Chapter 7.20
7.20 -Insect nets to protect crops of smallholder farmers
Lauren Curry, University of Guelph, Canada
Suggested citation for this chapter.
Curry,l. (2022) Insect nets to protect crops of smallholder farmers, The Encyclopedia for Small Scale Farmers. Editor, M.N. Raizada, University of Guelph, Canada. http://www.farmpedia.org
Introduction to Insect Nets
For many farmers, fruits and vegetables are important commodities that face many challenges during production. Insect pests and fluctuating weather trends are main contributors to low yielding crops, as well as low quality crops for many smallholder farmers (Subramanian, 2018). Insect pests either directly damage crops or indirectly damage through the spread of microbial disease (Subramanian, 2018). To combat this issue, insect nets provide a practical solution to protect crops from insects. Insect nets can be applied to leafy vegetables to exclude insects like moths, thrips, flies, aphids, and whiteflies that harm crop production (Grasswitz, 2019).
Types of Insect Nets
Insect nets serve various purposes for farmers. Most primarily focus on pest exclusion but can also affect microclimate modification, and protection from different environmental conditions (Subramanian, 2018). Most nets work by creating physical exclusion from pests by changing the size of the fibres and pores within the mesh net to prevent specific insects from getting through (Giannoulis et al., 2021). The pores and fibres are picked for the specific size of pest the farmer wishes to exclude from their crops (Giannoulis et al., 2021).
Photoselective nets are another type of insect netting. These work by selectively filtering light wavelengths to influence plant growth by changing the amount of shade plants get, and by discouraging certain pests from finding crops (Giannoulis et al., 2021). The yellow and pearl coloured nets are proven to be the most effective in preventing insects from harming plants compared to black and white nets (Lyu, 2023). With crops being harmed more by extreme weather conditions due to climate change than ever before, insect nets have qualities that can also protect crops from extreme weather conditions such as hail, wind, frost, and heavy rainfall (Giannoulis et al., 2021).
For smallholder farmers, insect nets are most effective at the seedling stages in nurseries which require less netting and thus reduced cost but can also be used for crop production (Martin et al., 2015). There are many structures that are required for insect nets to be stationed over crops. For smallholder farmers, there are two main structures that are most beneficial for nurseries:
The first insect netting structure is called a small net box (Figure 1) (Link, 2014). It can also be called floating row covers. These nets are particularly beneficial for protecting seedlings and are set up soon after planting seeds, as they provide warmth for quicker seed sprouting and prevent soil from compacting on plants after heavy rainfall (Lyu, 2023). This structure requires posts at each corner of the row of crops, and supportive posts in the middle (Link, 2014) (see Figure 1). Tension wire is then placed over the posts, and the insect netting is then draped over the posts (Link, 2014). The ends of the net are then secured to the ground by wood, rocks, sandbags, or any other available heavy material (Link,2014). This structure can cover one to three rows depending on the netting size acquired (Link, 2014). For these structures, small sports balls or any other smooth material available should be placed over posts to protect the net from snagging and tearing (Link, 2014).
Figure 1A. Small net-box design, illustrated by Madeleine Lyman (Link, 2014)
Figure 1B. Small net-box (Martin, T, 2015).
Another structure used for insect netting is tunnel netting (Figure 2). This type of structure is most suitable for closely spaced crops, where the nets are pegged to the ground (Lyu, 2023). To build this structure,e curved metal conduits are placed in the ground spaced equally apart along the crop row (Link, 2014). The net is then draped over the conduits and secured to the ground by any heavy material available (Link, 2014). Neither wire nor stakes need to be used in this structure.
Figure 2. Small net-box design, illustrated by Madeleine Lyman (Link, 2014).
To ensure that nets are working up to their potential, there are a few concepts that farmers should be aware of.
1. Before covering crops with insect netting, ensure that there are no existing pests or pathogens on the crops (Tokumaru et al., 2024).
2. The nets should be placed on crops before the pests are anticipated to attack crops (Tokumaru et al., 2024).
3. Net covers are most cost beneficial in seedling nurseries for smallholder farmers as they require less netting (Martin et al., 2015).
4. In areas where there are regular hailstorms, farmers should install a more pitched roof canopy (Figures 2 and 3), and for less hail storms a flat canopy netting (Figure 1) will work (Lyu, 2023).
Figure 4. Material Specifications. Installation (Joyeyou, 2020).
5. Farmers should try to not install nets on windy days, as the nets are more prone to tangling and damage (Lyu, 2023).
6. Ensure that crops are fully covered by netting and that there is sufficient space between the net and crops, so that pests are unable to lay eggs through the mesh of the net onto crops (Tokumaru et al., 2024).
7. Nets should also be regularly checked for tears or holes (Tokumaru et al., 2024).
8. For sub equatorial climates farmers should practise daily removal of netting to reduce the maximum temperature held under the nets (Simon et al, 2015). This can allow for more opportunities for natural enemies (Tokumaru et al., 2024).
9. Rotate crops so that farmers do not cover plants that may have had pest insect eggs in the previous year (Parker et al., 2012).
Benefits of Insect Nets
Insect nets increase crop yields and crop quality three-fold compared to unnetted crops (Grasswitz, 2019). For example, the average number of large cabbages in a netted plank was 93% higher yields than non-netted planks, which made the average income 69% higher for crops in netted planks (Vidogbéna et al., 2015). Insect nets have increased crop yields and quality by controlling temperatures in nurseries, light, humidity, and soil moisture (Giannoulis et al., 2021). The nets can also be reused for 3-5 years and have the ability to be recycled as well (Innovation Lab, 2024). Insect nets also drastically reduce pesticide use. Pesticides are a major source of pest control for many smallholder farmers, especially female farmers. Oftentimes pesticides are too expensive to buy, so farmers are left to use unlicensed chemicals to protect their crops (Vidogbéna et al., 2015). This risks toxicity to humans, animals, and the environment as well as promotes crop resistance to chemicals, leading to the need for more chemicals (Subramanian, 2018). In a sample taken from female smallholder farmers, 75% experienced negative health effects that they attributed to pesticides (SWOFON, 2022). Insect nets move away from these harmful chemicals to an eco-friendly alternative. The use of insect nets has reduced the use of harmful chemicals by reducing pests by 70-100% (Martin et al., 2015). The crops under insect nets also provide smallholder farmers greater predictability in their crop yields and quality (Mujuka, 2023). This allows smallholder farmers to better predict their cash income (Mujuka, 2023).
Challenges of Insect Nets
The initial cost of insect netting is approximately $0.36/square meter from Indiamart to 1000 - 9999 square metres for $0.65 from Alibaba. However, for every unit of cost there is a return rate of 2.66 units of benefit (Vidogbéna et al., 2015). The reusability factor of these nets for multiple years can also compensate for the initial cost (Tokumaru et al., 2024). However, the cost of netting fluctuates. The finer the mesh, the more expensive the nets will be (Lyu, 2023). In some cases, with intense heat, permanent netting can also be counter effective to crop protection. This is because though sunlight exposure is limited, the temperature under the net can become hotter due to reduced air flow, and humidity also begins to fluctuate more than usual. This can be due to a greenhouse effect, low ventilation and modification of water transfer which may harm crop production (Gogo, et al., 2014). Permanent netting can also decrease natural enemies of pests within the crop environment. To combat this, farmers can practise daytime removal of nets which can be effective in controlling temperature and humidity (Simon et al, 2015). However, daytime removal of nets does not have a great impact on beneficial natural enemies of pests (Subramanian, 2018). During cool seasons, nets work most effectively when left permanently (Simon et al, 2015). Although the removal of netting during daytime hours is effective, it can be quite labour intensive for smallholder farmers as nets can be quite heavy (Simon et al, 2015). Indeed, netting is quite labour intensive, as anytime a farmer needs to manage their crops, they must lift the nets and then place them back afterwards (Link, 2014). Accessibility is also a big constraint to this innovation. Smallholder farmers have limited access to insect nets as they may not be sold in nearby markets (Mujuka, 2023).
Helpful Links To Get Started
How to Install Nets – Videos and Manuals:
Parker, J, Miles, C, Murray, T, Snyder, W. (2012). How to Install a Floating Row Cover. Washington state university extension fact sheet. https://s3.wp.wsu.edu/uploads/sites/2071/2014/04/Install-a-Floating-Row-Cover-FS089E.pdf
Lyu, K. (2023). Agriculture Protection Netting Installation Guide. EyouAgro. https://eyouagro.com/blog/agriculture-netting-installation-guide/
Link, H. L. (2014). An Investigation of Insect Netting Trellis Systems to Manage Spotted Wing Drosophila for Vermont Blueberry Farms. College of Agriculture and Life Sciences. https://www.uvm.edu/sites/default/files/UVM-Extension-Cultivating-Healthy-Communities/horticulture/SWD/LinkThesis3-1-15.pdf
Link, H. L. (2014). Factsheet: Frames to Support Exclusion Netting over Blueberries to Prevent Spotted Wing Drosophila Damage. University of Vermont. https://www.uvm.edu/sites/default/files/UVM-Extension-Cultivating-Healthy-Communities/horticulture/SWD/SWDNettingFrameFactsheet.pdf
Youtube Videos
How to install row covers on vegetable cropsYouTube · U of M Extension Small Farms4 minutes, 14 secondsFeb 14, 2012
How to use anti-insect netting https://www.accessagriculture.org/ki/insect-nets-seedbeds
Where can Smallholder Farmers Obtain Insect Nets:
Icipe. (2019). Netting Technology: Providing Lucrative Farming Methods for Small Scale Farming. http://www.icipe.org/news/netting-technology-providing-lucrative-farming-methods-small-scale-farming
Innovation Lab for Horticulture. (2024). Pest-exclusion nets protect crops to boost yield. https://horticulture.ucdavis.edu/information/pest-exclusion-nets-protect-crops-boost-yield
Projects supported by the Horticulture Innovation Lab work with the US Agency for International Development to work towards a global hunger and food security initiative called Feed the Future (Innovation Lab, 2024). Farmers from this organisation work to hold projects that focus on training and product availability that can help smallholder farmers (Innovation Lab, 2024)
Best Quality Anti Insect Netting Manufacturers Supply for Nursery Fruit Fly Netting Plastic Fruit Tree Covers Anti Aphid Net. Alibaba. https://www.alibaba.com/product-detail/best-quality-anti-insect-nettingmanufacturers_1600659561509.html?spm=a2700.details.you_may_like.2.240a244dvq5gfJ
Agricultural Insect Net. Indiamart. https://www.indiamart.com/proddetail/agricultural-insect-net-15956032148.html
References
1. Agricultural Insect net. Indiamart. https://www.indiamart.com/proddetail/agricultural-insect-net-15956032148.html
2. Best Quality Anti Insect Netting Manufacturers Supply for Nursery Fruit Fly Netting Plastic Fruit Tree Covers Anti Aphid Net. Alibaba, https://www.alibaba.com/product-detail/best-quality-anti-insect-nettingmanufacturers_1600659561509.html?spm=a2700.details.you_may_like.2.240a244dvq5gfJ
3. Giannoulis, A, Briassoulis, D., Papardaki, N.-G, & Mistriotis, A. (2021). Evaluation of Insect-Proof Agricultural Nets with Enhanced Functionality. Biosystems Engineering, 208, 98–112. https://doi.org/10.1016/j.biosystemseng.2021.05.012
4. Gogo, F, Saidi, M, Itulya, F, Martin, T, Ngouajio, M. (2014). Eco-Friendly Nets and Floating Row Covers Reduce Pest Infestation and Improve Tomato (Solanum lycopersicon L.) Yields for Smallholder Farmers in Kenya. Agronomy, 4. 1-12. https://www.researchgate.net/publication/273686795_Eco-Friendly_Nets_and_Floating_Row_Covers_Reduce_Pest_Infestation_and_Improve_Tomato_Solanum_lycopersicon_L_Yields_for_Smallholder_Farmers_in_Kenya
5. Grasswitz T. R. (2019). Integrated Pest Management (IPM) for Small-Scale Farms in Developed Economies: Challenges and Opportunities. Insects, 10(6), 179. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6628405/
6. Pest-Exclusion Nets Protect Crops to Boost Yield. (2024). Innovation Lab for Horticulture. https://horticulture.ucdavis.edu/information/pest-exclusion-nets-protect-crops-boost-yield
7. Link, H. L. (2014). An Investigation of Insect Netting Trellis Systems to Manage Spotted Wing Drosophila for Vermont Blueberry Farms. College of Agriculture and Life Sciences. https://www.uvm.edu/sites/default/files/UVM-Extension-Cultivating-Healthy-Communities/horticulture/SWD/LinkThesis3-1-15.pdf
8. Link, H. L. (2014). Frames to Support Exclusion Netting over Blueberries to Prevent Spotted Wing Drosophila Damage. University of Vermont. https://www.uvm.edu/sites/default/files/UVM-Extension-Cultivating-Healthy-Communities/horticulture/SWD/SWDNettingFrameFactsheet.pdf
9. Lyu, K. (2023). Agriculture Protection Netting Installation Guide. EyouAgro. https://eyouagro.com/blog/agriculture-netting-installation-guide/
10. Martin, T., Simon, S., Parrot, L., Komlan, F.A., Vidogbéna, F., Adégbidi, A., Baird, V., Saidi, M., Kasina, M., Wasilwa, L.A., Subramanian, S., & Ngouajio, M. (2015). Eco-friendly Nets to Improve Vegetable Production and Quality in Sub-Saharan Africa. Acta Horticulturae. 1105(1105). https://www.researchgate.net/publication/271765393_Eco-friendly_nets_to_improve_vegetable_production_and_quality_in_sub-Saharan_Africa
11. Mujuka, E. & Parrot, Laurent & Baird, William & Delettre, E. & Simon, J. & Mburu, J. & Martin, T. (2023). Cost Benefit Analysis of a Netting Technology Package in Real Farming Conditions Among Smallholder Farmers in Kenya. Acta Horticulturae. 153-158. https://www.researchgate.net/publication/375261912_Cost_benefit_analysis_of_a_netting_technology_package_in_real_farming_conditions_among_smallholder_farmers_in_Kenya
12. Parker, J, Miles, C, Murray, T, Snyder, W. (2012). How to Install a Floating Row Cover. Washington State University Extension Fact Sheet. https://s3.wp.wsu.edu/uploads/sites/2071/2014/04/Install-a-Floating-Row-Cover-FS089E.pdf
13. Pesticide use among small scale women farmers. (2022). Alliance for Action on Pesticide in Nigeria. SWOFON, https://ng.boell.org/sites/default/files/2022-12/swofon-survey-final-draft.pdf
14. Simon, S, Assogba Komlan, F, Adjaïto, L,. Mensah, A, Coffi, H.K, Ngouajio, M, Martin, T. (2014). Efficacy of Insect Nets for Cabbage Production and Pest Management Depending on the Net Removal Frequency and Microclimate. International Journal of Pest Management, 60(3), 208–216. https://www.tandfonline.com/doi/citedby/10.1080/09670874.2014.956844?scroll=top&needAccess=true
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16. Tokumaru, S, Tokushima, Y, Ito, S, Yamaguchi, T, & Shimoda, M. (2024). Advanced Methods for Insect Nets: Red-Coloured Nets Contribute to Sustainable Agriculture. Scientific Reports, 14(1), 2255. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10866966/
17. Tossou, R, Vidogbena, F, Adegbidi, A, Assogba-Komlan, F, Martin, T, Ngouajio, M, Simon, S, Parrot, L, Garnett, S. T, Zander, K. K. Exploring Factors that Shape Small-scale Farmers’ Opinions on the Adoption of Eco-friendly Nets for Vegetable Production. Environ Dev Sustain, 18, 1749–1770. https://link.springer.com/article/10.1007/s10668-015-9717-z
18. Vidogbéna, F, Adégbidi, A, Assogba-Komlan, F, Martin, T, Ngouajio, M, Simon, S, Tossou, R, Parrot, L. (2015). Cost:Benefit Analysis of Insect Net Use in Cabbage in Real Farming Conditions Among Smallholder Farmers in Benin. Crop Protection, 78, 164-171. https://doi.org/10.1016/j.cropro.2015.09.003