Bats: The Answer To Macadamia Pests?

Despite being well known for their pest control abilities, bats remain understudied and misunderstood, and their numbers have been on the decline for various reasons. Now research is showing that these mammals may be invaluable to macadamia farmers, whose pest control costs are rising while their nut quality is dropping. Lindi Botha spoke to Dr Valerie Linden about bats’ potential to save the industry millions of rands.

- Lindi Botha

Plagued by stink bug populations that seem to multiply despite increased pest control application, the macadamia industry in South Africa is losing R200 million a year to insect pest damage. This damage is related to unsound kernel, a condition where the macadamia nut in the shell is damaged by insects while ripening on the tree.

Many farmers have reacted by applying ever more pesticide, which has only served to exacerbate the problem as natural predators to harmful insects are also eliminated, detrimentally affecting the entire ecology within orchards.

One of South Africa’s largest macadamia production areas, Levubu in Limpopo, happens to be home to 14 bat species. This, coupled with the economic significance that bats could offer macadamia farmers, led Dr Valerie Linden, from the Centre for Invasion Biology at the University Marble Hall of Venda, to conduct research that could eventually see bats protected and nurtured by the agricultural community.

“Bats are known to be active in South African macadamia orchards and to feed on major insect pest species, like the green vegetable bug (Nezara viridula), macadamia nut borer (Cryptophlebia ombrodelta), two-spotted stink bug (Bathycoelia natalicola) and litchi moth (C. peltastica),” says Linden. “What we didn’t know was just how much of the pest insect population these bats consumed, which is what we set out to study.