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Toxic Nectar Affects Behaviour of Insect Pollinators

Toxic Nectar Affects Behaviour of Insect Pollinators

16 December 2014

UK - Natural toxins in nectar and pollen can poison insects and affect their memory, behaviour and reproductive success.

Toxins in lupin pollen cause bumble bees to produce fewer offspring while chemicals found in rhododendron nectar are toxic to honeybees but not bumble bees, toxic effects that could be contributing to the worrying decline in pollinator species.

Professor Phillip Stevenson from the Royal Botanic Gardens Kew and Natural Resources Institute at the University of Greenwich with colleagues from Trinity College Dublin studied the impact on bees of naturally-occurring toxins in lupin and rhododendron flowers.

Plants produce these chemicals in their leaves and stems as a defence against herbivorous insects such as aphids, but they can also accumulate in pollen and nectar and affect the behaviour of insect pollinators visiting the flowers.

In this study, bumble bees given pollen treated with lupanine, a chemical found in lupin plants, at natural concentrations produced fewer, smaller males.

The consequences could be severe where lupins are cultivated and present the major food source for bees at particular times of the year.

Other chemicals called diterpenoids, which are found in the nectar of Rhododendron ponticum, were found to be toxic to honeybees and a wild mining bee species (Andrena carantonica), but bumble bees (Bombus terrestris) were unharmed by the compounds.

Further Reading

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