How does agricultural intensification impact insect diversity and abundance in the palm groves of Algeria's Sahara?

Biodiversity Data Journal 13: e170804 doi: 10.3897/BDJ.13.e170804 Research Article How does agricultural intensification impact insect diversity and abundance in the palm groves of Algeria's Sahara? Wahiba Boukhelouf , Imene Benzina , Abdelkrim Si Bachir , Faiza Marniche ‡ Department of Agronomy, Faculty of Sciences, University of Mohamed Khider, Biskra, Algeria § Laboratory Biodiversity, Biotechnology and Sustainable Development LBBDD, Faculty of Nature and Life Sciences, University Batna 2, Batna, Algeria | National Veterinary School ENSV, Rabie Bouchama, El Alia, Algiers, Algeria Corresponding author: Imene Benzina ([email protected]) Academic editor: David Bilton Received: 01 Sep 2025 | Accepted: 26 Nov 2025 | Published: 04 Dec 2025 Citation: Boukhelouf W, Benzina I, Si Bachir A, Marniche F (2025) How does agricultural intensification impact insect diversity and abundance in the palm groves of Algeria's Sahara? Biodiversity Data Journal 13: e170804. https://doi.org/10.3897/BDJ.13.e170804 Abstract This study investigated the impact of agricultural intensification (AI) on insect diversity and abundance in date palm orchards (Phoenix dactylifera L.) in north-eastern Algeria under a Saharan climate. Insect sampling was conducted using various traps from September 2020 to August 2021 in three orchards along a gradient of agricultural intensification (low, medium and high). The study involved the examination of 5,633 insect specimens representing 267 species spanning 11 orders, 93 families and 195 genera. The results indicate that the diversity and abundance of insects are highest in moderately managed palm groves, followed by highly intensified groves and are lowest in non-intensified groves. The species composition is significantly more similar between moderately and highly intensified palm groves. The degree of agricultural intensification has a diferential affect on various insect groups, favouring the diversity or abundance of some, while limiting that of others. This is the case of Diptera and Hymenoptera, which are sensitive to agricultural intensification. Globally, moderate intensification has a more positive impact on the diversity and abundance of various insect orders. This highlights ‡ § § | © Boukhelouf W et al. This is an open access article distributed under the terms of the Creative Commons Attribution License (CC BY 4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. the need for the rational and controlled use of chemical inputs in order to preserve the diversity of insects in palm groves where they provide vital ecosystem services. Keywords agricultural intensification, palm grove, insects, diversity, Sahara Introduction The intensification of agriculture is important to wrestle food insecurity, population growth and environmental degradation (Sariyev et al. 2025). This is pursued through two main strategies: expanding cultivable land and improving farming practices (Milleville and Serpantié 1994). Agricultural development programmes emphasising intensification were crucial during the green revolutions of the 1960s and remain vital for ongoing development in sub-Saharan Africa (Clay 2018). Since the 1960s, agricultural intensification (AI) has boosted crop yields, but negatively impacts pollinating insects and biodiversity, affecting both beneficial insects and pests (Deguines et al. 2014). Up to 40% of insects are at risk of extinction due to habitat loss caused by agriculture and urbanisation, as well as pesticide pollution (Sánchez-Bayo and Wyckhuys 2019). Although AI leads to higher yields per labour unit (Serra 1986), the practices harm biodiversity by adversely affecting key predator populations (Jacquot 2012). Intensified rice production in Asia has resulted in the emergence of multiple pests (Wilby and Thomas 2002). Intensive management practices in orchards and meadows of the northern Italian Alps negatively affect soil invertebrate communities (Guariento et al. 2020 ). Similarly, in olive groves, increased agricultural management intensity leads to a decline in insect and bird populations (Bouam et al. 2017, Bouam 2018). Agricultural land use has a significant impact on ecosystem services, as demonstrated in potato fields where it alters ecological interactions (Werling and Gratton 2010). While monocultures may offer short-term economic benefits, they often lead to reductions in biodiversity and disrupt ecosystem dynamics (Scarpa and Cicia 2000). Additionally, research conducted on La Réunion has shown that the intensity of agricultural practices influences predator species richness within mango agroecosystems (Jacquot et al. 2013). Environmental degradation in the Mediterranean Region is exacerbated by the intensification of agricultural activities (Caraveli 2000). It is essential to acknowledge the adverse impacts of intensive agriculture to facilitate a shift towards agro-ecological systems (Duflot et al. 2022). Innovation is vital for assisting smallholder farmers in Africa to enhance production, while minimising environmental impacts (Juma et al. 2013). Agroecology promotes autonomy in resource use and emphasises functional diversity within production systems, aiming to enhance sustainability and ecosystem resilience (Baccar et al. 2018). It is crucial to prioritise production growth through productivity enhancement rather than by increasing inputs, while balancing fruit production with the conservation of natural resources (Demestihas et al. 2017). Therefore, to quantify 2Boukhelouf W et al management intensity and better understand its ecological impacts, the Agricultural Intensification (AI) Index provides a widely used framework that integrates factors, such as fertiliser and pesticide use, irrigation, mechanisation and crop diversity (Ruiz-Martinez et al. 2015). Globally, the AI Index has been applied to link agricultural practices with biodiversity, functional diversity and ecosystem services, allowing comparisons across different agroecosystems (Gebhardt et al. 2023). In the Mediterranean Basin, AI has been common since the 1950s (Kizos and Koulouri 2006) and the area of land devoted to agricultural use has increased remarkably over recent centuries (Blondel and Aronson 1999). Perennial cropping systems have received comparatively less research attention than annual systems, despite notable differences in habitat structure and agricultural practices. Perennial crops typically exhibit more complex vegetation structure and are subject to lower levels of disturbance, which can have significant implications for biodiversity and ecological functioning (Matson et al. 1997, Bruggisser et al. 2010). AI impacts on biodiversity in North Africa are poorly studied. To our knowledge, aside from Bouam (2018), who examined olive groves, no research has focused on palm grove ecosystems, despite their unique location in harsh Saharan environments. This highlights a significant gap in ecological assessment in these agroecosystems. In this context, we hypothesise that moderate agricultural intensification within date palm groves promotes higher insect diversity by maintaining a balance between cultivated and semi-natural habitats. In Algeria, to boost date production, farmers are increasingly adopting monovarietal cultivation practices, particularly focusing on the Deglet Nour variety. However, this trend may have significant consequences on biodiversity within these agroecosystems, particularly as the effects of AI on insect diversity remain largely underexplored. This study aims to assess the impact of AI on insect communities across varying intensification levels. Field surveys were carried out in three palm groves located in the Saharan region of Algeria (Ziban, Biskra). The research aims to determine whether agricultural intensification affects the diversity and abundance of insect groups within palm grove ecosystems. This would highlight the need to consider the effects of agricultural practices on local biodiversity and the challenges of maintaining sustainable agroecosystems linked to date palms while preserving biodiversity. Material and Methods Study area The investigation was carried out in three palm orchards located in Biskra Province (Ziban Region, north-east Algeria), in the Chetma area, which is known as the main centre for the production of ‘Deglet Nour’ dates in the country (Fig. 1). To minimise the influence of large-scale environmental heterogeneity, all orchards were selected within the same locality, where topographic and climatic variability is minimal. The three sites are situated 1.7 to 2.8 km apart, covering a compact area of approximately 24 km², which ensures comparable environmental conditions across orchards and limits the How does agricultural intensification impact insect diversity and abundance ... 3 confounding effects of spatial variabilities. Meteorological data collected over the past 30 years showed a climate characterised by low and irregular precipitation, with an annual average of 107.57 ± 14.54 mm. April emerged as the rainiest month (24.6 ± 8.22 mm), while January recorded the lowest precipitation (1.0 ± 0.6 mm) and was also the coldest month (12.1 ± 0.1°C). The annual mean temperature was 23.1 ± 7.97°C, with July and August being the hottest months (34.9 ± 0.7°C and 34.7 ± 0.8°C, respectively). Relative humidity averaged 39.78 ± 9.38% and the mean wind speed was 11.11 ± 1.27 km/h. Evaluation of agricultural intensification To assess agricultural intensification in date palm cultivation, we calculated an Agricultural Intensification Index (IInAg), a tool widely used to compare production systems and evaluate their ecological impacts on biodiversity (Herzog et al. 2006, Flohre et al. 2011, Bouam 2018). We conducted a survey of 20 date producers in the region using a structured questionnaire covering key management practices, including pesticide application, mineral and organic fertilisation, irrigation methods, bagging, mechanical Figure 1. Geographical location of the three palm groves studied in the region of Biskra (north-east Algeria). (Uma: Unmanaged palm grove; Mma: Moderately managed; Ima: Intensively managed).  4Boukhelouf W et al weeding and tillage. Based on the responses, eight farms were initially retained as potentially suitable for our study. Subsequent field visits allowed us to verify the accuracy of the reported practices, after which we selected three palm groves that fully met our criteria; all three cultivate the ‘Deglet Nour’ variety and represent distinct levels of agricultural intensification. The IInAg used for assessing the AI for the three studied palm grove was calculated using the methods outlined by Herzog et al. (2006): The index is defined by observed values (y ), minimum (y ) and maximum (y ) values across orchards, with 'n’ representing the number of indicators. In our case, IInAg is calculated using seven indicators in the three sampled orchards: use of agrochemical products, use of fertilisers, use of organic manure, mechanical weeding interventions, plantation density, irrigation systems and the operation of bagging date stems. The main agrochemicals applied include Abamectin (18 g/l), used as an insecticide, acaricide and nematicide, as well as Cymoxanil (42 g/kg) and copper oxychloride (660 g/kg), both used as fungicides. All sampled orchards follow a monovarietal management system. (Table 1). Characteristics and operations Unmanaged palm grove UMa Moderately managed Palm grove MMa Intensively managed palm grove IMa Latitude 34°50'54.57"N 34°50'6.10"N 34°50'56.34"N Longitude 5°46'0.41"E 5°47'29.81"E 5°47'50.55"E Altitude (a.s.l. metres) 97 82 84 Surface (ha) 5 4 4 Number of uses of agrochemical products/year 0 2 4 Quantity of fertilisers used (kg/ year) 0 147.63 278.00 Quantity of organic manure used (kg/year) 0 1628.00 8148.00 Number of mechanical weeding interventions/year 0 1 1 Plantation density (palms/ hectare) 120 111 139 Irrigation system (presence/ absence) 0 1 1 i min max Table 1. Coordinates, values of the indicators and the agricultural intensification index calculated in the three studied palm groves. How does agricultural intensification impact insect diversity and abundance ... 5 Characteristics and operations Unmanaged palm grove UMa Moderately managed Palm grove MMa Intensively managed palm grove IMa Operation of date stems bagging (presence/absence) 0 0 1 InAg index value 4.59%46.15%100% Level of agricultural intensification Low Medium High Insect sampling and identification To sampling insect communities, we used differents traps: Barber pots, ground coloured traps and suspended coloured traps. For collecting insects by Barber pots, this consisted of using nine cylindrical pitfall traps (1 dm³), buried in a 400 m² plot, arranged in rows of three, 5 m apart. The Barber pots were filled with a mixture of water and detergent used as a preservative solution. Yellow traps (16 cm in diameter and height) were deployed, with four on the ground and four suspended from palm trees, all containing water and detergent. This sampling protocol was conducted monthly from September 2020 to August 2021. Trap contents were collected after 48 hours, preserved in 70% alcohol and identified at the laboratory LBBDD Biodiversity, Biotechnology and sustainable development (Batna 2 University) and the National Veterinary School in Algiers. Data analysis To illustrate the density of different insect populations, we calculated the total number of specimens collected in each type of groves (N). The diversity of insect communities in the three study palm groves, was evaluated by: the total taxa richness (S), which correspond to the total number of taxa recorded; and the Shannon diversity index H’ = -Ʃ Pi log Pi (where Pi = ni/N, the proportion by number of the taxa i) (Magurran 2004). The diversity in three palm groves, in relation to AI, was assessed through total species richness (S) rarefaction-extrapolation curves, Shannon diversity indices and sampling coverage. Non-metric Multidimensional Scaling (NMDS) and Generalised Linear Mixed Models (GLMM) were performed in order to analyse the effect of AI on insect communities. All statistical analyses were performed using R software Core Team 2015. Results Diversity and abundance of insect communities according to the level of agricultural intensification This study allowed identifying 5,633 insect specimens, representing 267 species, 195 genera, 93 families and 11 orders. Moderately managed palm grove (MMa) showed the highest values across all biodiversity metrics, with a total abundance of 2,624 individuals, species richness (S) of 184 and a Shannon diversity index (H') of 5.42. In comparison, the intensively managed palm grove (IMa) and the unmanaged palm grove (UMa) ranked second and third, respectively for the three parameters dominated by the moderately intensified palm grove (Table 2). 2 6Boukhelouf W et al Parameter Unmanaged palm grove UMa Moderately managed palm grove MMa Intensively managed palm grove IMa Abundance 1108 2624 1901 Taxa richness S 141 184 167 Shannon index H' 4.93 5.42 5.30 The confidence intervals for MMa and IMa show a degree of overlap, suggesting a relative similarity in species richness (Fig. 2A) and Shanon index diversity (Fig. 2B). The sampling coverage rate indicates a satisfactory rate (over 75 percent) for all three palm groves (Fig. 2C). The abundance of the different orders of insects recorded varies from one type of palm grove to another depending on its degree of AI. Coleoptera, Hymenoptera, Lepidoptera and Diptera exhibited the highest density in the moderately managed palm grove (MMa). Orthoptera, Hemiptera, Neuroptera and Trichoptera were the most abundant in intensively managed orchard (IMa). Thysanoptera and Blattoptera were dominant in unmanaged orchards (UMa). Dermaptera is the order whose numbers were roughly the same in MMa and IMa (Fig. 3). The NMDS analysis reveals a clear distinction between the insect community in UMa palm grove and that of MMa and IMa palm groves. Meanwhile, MMa and IMa insect communities exhibit significant overlap, indicating similar compositions (Fig. 4). Table 2. Abundance and diversity parameters of insect communities according to agricultural intensification in palm groves. Figure 2. Rarefaction curves of observed species richness as a function of the number of surveys conducted. A Shannon diversity index; B Sample coverage rate; C At three levels of agricultural intensification (Unmanaged: UMa; Moderately managed: MMa; Intensively managed: IMa).  How does agricultural intensification impact insect diversity and abundance ... 7 Figure 3. Density of insect orders according to agricultural intensification level in three palm groves (Unmanaged: UMa; Moderately managed: MMa; Intensively managed: IMa).  Figure 4. Ordination diagrams of the results from the non-metric multidimensional scaling (NMDS) analysis of three palm groves according to the level of agricultural intensification. (Unmanaged: UMa; Moderately managed: MMa; Intensively managed: IMa).  8Boukhelouf W et al Impact of agricultural intensification on species richness and abundance of insect communities The GLMM analysis applied for five of the 11 orders of insects listed (Coleoptera, Diptera, Hemiptera, Hymenoptera and Lepidoptera) indicated significant differences in total species richness for the entire community of insects recorded and for all the insect orders amongst the UMa, MMa and IMa palm groves. No significant difference was noted between MMa and IMa whether for all insects or for the five insect orders considered in this analysis. For Coleoptera, significant differences were found between UMa and IMa, but not between UMa and MMa or MMa and IMa. Diptera exhibited significant differences amongst the three palm groves. Hemiptera and Hymenoptera showed significant differences between UMa, MMa and IMa, with no difference between MMa and IMa (Fig. 5). The GLMM analysis applyed for the variation of abundance of the total insects revealed highly significant differences amongst the UMa palm grove, MMa grove and IMa grove, including between MMa and IMa. For Coleoptera, significant differences were noted amongst the three palm groves, with no difference between MMa and IMa. Diptera exhibited highly significant differences across all palm groves. Hemiptera showed Figure 5. Results of the GLMM testing the correlations of species richness for all species combined (top left), as well as for the main orders of insects recorded in the palm groves studied. p-values: *p < 0.05; **p < 0.01; ***p < 0.001.  How does agricultural intensification impact insect diversity and abundance ... 9 • Milleville P, Serpantié G (1994) Agrarian dynamics and the question of the intensification of farming in the Saherian and savanna zones of Africa. In: Orstom (Ed.) 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