Unpredictable weather patterns and the spread of crop-destroying fall armyworm caterpillars could lead to "no food at all" for communities across Africa, experts have warned.

The caterpillars, which were discovered in Africa in 2016 and are believed to have come from South America, have now been identified in 44 countries, up from 28 last year.

The director-general of development at Centre for Agriculture and Biosciences International (CABI), Dennis Rangi blamed globalization for the spread of the pest.

But it could have a potentially devastating effect combined with unpredictable weather patterns, he said on the sidelines of an agricultural conference in Kigali.

"Rainfall is not very reliable anymore so when you get a combination of a little drought and the fall armyworm you are going to be talking about no food at all," he told AFP on Wednesday.