Biological control of an agricultural pest can protect tropical forests

Southeast Asia
Kris A.G. Wyckhuys

An international team of scientists*, involving entomologists, conservation biologists, agro-ecologists and geographers, has just revealed how on-farm insect biological control can slow the pace of tropical deforestation and avert biodiversity loss on a macro-scale. The case study concerns biological control of the invasive mealybug Phenacoccus manihoti with the introduced host-specific parasitic wasp Anagyrus lopezi in Southeast Asia. The results of this study have just been published in Communications Biology – Nature.

Mealybug attack, Photo credit: Georgina Smith / CIAT


Though often perceived as an environmentally-risky practice, biological control of invasive species can restore crop yields, ease land pressure and contribute to forest conservation. This paper illustrates the positive impacts of Biological control when done properly and using the mealybug Phenacoccus manihoti (Hemiptera) in cassava as an example, Cassava is a key food, feed and fiber crop grown on around 4 million ha in tropical Asia where use of a parasitoid wasp decreases crop losses and consequently slows deforestation. This newly-arrived mealybug caused drops in Thailand’s cassava yields during 2009-2010, triggering sharp increases in cassava prices and spurring region-wide expansion of cassava crop surfaces. This coincided with 185-608% surges in peak deforestation rates in neighboring countries. Following release of the host-specific neotropical parasitoid Anagyrus lopezi (Hymenoptera) in 2010, mealybug outbreaks were reduced, the cropped area contracted, and the pace of deforestation slowed by 31-95% in individual countries. Hence, when used sensibly and according to established guidelines, biological control of a crop pest can avert the need for synthetic pesticides, shield tropical biodiversity and deliver long-lasting environmental benefits on a macro-scale.


Expansion of the agricultural frontier & forest loss tracked with (near) real-time satellite imagery in Southeast Asia. Photo credit: Terra-i Project / CIAT


Insects provide invaluable services to humanity, including the natural control of agricultural pests, a service worth $4.5-17 billion annually to US agriculture alone. This study reveals how a judiciously-selected pest-killing insect – a minute parasitic wasp – helps resolve invasive pest problems, augments crop yields and protects tropical biodiversity. "Insect biological control reconnects insect friends and foes, and restores ecological balance in invaded agro-ecosystems", says Kris Wyckhuys, agro-ecologist at University of Queensland (Australia) and IPP-CAAS (China), and coordinator of the study. "Such nature-based approaches provide a self-sustaining ‘win-win’ solution that tackles invasive species mitigation, biodiversity conservation and profitable farming. Collaboration between conservation biologists and crop protection scientists can thus be beneficial to balance farmer realities on the ground with biodiversity conservation”.


This study underlines the ample environmental benefits of insect biological control, as a desirable alternative to insecticide-based approaches for tackling pest problems, supporting sustainable intensification and sparing land for conservation. "It is often difficult to reconcile socio-economic and ecological issues, and smallholder farmers are regularly tempted to resort to costly and environmentally damaging chemical pesticides to control pests. This study confirms that appropriate use of biological control can resolve socio-economic, environmental and ecological issues simultaneously, especially in tropical countries", adds Jean-Philippe Deguine, agro-ecologist and entomologist at CIRAD and co-author of the paper.


Agro-ecological Crop Protection, a way to preserve biodiversity in the tropics

When used with established safeguards, biological control can permanently resolve invasive species problems. The scientifically-guided introduction of specialist natural enemies to provide pest control services in field crops is in line with agro-ecological crop protection. As a cost-effective alternative to pesticide-based approaches, and relying upon nature’s services to suppress crop pests, agro-ecological crop protection aims to restore and optimize ecosystem functioning and helps ensure that crop protection benefits farmers’ pockets, consumer and producer health and the broader farming environment.

More information on agro-ecological crop protection in Southeast Asia:




Wyckhuys K.A.G., Hughes A.C., Buamas C., Johnson A.C., Vasseur L., Reymondin L., Deguine J.-P., Sheil D., 2019. Biological control protects tropical forests. Communications Biology - Nature.


 *Partners of the study:

- Institute of Applied Ecology, Fujian Agriculture & Forestry University, People’s Republic of China

- China Academy of Agricultural Sciences CAAS, Beijing, People’s Republic of China

- University of Queensland, Brisbane, Australia

- Zhejiang University, Hangzhou, People’s Republic of China;

- Xishuangbanna Tropical Botanical Gardens, China Academy of Sciences CAS, Xishuangbanna, Yunnan, People’s Republic of China

- Department of Agriculture (DoA), Ministry of Agriculture and Cooperatives, Bangkok, Thailand

- Charles Sturt University, Orange, NSW, Australia

- Brock University, St. Catharines (Ontario), Canada

- International Center for Tropical Agriculture CIAT – Asia regional office, Hanoi, Viet Nam

- CIRAD, UMR PVBMT, La Réunion, France

- Norwegian University of Life Sciences, Ås, Norway

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