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Building Digital Education of Heirloom Crops

for the Resilience of African Food Systems in the Climate Crisis

Lecture 8

Protect Pollinators, Reduce Pesticides!

The importance of insects in nature and agriculture

 

Our planet is a complex ecosystem where every organism plays a specific role. Insects are one of the most diverse and significant animal groups on Earth. They participate in various natural processes, from plant pollination to nutrient recycling. However, the insect population has rapidly declined in recent years, causing serious consequences for both nature and humans.

Insects are an integral part of the natural food chain. They break down organic matter, improving soil fertility and providing nutrients for plants. Without insects, many plants would be unable to reproduce, as insects are the primary pollinators. Approximately 90% of flowering plants depend on insect pollination, and 75% of crop yields are directly linked to insect activity.

Reasons for the decline in insect populations

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The decline in insect populations is a multifactorial process. The main reasons are:

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  • Intensive agriculture: The widespread use of pesticides and herbicides in agriculture destroys insects and their habitats.

A study from 2019 (Sánchez-Bayo and Wyckhuys (2019) [1]) found that 40% of the world’s insect populations are on a path to extinction, and agricultural practices are implicated in almost half of these declines. ​

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  • Habitat loss: Deforestation, urbanization, and the expansion of agricultural land reduce natural habitats for insects.

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  • Alien insect species compete with native species for resources and spread diseases. Additionally, extreme weather events are disrupting insect life cycles and distribution.

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Consequences of the decline in insect populations​

The decline in insect populations has severe implications for ecosystems and humans:

  • Reduced plant diversity: Without insect pollination, many plants will not be able to reproduce, leading to a decline in plant diversity.

  • Reduced yields: A decrease in insect populations means reduced agricultural yields, which can lead to rising food prices.

  • Ecosystem imbalance: Insects are an essential link in the food chain, and their decline can lead to ecosystem imbalance.

  • Disruption of food webs: Insects are food for many birds, fish, and other animals, so their decline also affects other living organisms.

Look at the comparison between formerly and recently sampled samplings from f fall 2004 (10th–12th of October, 12.833 g/d ≙ 3275 insects) and for the same period in g fall 2019 (0.8533 g/d ≙ 195 insects),  illustrating the change in daily suction trap catches (3 days each) in Germany. Tim M. Ziesche et al. (2023) [3]

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What can we do?

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To reduce the decline in insect populations, joint efforts are needed:

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  • Support sustainable agriculture: Choose products produced using environmentally friendly methods.

  • Preserve natural habitats: Promote forest restoration, create more city green spaces, and reduce lawn mowing.

  • Limit pesticide use: Use alternative pest control methods, such as biological insecticides and natural predators.

  • Educate the public: Inform people about the importance of insects and ways to protect them.

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Agriculture pesticides – the impact on nature and health

 

Agriculture is simultaneously developing and driving itself into a dead end. The number of hectares of arable land is increasing, grain growers are experiencing record harvests, and various monoculture fields bloom magnificently in spring. However, the use of substances harmful to nature and human health in agriculture is also increasing. The volume of harvested crops and farmers' profits are growing, but this has consequences - narrow economic gains are being made at the expense of ecosystems. 

Not only nature suffers. In many rural areas, the living environment has also become dangerous for people - farmers use chemical pesticides in fields located in the immediate vicinity of residential houses, schools, and inhabited areas, and the legislation does not require them to at least warn the surrounding people about their activities. The first victims of these substances, often without even realizing it, are rural residents exposed to the so-called pesticide drift. Under wind and other conditions, harmful substances end up outside the farmers' fields - also in people's yards, homes, and organisms.

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Using pesticides puts pressure on the environment - it can threaten the quality of groundwater and surface water, soil quality, biodiversity, ecosystems, and human health by entering the food chain as residues. The active substances (AS) used to spray fields end up in the surrounding land and water (see Figure 1). AS affects plants and animals and can contribute to biodiversity loss, including the decline of insect populations. For example, the Intergovernmental Science-Policy Platform on Biodiversity and Ecosystem Services has recognized AS as one of the main drivers of the decline of pollinator populations.

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Studies about pesticide impact

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Europe has the strictest pesticide regulations in the world. However, even so: 

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  • Study No. 1 - In Germany, pesticide coverage was found throughout the territory - agricultural pesticides were found in the air in each of the 69 test areas, and in some cases, even more than 30 active substances. The distance from intensive agricultural fields did not significantly change the results. https://www.researchgate.net/publication/355143551_Pesticides_and_pesticide-related_products_in_ambient_air_in_Germany [4]

  • Study No. 2 - In France, more than 30 pregnant women's hair was searched for, and in 70% of cases, 28 different pesticides were found. Some of the pesticides were at extremely high concentrations. Researchers warn that pesticides in a mother's body can affect the newborn's health! https://www.sciencedirect.com/science/article/abs/pii/S1438463919304079 [5]

  • Study No. 3 - In Latvia, measurements of the presence of pesticides in bee hives continue, but it is already clear that at least 13 different pesticides are found even in hives located in the wildest areas. [6]

FAO data shows pesticide consumption in Latvia and Ghana (kg/ha) [7]

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Beware! Pesticides are formulated to kill living organisms. These poisons harm not only the target pests but also beneficial insects and other living beings. By using pesticides on your farm, you are putting your health and the health of your children at risk!

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Organic pest control – nature's balance in your garden

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Organic pest control is a sustainable and environmentally friendly way to protect plants from pests without using chemicals. This method relies on natural balances, promoting the activity of beneficial insects and microorganisms.

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Popular organic pest control methods:

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Monitoring and Early Detection

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  • Regular inspections: Conduct weekly or biweekly checks for signs of pests, such as damage to leaves, stems, or fruits.

  • Using magnifying glasses: Examine plants closely to identify pests and their eggs.

  • Keeping records: Maintain a garden journal to track pest activity and the effectiveness of control measures.

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Cultural Controls

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  • Sanitation: Remove and destroy infected plant parts to prevent pests from spreading.

  • Row covers: Use row covers to protect plants from flying pests like cabbage butterflies.

  • Mulching: Apply mulch around plants to retain moisture, suppress weeds, and create habitat for beneficial insects.

Biological controls

 

Organic farming often relies on natural enemies to control pests. Beneficial insects like parasitic wasps and predatory mites are introduced to prey upon harmful pests such as aphids, spider mites, and caterpillars. Additionally, microbiological insecticides made from naturally occurring microorganisms provide targeted pest control with minimal environmental impact.

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  • Beneficial nematodes: Introduce beneficial nematodes into the soil to control root-knot nematodes and other soil pests.

  • Bacillus thuringiensis (Bt): Apply Bt to control caterpillars and other insect larvae.

  • Ladybugs: Release ladybugs to feed on aphids and other soft-bodied insects.

Physical controls

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  • Handpicking: Manually remove pests and their eggs from plants.

  • Water sprays: Use strong water sprays to dislodge aphids and other pests.

  • Sticky traps: Hang sticky traps to capture flying pests like whiteflies and fruit flies.

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Plant extracts and repellents

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  • There are plenty of tropical plants that have pesticidal impact: The application of six established pesticidal plants (Bidens pilosa, Lantana camara, Lippia javanica, Tephrosia vogelii, Tithonia diversifolia, and Vernonia amygdalina) were compared to positive and negative controls for their impact on yields of bean (Phaseolus vulgaris), cowpea (Vigna unguiculata), and pigeon pea (Cajanus cajan) crops and the abundance of key indicator pest and predatory arthropod species. Analysis of field trials showed that pesticidal plant treatments often resulted in crop yields that were comparable to the use of a synthetic pesticide (lambda-cyhalothrin). The best-performing plant species were T. vogelii, T. diversifolia, and L. javanica. [8]

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  • Neem oil or neem leaf powder: A natural insecticide derived from neem tree seeds or leaves that is effective against various pests.

  • Garlic and onion sprays: Repellent to many pests, including aphids and flea beetles.

  • Companion plants: Interplant aromatic herbs like basil, thyme, and marigolds to deter pests.

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Crop rotation and diversification

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  • Crop rotation: Rotate crops annually to disrupt pest life cycles and reduce populations.

  • Diversified planting: Plant various crops to create a less hospitable environment for pests.

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Remember:

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Organic pest control often requires patience and persistence. It may take time to see results, but the long-term benefits to your garden and the environment are significant. Combining various methods and monitoring your garden regularly allows you to effectively manage pests without using harmful chemicals.​

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Recap

 

​Farmers play a crucial role in supporting insect populations by making conscious choices that protect ecosystems. By reducing or eliminating the use of harmful pesticides and adopting organic pest control methods, farmers can create environments where insects, especially pollinators, can thrive. This shift not only benefits nature but also enhances soil health, plant diversity, and agricultural yields. By minimizing exposure to harmful pesticides, farmers reduce the risk of pesticide-related health issues, creating a safer environment for themselves, their children, and their communities. Sustainable practices such as crop rotation, biological controls, and natural habitat preservation are essential for safeguarding insect populations, which are vital to the ecosystem.

Farmers, by embracing these alternatives, can actively contribute to reversing insect decline and fostering a healthier, more balanced environment.

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References

[1] - Sánchez-Bayo, Francisco and  Wyckhuys Kris A.G. (2019), “Worldwide decline of the entomofauna: A review of its drivers,” Biological Conservation, 2019, 232:8-27. DOI: 10.1016/j.biocon.2019.01.020.

[2] - Dirzo (2014), Defaunation in the Anthropocene, Science 25 Jul 2014, Vol 345, Issue 6195

. http://science.sciencemag.org/content/345/6195/401/

[3] - Tim M. Ziesche et al. (2023) Ziesche, T.M., Ordon, F., Schliephake, E. et al. Long-term data in agricultural landscapes indicate that insect decline promotes pests well adapted to environmental changes. J Pest Sci 97, 1281–1297 (2024). https://doi.org/10.1007/s10340-023-01698-2

[4] - Kruse-Plass et al. (2021) Kruse-Plass, Maren & Hofmann, Frieder & Wosniok, Werner & Schlechtriemen, Ulrich & Kohlschütter, Niels. Pesticides and pesticide-related products in ambient air in Germany. Environmental Sciences Europe. 33. 10.1186/s12302-021-00553-4. https://www.researchgate.net/publication/355143551_Pesticides_and_pesticide-related_products_in_ambient_air_in_Germany 

[5] - Rémi Béranger et al. (2020) Rémi Béranger, Emilie M. Hardy, Anne-Claire Binter, Marie-Aline Charles, Cécile Zaros, Brice M.R. Appenzeller, Cécile Chevrier, Multiple pesticides in mothers' hair samples and children's measurements at birth: Results from the French national birth cohort (ELFE), International Journal of Hygiene and Environmental Health, Volume 223, Issue 1, 2020, Pages 22-33, ISSN 1438-4639, https://doi.org/10.1016/j.ijheh.2019.10.010. 

https://www.sciencedirect.com/science/article/abs/pii/S1438463919304079

​[6] - Insignia (2024) Environmental monitoring of pesticide use through honey bees (ret PP-1-1-2018) with the acronym INSIGNIA-bee

https://www.insignia-bee.eu/publications/

[7] - FAO data shows pesticide consumption in Latvia and Ghana (kg/ha).[7]

[8] - Yolice Tembo (2020), Yolice Tembo,Angela G. Mkindi,Prisila A. Mkenda,Nelson Mpumi,Regina Mwanauta,Philip C. Stevenson,Patrick A. Ndakidemi,Steven R. Belmain, Pesticidal Plant Extracts Improve Yield and Reduce Insect Pests on Legume Crops Without Harming Beneficial Arthropods, Front. Plant Sci., 28 September 2018, Sec. Plant Metabolism and Chemodiversity, Volume 9 - 201,  https://doi.org/10.3389/fpls.2018.01425

https://www.frontiersin.org/journals/plant-science/articles/10.3389/fpls.2018.01425/full

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The content of this page was created as part of the project 'Building Digital Education of Indigenous Inherited Crops for the Resilience of African Food Systems in the Climate Crisis Development.' The project was funded by the Ministry of Foreign Affairs in 2024 from the development cooperation budget. This content reflects only the views of the project partners.

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