Vergelegen Wine Estate in South Africa\u2019s Western Cape is using an unconventional method to keep its 130 hectares of vineyards both virus and pesticide free. Pairing technology and nature, the 324-year-old wine estate is using drones to drop predatory wasps that control pests without the use of insecticides. <\/p>\n
The project is being carried out by SkyBugs, a partnership between Cape Town-based FieldBUGS, which supplies the predatory insects, and agritech company Aerobotics, which works with a network of drone pilots to disperse the bugs accurately. <\/p>\n
Predatory wasps are increasingly being used for pest control in South Africa, and other parts of the world. SkyBugs\u2019 drones fly roughly 30 meters above the vineyard, carrying a \u201cmotor-driven mechanism equipped with a cartridge,\u201d says Matt Davis, head of mapping operations at Aerobotics. \u201cAs the motor rotates, a plastic film unfolds, releasing wasp pupae (the stage of an insect between larva and adult).\u201d <\/p>\n
Each flight covers up to 20 hectares and 500 Anagyrus wasps \u2014 which are indigenous to South Africa \u2014 are released per hector, before the drone lands so the team can insert a fresh battery and insect cartridge. Data is also collected via an app. <\/p>\n
The target of the tiny, 3-milimeter-long <\/strong>Anagyrus is the troublesome mealybug,<\/strong> which can spread the debilitating vine disease known as leafroll virus, which is detrimental to the overall grape harvest. <\/p>\n For farmers, spotting the virus and controlling the mealybugs can be costly, time consuming and labor-intensive. SkyBugs says aerial drone application is proving to be faster and much more cost effective than spraying insecticides, which can be detrimental to the environment and to insects, such as the cross-pollinating bees that are integral to the ecosystem. <\/p>\n After the pupae are dropped, adult wasps emerge and are attracted by the mealybugs\u2019 pheromones. The wasps lay eggs inside the mealybugs, consuming them from the inside out \u2014 known as parasitizing \u2014 leaving their host hollow and dead. <\/p>\n \u201cThe leafroll virus has virtually been eradicated in the farm,\u201d says Rudolf Kriel, viticulturalist at Vergelegen. <\/p>\n For over 20 years the Vergelegen team has worked closely with virologist and leafroll virus expert Gerhard Pietersen. Formerly a professor at the University of Pretoria, and at Stellenbosch University, Pietersen founded a biotech company called Patho Solutions to further tackle agricultural diseases. <\/p>\n \u201cGrapevine leafroll associated virus-3 (GLRaV-3) or \u2018Type three\u2019 is an extremely serious virus of grapevines,\u201d Pietersen explains. \u201cThe virus replicates itself in the plant\u2019s vascular system, preventing the nutrients from flowing. The virus\u2019s weakness is that its only host in nature is the grapevine. Not all plant viruses have such limits to the hosts that they can infect.\u201d <\/p>\n \u201cThe result of infestation is that the berries on the bunch ripen unevenly, failing to achieve the desired color and take a long time to build up sugar which is essential in wine making,\u201d he adds. <\/p>\n Once a vine is infected, signs of the virus can be spotted with the naked eye. Starved of much-needed nutrition, the leaves turn red in autumn and reveal green veins, followed by a slight downward curling of the leaves. <\/p>\n \u201cAny attempts to take out an infected vine and replace it with a new one can prove ineffective if pieces of the infected vine are left behind in the soil,\u201d says Pietersen. <\/p>\n He adds that the best way to control this virus is \u201cto remove all infected vines in a vineyard along with controlling the mealybug vector. This is best achieved over a whole estate, but this is not economically viable as the input costs to start over are very high.\u201d <\/p>\n Cultivating the predator\u2019s playground<\/h2>\n