Tropical forests and farmer based tree farms are notably dependent on fruit eating birds and mammals for dispersal of their seeds.

Agro forestry experts have already suggested that the spectacular evolutionary success of tropical flowering plants over the past millions of years can be attributed to their reliance on animals for pollination and seed dispersal, rather than the wind.

Seed dispersal by animals is advantageous in tropical habitats for a number of important reasons because it allows seeds and seedlings to escape from such natural enemies as invertebrate and vertebrate seed-eaters, herbivores and fungal pathogens.

Secondly it reduces the competition seedlings would experience if they germinated at high densities around the parent plant and finally widespread dispersal by creatures as mobile as birds and mammals allows plants to colonize new habitats.

One such mammal are bats which go consuming various fruit species and they keep dropping seed using their beak or through its faecal matter.

This is the reason as to why in the past years a number of fruits such as quava, pawpaw, mangos, Mustaferri including vegetables such as tomatoes where found grown in the wild for humans to harvest.

Background

Uganda is one of the few countries in Africa that has been experiencing outbreaks of viral hemorrhagic fevers such as Ebola, Marburg and Crimean-Congo Hemorrhagic fevers.

In 2017 Uganda experienced a Marburg Virus Disease (MVD) outbreak with case fatality rate of 100% in Kween district.

Although hunting for wild meat was linked to the MVD outbreak, less was reported on the land use changes, especially the changing animal grazing practices.

However scientists note that these are zoonotic diseases which occur both in human and animals with mammals such as bats being the source of transfers causing infection in both wild and domesticated animals.

It is a known fact that bats can have both benefits in the agricultural sector as well as disadvantage through harbouring diseases.

As such veterinary scientists at Queen Elizabeth National Park, Mweya safari science laboratory studying trends of bats species, their habitat and disease spread including their usefulness in seed spread interacted with Seeds of Gold during the annual biosafety Forum in Kampala recently and below are the details

Bat Habitat

Gloria Akurut a Laboratory technologist with Uganda Wildlife Authority at Mweya Diagnostics and Research Laboratory Queen Elizabeth National Park while presenting a paper about research work she has done with a team of Vet scientists concerning science of bats said, the mammals can be both a threat and a beneficiary to human and animal communities.

She contends that Bats play a vital role in ecosystems around the world. They are a diverse group of mammals accounting for over 20% of the world's mammals.

Bats are Idicator species because changes to bat populations can indicate changes in aspects of biodiversity.

A case in point is that bats might suffer when there are problems with insect populations because they bats feed on insects or when habitats are destroyed or poorly managed such as woodlands were they largely live.

Most bats in Uganda live in forests, caves and in homestead roofs in villages but those in game parks live mainly in caves and the thicket woodland.

Agricultural Benefits of bat

Akurut notes that there are a number of bat species in Uganda but the most prominent is the Egyptian fruit bat or Egyptian rousette (Rousettus aegyptiacus) a species of megabat that is found in Africa, the Middle East, the Mediterranean and the Indian subcontinent.

These bats are useful in the agricultural sector in that they spread seed mainly of fruits which they consume thereby contributing to the forest cover of the country.

She contends that there are farmers in various parts of the country whose small scale forests are boosted as a result of these bats spreading seed of trees from another part of the ecosystems in their village home owned forests.

Usually when such forest farms are not depleted by the owners, the level of afforestation is boosted because the bats will drop seeds of plants which will eventually germinate and grow naturally.

They also act as pest control because bats consume any type of insect such as grasshopper, beetles, Aphids, spider among others which can be disastrous to crops in farmer fields.

This means farmers growing crops such as maize, groundnuts, sorghum, simsim, rice and fruits such as mangos, guava, and others whose fruits attract insects can be protected against such destructive insects in the presence of bats.

Bats also act as tourist attraction because there are a number of external tourists who come to watch these bats especially those that are living in caves.

There are different cave spots identified by Akurut and her team where these bats live and the scientists have constructed glass barriers close to the caves for people who come to watch these bats to avoid direct contact with the mammals

Akurut says farmers growing crops or rearing animals to areas where these bats are in plenty can devise means of creating caves for them to dwell. Her team can come in handy to provide glass protection so such that the place becomes a tourist attraction for the farming community as income earning initiative.

Short-tailed Fruit Bat
There is also the short tailed fruit bats mainly found Cost Rica which is also believed to be available in African continent because they are fruit eating bats.

Scientists say their impact on the dynamics of tropical forests has been investigated only recently. The most intensive of these studies is one that several scientists conducted between 1974 and 1984 on the behavioral ecology in the tropical dry forest of Santa Rosa National Park, Costa Rica.

The studies indicates these bats play a major role in spread of seed in forests in the tropics contributing to tree growth in these forests.

Bats as source of disease spread

In addition to their important roles in many environments around the world, bats have also been recognized as hosts of some viruses that can impact human and animal health.

Akurut explains that these are called zoonotic diseases human diseases originating in animals.

The transmission of a virus or other vector of disease from wild animals to humans is normally the result of human alterations to the environment.

For example with bats, destroying their habitat by deforestation and intensive building and the intensification of livestock farming, can mean that bats are forced to live more closely to humans, livestock and pets than they would do naturally.

This closer contact can result in cases of spillover of a virus into human populations either directly or via an intermediate host which in this case is livestock.

The diseases Akurut and her team carried research on being harbored by Egyptian fruit bat species Murberg which is the commonest. These bat species are reservoir as such scientists advice humans not be close to them as well as avoid killing and consuming them.

Another disease is Kasokero virus which is present in these bats. This virus was isolated by scientists in 1997 at Kasekero cave located in Masaka.

The third virus is the sosuga virus is believed to be present in bats in various locations in Uganda. This virus was discovered after a wildlife biologist from UK came over to conduct research in Uganda and Sudan in 2012.

Upon return to his country she fell sick with symptoms of fever, malaise, headache, generalized myalgia and arthralgia, stiffness in the neck and sore throat. It was neither Marburg nor Ebola but identified to be a virus being harbored by Egyptian fruit bat.

The scientists contend that these virus are present in the bat species in Uganda which if transformed to humans and livestock will lead to serious fatality. 

The scientists advice humans to avoid consuming bats, live with them in same habitat as well as domesticated animals including consuming fruits bitten by bats.

It is not true that all bats act as reservoir of these viruses, there are some which may not harbor these viruses but no one can know unless the mammal is tested.