in European countries, however there are accounts of CCD in America so is possibly worldwide.
2a What is the varroa mite? (2 marks) Varroa destructor is an external parasitic mite that attacks honey bees giving them the disease varroatosis.
b How could the mite lead to CCD? (2 marks) It attaches to the body of the bee and weakens the bee by sucking hemolymph. It can give the bee such viruses as the diformed wing virus.
3 aWhat is the suggested link between nicotine-based pesticides and CCD? (2 marks) Sucking dew from maize leaves that absorbed neonicotinoids, disoriented bees can’t find their way to the apiary. Massive numbers of bees get lost and die.
b Do all countries use nicotine-based pesticides? If not, do bees in countries that don’t use these pesticides also suffer from CCD? (2 marks) No, and the countries that have stopped using nicotine based pesticides have seen an decrease in the number of bees that have gotten lost and CCD has gone down.
4a Are wild bees, such as bumble bees, showing the same changes in colony numbers as honeybees? (1 mark) Bumble Bees have also started declining in numbers, possibly suffering from the same colony collapse disorder as the honey bees.
b If so, what causes are suggested for their decline? (2 marks) Fungus or viral infections in the plants and surrounding environment could be a possible cause, as well as pesticides.
5a What is the suggested link between bee health and diversity of food plants? (2 marks) Because their habitats and food supplies are being destroyed by humans, bees are finding it hard to collect nectar and pollen which has led to a decline in the health of the hive.
b How could farming practices be causing a decline in bee numbers? (3 marks) Farmers are using pesticides that have infected flowers that bees pollinate and collect nectar from. A chemical company in Germany supplies a large proportion of the world’s farmers and agriculturalists with ‘neonics’ which are affecting the bees nervous system and damaging their homing abilities, meaning they cannot make it back to the hive. Genetically modified crops also contain pesticides in their genetic structure with will damage the bees immune systems further.
6 Is the evidence strong enough yet to suggest that diversity is the main cause of bee decline across the world? If so, list the evidence. If not, suggest why not. (2 marks) Although the diversity of food is a large factor, the use of pesticides in the bee’s natural habitat and food has a huge impact on their health and the health of their hive.