Banana weevils destroy more than 90 per cent of crops in some regions of Africa

Fabrice Vinatier

Spying on insects could help farmers around the world improve their fight against the devastating weevil pest, in banana, potatoes and soybeans, according to scientists.

Farmers already use alternative pest management techniques, such as pheromone traps that use scents to trap pests, with some success.

But to maximise their effectiveness it is important to understand how the pests behave, said Fabrice Vinatier, lead author of the study, published in Agriculture, Ecosystems and Environment this week (22 November), and a researcher at the Center for International Cooperation in Agronomic Research for Development, in Martinique, French West Indies.

His team tagged banana weevil pests with radio frequency identification (RFID) which use radio waves to transfer data from the tag to a computer and allows tracking of the insects' movements.

Vinatier and colleagues tracked banana weevils in several plantations in Martinique and found how their natural movement can be used against them.

It is the first time that the technology has been used to track crawling insects, say the authors, and it could be adapted for other weevil pests such as the Andean potato weevil and the long-horned soybean weevil.

They used the data to help build a reliable computer model to simulate the pattern of weevil attack, considering factors such as the spacing of banana trees and the placement of pheromone traps on a farm, and the presence of plant residue.

When banana trees were grouped it took weevils longer to colonise the plots — but once they did, the percentage of individual banana plants with severe attacks was higher, Vinatier told SciDev.Net.

He added that separating banana plots with fallow areas also increased infestation within each plot.

In addition, Vinatier said, pheromone traps "were much more efficient" when placed on bare soil than on crop residues, so clearing out areas where traps are set could greatly improve their efficiency.  

The computer model "can be seen as a virtual laboratory for studying different agricultural practices in developing countries without [researchers having to conduct] long and expensive experiments", said Vinatier.

Haruna Braimah, who is developing alternative approaches to managing the banana weevil at the Council for Scientific and Industrial Research's Crops Research Institute, in Ghana, said that, if carried out effectively, the method could help better understand the weevil's foraging behaviour.  

He added: "Farmers who fail to clean their planting materials before planting transfer weevils from old to new fields."

The banana weevil affects banana crops worldwide. The problem is particularly acute in Africa, where, in some regions, the pest can destroy more than 90 per cent of the crop.

Link to abstract in Agriculture, Ecosystems and Environment