A VISITING US entomologist has slammed Australia’s use of insecticide seed dressings as a prophylactic treatment saying the treatments may be doing more harm than good by killing off beneficial insect species.
Jonathan Lundgren, Blue Dasher Farm, South Dakota, said both predatory insect species that feed on problem pests and bees, critical for the pollination of some crops, were adversely impacted by seed dressings in particular by neo-nicotinoid products, which are popular as seed treatments in Australia.
Neo-nicotinoid based insecticides are also popular in North America, but have been banned in Europe due to concern about the adverse effect on bee populations.
Speaking at the Victorian No Till Farmers Association annual conference in Bendigo earlier in the month Dr Lundgren said in research on his South Dakota farm he had found no real benefit from the use of a seed dressing.
“You’re paying $US10-15 an acre ($A32-48 a hectare) for seed dressings for crops such as soybeans and corn, you often can’t find an alternative seed without the treatment and, from what I’ve found, you might as well pay a musician to come and play the trumpet out in the field for all the good it does.”
Dr Lundgren said the adverse impact on the bee population was huge for crops requiring pollination such as canola.
“Why do we care about bees? Yields in canola are 18-40pc influenced by pollination from bees, so with no bees you have a big problem.”
“Research has shown neo-nicotinoid products are more toxic to bees than DDT.”
Instead, he urged farmers to focus on an integrated weed management (IWM) strategy and to build biodiversity.
“In North America in particular we have eliminated biodiversity in favour of a simplified rotation of soy and corn and we are replacing the function of the biodiversity with chemicals.”
“It easier in the short term to maintain these simplified, degraded agro eco systems with pesticides but this is not sustainable, we’ve replaced biotic resistance with pesticide and this won’t work forever.”
He said the problem for farmers was not that there were insects in the paddocks but that there were uneven populations where problem insects built up in large numbers because of a lack of predator species.
“We need to increase the biodiversity and that means smaller paddocks, wider verges and margins on the edge of fields and more diverse rotations.”
“In research, we’ve found rotations with four to seven different crop types work best.”
Dr Lundgren also suggested growers look at cover crops over summer as a means of building up a habitat capable of sustaining a range of beneficial insect species, along with intercropping two crop species within the one paddock.
Dr Lundgren previously worked for the US Department of Agriculture (USDA) but quit after he alleged he was suspended after complaining USDA was blocking his research into the harmful effects of insecticides on pollinators.
Bayer, distributor of Gaucho, a major neo-nicotinoid seed dressing in Australia was contacted for comment but is yet to reply.