Biological control of fruit flies in citrus: Effective IPM approach

Introduction: the threat of fruit flies in citrus farming

Fruit flies (Diptera: Tephritidae) are among the most destructive pests of citrus crops worldwide, causing significant economic losses through direct fruit damage and trade restrictions (Umeh & Garcia, 2008; Ismail et al., 2023). Effective management of these pests is very important for sustainable citrus production, particularly as reliance on broad-spectrum insecticides becomes increasingly unsustainable due to resistance development and environmental concerns (Montoya et al., 2020; Azeem et al., 2022).

Biological control methods in IPM

Integrated Pest Management (IPM) strategies, which combine biological, cultural, and chemical controls, have emerged as a promising approach to mitigate fruit fly infestations while minimizing ecological disruption (Paranhos et al., 2019; Wen et al., 2024). Biological control methods, including the use of parasitoids such as Tetrastichus giffardianus and Fopius arisanus, have demonstrated long-term efficacy in suppressing fruit fly populations (Paranhos et al., 2019). Similarly, natural predators like weaver ants (Oecophylla smaragdina) and ground-dwelling beetles (Pseudoophonus rufipes) contribute to reducing infestation rates (Peng & Christian, 2006; Monzó et al., 2011). Cultural practices, such as field sanitation and cover cropping with alfalfa (Medicago sativa), further enhance pest suppression by disrupting breeding sites and promoting natural enemy abundance (Ismail et al., 2023; Bayegan et al., 2025). Additionally, innovative techniques like the sterile insect technique (SIT) combined with entomopathogenic fungi (Beauveria bassiana) show promise in reducing wild populations (Montoya et al., 2020). Despite these advances, the effectiveness of IPM strategies varies depending on regional conditions, pest species, and farming practices (Rachid & Ahmed, 2018; Wu et al., 2024). This study aims to evaluate and synthesize the most effective, economically viable, and ecologically sustainable strategies for fruit fly management in citrus orchards. This paper provides actionable insights for farmers and researchers seeking to optimize pest management by integrating biological control, cultural practices, and selective chemical interventions while ensuring environmental and economic sustainability.

Biological control methods of fruit flies

Traditional use of chemical insecticides to control fruit flies can lead to resistance development, environmental contamination, and cause harm to non-target organisms (Azeem et al., 2022; Ismail et al., 2023). Consequently, biological control methods have gained prominence as sustainable alternatives within IPM frameworks (Ray, 2025). These methods leverage natural enemies, microbial agents, and ecological strategies to suppress fruit fly populations while minimizing adverse effects (Paranhos et al., 2019).

citrus fruit fly.PNG

Source: https://deepgreenpermaculture.com/2020/03/15/how-to-control-queensland-fruit-fly-in-the-home-garden-an-integrated-pest-management-approach/

Natural Enemies: Parasitoids and Predators

Parasitoid Wasps to suppress fruit fly populations

Parasitoids are among the most effective biological control agents against fruit flies. Species such as Tetrastichus giffardianus and Fopius arisanus have demonstrated high parasitism rates (13.52–69.10%) across different citrus varieties (Rahmawati et al., 2024). Diachasmimorpha longicaudata, another key parasitoid, locates host larvae using chemical cues and significantly increases medfly (Ceratitis capitata) mortality when released in high densities (Devescovi et al., 2024). However, parasitoid efficacy depends on environmental conditions, host availability, and the absence of disruptive pesticides (Buonocore Biancheri et al., 2023).

parasitoid wasps to manage fruit flies.PNG

Parasitoid Wasps

Source: https://specialtycropgrower.com/parasitic-wasp-uga-spotted-wing-drosophila/

Role of predatory arthropods in fruit fly reduction

Generalist predators, including wolf spiders (Pardosa cribata), lacewings (Chrysopidae), and weaver ants (Oecophylla smaragdina), contribute to natural suppression. DNA-based studies confirm that P. cribata preys on C. capitata, with predation rates peaking at 15% during high fly emergence (Monzó et al., 2010). Weaver ants, in particular, reduce fruit damage comparably to chemical treatments, making them a viable option for organic orchards (Peng & Christian, 2006). Ground beetles (Pseudoophonus rufipes) also target medfly pupae, enhancing biological control when combined with parasitoids (Monzó et al., 2011).

Microbial and Ecological Strategies

Entomopathogenic Fungi and Nematodes

The entomopathogenic fungus Beauveria bassiana and nematodes such as Steinernema carpocapsae infect fruit fly larvae and pupae, offering an eco-friendly alternative to chemicals (Dolinski & Lacey, 2007). When paired with sterile insect technique (SIT), B. bassiana enhances wild fly infection rates, improving population suppression (Montoya et al., 2020). Similarly, rhizobacteria (Pseudomonas spp.) exhibit insecticidal effects on C. capitata, suggesting potential for bioinsecticide development (Qessaoui et al., 2022).

Habitat Manipulation: Cover Crops and Push-Pull Systems

Planting alfalfa (Medicago sativa) as a cover crop reduces medfly populations by enhancing predator diversity, including spiders and ground beetles (Bayegan et al., 2025). Push-pull strategies, combining repellents (e.g., abamectin) and attractants (e.g., methyl eugenol), further reduce infestations while minimizing pesticide use (Wen et al., 2024). Such approaches align with conservation biological control, promoting ecosystem resilience.

Life cycle of fruit fly.PNG

Life cycle of fruit fly (Drosophila)

Source: https://animalia-life.club/qa/pictures/fruit-flies-life-cycle

Comparative Efficacy and Implementation Challenges

While biological control methods are promising, their success varies by region and citrus system. Parasitoids perform best in stable environments with minimal pesticide interference, whereas predator-based systems (e.g., weaver ants) are more adaptable but require habitat management (Peng & Christian, 2006). Microbial agents like B. bassiana show high pathogenicity but depend on favorable humidity and temperature (Montoya et al., 2020). Economic feasibility is another consideration; locally produced protein baits, for instance, match the efficacy of commercial products at lower costs (Umeh & Garcia, 2008).

Conclusion and Future Directions

Biological control methods offer sustainable solutions for fruit fly management in citrus, reducing reliance on synthetic pesticides. Integrating parasitoids, predators, and microbial agents within IPM frameworks could enhance long-term efficacy (Paranhos et al., 2019). Future research should focus on optimizing field applications, assessing large-scale economic impacts, and developing region-specific strategies. For farmers, adopting practices such as cover cropping, mass trapping, and selective biocontrol releases can mitigate fruit fly damage while supporting ecological balance (Ismail et al., 2023; Bayegan et al., 2025).