Mutualism: eight examples of species working together to get ahead
The eggs, larvae and beeswax contained in honeycombs are an essential food source for large honey guides (indicator indicator). One of the ways these birds gain easy access to a nutritious meal is by leading other honey-hungry species to the nest and allowing them to do the hard work of breaking in.
The human-honey guide relationship is the best documented of these partnerships. Wild Honey Guides recruit people with a demanding call, indicating that they have found a honeycomb. Honey-hunting humans respond with calls passed down from generation to generation and follow the bird.
When they reach the nest, humans overpower the bees, for example with smoke, enter the nest and help themselves to the sugar-rich honey it contains. The Hadza people of Tanzania are a group known for working with honey guides. It was estimated that up to 10% of their diet is acquired with the help of birds.
After the bees are dispatched and the humans are satisfied, the honey guides must feed on the beeswax, eggs, and larvae left behind.
8. The senita cactus and the senita moth
As the sun sets over the Sonoran Desert in North America, the nocturnal blooms of senita cacti (Lophocereus schottii) are visited by tiny senita butterflies (Upiga virescens).
Female butterflies collect pollen on specialized abdominal scales and transfer it from flower to flower, pollinating cacti as they go. The senita butterfly is the sole nocturnal pollinator of this cactus and is responsible for 75-95% of its pollination. The rest is attributed to other insects that are active during the day.
During her visits, the female butterfly will lay an egg on a flower petal. When the flower closes and the larva hatches, it will burrow into the top of the developing fruit, spending about six days feeding on the seeds and tissues of the fruit.
The moth larvae do not eat all the seeds or all the fruit – they have been found to only destroy around 21% of the developing fruit, meaning the cactus can continue to thrive.
There are several similar mutualistic relationships, such as yuccas and yucca moths, figs and fig wasps, and Phyllanthaceae and epicephalic night butterflies. Senita butterflies differ from these in that although the relationship is highly specialized, they are not the sole pollinator of their host plant, but their relationship to the cactus clearly plays an important role in the survival of the cactus.