More than a thousand varieties of mangoes exist in India, the popular ones being Banganapalli, Dassheri, Alphonso, Badaami, Imaam Pasandh, and Mulgoa. There is even a “Lalbagh” variety in Bengaluru. Many of us associate the fruit with a summer childhood memory, of eating it with our bare hands, the mango juice dripping on our clothes.
More recently, the fruit has become popular on social media platforms, where users explain hundreds of ways to cook and eat it. This year, the fruit’s popularity reached a new height: the red carpet at the Met Gala in New York. Mangoes and Indian summers go hand-in-hand, yet do you know how this fruit comes to be?
In other words, the mango tree gives out flowers… and then what happens?
Making a mango
Between December and March every year, mango trees across the country bloom and issue a sweet yet slightly fermented odour. Look closer at a mango tree in this time and you will find a branch with several bouquets of small, cream-coloured flowers. Each branch, which botanists call a panicle, contains a few hundred to up to 10,000 individual flowers. And a single mango tree can carry up to some 3,000 panicles, depending on its size and branching.
Each one of these flowers is the start of a mango in the making. Some flowers carry only the male parts while others only the female parts, and sometimes there can be flowers with both (which are biologically called hermaphrodites). Regardless, for the mango to form, pollen must travel between these flowers.
A colony of bees is seen at a hive in the backyard of University of Maryland bee researcher Nathalie Steinhauer, June 21, 2023.
| Photo Credit:
AP
This is where pollinators make their mark. There is a curious history here. Mango cultivars had once insisted that mango flowers are pollinated only by wind. But this theory could not explain why the flowers issued a sweet odour. It had to be to attract insects.
To confirm that insects were indeed pollinators, researchers in Bengaluru teamed up with their peers from Germany to survey several Badami mango farms in the city’s urban and rural areas. Their findings, published in 2023, were striking: when flying insects were excluded from visiting the flowers, the mango yield dropped as much as 350% compared to when flowers were left open to all visitors.
These flying insects were found to include wild bees such as the dwarf honey bee (Apis florea), giant honey bee (Apis dorsata), and stingless bees (Tetragonula sp.). Other important flying visitors included hoverflies, which look like bees (Syrphus sp.), the common house fly (Musca domestica), and the blow fly (Calliphoridae family).
Effective pollination
The researchers also observed that the mango yields dropped when they barred crawling insects, such as ants, from the flowers. Soubadra Devy, a senior researcher at the Ashoka Trust for Research in Ecology and the Environment, Bengaluru, and an author of the study, said ants are “messy pollinators” and that it is essential to investigate them as pollinators of mango in future studies.
Dr. Devy also said she anticipates that the pollinator community is not any different for other Indian mango varieties since the “floral traits, i.e. the flower structure, pollen, and nectar are likely to be very similar”.
A bee is covered with pollen as it approaches a dandelion blossom on a lawn in Klosterneuburg April 29, 2013.
| Photo Credit:
Reuters
Researchers have conducted similar studies in Mexico, on the ‘Ataulfo’ mango, and in Australia, on the ‘Kensington Pride’ variety — and have revealed similar findings. Both teams also took more steps to determine which insects were the pollinators. They calculated a ‘pollination effectiveness’ metric based on the abundance of pollinators, the number of visits to flowers (with a ‘legitimate’ visits quantified using video cameras on trees), and the number of pollen grains deposited. And both studies showed that wild and native insects were most efficient at pollination, producing a higher yield of fruits.
Non-native bees to Mexico, such as European honey bees (Apis mellifera), were abundant and contributed to 80% of the pollination. Paradoxically, however, that did not result in a higher yield. The reason was that these non-native bees stayed around the same trees or in the same orchard and delivered the wrong pollen, resulting in malformed fruits. On the other hand, the native bees transferred pollen between orchards, giving rise to more full and juicy fruits.
Farmers’ friends
Yet these native bees are under threat from the same insecticides that protect the mango crop from pests. Neonicotinoid insecticides, which are commonly sprayed on mango trees, are neurotoxic and affect cognitive functions in bees, such as navigation, learning, and memory, and eventually their survival. This ripples through the entire colony, as the insecticides travel to the pollen and nectar and are brought back to the hive by bees.
The Bengaluru-based study observed that fewer bees visited the mango flowers, and the harvested fruits were lighter by almost 30%, resulting in a three-way loss for the farmer: expensive pesticides, loss of pollinators, and a loss in the fruit yield.
Dr. Devy said monoculture farms that prevail in rural areas are more prone to pest attacks, and hence suffer higher pollinator loss as well. However, she also said she sees hope in bee-safe pesticides and in farmers timing their sprays to avoid peak pollinator activity — practices already in use in several western countries.
Display of mangoes in Srirangam for the summer season in Tiruchi, Tamil Nadu, on April 29, 2018.
| Photo Credit:
Srinath M./The Hindu
“One recent welcome move”, in her words, was the Indian government recognising pollinators in the country’s new ‘environmental accounting’ framework. This framework recognised that India has more than 800 bee species, plus butterflies, moths, beetles, birds, bats and flies as pollinators and that they are ecologically important for agriculture. The government has also attached a monetary value equivalent to 8-10% of the total crop output value, amounting to ₹2.6 lakh crore in 2021-22, to pollinators.
Rights of pollinators
Attaching a monetary value could nudge policy towards actively protecting our pollinators, through changes at the farm and landscape levels. These could include, as the Mexico study suggested, increasing the spread of natural and semi-natural areas near orchards, such as native forest patches and wildflower strips, to attract more wild insects.
Dr. Devy also pointed out that in May, stingless bees in Peru had become the first insects to win the legal rights to exist, thrive, and be represented in court. This is significant for the conservation of the species against insecticides, climate change, and competition from non-native insects.
The question then arises: will India accord similar rights to its pollinators, which carry the weight of the country’s agriculture? As you relish this season’s mangoes, it could also be your food for thought.
Kavitha Kannan is a biologist and science writer.
