For the first time, researchers in Australia have documented insecticide resistance in field-collected populations of bluegreen aphids, Acyrthosiphon kondoi—a worldwide pest of pulses and other legume crops.
The study, published in Pest Management Science, serves as a warning to growers globally and highlights the need for new strategies to manage this pervasive pest.
Evatt Chirgwin, evolutionary biologist at Cesar Australia and corresponding author of the study, explained that the research was prompted by reports of conventional insecticides failing to control A. kondoi populations.
"Our primary motivation was to help Australian growers understand an emerging pest management challenge," said Chirgwin. "Australian growers have traditionally relied upon two types of insecticides (organophosphate and carbamates) to protect their legume crops from A. kondoi. However, in recent years, multiple growers in Southern Australia reported these insecticide sprays were no longer controlling A. kondoi, which indicated this pest may have evolved insecticide resistance for the first time."
A. kondoi is an agricultural pest in the U.S., South America, Asia, Europe, Africa and Australia. Chirgwin explained that they damage crops by feeding on upper leaves, stems, and terminal buds. "A. kondoi also causes indirect damage by spreading plant viruses, including cucumber mosaic virus and bean yellow mosaic virus," he noted.
The team collected A. kondoi populations from lentil and alfalfa paddocks where insecticide control failures have recently been reported across Victoria, South Australia, and New South Wales. The populations were exposed to different insecticides in bioassays, revealing moderate resistance to three insecticide groups: organophosphates, carbamates, and pyrethroids.
Explaining the impact of resistance at this level to Australian growers, Chirgwin said, "On a practical level, growers cannot rely on organophosphates and carbamates (at the registered rate) to confidently control these newly evolved A. kondoi populations. Still, the low-to-moderate levels (20-40 fold) of resistance shown by A. kondoi in this study is less than some other aphid species (i.e., >100 fold) have been able to evolve to these chemicals."