Insect Pest Infestations

Primary reference(s)

IPPC Secretariat, 2024. Glossary of phytosanitary terms. International Standard for Phytosanitary Measures No. 5. Rome. FAO on behalf of the Secretariat of the International Plant Protection Convention. Accessed 20 March 2025.

Annotations

Key relevant UN convention / multilateral treaty

The International Plant Protection Convention (1997) is an intergovernmental treaty signed by over 180 countries, aiming to protect the world’s plant resources from the spread and introduction of pests and promote safe trade (FAO, 2011). The Convention introduced international standards for phytosanitary measures as its main tool to achieve its goals, making it the sole global standard-setting body for plant health (FAO, 2005). The IPPC is one of the ‘Three Sisters’ recognized by the World Trade Organization’s (WTO) Sanitary and Phytosanitary Measures (SPS) Agreement, along with the Codex

The Convention on Biological Diversity (1992) has three main objectives: the conservation of biological diversity, the sustainable use of the components of biological diversity, and the fair and equitable sharing of the benefits arising out of the utilization of genetic resources (United Nations, 1992). At the time of writing, there were 196 parties to the Convention on Biological Diversity (Convention on Biological Diversity, 2021).

Codex Alimentarius (Codex Alimentarius, no date).

WTO Agreement on the Application of Sanitary and Phytosanitary Measures (SPS Agreement) (1994) (WTO, no date).

Drivers

The agriculture and forestry sectors face many risks, such as climate and market volatility, pests and diseases, extreme weather events, and an ever-increasing number of protracted crises and conflicts. Issues around outbreaks of animal and plant pests and diseases are of major concern due to their role in biological disasters and in many food chain emergencies.

Favourable climatic conditions, disruption of ecosystems and negligence of crop/forest hygiene contribute to growth in insect populations which can cause substantial damage regularly. In many cases, the long-distance spread of insects results from the transportation of infested goods.

Higher temperatures, severe and extreme weather events and drought stress can all result in reduced vigour of trees, making them more vulnerable to outbreaks of native and introduced pests and diseases. For example, the dieback of millions of hectares of pine forests caused by outbreaks of native bark beetles in Central America, Europe and North America is associated with climate change, impacts of extreme weather events and, in some cases, inadequate forest management practices (FAO, 2020a).

Impacts

The food chain is under continuous threat with an alarming increase in the number of outbreaks of transboundary animal and plant pests and diseases. Crop pests, forest pests and animal diseases are among the costliest disasters in Africa – more so than in Latin America and Asia – accounting for over USD 6 billion in agricultural loss between 2005 and 2015, with insect pests ravaging up to 85 million hectares of forests, mainly in temperate North America (FAO, 2018). 

There are over a million species of insects. These include some key species causing direct damage to crops, and natural vegetation such as locusts, grasshoppers, armyworms and fruit flies as well as those that also function as vectors for the transmission of plant disease agents such as white flies, aphids, spittlebugs and mealybugs (FAO, 2021). 

The most recent global-scale insect pest infestation is caused by fall armyworm (FAW) spreading to almost the whole of Africa and south and southeast Asia following its jump from Latin America to Africa in 2016. It is currently causing damage to millions of hectares, particularly on maize but also other crops, creating significant food security risks. The Food and Agriculture Organization of the United Nations (FAO) has launched a Global Action for FAW Control to facilitate international collaboration to combat the insect (FAO, 2020b).  

Insect pest infestations may cause food security challenges especially if the staple food crops are affected. They can also result in market or price instability. In certain cases, such infestations can cause severe food insecurity as in the case of desert locust upsurges in the Horn of Africa and Yemen in 2020-21 (FAO, 2022). Similarly, the rapid expansion of fall armyworms in Africa and Asia has put many countries in difficult positions to protect crops, particularly of smallholder farmers.  

In addition to the impact on food security, insect pest infestations can also devastate natural landscapes. Other implications on local populations can include local conflicts or migration due to shortages in severe cases, happen in severe locust upsurges. Furthermore, in certain cases, insecticide sprays can have implications concerning the health of local habitants.

Multi-hazard context

The figure below summarises common interactions between insect pest infestations and other hazards. This information should be used with caution and not be solely relied upon in Disaster Risk Management, particularly as some interactions may not have been included. Note that hazardous events occurring together or locally in space or time may not necessarily cause, amplify or be otherwise related to each other. Specific examples of multi-hazard context can be found in the ‘Hazard drivers’ and ‘Impacts’ sections above.

Multi-hazard diagram

Risk Management

Following principles of sustainable plant production, sustainable forest management and integrated pest management practices are the best approach for control, focusing on diversified production systems, regular surveillance, preparedness before potential outbreaks, and a rapid response to prevent escalation to unmanageable scales (Guzewich et al., 1997).  

Improving national capacities in preparedness, contingency planning, surveillance and rapid response is crucial for preventing infestations and mitigating their impact. Likewise, international cooperation, data sharing and knowledge exchange are essential for addressing transboundary infestations and upsurges. Good examples of international collaboration include risk-informed response to the expansion of fall armyworm across Africa and Asia as well the desert locusts upsurge in 2020-21. FAO has developed and implemented several global initiatives to address these challenges (FAO, 2020c). In the case of desert locusts, collective efforts by FAO, governments and partners averted 4.5 million tonnes of crop losses, saved 900 million litres of milk production and secured food for nearly 42 million people (FAO, 2022). 

Post-disaster needs assessment (PDNA) is designed to evaluate immediate needs for recovery and restoration for better disaster response. The focus of this mission, however, is on estimating socioeconomic impact; and currently does not take into account longer-term damage and loss caused to natural environments and forests. In addition, damage caused by small-scale fires, small windthrow events, and localised pest infestations remains largely unreported, despite meeting the universally established definition of a disaster (FAO, 2018). 

Regarding insect pest infestations in forests, much of what is currently known about the damage and its assessment is in the form of research reports on the application of remote sensing and does not constitute a solid basis for a rigorous sector-specific assessment (FAO, 2018). In the case of Emerald Ash Borer infestations, the spread of the insect imposes important biodiversity losses and substantial costs on forestry and urban management. This affects forest-dependent communities whose incomes are directly tied to the health and productivity of forest ecosystems. As ash trees decline, industries such as logging, woodworking, and nurseries suffer, leading to reduced income for those who rely on these activities. Additionally, non-timber forest products, like nuts and medicinal plants which thrive under the canopy of ash trees, are also affected, further impacting vital ecosystem services for rural communities. 

International knowledge sharing and collaboration is critical for establishing early warning communications. At global level, the pest reporting system of IPPC can be considered the most official resource for reports of the occurrence of quarantine plant pests including diseases (IPPC, 2025). Although such reports are deposited well after the establishment of a pest, they still can serve as early warning resources for other affected countries. One of the most efficient functioning monitoring and early warning systems is the desert locust monitoring system operated by FAO. The system is supported by three commissions (Western Region, Central Region and Southwest Asia) as well as the desert locust control committee (DLCC) (FAO, 2025a). The system utilizes a network of concerned countries that run surveys and share data over satellite tools with the Desert Locust Information System (DLIS) operating since 1978 (FAO, 2025b), and is housed at the headquarters of FAO. Data collected is analysed together with geospatial and meteorological data, helping monitor the overall situation and produce forecasts and early warnings for potential outbreaks which are shared publicly with the concerned countries. Similar tools are currently being developed for locust monitoring in Central Asia and Caucasus (FAO, 2025c), for the monitoring of fall armyworm at the global level (FAO, 2025d). At regional scale, a monitoring tool was developed for red palm weevil monitoring in the Near East. 

Regarding the emerald ash borer, infested trees show distinctive symptoms and signs, but due to their late appearance, surveillance based on symptoms is not suited for detection at low insect densities. The use of traps baited with attractants targeting adult beetles is an effective method to detect the pest at the early stages of infestation and is the recommended approach for implementing surveillance within the EU. (EFSA, 2023).

Monitoring

The section and the table below offer an overview of monitoring for insect pest infestations. This information can be used for forecasting within a national early warning system (EWS). Since EWS capacities and processes differ across countries, the most current and specific information regarding EWS should be obtained from the appropriate national or regional agency/authority responsible for disaster management.

Several monitoring systems focus on plant pests and diseases particularly at the regional level, such as those in Europe (Peter et al., 2011) and North America (Meissner et al., 2015).