Purdue Improved Crop Storage (PICS) bags

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Purdue Improved Crop Storage (PICS) bags (formerly Purdue Improved Cowpea Storage bags)[1] provide a simple, low-cost method of reducing post-harvest cowpea (Vigna unguiculata) losses due to bruchid infestations in west and central Africa.[2]

A PICS bag consists of two layers of polyethylene bags, these are then surrounded by a third layer of woven polypropylene,[3] thereby creating a hermetically sealed environment in which harvested cowpeas are stored. This oxygen-deprived environment proves fatal for Bruchidius atrolineatus[4] and Calloso bruchus maculatus.[5]

The Problem[edit]

Bruchidius atrolineatus[4] and Calloso bruchus maculatus,[6] (commonly known as cowpea weevils, or bruchids) pose significant threat to cowpea harvests. Bruchids carry out their life cycle within cowpeas,[4] and their presence makes the crop unfit for human or animal consumption. These bruchids reproduce rapidly, thus only a few of the insects within a collection of cowpeas can cause significant damage within a month.[7]

Cowpea is an extremely important crop to Western and Central African countries.[8] Not only are cowpeas highly nutritious for humans, but they are also a source of fodder for animals, and are regularly used by rural women to generate their own income, thus providing an important source of liquidity for farmers.[4]

Geography[edit]

This project was first developed in Cameroon, but it has since spread to ten nations in West and Central Africa[9] in which over 70% of world cowpea production occurs.[4] To date, PICS bags have been introduced and are in use in the following nations: Cameroon, Chad, Benin, Burkina Faso, Ghana, Mali, Niger, Nigeria, Senegal, and Togo.[10]

History[edit]

In 1987, Professor Larry Murdock of Purdue University, in partnership with Bean/Cowpea CRSP and USAID,[4] led a team of researchers working to combat bruchid infestations of cowpea harvests in Cameroon.[7] The outcome of this initiative were PICS bags.[11]

Since 2007, more than 1.75 million PICS bags have been sold in West and Central Africa[7] and demonstrations of their effectiveness have been conducted in 31,000 villages.[7] Currently, this project is funded with $11.4 million (USD) by the Bill and Melinda Gates Foundation.[12]

Project objectives[edit]

The specific objectives of this project involve determining the optimal design for a triple-layer, hermetically sealed, commercially available cowpea storage bag. Another goal is to increase the knowledge of farmers and rural-development groups on non-chemical cowpea storage methods, and to demonstrate the most effective cowpea storage methods for these groups. It is also important to the project to develop a local supply chain for PICS bags that makes the technology available to rural farmers, as well as providing development opportunities for local businesses.[13]

Using PICS bags[edit]

After harvesting and thoroughly drying the grain, farmers place cowpeas into a polyethylene bag capable of holding either 50 kg of 100 kg of cowpeas.[14] The bag is then tightly sealed, preventing air from entering.[7] The first polyethylene bag is surrounded by a second identical bag, which is also sealed, making it airtight.[7] The double-bagged cowpeas are then sealed inside a third woven nylon bag, which provides the mechanical strength for PICS bags.[15]

This method of triple bagging creates an airtight environment, and seals any bruchids present in the crop inside the bag. These bruchids briefly continue to consume oxygen, but as oxygen levels in the bags drop, and CO2 concentrations rise,[4] the bruchids stop feeding on cowpeas, and quickly die, thereby protecting the crop from further damage.[7]

Recent studies have shown that bruchids sealed in PICS bags do not die from asphyxiation, but rather from thirst. This subfamily of bruchids have the ability to produce water through their own metabolism.[7] This process requires oxygen, so when oxygen levels in PICS bags decrease the bruchids lose the ability to produce water and die of dehydration.[7]

Advantages of PICS bags[edit]

PICS bags provide many benefits to smallholder farmers. Not only is this an effective insecticide-free, low-cost method of storing cowpeas[7] but it is easy to explain to farmers,[4] and PICS bags can be stored in family homes– making this an effective way for smallholder farmers to protect their harvests.[4]

In addition, the bags can be opened at any time – when they are unsealed the cowpeas are ready to be consumed.[4] The PICS bags can then be reused, provided they are free of holes and tears.[16] Studies have demonstrated that storing cowpeas in once-used PICS bags preserves the peas as well as storing them in unused bags.[17]

Storing cowpeas until they reach a high market value allows farmers to gain greater profits, and storage provides communities with food reserves during the post-harvest season.[4] Even after several months of storage in PICS bags, the quality of the cowpeas does not decline.[18]

PICS bags and economic development[edit]

This project aims to increase the incomes of smallholder cowpea producers.[4] Each household that adopts the use of PICS bags is expected to save $150 (USD) annually.[7] With widespread adoption of PICS bags, global savings of cowpea harvests are predicted to be worth half a billion US dollars annually.[7]

The additional income provided through the use of PICS bags will allow smallholder producers to invest in their own farming practices and local communities, thereby encouraging local development.[4]

Disadvantages of PICS bags[edit]

Some problems with this technology are that PICS bags are prone to theft, and therefore need to be protected.[4] In areas where cowpeas have always been immediately sold after harvest, storage areas may not exist for PICS bags – therefore their introduction to some communities may also require the construction of new storage facilities.[4] In addition, it is essential that grain intended to be stored in PICS bags be thoroughly dried prior to storage in order to prevent mould growth and grain rot.[19] Furthermore, while PICS bags protect cowpeas against damage caused by insects, they do not provide a barrier against mice, rats, or other animals.[4] Finally, the environmental impact of PICS bags remains largely unstudied,[20] and should be seriously considered.

Practical Information[edit]

In order to increase the effectiveness of PICS bag technology, the following suggestions should be considered:

As studies show, PICS bags work not only by depriving bruchids of oxygen, but also by dehydrating their environment.[7] Therefore, this technology could be improved by finding additional methods of quickly lowering the moisture content within sealed bags.[7] Since PICS bags do not provide protection from mice, rats, or other animals, any NGO aiming to increase their use should ensure that farmers are taught to keep their stored cowpea harvest in an environment free of these exterior threats. There is potential for PICS bags to be improved through the use of an additional barrier that cannot be punctured by animals. Due to low levels of local literacy, this project aims to communicate PICS bag technology to communities through verbal demonstrations and also through information communicated via radio.[4] In order to ensure full community participation in effective cowpea storage, women, men, and children must all participate in PICS bag demonstrations.[4]

Solutions competing with PICS bags to prevent bruchid-induced post-harvest cowpea losses are other forms of hermetically sealed containers, such as the GrainPro bag.[21] A similar method of protecting the crop is to store cowpeas inside sealed steel drums.[22] Furthermore, the same basic principles of disabling insects within hermetically stored containers could potentially be applied to other crops in the region. Research is currently underway to determine if PICS bags reduce post-harvest losses for beans, sorghum, corn (maize), and other grains.[7]

References[edit]

  1. ^ ,Purdue University, http://www.entm.purdue.edu/PICS2/project_overview.php, "Purdue Improved Crop Storage Project Overview", 2012.
  2. ^ Baributsa, D., I. Baoua, J. Lowenberg-DeBoer, T. Abdoulaye, and L. L. Murdock.Purdue Improved Cowpea Storage (PICS) Technology. Rep. 262nd ed. Vol. E. West Lafayette: Purdue University, 2013. Department of Entomology. Oct. 2013. Web. 19 Nov. 2013.
  3. ^ ,Murdock, L.L., Margam, V., Baoua, I., Belfe, S., Shade, R.E. 2012. Death by desiccation: Effects of hermetic storage on cowpea bruchids. Journal of Stored Products Research, 40: 166-170.
  4. ^ a b c d e f g h i j k l m n o p q r Purdue Improved Cowpea Storage - Technician Training Manual. Rep. Purdue Improved Cowpea Storage Project, 2008. Web. 18 Nov. 2013.
  5. ^ Baoua, I. B., V. Margam, L. Amadou, and L. L. Murdock. "Performance of Triple Bagging Hermetic Technology for Postharvest Storage of Cowpea Grain in Niger." Journal of Stored Products Research 51 (2012): 81-85.. 31 July 2012. Web. 19 Nov. 2013.
  6. ^ Baoua, I. B., V. Margam, L. Amadou, and L. L. Murdock. "Performance of Triple Bagging Hermetic Technology for Postharvest Storage of Cowpea Grain in Niger." Journal of Stored Products Research 51 (2012): 81-85. 31 July 2012. Web. 19 Nov. 2013.
  7. ^ a b c d e f g h i j k l m n o "Hermetic Bags save African Crop, but Not How Experts Once Thought." University News Service. Purdue University, 21 Feb. 2012. Web. 18 Nov. 2013.
  8. ^ Coulibaly, J., S. D’Alessandro, T. Nouhoheflin, C. Aitchedji, M. Damisa, D. Baributsa, and J. Lowenberg-DeBoer. Purdue Improved Cowpea Storage (PICS) Supply Chain Study. Working paper. 4th ed. Vol. 12. West Lafayette: Purdue University, 2012. Print.
  9. ^ "Project Overview." Purdue Improved Crop Storage. Purdue University, 2010. Web. 18 Nov. 2013.
  10. ^ "Project Overview." Purdue Improved Crop Storage. Purdue University, 2010. Web. 18 Nov. 2013.
  11. ^ Baributsa, D., I. Baoua, J. Lowenberg-DeBoer, T. Abdoulaye, and L. L. Murdock Purdue Improved Cowpea Storage (PICS) Technology. Rep. 262nd ed. Vol. E. West Lafayette: Purdue University, 2013. Department of Entomology. Oct. 2013. Web. 19 Nov. 2013.
  12. ^ "Project Overview." Purdue Improved Crop Storage. Purdue University, 2010. Web. 18 Nov. 2013.
  13. ^ Coulibaly, J., S. D’Alessandro, T. Nouhoheflin, C. Aitchedji, M. Damisa, D. Baributsa, and J. Lowenberg-DeBoer. Purdue Improved Cowpea Storage (PICS) Supply Chain Study. Working paper. 4th ed. Vol. 12. West Lafayette: Purdue University, 2012. Print.
  14. ^ Coulibaly, J., S. D’Alessandro, T. Nouhoheflin, C. Aitchedji, M. Damisa, D. Baributsa, and J. Lowenberg-DeBoer. Purdue Improved Cowpea Storage (PICS) Supply Chain Study. Working paper. 4th ed. Vol. 12. West Lafayette: Purdue University, 2012. Print.
  15. ^ Baoua, I. B., V. Margam, L. Amadou, and L. L. Murdock. "Performance of Triple Bagging Hermetic Technology for Postharvest Storage of Cowpea Grain in Niger." Journal of Stored Products Research 51 (2012): 81-85. 31 July 2012. Web. 19 Nov. 2013.
  16. ^ Baributsa, D., I. Baoua, J. Lowenberg-DeBoer, T. Abdoulaye, and L. L. Murdock. Purdue Improved Cowpea Storage (PICS) Technology. Rep. 262nd ed. Vol. E. West Lafayette: Purdue University, 2013. Department of Entomology. Oct. 2013. Web. 19 Nov. 2013.
  17. ^ Baoua, I. B., V. Margam, L. Amadou, and L. L. Murdock. "Performance of Triple Bagging Hermetic Technology for Postharvest Storage of Cowpea Grain in Niger." Journal of Stored Products Research 51 (2012): 81-85. . 31 July 2012. Web. 19 Nov. 2013.
  18. ^ Baributsa, D., I. Baoua, J. Lowenberg-DeBoer, T. Abdoulaye, and L. L. Murdock. Purdue Improved Cowpea Storage (PICS) Technology. Rep. 262nd ed. Vol. E. West Lafayette: Purdue University, 2013. Department of Entomology. Oct. 2013. Web. 19 Nov. 2013.
  19. ^ Baributsa, D., I. Baoua, and L. Murdock. Purdue Improved Crop Storage (PICS) Bag: Size Matters! Rep. no. E-263-W. Purdue University Extension, Oct. 2013. Web. 4 Dec. 2013.
  20. ^ Coulibaly, J., S. D’Alessandro, T. Nouhoheflin, C. Aitchedji, M. Damisa, D. Baributsa, and J. Lowenberg-DeBoer. Purdue Improved Cowpea Storage (PICS) Supply Chain Study. Working paper. 4th ed. Vol. 12. West Lafayette: Purdue University, 2012. Print.
  21. ^ Baributsa, D., I. Baoua, J. Lowenberg-DeBoer, T. Abdoulaye, and L. L. Murdock. Purdue Improved Cowpea Storage (PICS) Technology. Rep. 262nd ed. Vol. E. West Lafayette: Purdue University, 2013. Department of Entomology. Oct. 2013. Web. 19 Nov. 2013.
  22. ^ Baributsa, D., I. Baoua, J. Lowenberg-DeBoer, T. Abdoulaye, and L. L. Murdock. Purdue Improved Cowpea Storage (PICS) Technology. Rep. 262nd ed. Vol. E. West Lafayette: Purdue University, 2013. Department of Entomology. Oct. 2013. Web. 19 Nov. 2013.
  • Baoua, I. B., V. Margam, L. Amadou, and L. L. Murdock. "Performance of Triple Bagging Hermetic Technology for Postharvest Storage of Cowpea Grain in Niger." Journal of Stored Products Research 51 (2012): 81-85. 31 July 2012. Web. 19 Nov. 2013.
  • Baributsa, D., I. Baoua, J. Lowenberg-DeBoer, T. Abdoulaye, and L. L. Murdock. Purdue Improved Cowpea Storage (PICS) Technology. Rep. 262nd ed. Vol. E. West Lafayette: Purdue University, 2013. Department of Entomology. Oct. 2013. Web. 19 Nov. 2013.
  • Coulibaly, J., S. D’Alessandro, T. Nouhoheflin, C. Aitchedji, M. Damisa, D. Baributsa, and J. Lowenberg-DeBoer. Purdue Improved Cowpea Storage (PICS) Supply Chain Study. Working paper. 4th ed. Vol. 12. West Lafayette: Purdue University, 2012. Print.
  • "Hermetic Bags save African Crop, but Not How Experts Once Thought." University News Service. Purdue University, 21 Feb. 2012. Web. 18 Nov. 2013.
  • "Project Overview." Purdue Improved Crop Storage. Purdue University, 2010. Web. 18 Nov. 2013.
  • Purdue Improved Cowpea Storage - Technician Training Manual. Rep. Purdue Improved Cowpea Storage Project, 2008. Web. 18 Nov. 2013.