Spiders’ web of sustainability
by Vincent Ciccarello
The notorious redback spider may have an important role to play in pest control and stopping
the spread of disease.
Frogs might find they have a challenger to their status as markers of a healthy environment – spiders.
Unlike frogs, spiders are suited to most climates, ranging from natural forests to deserts. They are also very efficient predators of pests in a variety of agricultural ecosystems.
According to spider biodiversity expert, Dr Sivasubramanian Karuppusamy from Tamil Nadu Agricultural University, spiders are underrated.
"Spiders, especially venomous ones, are considered pests," he said. "But their potential as pest controllers, and in controlling vectors of disease, is not really appreciated."
As part of a professional development program, Dr Karuppusamy is learning ecological risk assessment methodologies under the supervision of Professor Nanthi Bolan at UniSA’s Centre for Environmental Risk Assessment and Remediation.
Dr Karuppusamy’s interest in the role of spiders in the globally booming organic farming sector led him to The Organic Advanced Agricultural Concepts farm at Tooroot on the Victoria/SA border, which managed by former Tamil Nadu Uni colleague Dr Gunasekar Nachimuthu.
It was there, while surveying spider diversity, that he encountered the redback spider for the first time.
"The redback has a notorious reputation in Australia but, like most spiders, it will only bite if it is disturbed directly in its habitat. If we handle it thoughtfully, there is a lot the redback and other spiders can offer us," he said.
One benefit is the elimination of pests, such as aphids and thrips without the need for pesticides; less obvious is the control of disease-carrying pests such as mosquitoes.
Dr Karuppusamy said buyers of organic produce need not be afraid of finding an eight-legged surprise.
"Spiders will remain in the cropping. They usually stay in their webs where they catch their prey. There is no risk to consumers, rather, they can be considered friends to all growers and consumers as they serve as a natural pest control agent and help in producing a chemical free produce," he said.
"And farmers have to take adequate precautions, such as wearing gloves when weeding or fertilising."
By developing a better understanding of spiders and their prey, Dr Karuppusamy says it should be possible to mass propagate specific species of spiders and to release them into the agricultural system as a natural bio-control agent.