Efficient chemical weed management considers precise application of herbicides, maximizing herbicide retention and absorption, reducing the impact of abiotic factors, and mitigating off-target movement in order to optimize herbicide efficacy. Hence, this study assessed the employability and cost-efficiency of an unmanned aerial vehicle (UAV) for pre-planting application and post-emergence selective grass weed control infesting legume cover crops (LCCs) in immature oil palm (Elaeis quineensis Jacq.) plantation. Field experiments were conducted in 2020 and 2021 at a research center and an oil palm replanting area in Jerantut, Pahang, Malaysia. Droplet deposition and distribution analyses revealed that the pressure at 0.25 MPa yielded better spraying coverage and increased droplet counts compared to 0.15 MPa. For pre-planting application, both UAV and mist blower resulted in total weed control. Meanwhile for selective grass control in the LCCs, conventional knapsack sprayer (CKS) application provided slightly better weed control than the UAV over the 12 weeks observation. However, cost-efficiency analysis revealed that UAV spraying yielded economically favorable for areas over 3,000 hectares, with potential savings ranging from 4% to 28%. Furthermore, UAV spraying demonstrated superior operational efficiency and reduced working hours by 37%, water consumption by 91%, and human labor expenses by 81% compared to both conventional methods. These findings underscore the potential of UAV-based spraying for large-scale weed control in oil palm plantations and highlight its efficiency, comparable effectiveness, and cost-saving benefits.

Conversion of primary forest into oil palm plantations is common in tropical countries, affecting soil properties, ecosystem services and land-use management. However, little is known about the short-range spatial soil distribution that is important for soil scientists, ecologists, entomologists, mycologists or microbiologists. In this study, seven soil properties (pH, EC (µS/m), P (mg/kg), NO3- (mg/kg), N%, C% and C:N) were measured to quantify the spatial autocorrelation across primary forest, selectively logged forest and oil palm plantation in Sabah, Malaysian Borneo. Local variograms were calculated (range ∼5 m) to determine the short-range variation, and a decision tree as well as principal component analysis were implemented to determine if the overall (global) mean differed between land uses. As hypothesised, oil palm soils deviated the most from primary forest soils, which had more fluctuating variograms and in general, a shorter range. Oil palm plantations also showed a difference in the global mean except for electrical conductivity. Selectively logged forests also differed in their short-range spatial structure; however, the global mean and variance remained similar to primary forest soil with the exception of labile phosphorus and nitrate. These results were attributed to initial plantation development, removal of topsoil, fertiliser application and topography.

Oil palm is one of Southeast Asia’s most common crops, and its expansion has caused substantial modification of natural habitats and put increasing pressure on biodiversity. Rising global demand for vegetable oil, coupled with oil palm’s high yield per unit area and the versatility of the palm oil product, has driven the expansion of oil palm agriculture in the region. Therefore, it is critical to identify management practices that can support biodiversity in plantations without exacerbating negative impacts on the environment. This study focuses on day-flying Lepidoptera (butterflies and moths), which contribute to the ecosystem functioning as pollinators, prey, and herbivore species. We assessed whether density and behaviours of day-flying Lepidoptera varied between different habitats within oil palm plantations and across seasons. We surveyed the density and behaviours of Lepidoptera communities in mature industrial oil palm plantations within the Biodiversity and Ecosystem Function in Tropical Agriculture (BEFTA) Programme sites, in Riau, Indonesia. We surveyed two distinct habitats within the plantations in March and September 2013: Edge habitats, which were bordered by plantation roads on one side, and Core habitats in the centre of oil palm planting blocks. We conducted analyses on the effect of habitat type and season on both the overall density and behaviour of Lepidoptera communities and, independently, on the most common species. In our surveys, we observed 1464 individuals across 41 species, with a significantly higher density in Edge than in Core habitats. While there was no significant difference between overall density in March and September surveys, there was an interaction between season and habitat, with density increasing more markedly in Edge than Core areas in September. There was also a significant effect of habitat and season on behavioural time budget for the community as a whole, with more active behaviours, such as foraging and mating, being recorded more frequently in Edge than Core habitats, and more commonly in September than March. The effect of habitat type, season, and their interaction differed between the six most common species. Our findings indicate that Lepidoptera abundance is affected by habitat characteristics in a plantation and can therefore be influenced by plantation management practices. In particular, our study highlights the value of road edges and paths in plantations for day-flying Lepidoptera. We suggest that increased non-crop vegetation in these areas, achieved through reduced clearing practices or planting of flowering plants, could foster abundant and active butterfly communities in plantations. These practices could form part of sustainability management recommendations for oil palm, such as those of the Roundtable on Sustainable Palm Oil.

Drawing on empirical research from Pujehun and Port Loko districts in Sierra Leone, this article explains the variable pathways of civic activism mobilised by environmental advocacy, and legal empowerment organisations, in response to two prominent land grabs. By grounding the analysis within the ontology of place, this study examines the dynamic interplay between national politics, global corporate interests, transnational advocacy, and civic agency in each place. The article finds that although the balance of power between these actors matters, the nature of corporate interests involved can be significant in determining the exact trajectory of civic mobilisation, and ultimately its success.

This paper draws on archival research to trace the techniques used by scientists and government officials involved with palm oil at the turn of the twentieth century. For them, mundane practices of “carefulness” were paramount as they worked on collecting, identifying, marketing, and improving the oil palm. But they also applied this so-called care to people: care of the oil palm was thought to presuppose care of the “native,” providing a correction for what were seen as “careless” local manners of cultivation. Colonial techniques of care thus sought to encompass both plants and peoples within contemporary liberal rhetorics of efficiency and moral improvement. This embodies how scientific and political care can interlink through their undersides of control, exploitation, and domination, which remain obscured by narratives of care themselves. Examining these links between commodity histories and scientific techniques is therefore essential for understanding environmental and social concerns regarding oil palm plantations today. An awareness of the afterlives of colonial discourses might encourage a more critical “care” in response to these issues today, challenging taken-for-granted notions of the benefits of corporate care.

Sarawak is the largest state in the megadiverse country of Malaysia. Its rich biodiversity is threatened by land-use change and hunting, with mammalian carnivores particularly affected. Data on the ecology, occurrence and distribution of small carnivores are crucial to inform their effective conservation, but no large-scale assessments have previously been conducted in Sarawak. Here we examine the status of the five species of felids in Sarawak based on data from camera-trap studies over 17 years (May 2003–February 2021) across 31 study areas, including protected areas of various sizes, production forests and forest matrix within oil palm plantations. Felids were detected at 39% of 845 camera stations. The marbled cat Pardofelis marmorata and Sunda clouded leopard Neofelis diardi had higher probabilities of occurrence in protected than unprotected areas, and vice versa for the leopard cat Prionailurus bengalensis and bay cat Catopuma badia. The marbled and bay cats were mostly diurnal, and the leopard cat was predominantly nocturnal; activity patterns did not substantively differ between protected and unprotected sites. The probabilities of occurrence of marbled and bay cats increased with greater distance from roads. The leopard cat and flat-headed cat Prionailurus planiceps were more likely, and the clouded leopard less likely, to occur near rivers. Flat-headed cats preferred peat swamp forest, bay cats lowland forest, and marbled cats and clouded leopards occurred in both lowland and montane forest. Felids may tolerate higher elevations to avoid anthropogenic disturbance; therefore, it is critical to preserve lowland and mid-elevation habitats that provide refugia from climate change and the destruction of lowland habitat.

Oil palm (Elaeis guineensis Jacq) is an economically important crop in South-east Asia, especially in Malaysia and Indonesia. In Malaysia, oil palm is the most profitable commodity in the agriculture sector. The future of oil palm lies in obtaining a higher yield that is aligned and directed towards achieving the Sustainable Development Goals (SDG) by 2030. Elaeidobius kamerunicus was introduced into Malaysia during the late 1980s to boost the production of oil palm fruit bunches. Almost 40 years since the introduction of E. kamerunicus, significant improvements have been witnessed in the increase of oil palm yield. Nevertheless, the current concern in the oil palm sector is regarding the decreasing of fruit set that may be affected by E. kamerunicus. The weevil population plays a crucial factor in the pollination of oil palm. Several factors had been reported to reduce the weevil population such as natural enemies, interaction with local insects, pesticides, climate and male inflorescence. These factors have been addressed in this article based on various studies conducted since the first investigation in Cameroon by Syed in 1977. The role of the pollinator in terms of its biology, behaviour and pollination mechanism is also described in this article, together with the population management of the weevils. This review article will provide a summary of the current state of Elaeidobius kamerunicus in Malaysia and other neighbouring oil palm-producing countries.

The area of individual leaves in oil palm has been conventionally estimated from a regression equation that is based on the size and number of leaflets. The aim of the present study is to verify the accuracy of this equation, which became standard in oil palm research. Therefore, true leaf area, measured with a video camera, was estimated from the product of number of leaflets per leaf (n) with mean length (l) times mid-width (w) of six of the longest leaflets (nlw). The database was assembled, annually for the first 4 years after planting, from 2961 leaves of dura × pisifera testcrosses descending from six distinct pisifera origins. The regression coefficients of the regression lines of nlw plotted against true area did not show a trend with age of the palms or a difference among pisifera origins. The common regression equation fitted through all data of this study accurately estimated true leaf area of the testcrosses and also the areas of 2- to 3.5-year-old dura palms of three distinct origins as well as 18-year-old tenera palms. These outcomes are at odds with the conventional regression equation that overestimates the true leaf areas by about 24%. A more recently-developed variant underestimates true area of the young tenera and dura palms by 28%, while overestimating true area of old tenera palms by 19%. Possible causes for these deviations from true area are discussed. The paper argues that parameters depending on leaf area of previous physiological studies need to be reassessed.

Beninese smallholders associate food crops and cash crops with immature oil palms to reduce field maintenance costs and gain income before the palms reach productive phase. Little is known about the effects of these crops on the nutritional status and growth of the palms in their immature phase even though the yield of adult palms can be affected by the management practices during this phase. The objective of this study was to evaluate the most common oil palm-based intercropping systems found in southern Benin in terms of nutritional status and growth of the palm. Within 15 oil palm farms, we compared 15 immature oil palm fields where the crop succession associated with the oil palms was dominated by maize, cassava, tomato, and pineapple. The nutrient concentrations in the soil and the palm leaves, and growth indicators were measured at the end of the immature phase. We found that the palm growth indicators were the lowest in the successions with pineapple. N and P nutrition of the immature palms was satisfactory but K was deficient in all systems, especially in those with pineapple. The K levels in the soils and palm leaves were correlated. Rough field budgets comparing the amounts of N and K applied to the crop successions with their N and K exports from non-returning products indicated that soil indigenous K supply would be particularly depleted in the systems with pineapple. We concluded that the young oil palms were affected by the competition for K exerted by the crop successions with pineapple even though they were the most fertilized in the region. The high profitable crop is therefore associated with the lowest growth rates of the immature palms. The mineral fertilizer management in these oil palm temporary intercropping systems should be improved.

This study uses food as a lens to examine three historical phenomena: globalization’s limits, the rise of plantation-centric monocultures, and the resilience of social norms within migrant societies. The article scrutinizes the West African oil palm’s initial journey to, and reception within, the Malay Peninsula, one of the world’s largest exporters of palm oil by the end of the twentieth century. The article pays special attention to changes in the crop’s perceived food value during the interwar years, a facet overlooked by earlier scholarship. Five different migrant groups in Malaya – planter households, Asian cooks, colonial officials, government chemists, and estate labourers – played critical roles in transforming palm oil into a crop purely for industrial purposes, rather than subsistence. The peculiarities of Malaya’s social context are further sharpened by comparisons with Latin America and West Africa, where different clusters of migrants propagated the oil palm’s subsistence cultures, instead of shunning them.

Attempts to mitigate the environmental impact of oil-palm expansion by improving production standards have been of limited success. An alternative approach aims at a better understanding of the factors that drive consumers to reduce excessive vegetable oil consumption. Our studies focused on consumers’ environmental knowledge as a potential determinant of palm oil consumption. They revealed critical limitations in consumers’ palm oil-related knowledge across different domains, study settings and assessment approaches. The more our participants knew about palm oil and its environmental consequences, the stronger were their reported intentions to reduce their consumption. This relationship was significantly stronger for subjective versus objective palm oil-related knowledge. In addition, we examined whether consumers can be stimulated to consult information about palm oil by making information access the default option. While this simple situational nudge promoted information access, we did not find it to significantly increase actual engagement with the information material. This result suggests that it might be necessary to complement default nudges for information access with other measures to enhance palm oil-related knowledge and to reduce palm oil consumption to more sustainable levels.

Tropical forest regions in equatorial Africa are threatened with degradation, deforestation and biodiversity loss as a result of land-cover change. We investigated historical land-cover dynamics in unprotected forested areas of the Littoral Region in south-western Cameroon during 1975–2017, to detect changes that may influence this important biodiversity and wildlife area. Processed Landsat imagery was used to map and monitor changes in land use and land cover. From 1975 to 2017 the area of high-value forest landscapes decreased by c. 420,000 ha, and increasing forest fragmentation caused a decline of c. 12% in the largest patch index. Conversely, disturbed vegetation, cleared areas and urban areas all expanded in extent, by 32% (c. 400,000 ha), 5.6% (c. 26,800 ha) and 6.6% (c. 78,631 ha), respectively. The greatest increase was in the area converted to oil palm plantations (c. 26,893 ha), followed by logging and land clearing (c. 34,838 ha), all of which were the major factors driving deforestation in the study area. Our findings highlight the increasing threats facing the wider Littoral Region, which includes Mount Nlonako and Ebo Forest, both of which are critical areas for regional conservation and the latter a proposed National Park and the only sizable area of intact forest in the region. Intact forest in the Littoral Region, and in particular at Ebo, merits urgent protection.

The Endangered proboscis monkey Nasalis larvatus is endemic to the island of Borneo. Habitat loss is a major threat to this species, and an understanding of long-term demographic trends is crucial for its conservation. We assessed the population trends and group sizes of proboscis monkeys over 10 years in the Lower Kinabatangan floodplain in Sabah, Malaysian Borneo. Comparisons of observed populations between 2004 and 2014 revealed significantly reduced group sizes, which is probably a result of forest fragmentation. Three long-term studies over 34–73 months in specific areas showed fluctuating estimated densities in each area, but no overall population increase or decrease. Riparian forests are the most important habitat for these monkeys, and one reason for the relatively stable population could be that there were only minor losses of forest along rivers during 2004–2014 because protected areas have been established in the region in 2005. However, proboscis monkey habitat remains under threat in areas allocated for oil palm, and protection of these areas is paramount to maintaining this population.

Loss and degradation of natural habitats continue to increase across the tropics as a result of agricultural expansion. Consequently, there is an urgent need to understand their effects, and the distribution and habitat requirements of wildlife within human-modified landscapes, to support the conservation of threatened species, such as felids. We combined camera trapping and land cover data into occupancy models to study the habitat use and space partitioning by four sympatric felid species in an agricultural landscape in Colombia. Land use in the area includes cattle ranching and oil palm cultivation, the latter being an emerging land use type in the Neotropics. Factors determining species occupancy were the presence of wetlands for jaguars (positive effect); water proximity for pumas (positive effect); and presence of pastures for ocelots and jaguarundis (negative effect). Only ocelots were occasionally recorded in oil palm areas. Our results suggest that to align development with the conservation of top predators it is crucial to maintain areas of forest and wetland across agricultural landscapes and to restrict agricultural and oil palm expansion to modified areas such as pastures, which are of limited conservation value. Because there is no spatial segregation between the felid species we studied, conservation strategies that benefit all of them are possible even in modified landscapes.

Largely as a result of the expansion of oil palm Elaeis guineensis, forest fragmentation has occurred on a large scale in Borneo. There is much concern about how forest-dependent species, such as the Vulnerable sun bear Helarctos malayanus, can persist in this landscape. The absence of sufficient natural food in forest fragments could drive sun bears into oil palm plantations, where they risk coming into conflict with people. We interviewed oil palm plantation workers and farmers in the Lower Kinabatangan region of Sabah, Malaysian Borneo, to ascertain if sun bears were utilizing plantations, if they were causing damage to the crop, and how the bears were perceived by people. To obtain a comparative baseline we extended these questions to include other species as well. We found that bears were rarely encountered in plantations and were not considered to be destructive to the oil palm crop, although they were generally feared. Other species, such as macaques Macaca spp., bearded pigs Sus barbatus, and elephants Elephas maximus, had more destructive feeding habits. Sun bears could use this readily available food resource without being targeted for retribution, although incidental human-related mortality remains a risk. Although bears could gain some nutritional benefit from oil palm, plantations do not provide the diversity of food and cover available in a natural forest.

Although often associated with colonial times, tropical plantations growing industrial crops such as rubber, sugar, and oil palm are once again expanding. They employ hundreds of thousands of workers, who still use remarkably basic tools. Flagging colonial continuities, labor activists campaign against the reemergence of unfree labor and “modern forms of slavery.” Paradoxically, labor activists also highlight the opposite problem: the casualization of plantation work, as workers are hired daily and fired at will. Recognizing that both “free” and unfree labor regimes have a long history in Indonesia, and plantations have pivoted between these modes more than once, my study compares plantation labor regimes in the colonial, New Order, and “reform” periods (post-1998) to answer three questions. First, given that employers always want to access disciplined labor at the lowest possible price, what were the conditions that led employers to rely on unfree labor in some cases, and “free” labor in others? Second, to what extent was unfreedom imposed as a response to excessive freedom among workers and peasants? Third, how were the costs of social reproduction distributed between workers and employers, and what pressures from workers or regulators (state, colonial, transnational) affected this distribution? In addition to published sources, I draw on my ethnographic research in West Kalimantan (2010–2015) to explore contemporary experiences of un/freedom among workers on state and private oil palm plantations.

Next-generation sequencing is a new technique for plant genome sequencing at a large scale that is faster and cheaper than previous sequencing technologies. The present work reports the development of new polymorphic simple sequence repeat (SSR) markers in oil palm (Elaeis guineensis Jacq.) using Illumina HiSeq sequencing data. More than 39 Gb (total 39,086,646,904 bases) was generated from the selected oil palm clone, D4. After de novo assembly, a total of 130,840 potential SSRs were identified. For SSR validation, 144 out of 762 SSR primer pairs were designed, including tri-nucleotide motifs, from the D4 contigs. Using 11 lines from three different clones of oil palm, 61 SSR primers revealed polymorphic alleles and high average polymorphic information content (PIC) values. Cluster analysis separated all oil palm plants into three clusters: clones A, B and C. These identified genome-wide SSR markers will enrich current genomic resources of the oil palm crop.

Understanding of genetic diversity and its distribution is essential for promoting the use of genetic resources. The development of core collections using molecular tools has been proposed as a strategy for increasing the economical use and conservation of genetic resources. In this study, we investigated the genetic variation among different geographical origins and potential entries that constituted a core collection of oil palm, using 29 microsatellite markers and by evaluating 788 oil palm accessions. Our results revealed important genetic diversity (HT= 0.759) between oil palm accessions from Angola and Cameroon, which exhibited a low coefficient of genetic differentiation between populations (GST= 0.022). However, the inclusion of oil palm accessions from Indonesia in the analysis resulted in a high coefficient of genetic differentiation between populations (GST= 0.251). We found that the combination of stratified sampling based on a sorting method and a heuristic algorithm was the most effective method for the development of an oil palm core collection set. Using this method, two core collections were identified. The first core collection, comprising 289 entries, contained 271 retained alleles in a sample representing 37% of the entire collection. The second one is a mini core collection, comprising 91 entries, that contained 271 retained alleles with a total He value of 0.72 in a sample representing 11% of the entire collection. The information reported in this study will be of great interest to oil palm researchers because new strategies for breeding programmes can be developed based on these advances.

During a 7-day conditioning treatment of clumps of oil palm (Elaeis guineensis Jacq.) somatic embryos on a medium containing 0.75 M sucrose, the fructose and glucose concentrations remained constant, whereas a ten-fold and twenty-fold increase were noted for sucrose and starch concentrations, respectively. The only new sugar detected was arabinose which remained at a low concentration. After conditioning on media supplemented with various sugars and polyols at similar osmolarities, recovery of clumps of embryo growth was satisfactory except with ribose. After an additional desiccation period, survival was optimal with fructose, galactose, sucrose and glucose, intermediate with maltose and lower with other compounds. When embryos were cryopreserved without previous desiccation, survival was noted after conditioning treatment with sucrose only. In contrast, when freezing was performed after dehydration, survival could be obtained with several substances. It was optimal with sucrose, fructose, galactose and raffinose but was possible also with sorbitol and glucose. Intensity of recovery of proliferation was highest with embryos conditioned with sucrose.