This is the VOA Special English Agriculture Report.

Airtight plastic bags can help farmers protect their harvests without the use of harmful chemicals. These bags are designed to keep air out of crops in storage. They are a simple way to fight insects and keep food fresh.

Ten countries in West and Central Africa are involved in a project to improve the storage of cowpeas, also known as black-eyed peas.

Farmers can lose much of the harvest to insects called bruchids. These grow from egg to adult in a few weeks and then lay 40 to 60 more eggs. They can destroy the whole harvest within months.

Farmers can sell their crop immediately. But selling at harvest time means more competition and lower prices. Or they can use pesticides to kill the bugs. But crop scientist Dieudonne Baributsa says that is also risky.

DIEUDONNE BARIBUTSA: "They end up misusing or overusing the pesticide. In Nigeria, they have reported a lot of cases of death. They usually call it in Nigeria 'killer beans.'"

Mr. Baributsa is a researcher at Purdue University in the American state of Indiana. The project is called PICS, for Purdue Improved Cowpea Storage.

Mr. Baributsa says the storage bags are thick enough that any insects already in the cowpeas will die from a lack of oxygen. The lack of air will also help prevent the growth of bacteria and fungi that can ruin the harvest.

DIEUDONNE BARIBUTSA: "If you go in the market in Africa, you find those bags with a small liner inside, like if you buy sugar and so on. Those are low density, so they are very permeable to oxygen. So if you put your cowpeas in there, they will be destroyed because the insects will still access the air."

The bags cost about two dollars each. Mr. Baributsa says that is not much, especially if it means farmers can wait long enough to get a better price for their crop.

The bags are produced locally. Donors currently support the project, but the groups involved are working to build a lasting market for the bags.

DIEUDONNE BARIBUTSA: "With many development projects, what [you do is], you go in the village and you give the farmers the bags. And then once the project ends, that farmer cannot find the bag on the market. We feel like that is not a sustainable approach to development."

The bags are being advertised by radio and mobile phone videos in local languages.

The project includes Nigeria, Niger, Burkina Faso, Ghana and Mali. The other countries are Senegal, Cameroon, Benin, Togo and Chad.

A company based in the United States called GrainPro makes another kind of airtight bag. These are called SuperGrainbags. Phil Villers, the company president, says safely storing a harvest not only earns more money for farmers. It also reduces the amount of food lost to insects, spoilage and mishandling.

PHIL VILLERS: "What does not get wasted and eaten means it is available to feed a hungry world."

And that's the VOA Special English Agriculture Report. To see what the PICS bag looks like, go to voaspecialenglish.com, where you can also find transcripts and MP3s of our reports. I'm Bob Doughty.

bruchid: 豆象（鞘翅目的小甲虫，头部具状突起，危害豆科的籽实）

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（来源：VOA 编辑：陈丹妮）