What do bees see? Developing urban gardens to attract pollinators

  • Complex flowers attract more bees. The diversity of flower species and its density play a role in attracting bees.
  • Studies on the economic value of pollinators have shown that bees and other insects make a significant economic contribution with their pollination services.
  • There are many ways to support pollinators, from pollinator-friendly urban gardens to roadside gardens with appropriate plants and trees.

The mid-morning mood in the wild terrain next to my house is consumed by the ecstatic buzz of many busy bees. And as news of their staggering contribution to global economies rolls in steadily, I wandered around and wondered what exactly the bees saw in this garden and others like it, or what they preferred to see.

General observations indicate that the eyes of bees are more sensitive to ultraviolet light and that they prefer blue and purple flowers. And while it’s possible that bees’ vision evolved to accommodate flowers, it’s more likely that flowers evolved to attract pollinating insects. Flowers often describe ‘landing zones‘, pointing the bees to the part of the plant containing the nectar and pollen.

Mahua Ghara, whose extensive research into floral color evolution and fig-wasp mutualism has yielded some fascinating insights, says, “It is true that bees love blue flowers and can also see in the ultraviolet range. But bees rely on a combination of signals that include color, scent, shape, size, etc. to find pollen or nectar. Thus, if a bee finds a rewarding flower, it will tend to visit the flower regardless of its color.

Complex flowers attract more bees and both species diversity and density matter, confirms Parthib Basu, Director of the Center for Pollination Studies and Associate Professor, Ecology Research Unit, Department of Zoology and Center of Modern Biology, University of Calcutta. “In our studies of pollinators in semi-natural habitats of agricultural landscapes in the tropics (S. Laha et al, 2020), we found that bees look not only at color but also at structure. An ideal seed mix for creating flower strips could include the Fabaceae and Lamiaceae families, essentially a high diversity of plant species with synchronous flowering,” he says.

Most of our food crops are highly dependent on pollinators, making them an indispensable part of the agricultural industry. Photo by Nikhilmore/Wikimedia Commons.

In 2011, Basu’s team assessed pollinator-dependent vegetable production in India using FAO data over 45 years (1963-2008), the first-ever such assessment for a country. The crop pollination dependence (DI) index was considered when analyzing pollinator limitation (decrease in relative yield growth rate) and pollinator dependence (increase in crop area). pollinator-dependent crops). The economic value was found to be $3,720 million. The total EVIP (Economic Valuation of Insect Pollination) of the six most commonly grown pollinator dependent crop species in India has been calculated at $726 million. The EVIP for vegetables with moderate to high DI (0.25 – 0.95), for example (brinjal, cucumbers, pumpkins, squash and squash) accounts for more than 80%, which proves the extreme level of socio-dependency – economics of Indian agricultural systems vis-à-vis pollination.

According to a 2017 study published by the Indian Journal of Agricultural Sciences (OP Chaudhary et al), the direct contribution of insect pollination to Indian agriculture is estimated at Rs. dollars) per year.

Another related study aimed at improving the stability of pollinator populations suggests that Rattlesnake pallidaand Ocimum basilicum would be the recommended species and for populations of natural enemies, Senna alata would be the recommendation. These species mixes can be used for on-farm or off-farm planting to maximize pollination or pest regulation (Laha et al, 2022). Selecting seed mixes that support pollinators throughout the year will be appropriate.

Attracting pollinators to urban gardens

Poorva Lalbhai runs an Instagram page called Bees in my garden. His date with the bees began when pandemic concerns and lockdowns surfaced. “As an average urban resident is paranoid about bees and wasps, so am I. The general perception is that it will sting….stay away! After initially observing them, I moved on to monitoring and documenting the mind-boggling diversity of native bees and other pollinators that visit my garden – those who are part of hives or solitary, and why they do what they do” , she says.

In urban gardens, Lalbhai says she feels “the initial use of a term like ‘butterfly friend’ may get more people excited because they are beautiful, stingless and harmless. It is important to choose an appropriate and robust combination of trees/grasses/shrubs that attract a variety of pollinators, even sensitively chosen potted plants. I found that even common trees like karanj (pinnate pongamia), kashnar (Bauhinia variegata), Amaltas (Cassia fistula), moringa (Moringa oleifera), jamun (Syzygium cumini) and kadipatta (Murraya koenigii) are highly valued by pollinators.

Basu adds, “Pollinator-friendly urban gardens can form extended safety nets for these beneficial insects. Appropriate plant species can be identified and made accessible. Nurseries selling wildflower seeds, etc. are more accessible abroad. In developing tropical countries like ours, even basic information for informed decision-making is sadly lacking.

The image shows a bee feeding on a yellow flower
Pollinator-friendly gardens that are free of pesticides and away from busy roads and glass buildings can be extremely helpful in keeping bees thriving in urban areas. Photo by Bhaskar/Wikimedia Commons.

In some countries it is common to have roadside shoulders that support bees. This could serve as inspiration for India where multitudes of road medians could be consciously filled with pollinator-friendly plants and avenue tree species could be similarly selected to support the bees that need tree branches or hollow stems, recommends Ghara. Nest boxes or bee hotels can be kept in the garden. If the soil is free of chemicals, ground-nesting bees can also thrive. But bees are just one of the pollinators, and domesticated honey bees seem to be attracting attention. There are also a large number of interesting but understudied wild bees. Another important group of pollinators are flies like hoverflies, an unknown pollinator in our gardens, says Ghara.

Dave Goulson, professor of biology at the University of Sussex and popular author of several books, including Bumblebees: their behavior and ecology (2003), Silent Earth: Avoiding insect apocalypses (2021) and The Garden Jungle (2019) has often said that the simplest thing most people can do “is to plant a few bee-friendly flowers in their garden. Also, don’t use insecticides (they really aren’t needed in a garden – what’s the worst thing that can happen without them – a few aphids on the roses?). If possible, leave a corner of the garden for the grass to grow for a long time.

“Encouraging urban wildlife is both a way to tackle the biodiversity crisis and an opportunity to engage people with nature. There is no significant downside, and there is ample evidence that we healthier and happier if we can see green leaves, hear the sound of birds, bees, etc.,” he says. “Gardens can also be a place to grow food, and then we need pollinators to get good crops.Even a few weeds in a planter are better than none – and bees are remarkably good at sniffing them out when they bloom.

Read more: No honey, no hives, but solitary bees have important lives

Banner image: Bees use both UV and radiant light to navigate and find nectar-rich flowers with their compound eyes. Photo by Rajesh Rane/Wikimedia Commons.