Insects play a crucial role in Tasmanian agriculture - supporting crop production, soil health and natural pest control. However, climate change has the potential to significantly disrupt these systems, increasing the risk of pest outbreaks and crop damage across the state.
Tasmanian Institute of Agriculture (TIA) entomologist Dr Jon Finch spoke about the potential impacts of a changing climate at the TIA Vegetable Research Field Day at Forthside in December, urging Tasmanian farmers to consider how insect populations could change in the years ahead.
"One of the biggest threats to agricultural productivity in Tasmania and across Australia is climate change," he said.
"There are three main ways that insects are going to be influenced by climate change.
"The first main way is by changes in temperature. Insects respond to temperature and they grow faster and they reproduce more so that means we're going to have more insects.
"The second major change will come from an increase in carbon dioxide levels. If there's more carbon dioxide in the atmosphere that means plants will actually photosynthesise more which sounds positive but also reduces the nutritional quality of plants.
"The amount of carbon goes up, the amount of nitrogen goes down and insects are going to have to eat way more of our crops in order to complete their development, so they're going to cause a lot more crop damage."
Dr Finch said climate change is likely to cause the protein content of plants to drop by around 15 per cent while insect consumption could increase by approximately 20 per cent to compensate.
"That combination has the potential to significantly increase crop damage," he said.
Changes in rainfall patterns also has the potential to impact insect numbers.
"Rainfall is really important because insects respond very quickly to it. It's likely that when we get a big drought that everything is going to die off, the pests and their predators included, but when the rains hit the pests are going to bounce back much faster," Dr Finch said.
"With changes in temperature, carbon dioxide and rainfall, it's likely we'll see increased pest pressure in the future. We need to start thinking about how to equip growers to deal with that challenge, through better forecasting, improved control methods and stronger cultural control methods."
Because insects are cold blooded, their biology is highly sensitive to rising temperatures. This leads to faster growth and reproduction, more generations per year and improved survival in mild winters.
"Severe drought causes water stress, making plants more susceptible to pests and diseases. Irrigation may make crops more resilient but also more attractive to pests," Dr Finch said.
Dr Finch said growers should be aware that climate change is likely to alter where pests can survive.
"Some pests will shift their range as the climate warms. Species like Queensland fruit fly and fall armyworm will be more capable of surviving in Tasmania year-round under a warming climate. Strong biosecurity is more critical than ever in order to keep these pests out," he said.
Dr Finch warned that increased pest pressure may lead to greater reliance on pesticides
He said a broader toolbox of management strategies was needed including crop rotations, intercropping and regional production breaks, however more Tasmanian specific research is needed.
"It's very likely that the response of this is there's going to be more pesticide use. If people feel threatened or their livelihood is threatened, they're probably going to spray more things," Dr Finch said.
"We can't afford to do that as pests will just become more resistant, we need to think of new things to do.
"There's also a need for better monitoring and forecasting to detect sudden changes in pest populations.
"Monitoring and forecasting will be key to maintaining current levels of production into the future."
