Purdue Improved Crop Storage (PICS) bags (formerly known as Purdue Improved Cow-pea Storage bags) are bags developed by scientists at

Purdue University Purdue University is a Public university#United States, public Land-grant university, land-grant research university in West Lafayette, Indiana, United States, and the flagship campus of the Purdue University system. The university was founded ...

to store grain and seeds. They use hermetic storage technology to reduce loss of post-harvest

cowpea The cowpea (''Vigna unguiculata'') is an annual herbaceous legume from the genus '' Vigna''. Its tolerance for sandy soil and low rainfall have made it an important crop in the semiarid regions across Africa and Asia. It requires very few inpu ...

(''

Vigna unguiculata The cowpea (''Vigna unguiculata'') is an Annual plant, annual Herbaceous plant, herbaceous legume from the genus ''Vigna''. Its tolerance for sandy soil and low rainfall have made it an important crop in the Semi-arid climate, semiarid regions a ...

'') due to bruchid infestations in West and Central

Africa Africa is the world's second-largest and second-most populous continent after Asia. At about 30.3 million km2 (11.7 million square miles) including adjacent islands, it covers 20% of Earth's land area and 6% of its total surfac ...

. A PICS bag consists of two layers of

polyethylene Polyethylene or polythene (abbreviated PE; IUPAC name polyethene or poly(methylene)) is the most commonly produced plastic. It is a polymer, primarily used for packaging (plastic bags, plastic films, geomembranes and containers including bott ...

liners and a layer of woven

polypropylene Polypropylene (PP), also known as polypropene, is a thermoplastic polymer used in a wide variety of applications. It is produced via chain-growth polymerization from the monomer Propene, propylene. Polypropylene belongs to the group of polyolefin ...

. Each layer is closed separately to create a

hermetically sealed A hermetic seal is any type of sealing that makes a given object airtight (preventing the passage of air, oxygen, or other gases). The term originally applied to airtight glass containers but, as technology advanced, it applied to a larger ca ...

container for harvested grain. This oxygen-deprived environment kills ''Bruchidius atrolineatus'' larvae'',''Purdue Improved Cowpea Storage - Technician Training Manual. Rep. Purdue Improved Cowpea Storage Project, 2008. Web. 18 Nov. 2013. the cow-pea

weevil Weevils are beetles belonging to the superfamily Curculionoidea, known for their elongated snouts. They are usually small – less than in length – and herbivorous. Approximately 97,000 species of weevils are known. They belong to several fa ...

(''

Callosobruchus maculatus ''Callosobruchus maculatus'' is a species of beetles known commonly as the cowpea weevil or cowpea seed beetle.Tran, B. M. D. and P. F. Credland. (1995)Consequences of inbreeding for the cowpea seed beetle, ''Callosobruchus maculatus'' (F.) (Cole ...

''), and some other post-harvest pests.

History

The development of PICS bags began in 1987 when Professor Larry Murdock of

, along with Bean/Cow-pea CRSP,

USAID The United States Agency for International Development (USAID) is an agency of the United States government that has been responsible for administering civilian United States foreign aid, foreign aid and development assistance. Established in 19 ...

, and BIFAD, sought a solution to combat orchard infestations of cow-pea harvests in

Cameroon Cameroon, officially the Republic of Cameroon, is a country in Central Africa. It shares boundaries with Nigeria to the west and north, Chad to the northeast, the Central African Republic to the east, and Equatorial Guinea, Gabon, and the R ...

."Hermetic Bags save African Crop, but Not How Experts Once Thought." University News Service. Purdue University, 21 Feb. 2012. Web. 18 Nov. 2013. As of 2007, over 1.75 million PICS bags have been sold in West and Central Africa, and demonstrations of their use have been conducted in 31,000 villages. As of 2023, the project has been funded with $11.4 million (USD) by the

Bill and Melinda Gates Foundation The Gates Foundation is an American private foundation founded by Bill Gates and Melinda French Gates. Based in Seattle, Washington, it was launched in 2000 and is reported to be List of wealthiest charitable foundations, the third largest char ...

."Project Overview." Purdue Improved Crop Storage. Purdue University, 2010. Web. 18 Nov. 2013.

Objectives

The PICS project has evolved since its original conception. As such, the project's focus has also evolved to address the need for providing safe, cheap, and effective post-harvest storage solutions to smallholders.

PICS1 (Purdue Improved Cow-pea Storage)

Active from 2007 to 2011, this phase of the project aimed to create the ideal design for a triple-layer, hermetically sealed, commercially available cowpea storage bag. Another aim was to educate farmers and rural development groups about non-chemical cowpea storage methods and to demonstrate the most effective cowpea storage methods. The project also strove to develop a local supply chain, making them more available for rural farmers, while providing development opportunities for local businesses.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. This received funding of $11.4 million for 5 years.

PICS2 (Purdue Improved Crop Storage)

Active from 2011 to 2014, PICS2 sought to expand the original scope of the PICS program. Its goals were to identify other agricultural commodities that suffer loss to insects and other pests during storage, test the PICS bags through collaborative projects with scientists in sub-Saharan developing nations, implement economic analyses to estimate the potential benefits of optimizing the PICS technology for specific commodities, and develop plans to disseminate the technologies for those commodities where they will provide the greatest benefit. Funding was $1.1 million for 30 months.

PICS3

The third phase of the program began in April 2014, and is ongoing as of 2024. The program is currently funded by the

. The Gates Foundation also funded the initial PICS1 and PICS2 projects. PICS3 aims to improve market access, income, and food security for smallholders in

Sub-Saharan Africa Sub-Saharan Africa is the area and regions of the continent of Africa that lie south of the Sahara. These include Central Africa, East Africa, Southern Africa, and West Africa. Geopolitically, in addition to the list of sovereign states and ...

by expanding the availability of PICS technology to reduce post-harvest storage loss.

Use

This project was first developed in

, but it has since spread to 23 nations in Africa and Asia. To date, PICS bags have been introduced and are in use in

Afghanistan Afghanistan, officially the Islamic Emirate of Afghanistan, is a landlocked country located at the crossroads of Central Asia and South Asia. It is bordered by Pakistan to the Durand Line, east and south, Iran to the Afghanistan–Iran borde ...

Benin Benin, officially the Republic of Benin, is a country in West Africa. It was formerly known as Dahomey. It is bordered by Togo to the west, Nigeria to the east, Burkina Faso to the north-west, and Niger to the north-east. The majority of its po ...

Burkina Faso Burkina Faso is a landlocked country in West Africa, bordered by Mali to the northwest, Niger to the northeast, Benin to the southeast, Togo and Ghana to the south, and Ivory Coast to the southwest. It covers an area of 274,223 km2 (105,87 ...

Burundi Burundi, officially the Republic of Burundi, is a landlocked country in East Africa. It is located in the Great Rift Valley at the junction between the African Great Lakes region and Southeast Africa, with a population of over 14 million peop ...

Chad Chad, officially the Republic of Chad, is a landlocked country at the crossroads of North Africa, North and Central Africa. It is bordered by Libya to Chad–Libya border, the north, Sudan to Chad–Sudan border, the east, the Central Afric ...

, the

Democratic Republic of the Congo The Democratic Republic of the Congo (DRC), also known as the DR Congo, Congo-Kinshasa, or simply the Congo (the last ambiguously also referring to the neighbouring Republic of the Congo), is a country in Central Africa. By land area, it is t ...

Ethiopia Ethiopia, officially the Federal Democratic Republic of Ethiopia, is a landlocked country located in the Horn of Africa region of East Africa. It shares borders with Eritrea to the north, Djibouti to the northeast, Somalia to the east, Ken ...

Ghana Ghana, officially the Republic of Ghana, is a country in West Africa. It is situated along the Gulf of Guinea and the Atlantic Ocean to the south, and shares borders with Côte d’Ivoire to the west, Burkina Faso to the north, and Togo to t ...

India India, officially the Republic of India, is a country in South Asia. It is the List of countries and dependencies by area, seventh-largest country by area; the List of countries by population (United Nations), most populous country since ...

Kenya Kenya, officially the Republic of Kenya, is a country located in East Africa. With an estimated population of more than 52.4 million as of mid-2024, Kenya is the 27th-most-populous country in the world and the 7th most populous in Africa. ...

Malawi Malawi, officially the Republic of Malawi, is a landlocked country in Southeastern Africa. It is bordered by Zambia to the west, Tanzania to the north and northeast, and Mozambique to the east, south, and southwest. Malawi spans over and ...

Mali Mali, officially the Republic of Mali, is a landlocked country in West Africa. It is the List of African countries by area, eighth-largest country in Africa, with an area of over . The country is bordered to the north by Algeria, to the east b ...

Mozambique Mozambique, officially the Republic of Mozambique, is a country located in Southeast Africa bordered by the Indian Ocean to the east, Tanzania to the north, Malawi and Zambia to the northwest, Zimbabwe to the west, and Eswatini and South Afr ...

Niger Niger, officially the Republic of the Niger, is a landlocked country in West Africa. It is a unitary state Geography of Niger#Political geography, bordered by Libya to the Libya–Niger border, north-east, Chad to the Chad–Niger border, east ...

Nigeria Nigeria, officially the Federal Republic of Nigeria, is a country in West Africa. It is situated between the Sahel to the north and the Gulf of Guinea in the Atlantic Ocean to the south. It covers an area of . With Demographics of Nigeria, ...

Rwanda Rwanda, officially the Republic of Rwanda, is a landlocked country in the Great Rift Valley of East Africa, where the African Great Lakes region and Southeast Africa converge. Located a few degrees south of the Equator, Rwanda is bordered by ...

Senegal Senegal, officially the Republic of Senegal, is the westernmost country in West Africa, situated on the Atlantic Ocean coastline. It borders Mauritania to Mauritania–Senegal border, the north, Mali to Mali–Senegal border, the east, Guinea t ...

Tanzania Tanzania, officially the United Republic of Tanzania, is a country in East Africa within the African Great Lakes region. It is bordered by Uganda to the northwest; Kenya to the northeast; the Indian Ocean to the east; Mozambique and Malawi to t ...

Togo Togo, officially the Togolese Republic, is a country in West Africa. It is bordered by Ghana to Ghana–Togo border, the west, Benin to Benin–Togo border, the east and Burkina Faso to Burkina Faso–Togo border, the north. It is one of the le ...

Uganda Uganda, officially the Republic of Uganda, is a landlocked country in East Africa. It is bordered to the east by Kenya, to the north by South Sudan, to the west by the Democratic Republic of the Congo, to the south-west by Rwanda, and to the ...

, and

Zambia Zambia, officially the Republic of Zambia, is a landlocked country at the crossroads of Central Africa, Central, Southern Africa, Southern and East Africa. It is typically referred to being in South-Central Africa or Southern Africa. It is bor ...

. After harvesting and thoroughly drying the grain, farmers put it into a polyethylene bag that holds either 50kg or 100kg. The bag is then tightly sealed, preventing air from entering. The first polyethylene bag is surrounded by a second identical bag, which is also sealed, making it airtight. The double-bagged grain is then sealed inside a third woven polypropylene bag, which provides the mechanical strength for PICS bags.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. This method creates an airtight environment and seals any insects present in the crop inside the bag. These insects briefly continue to consume oxygen, but as oxygen levels in the bags drop, and CO₂ concentrations rise, the insects stop feeding and quickly die, thereby protecting the crop from further damage. Recent studies have shown that bruchids sealed in PICS bags do not die from

asphyxiation Asphyxia or asphyxiation is a condition of deficient supply of oxygen to the body which arises from abnormal breathing. Asphyxia causes generalized hypoxia, which affects all the tissues and organs, some more rapidly than others. There are ...

, but rather from

dehydration In physiology, dehydration is a lack of total body water that disrupts metabolic processes. It occurs when free water loss exceeds intake, often resulting from excessive sweating, health conditions, or inadequate consumption of water. Mild deh ...

. This subfamily of ''

Chrysomelidae The beetle family Chrysomelidae, commonly known as leaf beetles, includes over 37,000 (and probably at least 50,000) species in more than 2,500 genera, making it one of the largest and most commonly encountered of all beetle families. Numerous s ...

'' has the ability to produce water through their own

metabolism Metabolism (, from ''metabolē'', "change") is the set of life-sustaining chemical reactions in organisms. The three main functions of metabolism are: the conversion of the energy in food to energy available to run cellular processes; the co ...

. However, this process requires oxygen, so when oxygen levels in PICS bags decrease, the orchids lose the ability to produce water and die of dehydration.

Advantages

PICS bags can assist smallholders in a few ways. They are an

insecticide Insecticides are pesticides used to kill insects. They include ovicides and larvicides used against insect eggs and larvae, respectively. The major use of insecticides is in agriculture, but they are also used in home and garden settings, i ...

-free, relatively cheap method of storing cow-peas and other grains. The PICS bags can be stored in homes, making this an effective way for smallholders to protect their harvests. Furthermore, the bags can be opened at any time. When they are unsealed, the cow-peas are ready to be consumed. The PICS bags can then be reused, provided they are free of holes or tears.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. Studies have demonstrated that PICS can be used multiple times for several years without quality loss. Additionally, the storage allows communities to create food reserves during the post-harvest season. Even after several months of storage in PICS bags, the quality of the grain does not decrease.

Economic development

The PICS project aims to increase the incomes of smallholder producers. By 2012,

researchers expected each household that used the PICS bags to increase their annual income by an average of $150 USD. With widespread adoption of PICS bags, global savings of cow-pea harvests were predicted to be worth $500 million USD annually. The additional income provided through the use of PICS bags is expected to allow smallholder producers to invest in their own farming practices and local communities, thereby stimulating local development.

Disadvantages

Some disadvantages of this technology are that PICS bags are prone to being stolen and therefore need to be protected. In areas where grain has always been sold immediately after harvest, storage areas may not exist for PICS bags. New storage facilities may thus need to be built when the bags are introduced to these communities. It is also essential that grain intended to be stored in PICS bags be thoroughly dried prior to storage to prevent

mold A mold () or mould () is one of the structures that certain fungus, fungi can form. The dust-like, colored appearance of molds is due to the formation of Spore#Fungi, spores containing Secondary metabolite#Fungal secondary metabolites, fungal ...

growth and grain rot.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. While PICS bags protect cow-peas against damage caused by insects, they do not provide a barrier against intrusion and mechanical damage by

mice A mouse (: mice) is a small rodent. Characteristically, mice are known to have a pointed snout, small rounded ears, a body-length scaly tail, and a high breeding rate. The best known mouse species is the common house mouse (''Mus musculus' ...

rat Rats are various medium-sized, long-tailed rodents. Species of rats are found throughout the order Rodentia, but stereotypical rats are found in the genus ''Rattus''. Other rat genera include '' Neotoma'' (pack rats), '' Bandicota'' (bandicoo ...

s, or other animals. The environmental impact of PICS bags also remains unstudied.

Practical information

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. Therefore, it has been suggested that this technology could be improved by finding additional methods of lowering the

moisture content Water content or moisture content is the quantity of water contained in a material, such as soil (called ''soil moisture''), rock, ceramics, crops, or wood. Water content is used in a wide range of scientific and technical areas, and is expressed ...

within sealed bags quickly, to facilitate quicker dehydration of pests and insects. Since PICS bags do not provide protection from mice, rats, or other larger animals, any Non-Governmental Organization (NGO) aiming to increase their use should ensure that farmers are taught to store their cowpea harvest in an environment as free of these exterior threats as possible. There is also potential for PICS bags to be improved through the use of an additional barrier that cannot be punctured by animals. Other projects competing with PICS bags to prevent insect-induced post-harvest grain losses are other forms of hermetically sealed containers, such as the Grain-pro bag. An alternative hermetic method of protecting the crop is to store grain inside sealed steel drums.

References

Sources

*Baoua, I. B., V. Margam, L. Amadou, and L. L. Murdock. "Performance of Triple Bagging Hermetic Technology for post-harvest 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. {{bags Food storage containers Bags