Periodic Reporting for period 1 - CHOCOLATE4LIFE (Achieving sustainable agriculture in African cacao through DNA metabarcoding and food web models)
Période du rapport: 2019-08-01 au 2021-07-31
Cocoa, which fuels the multi-billion dollar chocolate market, is grown in tropical rainforest—mostly in Sub-Saharan Africa on small, family owned farms. African farmers, which produce about 70% of cocoa worldwide, typically cannot afford pesticides, so they rely nature for pest insect removal, but neither farmers nor scientists know which birds and bats provide this service. Shade trees also provide habitat for the African birds and bats that undoubtedly save farmers millions of dollars through pest control. Surprising little is known from a scientific perspective about how to manage African cocoa plantations—either for improvement of agricultural production or for the benefit of biodiversity. However, cutting edge new genetics techniques now allow us to sequence the bits of insect and plant DNA left in birds and bat faeces. We can then map thousands of species in the food web, which ultimately can help us predict how agricultural systems will respond to management. Further, exclusion experiments (ie., covering cocoa trees with bird/bat-proof netting) can help us quantify the value of the ecosystem services.
Ultimately, a high-resolution food web, along with exclusion experiments, will help us to understand the following:
1. Which birds and bats consume pest arthropods?
2. How much do birds and bats save farmers via ecosystem services?
3. What management scenarios benefit birds and bats?
4. And ultimately, what are win-win management scenarios that benefit BOTH African farmers and biodiversity?
With this novel framework, we seek to build towards a system in which African farmers benefit through inexpensive, sustainable management of cocoa, and rainforest animals benefit through the planting of trees that mimic their natural habitat.
Our exclusion experiment showed that relative to experimental trees with birds and bats excluded, control trees had 3.9 times more flowers and 3.2 times more large pods at high levels of shade cover (90%), whereas at low levels of shade cover (10%) trees had 5.2 times fewer Flowers and 3.7 times fewer large pods. This suggests not only that bats and birds consume large numbers of cocoa pests, but that the ecosystem services provided by birds and bats are even more important in full sun farms.
More generally, we conclude that cocoa, though diverse in birds and bats, is not suitable as an alternative to primary forest as it lacks forest specialists, insectivores and ant-following birds. Well-managed cocoa farms are diverse (higher gamma diversity than forest), and may be suitable as buffers of primary forest or corridors between patches.
Ultimately, a high-resolution food web, along with exclusion experiments, will help us to understand the following:
1. Which birds and bats consume pest arthropods?
2. How much do birds and bats save farmers via ecosystem services?
3. What management scenarios benefit birds and bats?
4. And ultimately, what are win-win management scenarios that benefit BOTH African farmers and biodiversity?
With this novel framework, we seek to build towards a system in which African farmers benefit through inexpensive, sustainable management of cocoa, and rainforest animals benefit through the planting of trees that mimic their natural habitat.
Our exclusion experiment showed that relative to experimental trees with birds and bats excluded, control trees had 3.9 times more flowers and 3.2 times more large pods at high levels of shade cover (90%), whereas at low levels of shade cover (10%) trees had 5.2 times fewer Flowers and 3.7 times fewer large pods. This suggests not only that bats and birds consume large numbers of cocoa pests, but that the ecosystem services provided by birds and bats are even more important in full sun farms.
More generally, we conclude that cocoa, though diverse in birds and bats, is not suitable as an alternative to primary forest as it lacks forest specialists, insectivores and ant-following birds. Well-managed cocoa farms are diverse (higher gamma diversity than forest), and may be suitable as buffers of primary forest or corridors between patches.
During the project period, we performed three five week field seasons in southern Cameroon. Our last field season was performed remotely during the COVID-19 pandemic: our team of young Cameroonian technicians performed an admirable job of collecting data entirely on their own: they sent the data and samples to us in the UK. We sampled 20 farms per field season. We had 3 previous field seasons' worth of data as well, which were performed prior to the grant period.
We totaled 1536 bat captures of 34 species, and 3750 bird captures of 146 species. We collected faeces samples from most birds and bats - more than 500 of which have been metabarcoded to date (with nearly 1000 more currently being prepped in the lab). We identified all shade trees on all our focal farms and measured % shade as well as understory vegetation. We worked with farmers to quantify yield on each farm, and we quantified pest insect abundance as well as the abundance of other arthropods. We also performed a year-long exclusion experiment on 8 farms (Ferreira et al. in prep.), during which we covered trees with netting to exclude them from consuming insects, and compared these results to control trees which were not covered.
Key Findings:
We found strong DNA evidence that 6 bat species and 11 bird species consume brown capsids: Africa's most destructive cocoa pest. Many secondary pests that we documented eating cocoa flowers, leaves or fruits are also consumed by both birds and bats (Ferreira et al. in prep).
We also found that at least three species of birds and bats consume Anopheles mosquitos--the vector for human malaria, which causes millions of mortalities and morbities annually each year.
In the final grant period, our year-long exclusion experiment showed that relative to experimental trees with bats excluded, control cocoa trees had 3.9 times more flowers and 3.2 times more large pods at high levels of shade cover (90%); with low shade cover (10%) cocoa trees had almost 5.2 times fewer Flowers and 3.7 times fewer large pods (Ferreira et al in prep).
Gamma diversity of birds was higher in cocoa than in forest; although alpha diversity was similar. However, cocoa forest had a marked loss of insectivores, forest specialists and forest specialists (Jarrett et al. 2021). Farms high shade cover in forested landscapes had higher relative abundance and richness of sensitive forest species; shady farms contained up to five times the proportion of forest specialists than sunny farms. Even the shadiest cocoa farms are not substitutes for primary forest, and therefore we argue that within a land-sharing scenario there must be areas of forest preserved on the landscape. To prevent extreme deforestation and biodiversity loss, policymakers should actively encourage ecologically sustainable agricultural practices such as shaded cocoa agroforestry that employs science-based management.
This project has produced a number of publications: published (3), accepted (1) in review (2), and in prep (7)
We totaled 1536 bat captures of 34 species, and 3750 bird captures of 146 species. We collected faeces samples from most birds and bats - more than 500 of which have been metabarcoded to date (with nearly 1000 more currently being prepped in the lab). We identified all shade trees on all our focal farms and measured % shade as well as understory vegetation. We worked with farmers to quantify yield on each farm, and we quantified pest insect abundance as well as the abundance of other arthropods. We also performed a year-long exclusion experiment on 8 farms (Ferreira et al. in prep.), during which we covered trees with netting to exclude them from consuming insects, and compared these results to control trees which were not covered.
Key Findings:
We found strong DNA evidence that 6 bat species and 11 bird species consume brown capsids: Africa's most destructive cocoa pest. Many secondary pests that we documented eating cocoa flowers, leaves or fruits are also consumed by both birds and bats (Ferreira et al. in prep).
We also found that at least three species of birds and bats consume Anopheles mosquitos--the vector for human malaria, which causes millions of mortalities and morbities annually each year.
In the final grant period, our year-long exclusion experiment showed that relative to experimental trees with bats excluded, control cocoa trees had 3.9 times more flowers and 3.2 times more large pods at high levels of shade cover (90%); with low shade cover (10%) cocoa trees had almost 5.2 times fewer Flowers and 3.7 times fewer large pods (Ferreira et al in prep).
Gamma diversity of birds was higher in cocoa than in forest; although alpha diversity was similar. However, cocoa forest had a marked loss of insectivores, forest specialists and forest specialists (Jarrett et al. 2021). Farms high shade cover in forested landscapes had higher relative abundance and richness of sensitive forest species; shady farms contained up to five times the proportion of forest specialists than sunny farms. Even the shadiest cocoa farms are not substitutes for primary forest, and therefore we argue that within a land-sharing scenario there must be areas of forest preserved on the landscape. To prevent extreme deforestation and biodiversity loss, policymakers should actively encourage ecologically sustainable agricultural practices such as shaded cocoa agroforestry that employs science-based management.
This project has produced a number of publications: published (3), accepted (1) in review (2), and in prep (7)
With support from the Waterloo foundation, we received a 3-year grant to perform workshops for Cameroonian cocoa farmers. To date, we have reached 18 villages and 405 farmers during these workshops. Our objective has been to provide information to farmers such that they can manage their farms in a sustainable, win-win fashion in order to balance income and biodiversity. We are also working with nurseries to grow beneficial shade trees for cocoa farmers, and to build bat boxes to attract pest-eating bats.
Our work on cocoa was featured in Ozy magazine, and we have disseminated our findings and photos in well over one hundred posts across Facebook, Instagram and Twitter.
The broader goal of the project is to create a novel framework for agriculture in which a deep, and high-resolution understanding of the ecosystem (food web), coupled with a dynamic integrated food web model can be used to manage ecosystems sustainably to balance biodiversity with farmer income.
Our work on cocoa was featured in Ozy magazine, and we have disseminated our findings and photos in well over one hundred posts across Facebook, Instagram and Twitter.
The broader goal of the project is to create a novel framework for agriculture in which a deep, and high-resolution understanding of the ecosystem (food web), coupled with a dynamic integrated food web model can be used to manage ecosystems sustainably to balance biodiversity with farmer income.