Preventing Crop Loss through Purdue Improved Crop Storage (PICS) Bags

The Purdue Improved Crop Storage (PICS) bag provides low-cost, hermetic grain-storage bags that prevent pest damage during crop storage without having to use chemicals. These bags allow farmers to consume or sell crops later in the season when prices might be higher, increasing food security and offering a healthier alternative to chemical pesticide.  When using PICS bags, farmers no longer need chemicals to control grain storage pests. PICS bag was developed by Purdue University and supported by USAID and Bill and Melinda Gates Foundation.

PICS bags was formerly Purdue Improved Cowpea Storage bags (PICS 1) which was originally meant to provide a simple, low-cost method of reducing post-harvest cowpea (Vigna unguiculata) losses due to bruchid infestations in West and Central Africa.  

After the success of PICS 1, the second phase, called PICS 2, sought to identify other food products that suffer losses to insects during storage and test the PICS bags through collaborative projects with scientists in developing nations, primarily sub-Saharan Africa.

PICS 3 which is supported by Bill and Melinda Gates Foundation is expanding the commercialization of PICS technology for several crops in Sub-Saharan Africa. Activities are focused in Burkina Faso, Ethiopia, Ghana, Malawi, Nigeria, Tanzania, and Uganda but will reach into other countries in Sub-Saharan Africa and beyond using leverage support.

PICS technology involves triple bagging of the grain in plastic bags. These bags are a great option for farmers who see major losses in their crops each year due to insect pests. The bag uses two liners of high-density polyethylene (HDPE) and an outer layer composed of woven polypropylene. 

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 the bag. Together, they create low-oxygen environments that reduce insect development. As much as 98% of all insect pests can be eliminated within just 1 month of storage, reducing damage and weight loss caused by feeding.

This method of triple bagging 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.

In addition to reducing post-harvest loss, the bags also reduce the risk of aflatoxin. Smallholder farmers find PICS bags to be more affordable and easier to use than other post-harvest storage systems, which require pesticides and training.

Small-scale farmers can use PICS bags to store either a few kilograms or a full 50 or 100 kilograms. Purdue and its partners have sold more than 1.75 million bags in West Africa in the last five years in 10 different countries.

Advantages of PICS bags

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

In addition, the bags can be opened at any time – when they are unsealed the grains are ready to be consumed. The PICS bags can then be re-used, provided they are free of holes and tears. Studies have demonstrated that PICS can be used multiple times across several years without any loss in quality.

Economic Development

The PICS project aims to increase the incomes of smallholder producers. Each household that adopts the use of the bags is expected to save $150 (USD) annually.  The additional income provided through the use of these bags will allow smallholder producers to invest in their own farming practices and local communities, thereby encouraging local development.