Press release: Birds and rain forests improve pest control

Nr. 62/2015 - 23.03.2015

Göttingen agricultural ecologists study insectivorous birds at Indonesian cacao plantations

(pug) Birds are highly important for pest regulation and can thus contribute to more successful harvests – particularly in the tropics. What is mostly unknown, however, is which species and landscape factors are key to maintaining effective natural pest suppression. Agricultural ecologists from Göttingen University were able to show that specifically the endemic bird species and the proximity to primary forest are determinants for successful pest regulation. The results were published in the Journal of Applied Ecology.

The Göttingen researchers studied cocoa plantations on the Indonesian island of Sulawesi – one of the largest cocoa producers worldwide. The cocoa tree is usually planted together with other tree species for shade management. This is why relatively high levels of biodiversity reign in such agroforestry systems. "Methods for utilising this natural biodiversity of species and the associated functions, like pest regulation by birds, for example, might help promote sustainable cocoa management, whilst also providing relief to bordering habitats and species,“ says Göttingen agricultural ecologist Dr. Bea Maas, the principal investigator of the study.

The investigated plantations differed in the amount of locally available shade and in their distance to the primary rain forest. To drive the predation success of locally available bird species, the researchers used dummy caterpillars made of plasticine. Based on the predation marks made by the beak impression in the plasticine they could judge the effectiveness of the birds' attacks. Larvae from the butterfly and beetle insect groups are the most common and most damaging to be found at cocoa plantations. "Of all endemic bird species on cocoa plantations, only the lemon-bellied white-eye was connected with larvae attacks," explains Dr. Maas. The occurrence frequency of the lemon-bellied white-eye along with the activity of this predator increase with proximity to the primary rain forest. "Therefore, the proximity of the forest is not only essential for maintaining biodiversity, but also for the ecosystem services provided by insectivorous birds," Dr. Maas adds.

The scientists emphasise the relevance of alternative land use methods to replace the use of pesticides and other chemicals. "The fact that the common lemon-bellied white-eye plays such an important role in pest regulation simplifies the implementation of sustainable management measures," explains Dr. Yann Clough from Göttingen University, adding: "Appropriate educational efforts, a greater supply of suitable nesting sites for the birds and protection of the remaining forests are the means by which cocoa can be protected against caterpillars without the use of pesticides."

Original publication: Bea Maas et al. Avian species identity drives predation success in tropical cacao agroforestry. Journal of Applied Ecology. Doi: 10.1111/1365-2664.12409

Contact address:
Dr. Bea Maas
Georg-August-Universität Göttingen
Faculty of Agricultural Sciences
Department of Crop Sciences
Grisebachstrasse 6, 37077 Göttingen
Mobile (Austria) +43-(0)650-4200494
E-mail: beamaas@gmx.at
Website: www.uni-goettingen.de/de/bea-maas/135572.html