CANMORE, Alta. – Controlling plagues of locusts is often an international effort led by groups such as the United Nations Food and Agriculture Organization.
The FAO formed a pesticide referee group in 1989 to recommend controls after a desert locust outbreak swept across northern Africa in the 1980s.
The international group makes recommendations on the most effective insecticides and what dosage could be used for spraying barrier strips or full cover applications when locusts start to swarm a vulnerable area.
The recommendations give locust-affected countries a choice of insecticides and strategies to prevent locust population development, protect crops and intercept marching bands of insects.
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“We realized there could be situations where perhaps more than one technique would be required,” said Graham Matthews, a founding member of the FAO pesticide group. He spoke at the recent International Orthopterists’ Society symposium held in Canmore. Orthopterists study locusts, crickets and grasshoppers.
When drawing up lists of recommended treatments and controls, the FAO uses data supplied by various independent organizations because it does not want to rely solely on chemical manufacturers that are trying to promote a product.
The committee looks for high levels of efficacy in the products it recommends while recognizing some take longer to work than others. It also considers environmental impacts on bees, water, birds, reptiles and mammals when looking at chemical and biological controls.
The list carries about 10 recommended products on a database with information on the formulation, risk levels and how quickly each works.
Since locust outbreaks are unpredictable, new groups of people need to be trained each time to use the control materials.
The committee tends to recommend ultra low volume spray. It has learned if problems arise with effectiveness, it is often because of the way people mixed the control formulation or how they applied it.
The committee’s list includes organophosphates, older chemicals that require high volumes to work on the insects. In conditions such as those experienced in the Sahara, this chemical is not always effective.
In addition, it does not linger enough because a new batch of locusts would appear in an area several days after the first round of spraying.
Pyrethroids are popular. They provide a high and quick knock down, but many locusts seemed to recover in a few hours.
The committee looked at different dosages and started recommending six grams per acre although seven grams was more effective in some cases while as little as five grams worked well.
Also in use are the phenylpyrazoles, which are persistent and work at low level dosage. It is an effective barrier treatment so overall spraying may not be required. It also controls termites.
Biopesticides such as fungal treatments are slow acting and specific to certain insect species. They are environmentally acceptable but farmers need to be educated about how this type of control works.
“Farmers wanted insects stone dead within a few hours or complained the product did not work,” Matthews said.
