Insects that visit flowers are very important to plants. They are collecting food (nectar and pollen) for themselves, but while moving between flowers they carry pollen from one flower to another. This transfer of pollen is called pollination. It is essential for plant sexual reproduction.
Staple crops (e.g. cereals) that provide the vast majority of human foods are wind- or self-pollinated. However, at least one third of the total volume of global agricultural produce relies on insect pollination to some extent (Klein et al., 2007). Insect-pollinated crops include many fruits, nuts, seeds, beans, coffee and oilseed rape (canola) (Klein et al., 2007, Free, 1993). These provide vital nutrients (e.g. vitamins) and variety to human diets worldwide, while in some developing countries insect-pollinated crops provide crucial subsistence calories and nutrients to people (Eilers et al., 2011).
Insect pollination is also important to the reproduction and persistence of many wild plants (Ollerton et al.2011), which underpin a wider and more complex network of animal and plant life. Pollination is therefore an important process in maintaining healthy and biodiverse ecosystems.
The main groups of insects that visit flowers include honeybees, bumblebees, solitary bees, hoverflies, beetles, butterflies and moths. In some parts of the world, bats and birds are also important (Ollerton et al.2011).