Citrus crops are of significant economic value in Indonesia, with production reaching 2.8 million tons in 2023, primarily led by East Java (Central Bureau of Statistics of Indonesia, 2024). Citrus orchards not only provide substantial benefits to farmers but also bolster both local and national markets (Lv et al., 2015); (Hidayat et al., 2022). Despite this importance, production is frequently threatened by pests and diseases. These biological threats attack plants from flowering to harvest, leading to heavy losses and significantly reducing fruit quality (Kilcher, 2005); (Abobatta, 2018). For instance, recent study in Langkat, North Sumatra, have identified 16 insect families as major pests in citrus orchards (Kurniawan & Siregar, 2023).

Mites pose a significant threat to citrus production, potentially reducing fruit yields by as much as 70% by cause brown skin discoloration, rough skin, and stunted fruit growth (Ebrahim & Aiad, 2019); (Wicaksono et al., 2022). Specifically, the citrus red mite Panonychuscitri (McGregor) (Tetranychidae) is a polyphagous species known to infest various food crops, trees, and ornamental plants (Hoy, 2011). P. citri is recognized as a major economic pest in citrus orchards globally, including regions across Asia, the Mediterranean Basin, North America, South America, and Africa (Urbaneja et al., 2020). Due to its adaptability, this mite can infest virtually all citrus varieties and species.

Severe P. citri infestations primarily impact citrus productivity and quality. The direct feeding damage prevents normal fruit development, leading to fruit drop, although remaining fruits may partially compensate by gaining weight, the overall effect is still a significant (~10%) reduction in yield (Faez et al., 2018). Physiologically, mites damage the plant by sucking cytoplasm from plant cells, which causes chlorotic (yellow) spots and can trigger premature leaf fall (Demard & Qureshi, 2022). This loss of cytoplasmic contents reduces chlorophyll levels and photosynthesis, further impairing tree health and potentially degrading fruit quality (Afzal et al., 2023); (Assouguem et al., 2024). Beyond agronomic losses, P. citri imposes substantial economic burdens. Infestation necessitates increased production costs, primarily through the need for more frequent acaricide applications and the implementation of integrated pest management (IPM) strategies. Furthermore, the external defects and poor quality resulting from major infestations severely reduce the marketability of fruits, negatively affecting both domestic and international commercial sectors (Faez et al., 2018); (Radonjić & Hrnčić, 2020).

To develop effective and sustainable control strategies for mites, it is essential to study their density and distribution in citrus orchards, requiring and integrated understanding of both local (field) and landscape factors (Rizali et al., 2024). Local factors, such as canopy density and pesticide application, directly influence pests and natural enemy presence. Canopy density affects the light penetration, which in turn dictates crucial microclimatic conditions like temperature and humidity (Devi & Challa, 2019); (Zhang et al., 2019). The significance of temperature is evident since P. citri can complete its life cycle in approximately one week at 25 °C, and its population often peaks during favorable temperatures periods in early spring or fall (Zhang, 2003); (Demard & Qureshi, 2023). Conversely, nonoptimal temperatures and humidity levels typically lead to a decline in arthropod populations (Shrestha 2019). Furthermore, frequent pesticide applications disrupts natural biological systems, induces pest resistance, and can ultimately lead to a resurgence or increase in pest population over time (Rattanpal et al., 2017); (Urbaneja et al., 2020); (Afzal et al., 2023); (Demard et al., 2024).

Landscape factors, particularly landscape composition, also play a crucial role by influencing fauna diversity and population density. Croplands situated near natural habitats generally exhibit greater natural enemy diversity and species richness (Pasaribu et al., 2024), while complex landscapes support more abundant and diverse natural enemies that indirectly regulate pest populations (Martin et al., 2016). For example, the presence of natural habitats within oil palm plantations affects the species richness and abundance of natural enemies (Rizali et al., 2024). Similarly, semi-natural habitats can acts as dispersal or refuge sites for predatory mites (Phytoseiidae) in vineyards, suggesting that the lack of such habitats may contribute to a decrease in their population (Möth et al., 2023).

While numerous studies have thoroughly examined the basic biology and ecology of P. citri(Kasap, 2009); (Zanardi et al., 2015); (Demard & Qureshi, 2022), research focusing on how local and landscape factors concurrently influence its population density and spatial variation in citrus orchards remains limited. Most existing research has highlighted the direct effects of pesticides on mites (Amiri-Besheli et al., 2020), but rarely incorporates landscape variables, such as landscape composition, into integrated mite management strategies (Möth et al., 2023). Specifically, studies investigating how the interplay of factors like canopy density, pesticide application, and landscape composition, collectively shape P. citri population are scarce. Therefore, this study aimed to investigate the effects of local factors (i.e., frequency of pesticide application and canopy density) and landscape factors (i.e., landscape composition) on the population density and spatial variation of P. citri in Indonesian citrus orchards.

Our study demonstrated that local factors, particularly canopy density, exert a stronger influence on the spatial variation of P. citri populations than do landscape factors. Crucially, we found that neither local nor landscape factors significantly influenced the average population densities of the mites. The positive effect of canopy density on the spatial variation of P. citri suggests that denser canopies promote a heterogeneous (uneven) distribution of the mite population within an orchard. A higher coefficient of variation (CV) value confirms this greater unevenness in the mite’s spread between trees (Asriyanti, 2013). This heterogeneity is likely driven by two key mechanisms facilitated by dense canopies: enhanced dispersal and aggregation and microclimate regulation. Connected canopies facilitate physical contact between leaves and branches, which is the primary mode of P. citri spread (Vashisth et al., 2021). This movement, whether by walking, wind currents, or human activity, allows mites to rapidly aggregate in specific microhabitats that favour survival and reproduction. When the canopy is closed, mites tend to gather in such optimal spots, thereby increasing the unevenness of their distribution. In contrast, open canopies may lead to a more even spread or present physical barriers due to gaps between trees (Mockford et al., 2024).

Canopy density significantly affects the microclimate by controlling sunlight exposure, which in turn influences temperature, humidity, and light (Devi & Challa, 2019); (Zhang et al., 2019); (Abobatta, 2020). Dense canopies maintain higher humidity, which prevents mite eggs and larvae from desiccating, and keep temperatures within the optimal 15–35 ºC range that supports P. citri development (Dong et al., 2020). Open canopies, by allowing more sunlight and air circulation, create drier conditions that can increase mite mortality rates (Zhang et al., 2019). Furthermore, dense canopies may offer complex habitats and protection for natural enemies, potentially increasing their survival and hunting efficiency (Prischmann et al., 2006); (Abobatta, 2020), which further contributes to localized mite suppression and, consequently, spatial variation.

Our finding that pesticide use did not affect the population density or spatial variation of P. citri mites suggests that the mite population remained relatively stable despite varying application frequencies. Based on farmer interviews, this lack of efficacy may be attributed to inappropriate application practices, such as mixing incompatible pesticides (e.g., fungicides and insecticides). Such misuse can reduce the effectiveness of the active ingredients and accelerate pest resistance (Asaad, 2008); (Rahmasari & Musfirah, 2020). This highlights a critical lack of proper pesticide knowledge among local farmers. Promoting the correct use of pesticides (right target, quality, type, dose, time, and method) and encouraging the adoption of eco-friendly alternatives, such as black soap and detergent mixes (Amiri-Besheli et al., 2020); (Assouguem et al., 2024), are necessary steps to achieve effective pest control.

Although complex landscapes are generally expected to boost natural enemies and plant diversity, thereby affecting pest populations (Syahidah et al., 2021); (Zuhran et al., 2021); (Rizali et al., 2024), the GLM analysis in this study found that landscape composition (number of patches and class area of semi-natural habitats) did not influence P. citri density or spatial variation. This suggests that the spread of P. citri is likely limited to the immediate local environment. While mites can spread by walking, human assistance, and wind (“ballooning”) (Demard & Qureshi, 2022); (Tehri, 2014), this airborne dispersal method is generally considered limited to short distances (Montes & Gleiser, 2025). The short-term nature of this movement may prevent a strong landscape factors effect on the overall population or its spatial arrangement. Additionally, the inherent biological traits of P. citri, including its short life cycle, high reproductive rate, adaptability, and ability to utilize resources in its current habitat, may override any mitigating effects offered by surrounding landscape heterogeneity (Zhang, 2003); (Tscharntke et al., 2016); (Devi & Challa, 2019); (Qureshi et al., 2021).

Our study revealed that the population of P. citri varied in both density and spatial distribution among the citrus orchards. We found that, in general, neither local nor landscape factors significantly influenced the mites’ overall population size. However, a key finding was that canopy density at the local level significantly influenced the spatial variation of P. citri, while pesticide use did not. This indicates that local conditions, specifically canopy proximity, are more important than broader landscape factors in determining how mites are distributed within an orchard. Consequently, effective P. citri management should focus on local factors. For instance, strategically pruning trees to create a more open canopy can alter the microclimate, making the habitat less favourable for mites while simultaneously benefiting natural predators that help control the population.