INVASIVE ALIEN PLANTS: Queen of the night cactus: Part 3

Last week’s article dealt with the cactus mealybug, one of two biocontrol agents used against queen of the night cactus. This week, the focus shifts to the second agent: the Harrisia cactus stem-boring beetle.

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The Harrisia cactus stem-boring beetle (Alcidion cereicola) from Argentina and Paraguay was made available to South Africa in 1990 by Australian researchers, who were using it to control Harrisia cactus. In South Africa, it is used to control queen of the night cactus (Cereus jamacaru).

The adult beetle is about 14mm long and 4mm to 6mm wide, with antennae almost as long as the rest of its body. Its wings are mottled brown and grey, making it almost impossible to see in dry vegetation. The female’s abdomen has a sharp-pointed tip, and the male’s has a two-lobed tip.

The beetle is nocturnal, feeding on the mature green tissue of the cactus during the night and hiding in crevices on the plant during the day.