Scientific evidence for the benefits of using Mee tree in
cultivations
The chemical composition and properties of the essential oil extract of
the Mee tree were studied and it was found to have high levels of
Farnesol and its’ analog, Farnesene. Farnesol is considered to act as a
pheromone for several insects and as a pesticide for mites. It also has
antimicrobial action against certain bacteria and fungi (Suryawanshi and
Mokat, 2019) .
Even though there is a scarcity of documented evidence for the use of
bat guano in Sri Lanka, there is plenty of documented evidence from
world history to understand the importance of bat guano use in
cultivation by ancient farmers. Andean people from the small islands of
Peru have used bat guano as a soil amendment as far as 1500 years ago
(Cushman and Guano, 2013). In Tanzania, the Kisarawe caves are said to
harbour three million bats producing one ton of guano per day (Juma,
2001). There are reports that over 3000 tons of bat guano were obtained
from these caves between 1934 and 1954 for agricultural use, especially
for farms near the areas of the cave of Sukumawera in Mbeya, South
Tanzania (Nilsen, 1980).
When considering the chemical composition of guano of insectivorous
bats, one study has shown that on average, oxygen was the most abundant
element (54.94%). This helps to increase the soil bacteria and other
helminths which enrich the soil structure. Additionally, macro-nutrients
such as nitrogen, phosphorus, potassium, calcium, magnesium and sulphur
were also abundant in the guano (Misra, Gautam and Elangovan, 2019). As
mentioned above, when a food chain developed around these trees,
eventually bat and bird guano dropped to the paddy field. The average
composition in the fresh guano of insectivorous bat and birds are around
50% carbon, 10% nitrogen, 2–7 % phosphorus pentoxide
(P2O5) with sulphur abundances of
10–20% (Shahack-Gross et al., 2004; Forbes et al., 2007). These key
elements nourished the ancient paddy fields and farmers managed to
control their cultivation in an eco-friendly manner. The incorporation
of bat guano into the soil enhances crop production and studies have
thus emphasized the importance of conservation of insectivorous bats and
their guano(Sridhar et al., 2006).
Remnants of insects including agricultural pests belonging to the orders
Coleoptera, Lepidoptera, Homoptera and Hemiptera were found in the
faecal matter of insectivorous bats in a study done in India (Misra,
Gautam and Elangovan, 2019) . There is a lack of published data except
for the indigenous knowledge of local farmers that bat pest control
contributed to the food security in Sri Lanka. However, there are plenty
of published data to provide evidence that both bats and birds increased
the yield of the crops. Indonesian cacao plantations produced increased
yield when the herbivorous insect population reduced with natural pest
control(Maas, Clough and Tscharntke, 2013). According to published data,
cotton yield worth USD 741,000 was protected annually in the United
States by bats feeding on cotton bollworms (Cleveland et al., 2006). It
has been shown that an estimated USD 3.7 billion worth of cotton harvest
was saved annually across the US by bat populations. A study conducted
in Thailand has shown that bats protects rice worth more than USD 1.2
million annually (Wanger et al., 2014). The same study highlighted that
the bats also feed on other major rice pests in Asia such as the brown
planthopper (Nilaparvata lugens- - Dumburu Pela Keedawa) and the
White-Backed Planthopper (WBP). The bats not only feed on adult male and
winged female White-Backed Planthoppers but also consume pregnant WBPs
which prevents future offsprings from hatching(Wanger et al., 2014). The
western world has understood the value of these bats and has taken steps
to attract bats to their farmlands. For example, in California, USA,
farmers have installed resting boxes for bats within their farmlands to
help control agricultural pests(Tuttle, Kiser and Kiser, 2005).