The scale of the plant’s importance is difficult to overstate. In Ethiopia’s Tigray region alone, cactus pear historically occupied more than 360,000 hectares, supporting roughly 200,000 rural households with virtually no alternative means of securing a livelihood. In some areas, the fruit provides up to 40 percent of the annual food intake for rural families, while during the lean summer months from June to August it serves as a critical bridge when other crops have not yet matured. The plant’s unique Crassulacean Acid Metabolism, a photosynthetic adaptation shared with other succulents, allows it to open its stomata at night and minimize water loss, giving it extraordinary water-use efficiency in landscapes where indigenous woody vegetation has long since declined. Beyond food, the cactus anchors a seasonal economy of harvesting, transport, and urban street vending that once provided employment for more than 183,000 households, offering a low-entry livelihood for youth and women in cities such as Mekelle, Adigrat, and Asmara.

The catastrophe began, ironically, as a business venture. In April 2003, the carmine cochineal insect, Dactylopius coccus, was intentionally introduced from South Africa to southern Tigray with formal authorization from the Federal Ministry of Agriculture and Rural Development, with the goal of launching a commercial carmine dye industry. The insects were officially released in September 2004 across three trial sites, including the Endayesus campus of Mekelle University. Early returns were promising: farmers collected and exported dried cochineal worth up to 984 dollars per hectare, and the venture generated more than 550,000 dollars in foreign exchange during its first ten months. But the project lacked structured containment protocols, and when the investor’s license was revoked in 2010, monitoring ceased entirely. The insects escaped cultivation and transformed from a managed bio-resource into a devastating invasive pest, capable of killing cactus plants within six to ten months of attack through chlorosis, dieback, and total tissue collapse.

By 2019, more than 75,000 hectares in Tigray were infested, and communities had organized remarkable grassroots responses, including community mobilization campaigns and buffer zones that held the spread roughly in check between 2016 and 2020. Then came the Tigray War. The conflict, which raged from 2020 to 2022, caused a total collapse of these community-led mechanical and chemical control systems. Routine physical monitoring, quarantine enforcement, and the pruning and burning regimens that had kept the pest at bay simply stopped. In the vacuum, wind-borne dispersion of the insect’s mobile first-instar crawlers, driven by prevailing seasonal wind patterns, accelerated unchecked across contiguous cactus belts. Regional infestation coverage surged from roughly 80,000 hectares in 2020 past a projected 120,000 hectares by 2026, a trajectory the review’s author, Mulat Kebede of the Tigray Agricultural Research Institute, characterizes as a rapid post-war surge driven directly by the collapse of human governance.

The review, which followed PRISMA guidelines and distilled 170 core studies from an initial pool of 3,159 records across Scopus, Google Scholar, and Web of Science, quantifies the ecological toll in stark terms. In Tigray, four key indicators of ecosystem health, biodiversity, faunal habitat, soil fertility, and drought resilience, are projected to approach near-zero values by 2026, with biodiversity and faunal habitat plummeting from baseline scores of 100 to approximately 10. In the Eritrean Highlands, the decline is slightly less steep but equally sobering, with drought resilience falling from a near-perfect 98 in 2004 to roughly 32 by 2026. The social consequences are captured in a social crisis index that reaches 95 in Tigray, alongside a degraded land index of 92 and an economic loss index of 88, reflecting a regional catastrophe in which the loss of food security, livestock feed, and soil conservation has fueled rising food insecurity and youth migration from rural areas.

One of the most alarming findings concerns carbon. Managed cactus pear plantations in Tigray sequester approximately 12.8 tonnes of carbon per hectare per year, among the highest rates of any evaluated land-use category in the region, while naturalized wild stands in Eritrea sequester 8.9 tonnes and even abandoned farmlands recolonized by the cactus store 4.5 to 5.1 tonnes annually. Under sub-optimal growing conditions typical of degraded landscapes, the Food and Agriculture Organization and ICARDA estimate that cactus pear can generate sequestration rates equivalent to roughly 30 tonnes of carbon dioxide per hectare per year. As these stands die and their woody biomass decomposes, that stored carbon is released back into the atmosphere, threatening to transform a climate-smart carbon sink into an active carbon source. In a region already battered by drought and displacement, the loss of this biological buffer compounds both the humanitarian and the climate crisis simultaneously.

The review also formalizes the conceptual framework of the conflict-pest nexus as a self-reinforcing feedback loop. Armed conflict drives insecurity, displacement, and institutional disruption, which in turn produce governance failures: diminished surveillance, weakened early detection, inadequate pest control, and collapsed agricultural extension services. These deficits unleash biological outbreaks, marked by heightened insect reproduction and rapid geographic dispersal, which then drive ecological degradation and the loss of forage, soil cover, and ecosystem resilience. The resulting socioeconomic hardship, from plunging household incomes to deepening food insecurity, further erodes societal resilience and administrative capacity, feeding directly back into the initial instability. It is a cascade in which ecological collapse and human suffering amplify one another, and it explains why the cochineal crisis in the Horn of Africa has progressed so much faster than comparable invasions elsewhere.

Yet the research also points to genuine hope, grounded in tools that smallholders can deploy even amid instability. Laboratory bioassays and field trials have shown that aqueous extracts of Tree Tobacco, Nicotiana glauca, mixed with liquid soap surfactants, dissolve the insect’s protective waxy coating and achieve mortality rates exceeding 90 percent. Even more striking, methanol extractions of Solanum linnaeanum, which concentrate lethal secondary metabolites such as tannins, saponins, and alkaloids, have secured up to 99.3 percent pest mortality in controlled tests. These botanical biopesticides, alongside evaluated extracts from neem, Tagetes minuta, and Euphorbia tirucalli, offer a low-cost, decentralized alternative to synthetic organophosphates like Dimethoate, whose supply chains and ecological risks make them poorly suited to conflict zones. Complementing these interventions, tissue-culture protocols using Murashige and Skoog media enhanced with benzylaminopurine can regenerate completely pathogen-free, high-vigor planting stock, while the selection of cochineal-resistant genotypes is supported by documented smallholder willingness to pay for resilient clones.

The taxonomic complexity of the invader adds another layer of urgency. While Dactylopius coccus was the species originally introduced for dye production, ongoing regional monitoring indicates morphological and genetic overlap with Dactylopius opuntiae across expanded infestation zones. This distinction carries real operational consequences, because biological control strategies depend on host-specific predatory beetles such as Cryptolaemus montrouzieri and Hyperaspis species, whose effectiveness varies with the target biotype. Management protocols must therefore verify biotype susceptibility before releasing mass-reared predatory agents, a task that requires exactly the kind of sustained surveillance capacity that conflict has destroyed. In the Near East and North Africa region, where similar cochineal invasions threaten cactus systems, research has moved toward resistant cultivars and biological control; in the Horn of Africa, by contrast, the science has become what the review describes as a science of survival.

Halting the terminal decline, the review concludes, demands a coordinated package: immediate regional stability, formal cross-border scientific cooperation between Ethiopia and Eritrea, tissue-culture propagation hubs producing entirely insect-free clean planting stock, and the large-scale deployment of conflict-resilient integrated pest management that combines field sanitation, resistant varieties, and botanical biopesticides. The stakes extend far beyond a single crop. The cactus pear of the Horn of Africa is a soil guardian, a carbon vault, a famine buffer, and an economic lifeline all at once, and its loss would ripple through food systems, livelihoods, and climate commitments across the borderlands. Whether these highlands retain their prickly green ramparts, or watch them dissolve into white, waxy colonies of a runaway insect, will depend on whether peace and science can arrive before the last cladodes succumb.

Subject of Research: The combined impact of armed conflict and cochineal insect invasion on cactus pear ecosystems and ecosystem services in the Horn of Africa

Article Title: The conflict and pest nexus drives the catastrophic decline of cactus pear ecosystem services in the Horn of Africa

Article References: Kebede, M. (2026). The conflict and pest nexus drives the catastrophic decline of cactus pear ecosystem services in the Horn of Africa. Discover Agriculture, 4(1), Article 293. https://doi.org/10.1007/s44279-026-00762-6

Image Credits: AI Generated

DOI: 10.1007/s44279-026-00762-6

Keywords: cactus pear, Opuntia ficus-indica, cochineal, Dactylopius coccus, Tigray War, conflict-pest nexus, invasive species, carbon sequestration, integrated pest management, botanical biopesticides, food security, Horn of Africa

The research team, led by scientists at Adigrat University, combined a PRISMA-informed systematic review of 59 peer-reviewed and institutional sources with extensive primary fieldwork. Between 2021 and 2024, the researchers carried out 42 key informant interviews and 12 focus group discussions across six districts and 80 villages in the Eastern Zone of Tigray, supplementing these with participatory rural appraisal exercises, transect walks, community mapping, and soil analyses. This triangulated design, the authors emphasize, was chosen deliberately: because no baseline measurements of cactus biomass or stand structure existed before the invasion, the team prioritized converging lines of evidence over over-confident single estimates, and they flag all numerical results as indicative extrapolations rather than precise measurements.

The historical record uncovered by the study reads as a cautionary tale of institutional failure. Cochineal was intentionally introduced between 2004 and 2007 at three sites near Mekelle, Wajarat, and Mehoni, with the goal of producing carminic acid, a valuable crimson dye. The experimental project was abruptly abandoned, however, without post-release monitoring, containment measures, or technical support to farmers. Infested cladodes were distributed across multiple districts, and the insect, which has no natural predators in the region and a high reproductive rate, spread unchecked. Community members in Raya Azebo could reconstruct the pest’s arrival years before it appeared in official reports, suggesting formal surveillance underestimated the true rate of expansion from the very beginning.

The numbers chart an accelerating catastrophe. By 2015, roughly 16,000 hectares were infested; the figure nearly doubled to 31,184 hectares within a single year, reached 75,570 hectares by 2018, and climbed to about 91,000 hectares by 2020, with cumulative damage now exceeding 96,000 hectares. In the southern and southeastern zones of Tigray, cactus pear production has collapsed entirely. Notably, the eastern zone had managed to contain the pest to just 2,676 hectares, about 5.7 percent of its cactus cover, through coordinated cultural, mechanical, and chemical control. That progress was undone when the Tigray war erupted in late 2020: community mobilization, monitoring, and control programs collapsed amid displacement and institutional destruction, and by May 2024 the infested area in the eastern zone had nearly doubled to 5,239 hectares, surpassing 11 percent of the zone’s cactus coverage.

The ecological stakes are considerable because cactus pear functions as a keystone dryland species. Using Crassulacean Acid Metabolism (CAM) photosynthesis, the plant opens its stomata at night to absorb carbon dioxide, dramatically reducing water loss and allowing it to thrive on degraded, saline, and drought-prone land where conventional crops fail. Under favorable conditions it can sequester up to 30 tons of CO2 per hectare per year, and literature values suggest roughly 12,500 kilograms of carbon stored per hectare. Extrapolating across the destroyed area yields an estimated 1.2 million tons of carbon whose sequestration capacity has been compromised, though the authors caution that, given the absence of baseline biomass data in wild stands, such figures should be read as indicative of foregone capacity rather than verified emissions.

The soil evidence is more concrete. Laboratory analyses showed that soils beneath cactus canopies hold substantially more organic carbon (2.48 percent versus 1.82 percent), organic matter (5.45 percent versus 3.23 percent), and total nitrogen (0.25 percent versus 0.19 percent) than adjacent open ground, with available phosphorus reaching 161 ppm compared with just 22 ppm. Canopy soils were also moister (9.49 percent versus 6.74 percent) and less compacted (bulk density of 1.28 versus 1.46 g/cm3). In effect, each cactus stand acted as a nutrient island, stabilizing slopes, dampening runoff, and sheltering understory vegetation. Farmers interviewed for the study described the aftermath bluntly: after the cactus died, the land began to erode away even with small rains. Field observations confirm increased gully formation, topsoil loss, reduced infiltration, and expanding barren patches across affected hillsides.

The loss has rippled through biodiversity as well. Residents reported declines in bird species that once nested on cactus branches and in small mammals that depended on cactus fruits, alongside the disappearance of the protective microenvironments that had allowed native shrubs and grasses to persist. Yet the study also documents unexpected glimmers of recovery: in places such as Shilen in the Maichew-Mekhoni corridor, previously suppressed indigenous woody and herbaceous species have begun to regenerate where cactus died back, suggesting that with active restoration, cochineal-driven mortality could open ecological niches for native vegetation to reclaim degraded land.

The socio-economic toll has been severe. Before the outbreak, cactus pear provided three to five months of household food security annually, along with drought fodder worth 20 to 30 tons of fresh cladodes per hectare, seasonal cash income averaging roughly USD 11,272 per hectare under good management, and informal employment in harvesting and marketing for landless youth, many of them women. The study estimates annual fruit production losses of about 84,985 tons across the region, with cladode losses of roughly 1.9 to 2.9 million tons per year regionally. Combining production losses with degraded ecosystem services, the researchers calculate total economic damages of approximately USD 1.082 billion annually, a figure informants considered conservative. Focus groups described longer hunger seasons, rising livestock mortality, increased labor migration from districts such as Atsbi, Hawzien, and Irob, and the breakdown of traditional coping mechanisms that had relied on cactus reserves as drought insurance.

Current control efforts remain fragmented and largely inadequate. Communities have resorted to labor-intensive measures such as manually removing and burning infested cladodes, selective pruning, and coordinated clean-ups, but these approaches falter once infestations become severe. Chemical control has been tried only sporadically and suffers from high costs and environmental concerns, while biological control agents that have proven effective elsewhere remain untested under Tigray’s arid conditions. The authors identify weak quarantine enforcement, absent post-release monitoring, poor inter-institutional coordination, and limited funding as the systemic gaps that allowed the invasion to flourish and that now hamper its containment.

The study’s recommendations are direct: implement integrated pest management with rigorously evaluated biological control options, restore cactus pear using resistant varieties, strengthen enforceable quarantine and surveillance systems, embed community-based monitoring in extension services, and fold restoration into broader climate adaptation strategies. The researchers also call for long-term monitoring, remote sensing, and field-based biomass assessments to replace today’s uncertain extrapolations with defensible carbon and impact estimates. As the authors conclude, the Tigray cochineal crisis is not merely a pest problem but a demonstration of how ecological, climatic, and institutional fragilities interact, and how the collapse of coordinated governance, whether through abandoned projects or armed conflict, can convert a well-intentioned introduction into a regional environmental and humanitarian emergency.

Subject of Research: Ecological and socio-economic impacts of cochineal insect infestation on cactus pear ecosystems in Tigray, Northern Ethiopia

Article Title: Environmental degradation and climate implications of cochineal (dactylopius coccus Costa) infestation on cactus pear: a case study from Tigray, Northern Ethiopia

Article References: Gebrekidan, T. K., Gebreziher, H. G., Kahsay, H. T., Weldemariam, N. G., Berhane, E., & Gebrekidan, E. W. (2026). Environmental degradation and climate implications of cochineal (dactylopius coccus Costa) infestation on cactus pear: a case study from Tigray, Northern Ethiopia. BMC Environmental Science, 3(1), Article 16. https://doi.org/10.1186/s44329-026-00054-w

Image Credits: AI Generated

DOI: 10.1186/s44329-026-00054-w

Keywords: Dactylopius coccus, cochineal, cactus pear, Opuntia ficus-indica, Tigray, Ethiopia, invasive species, carbon sequestration, soil degradation, food security, integrated pest management, dryland ecosystems