Mills leads a three-year MPI Sustainable Food and Fibre Futures project, supported by Vegetables NZ, which has six months remaining.
The project focuses on five key questions: where the pest occurs, when it becomes economically important, how it can be managed, how it fits within existing maize pest management, and what research remains necessary.
“Our challenge was not simply to control fall armyworm; it was to understand its place within the wider maize ecosystem,” Mills told the third annual fall armyworm research workshop.
The first challenge was knowing where fall armyworm was present and how populations changed over time.
To address this, the project established a national surveillance system that combined pheromone trapping, field scouting and seasonal monitoring.
Identification guides, grower resources and the fallarmyworm.nz website were also developed.
One of the project’s early findings was that while detecting moths is relatively easy, predicting crop damage is far more difficult.
“We also learned that effective surveillance depends on growers and advisers regularly inspecting crops, which remains one of the biggest practical challenges,” Mills said.
The research found fall armyworm management should be integrated into existing pest management programmes, but action needs to be taken earlier than for other maize pests.
“When larvae are detected early, management options are generally effective and straightforward,” Mills said.
“As larvae grow and move deeper into the plant, control becomes more difficult.
“This is why management decisions must be based primarily on crop scouting rather than trap captures alone.”
Mills said that while the Sustainable Food and Fibre Futures project had nearly finished, there was still plenty of work on fall armyworm at research agencies, including the Bioeconomy Science Institute.
“We still don’t fully understand how well fall armyworm overwinters in New Zealand or what drives seasonal population changes,” he said.
“Improving our ability to forecast outbreaks remains a key priority.”
First detected in New Zealand in 2022, fall armyworm is one of the world’s most significant maize pests.
Mills said the frequency and origin of new incursions remained an important question.
“Without frequent population genetic studies, we can’t determine what proportion of the FAW population is the result of over-winter survival versus new arrivals from Australia.
“This has important implications for both biosecurity and insecticide resistance management.”
Bioeconomy Science Institute entomologist Scott Hardwick said monitoring showed fall armyworm produced three to four generations a year in the Far North and warmer regions such as Gisborne and the East Coast compared with one to two generations in southern regions.
Far North entomologist Jenny Dymock has monitored six fall armyworm bucket pheromone traps and adjacent maize crops near Kaitāia for the past four years.
She advised maize silage and grain growers in the region to sow crops in November, not December, to help avoid larval feeding damage to seedlings and cobs from second-generation fall armyworm larvae.