Imported wasps fighting world’s worst citrus disease in California

The fight is on in California to stop the spread of huanglongbing, the worst disease in the world to attack citrus trees. According to a recent blog entry from the University of California Division of Agriculture and Natural Resources, researchers are trying to combat the insect responsible for spread of the disease, Asian citrus psyllid, with its natural enemies.

The tiny wasp Diaphorencyrtus aligarhensis and its cousin cousin, Tamarixia radiata, have both been introduced to southern California and, it is hoped, are helping curtail psyllid populations. Both wasps were originally imported from Pakistan by Mark Hoddle, a University of California Cooperative Extension biological control specialist.

In addition to importing natural predators, farmers have been spraying their orchards to keep Asian citrus psyllid numbers down, and agricultural officials are monitoring traps to track the pest’s movement.

The wasps are mass-produced by seeding cages with severely trimmed citrus trees that sport a lot of new growth. Asian citrus psyllid greedily feed on the new growth, and wasp populations in turn feed on them. These wasps are then harvested, and adult psyllids in the cages are killed.

Top image: Wasps like these are being used to fight the spread of citrus disease. (Credit: Mike Lewis)