A team of global ecologists are investigating the decline of insect populations in the world’s tropical forests, with the published review findings revealing that anthropogenic pressures, invasive species and climate change impacts could have disastrous consequences for ecosystems globally.
Griffith University entomologists Professor Emeriti Nigel Stork and Roger Kitching were part of the review paper published in Nature Reviews Biodiversity. The study was led by former Griffith PhD student Professor Louise Ashton and Dr Mike Boyle from Hong Kong University.
The team highlighted the crucial role that insects played and the threats they faced in understudied tropical regions.
“Most studies of insect declines are from modified landscapes in Europe and North America,” Professor Ashton said.
“However, most insect biodiversity is in the tropics. Due to a lack of long-term monitoring data, we do not fully understand how insect diversity changes over time.
“This review and our related projects highlight this issue and bring together new long-term insect data to help understand potential tropical insect declines and their consequences for ecological functioning.”
Insects on tropical islands were particularly vulnerable to invasive species, with many unique species already extinct.
Other threats included urbanisation, habitat loss and fragmentation, and pollution from agriculture and urban areas.
More broadly, climate change poses a huge threat to insect populations across the tropics, not just through rising temperatures but through disruptions to crucial weather cycles such as El Niño and La Niña.
“Declining insect biodiversity may have knock-on consequences for ecosystem processes such as carbon cycling and pollination, which could impact the Earth globally.”
Professor Emeritus Nigel Stork
“Changes in the ecosystem balance could also lead to increased outbreaks of pests and insect-vectored diseases such as dengue and malaria in humans, as well as similar diseases in livestock, affecting global health and reducing food security.”
The team emphasised large gaps remained in understanding due to insufficient data from tropical forests. However, recent advances in artificial intelligence and genetic methods were beginning to address these challenges.
Over the past three years, the team has conducted extensive field research across tropical Australia and Asia, revisiting forests where insect studies were previously undertaken.
Ongoing research in Lamington National Park, and at the Canopy crane at the Daintree Rainforest Observatory involved collecting ants, moths, beetles and butterflies using specialised traps to assess how climate change has re-wired these populations over the last two decades.
Similar studies were being carried out in Yunnan, China and Daintree, Australia, including the use of canopy cranes to collect insects from the rainforest canopy.
“The next stage of this research is to study the ecological roles and functions of insect species to understand how changing populations will impact tropical forest ecosystems,” Professor Kitching said.
“The important processes provided by beneficial insects, including regulating forest growth through herbivory and nutrient cycling, are dwindling over time, so it’s vital that we increase the understanding of insects and their roles in these regions as much as possible and now before it’s too late.”
The review paper ‘Causes and consequences of insect decline in tropical forests’ has been published in Nature Review Biodiversity.
