Tuesday, March 28, 2023

Alert: Brown locust outbreaks rearing its head

Estimated reading time: 4 minutes

Table grape farmers in the Hex River Valley, Hanover district of the Northern Cape Karoo and Cradock in the Eastern Cape reported brown locust outbreaks in varying levels of infestation in recent weeks.

The report from a livestock farmer 15 km north of Hanover early in August was surprising because a large swarm of flyers was on his farm at a time when the temperature was low to very low. This is unexpected because the brown locust is normally dormant in winter and only a few individuals may survive the cold conditions. The report from table grape farms in the Hex River Valley indicated that a large tract of land was covered in the solitary phase grasshoppers.

Solitary phase grasshoppers are larger and heavier than the migratory phase brown locust. Once the grasshoppers aggregate into larger swarms, they become migratory locusts of smaller size and significant numbers. A mid-August hatching of brown locusts close to Cradock was not unexpected because the insects invaded parts of the region during the late summer and early winter of 2022. This is, however, of concern because it is close to intensive crop farming areas.

Read more about locust officers here.

Expected outbreaks during the spring and summer of 2022

The Kalahari, Karoo, Eastern Cape grasslands and savannah, and Western Cape fynbos regions have all had rain during the summer, autumn, and winter of 2022. Soil moisture over the endemic outbreak areas of the Karoo is very high and conducive to brown locust outbreaks. The freezing cold that swept over the southern parts of Namibia into the Kalahari and Karoo may delay or even prevent a brown locust outbreak in those areas. However, locust outbreaks eastwards are very likely to occur as far south as Gqeberha (Port Elizabeth).

Read more about locust pest management here.

Preventing a mass outbreak is everyone’s responsibility

CropLife SA is of the opinion that the brown locust is a national challenge that warrants the buy-in of all citizens to prevent mass swarming as we have seen during the first half of 2022. Any hatching of the small black insects, hopper bands from the first instar (also known as rooibaadjies to flying swarms must be on the radar of all citizens. The purpose of early warning is to estimate what the magnitude of the outbreak will be and to perform control operations with the least impact on the environment.

The Department of Agriculture, Land Reform and Rural Development (DALRRD) has a dedicated directorate to deal with the migratory locusts and red-billed queleas that are listed as national pests in terms of the Agricultural Pests Act, 1983 (Wet 36 of 1983). However, DALRRD relies on farmers and citizens to execute their mandate to effectively manage these pests. Registered pyrethroid insecticides are provided by supplier companies to the state, which then uses a network of teams to control locust swarms.

It is imperative that all outbreaks are reported to DALRRD’s locust office in De Aar at 053 631 3122 or 053 631 3261, or to the locust office in Upington at 083 326 7773. Alternatively, any sightings or outbreaks can be reported to CropLife SA via WhatsApp on 082 446 8946, upon which we will report it immediately to the officials of DALRRD. Farmers should also avail themselves to the district locust control officers in their respective areas and keep their numbers on hand to report outbreaks.

Read more about Prieska’s locust problem here.

The impact of locust control operations on the arid zone ecology

Pest management operations need not have a devastating impact on the ecology. It is very important though to abide by the principles of ecologically compatible pest management, which, in the case of the brown locust, means that the outbreaks must be controlled at the earliest possible stages by integrating mechanical means of destroying or severely damaging hopper bands, and using only those insecticides that are registered for the brown locust strictly according to label instructions.

All efforts should be expended to prevent small hopper bands from aggregating into massive swarms. Flyer swarms of thousands of hectares were recorded in April 2022 in the Karoo around Jansenville and Graaff Reinet.

Early action is required this coming season to prevent a re-occurrence of a similar situation. Farmers in the Karoo and Namaqualand proved that they could destroy small hopper bands by chasing flocks of sheep over the swarms. For more information please contact Dr Gerhard Verdoorn, operations and stewardship manager at CropLife South Africa at gerhard@croplife.co.za or 082 446 8946. – CropLife South Africa

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