1. Introduction
Agricultural producers worldwide have traditionally relied on chemical products for pest control. However, the frequency and magnitude of this practice have raised concerns about food security and ecological disruption, leading to pest outbreaks that reduce both the quantity and quality of production [
1]. To address these challenges, the concept of sustainable pest management (SPM) has been introduced, promoting practices that align with natural processes, have reduced environmental impact, incorporate biological control, and enhance farmers’ livelihoods [
2].
According to Savary [
3], modern SPM is based on four principles: (1) biodiversity, (2) host plant resistance, (3) landscape ecology, and (4) hierarchies. These are essential for sustaining food webs and ensuring long-term crop protection as they influence plant physiology, trophic relationships, and farmer behavior. Similarly, Altieri [
4] emphasized that diversified agroecosystems inherently include natural pest-control mechanisms, as their structural and management attributes directly affect herbivore dynamics.
Deguine et al. [
5], in their review of SPM in cotton, highlighted that repeated use of broad-spectrum insecticides often increases pest pressure by reducing beneficial arthropod populations. In Australia, a lucerne/cotton companion planting system has been implemented to maintain the predator–pest balance and provide supplementary resources for natural enemies [
5].
Molecular biotechnology has also been integrated into SPM; for example, transgenic pest-resistant varieties have been developed. Zhang et al. [
6] demonstrated that cloning pest resistance genes in
Beta vulgaris (sugar beet) increased resistance to aphids, nematodes, and root larvae, reducing production costs and providing insights into the molecular mechanisms of plant defense.
However, such approaches are difficult to apply to species like the coffee berry borer (CBB),
Hypothenemus hampei (Ferrari) (Coleoptera: Curculionidae: Scolytinae), which lacks natural enemies outside its African center of origin [
7]. According to Vega et al. [
7], the CBB was first reported in Liberia in 1897 and later spread to Asia and the Americas. It is now present in nearly all coffee-producing countries, except Nepal, China, and Australia [
8].
Coffee is one of the most important agricultural commodities worldwide, generating annual revenues exceeding USD 70 billion. Approximately 70% of global coffee production, estimated at over 9 million metric tons, is cultivated by smallholders on farms smaller than 5 hectares [
9]. Climate change has intensified pest pressures, particularly benefiting the CBB, whose reproduction intensifies with rising temperatures [
10]. Adult females infest coffee berries about 120–150 days after flowering, boring galleries into the endosperm and laying over 100 eggs. Annual economic losses due to CBBs exceed USD 500 million [
7,
8,
11].
In Colombia, the CBB was first detected in 1988, prompting extensive research by the National Coffee Research Center (Cenicafé) on its biology, ecology, and management. This led to the implementation of integrated pest management (IPM) combining biological, cultural, and chemical strategies [
12]. Bustillo [
13] highlighted that promoting beneficial fauna and introducing natural enemies such as
Prorops nasuta Waterson, 1923 (Hymenoptera: Bethylidae) and
Phymastichus coffea LaSalle, 1990 (Hymenoptera: Eulophidae), as well as the fungus
Beauveria bassiana (Bals.-Criv.) Vuill., could strengthen Colombia’s biological control.
Globally, initiatives such as the European Green Deal’s “Farm to Fork” strategy aim to reduce pesticide dependence by adopting sustainable pest control methods [
14,
15]. Consistent with these goals, Benavides et al. [
16] reported up to an 81% reduction in CBB populations after releasing the parasitoid wasps
P. nasuta and
P. coffea on a large scale. Góngora et al. [
17] emphasized the importance of integrating an ecological understanding of insect–plant interactions, climate, and habitats for more sustainable CBB management.
Other studies explored the use of predators such as
Ahasverus advena (Walt, 1832) (Coleoptera: Cucujidae) and
Cathartus quadricollis (Guérin-Méneville, 1844) (Coleoptera: Silvanidae), which reduced CBB populations by 63.2% and 46.2%, respectively [
18]. Similarly,
Solenopsis picea Emery, 1896, and
Crematogaster crinosa Mayr, 1862 (Hymenoptera: Formicidae) ants exhibited predation rates of up to 78.3% and 34.3%, respectively, demonstrating strong potential as natural regulators [
19]. Entomopathogenic fungi have also shown effectiveness:
B. bassiana and
Metarhizium anisopliae (Metschn.). Sorokīn caused 91–94% CBB mortality and reduced field infestation by 18–47% [
20]. Benavides et al. [
21,
22] and Constantino et al. [
23] demonstrated that combining timely harvesting and fruit collection with fungal application maintained infestation below 5% and increased profitability. López et al. [
24] validated these findings in the department of Huila, Colombia, confirming that cultural control remains the foundation of integrated management. Economic evaluation tools, such as partial budgeting and marginal analysis, can be used to assess the profitability of these practices [
25,
26].
Considering the above, the objective of this study was to validate a new sustainable pest management program for controlling the coffee berry borer that combines cultural and monitoring practices, parasitoids, and fungal biopesticides and then to compare it with historical conventional control, based on the use of synthetic chemical insecticides on a large farm. We hypothesized that the SPM program to control coffee berry borer would significantly reduce infestation levels and insecticide dependence while maintaining or improving economic profitability.
4. Discussion
Historical records of chemical insecticide use at La Catalina coffee farm showed an increase in use from 2019 to 2021 (up to 27.2 L), followed by a decrease in 2022 (14.1 L). CBB levels were highest during 2015–2016, when fewer chemical insecticides were used, contrasting with the significant increase in pesticide use during 2019–2021, despite climatic conditions being less favorable for borers.
These facts indicate that the appropriate timing for implementing integrated pest management (IPM) strategies was not well understood. Since 2023, the management program has been based primarily on cultural practices, the release of two African-origin parasitoids, and the spraying of the entomopathogenic fungus
B. bassiana. This transition aligns with IPM principles and the global trend toward sustainable agricultural practices that aim to reduce dependence on chemical inputs and minimize environmental and human health risks [
14].
The use of
B. bassiana has been proven to be effective against coffee berry borers as part of the integrated management program, particularly when applied in combination with cultural measures such as harvesting fruits from the tree and the ground, reducing flying insect numbers during harvest and post-harvest by means of sealing sacks, capturing borers in a cherry collecting hopper, and managing berries and floats. Benavides and Arévalo, and Castro et al. [
29,
30] demonstrated that integrated management, which features timely harvesting, collection of remaining fruit, outbreak management, use of
B. bassiana, and post-harvest practices, can reduce infestation levels and maintain a quality suitable for export, with less than 5% of coffee infested by CBBs, even under unfavorable conditions. Cultural practices are the basis of the IPM strategy.
At the La Catalina coffee farm’s processing plant, the adoption of these measures was complemented by eliminating sources of re-infestation, such as coffee pulp and floats, following the recommendations of Castro et al. [
30], who demonstrated that the highest numbers of adult coffee berry borers escape from sacks opened in the field and during the drying of coffee floats. Containment measures can prevent the dispersal of up to 93% of live adults.
The use of sealed sacks and grease-impregnated covers on hoppers, as implemented at La Catalina coffee processing plant, is based on evidence that this practice significantly reduces the dispersal of berry borers from the processing area, preventing re-infestation in surrounding coffee plantations. Additionally, solarizing coffee floats eliminates insects at immature stages within coffee beans that have survived processing, a strategy validated by Castro et al. [
30].
The identification of specific areas with different productive and sanitary conditions within the coffee crop demonstrated the spatial heterogeneity of CBB infestation. In this case, the plots were classified by color according to crop age and production cycle (first to fourth harvest), showing a range of productivities and management requirements. Areas marked in red represent plots undergoing plantation renewal. This differentiation is essential for managing the CBB and establishing selective management programs to optimize resources [
31]. In fact, cultural practices can be readily applied to young coffee trees, and the use of sprayers is also feasible in this context. Using coffee crops older than 6 years old would decrease the efficacy of implementing any IPM measure.
During the evaluation period, coffee berry borers displayed active dynamics, with two critical peaks, one infestation in January 2024 (more than 50%) and another in April of the same year, characterized by the borers entering coffee berries (more than 80%). These peaks reflect the insect’s cyclical biology, its ability to synchronize with coffee phenological cycles, and the influence of climate on its emergence and dispersal.
These results are consistent with those reported by Benavides and Arévalo [
29], who found that even under extreme conditions, high infestation hotspots can persist if strict, consistent integrated measures are not applied over time. In their study, as in this case, localized patches of high infestation were identified that required specific intervention, such as targeted harvesting, targeted application of
Beauveria bassiana, and border demarcation with trap trees.
The trends observed in
Figure 3, i.e., constant variations in the position of the borer on the fruit and the abundance of adults in flight, emphasize the importance of continuous and localized monitoring, since management strategies must be adapted not only to the infestation situation in the field but also to the specific behavior of active hotspots. As noted by Castro et al. [
30], the aggregation of borers in certain locations on coffee plantations is a key characteristic that enables optimized control through targeted measures that reduce unnecessary chemical inputs.
In this study, early identification of these hotspots enabled the integration of management strategies to reduce the spread to and colonization of nearby fields. Therefore, the delimitation of these infestation hotspots and their relationship with the age and condition of the plots are key factors to consider in the integrated management of coffee berry borers, enabling timely decisions on coffee plant renewal and pruning, as well as targeted biological control. This contributes to the economic and environmental sustainability of the production system.
The significant reduction in weighted CBB infestation observed between 2023 and 2024, compared with historical records from 2012 to 2022, demonstrates the effectiveness of the SPM program in controlling coffee berry borer and highlights the overall success of sustainable pest management. In the historical period, the average infestation was 3.3%, exceeding the action threshold (2.0%) and even reaching the economic damage level in 2016 (5.4%), while in 2023 and 2024, infestation was below or equal to the action threshold, with an average of 1.7% and a statistically significant difference between groups.
The effectiveness of the sustainable management program of the coffee berry borer lies in the combination of cultural practices, the use of bio-inputs such as
Beauveria bassiana, and ongoing monitoring of CBB populations, adjusted to the coffee’s phenological cycles and environmental conditions [
17]. In this approach, the biological component does not act in isolation. However, it is enhanced by preventive and corrective measures in the field and post-harvest adopted in 2023 and 2024, such as the targeted application of
B. bassiana, the release of the two African-origin parasitoids
P. coffea and
P. nasuta, and practices to prevent dispersal during post-harvest processing.
The use of
B. bassiana in particular has been documented as an effective tool in biological control programs for CBBs, especially when applied systematically and combined with cultural practices [
22]. It has been reported that applying
B. bassiana to trees and onto the soil reduces the number of borer beetles reaching fruit by 50% and leads to a 40% mortality rate among those penetrating the fruit [
22]. Furthermore, the borer beetles that survive fungal treatment lay 90% fewer eggs than in a non-sprayed control, resulting in a 55% to 75% reduction in the number of borer beetles inside the fruit [
22].
Benavides et al. [
22] also emphasize the importance of mitigating aggregation hotspots through targeted harvesting, trap tree management, and monitoring the insect’s position within the fruit. This is especially relevant, given that borers can emerge in mass under conditions of high humidity and stable temperatures, as occurs during periods of climate transition or phenomena such as El Niño. Through the implemented sustainable pest management program, we were able to anticipate and mitigate these phenomena, as evidenced by the absence of critical infestation levels during these two years (2023–2024).
The monthly trends in weighted CBB infestation in dry parchment coffee between July 2023 and November 2024 show a clear relationship between harvest peaks and increasing infestation levels. During the second half of 2023, a progressive increase in infestation levels was observed, peaking in November (2.4%), coinciding with the highest monthly production volume (8616 kg). A similar pattern was observed in 2024, albeit with lower infestation levels (1.6% in October) despite an even higher production level (17,601 kg), followed by a drastic reduction in November (0.2%).
This behavior is consistent with that reported by Benavides and Arévalo [
29], who identified that the highest levels of infestation in dry parchment coffee tend to coincide with the main harvest peaks due to the increase in the supply of susceptible fruits and the possible emergence of remaining borers in the soil or from neighboring coffee berries in the plants. This is also supported by Constantino et al. [
23], who reported intense adult CBB flight activity between collecting events during the main harvests.
However, the significant decrease observed in November 2024 could be attributed to more effective implementation of management strategies in the field during harvesting, such as the application of the fungus B. bassiana in complex coffee plots and hotspots following each collection of coffee berries during the main harvest of 2024. This aligns with the cultural practices applied during harvest and post-harvest, as mentioned earlier.
The successful results of the SPM program during this period can be compared with those obtained at La Finaria farm, where, after rigorous implementation of an IPM program, CBB infestation was drastically reduced in dry parchment coffee, allowing 83% of the coffee to be marketed as high-quality export coffee [
29].
Furthermore, the fact that the economic injury level (5%) was not exceeded during 2024 and that the infestation remained below 2% in most months highlights the effectiveness of the sustainable approach adopted. This not only represents progress in terms of sustainability and reduction in the use of insecticides, the negative effects of which have been widely documented in the literature, but also in terms of the use of a resilient, long-term integrated management system.
Historical data (2012–2022) show that the highest CBB flight activity occurred between February and March, with a peak in the latter (504 individuals on average). This pattern is consistent with this pest’s biology, which includes emergence at adulthood, high population levels after the main harvest, and low availability of ripe fruit on trees, as well as favorable temperature and humidity conditions at the beginning of the year.
In contrast, the flight activity recorded in 2023 and 2024 was significantly lower in all months evaluated. In 2023, the highest number of captured individuals was recorded in March (81), but this was lower than the historical average. In 2024, a specific increase was observed in February (312 individuals), followed by consistently low values throughout the rest of the year. These differences suggest the positive effect of implementing this sustainable pest management program.
Decreasing flight activity reduces the dispersal of the CBB population, since adult females are responsible for colonizing new fruits [
32]. It also limits re-infestation and reduces the need for control interventions, increasing the sustainability of the production system.
The climatic variability observed during the study period, with average temperatures ranging from 20.3 °C to 24.4 °C and extreme rainfall variation from 450 mm (October 2015) to just 2 mm (January 2024), is a determining factor in coffee berry borer population dynamics. In particular, the extreme temperatures and precipitation recorded during events such as El Niño (for example, in February 2016) have been identified as conditions that can accelerate the insect’s lifecycle, increasing its reproductive rate and the pressure of infestation on crops.
Coffee berry borers exhibit high ecological plasticity, with the ability to produce more generations per year in hot, dry climates, as observed during El Niño-induced drought [
17]. This trend is consistent with the result documented in February 2016, when the highest temperature of the period was recorded (24.4 °C), coinciding with a significant increase in infestation recorded that same year (5.4%). Furthermore, the low precipitation recorded in January 2024 (2 mm) suggests water-stress conditions that may favor the emergence of coffee berry borer adults in search of available fruit, especially when combined with late harvests or fruit remaining permanently in the field. However, in contrast to 2016, infestation levels in 2024 remained below the action threshold (2.0%), indicating that the sustainable program implemented over the last two years has mitigated the adverse effects of climate on pest dynamics.
Under alternative climatic scenarios, such as La Niña or neutral conditions, characterized by lower temperatures and increased rainfall and generally associated with slower pest population growth, the effectiveness of the proposed sustainable pest management program is expected to be maintained or potentially enhanced.
Results from successive releases of
Prorops nasuta in dispersal plots in 2022, 2023, and 2024 demonstrate a consistent reduction in the population density of
Hypothenemus hampei, supporting its role as an effective component of a sustainable pest management program. The effectiveness of
P. nasuta lies in its dual behavior as a parasitoid and predator; this bethylid attacks CBBs at all stages within the fruit, feeding on eggs and first-stage larvae and parasitizing second-stage larvae, pre-pupae, and pupae [
16,
33].
Accordingly, the estimated number of wasps released annually (598,560 in 2022; 426,400 in 2023; and 266,011 in 2024) was proportional to the parasitoid content per grain and the parasitism rate (>80%). Overall, these results indicate that the release densities applied were sufficient to produce a measurable suppressive effect on CBB populations under field conditions.
The 32.1% decrease in the average number of borer stages per parasitized fruit (7.0 ± 0.7) compared to un-parasitized fruit (10.9 ± 0.3) supports the effectiveness of
P. nasuta as a predator. This finding is consistent with that reported by Benavides et al. [
16], who documented reductions of up to 81% in coffee berry borer density in fallen fruit following
P. nasuta release in dispersal plots within the context of Area-Wide biological control strategy.
Furthermore, the decrease in the number of instars per parasitized fruit suggests a reduction not only in host viability but also in host reproductive capacity. This pattern is consistent with the mode of action of
P. nasuta, whose average lifespan of 28 days allows for sustained action in the field [
16]. Unlike other introduced parasitoids,
P. nasuta has demonstrated the ability to establish itself permanently in the Colombian coffee ecosystem, with its presence recorded on 65% of the farms evaluated and with natural parasitism levels as high as 50% in certain regions [
34].
Unlike the relatively stable response observed for P. nasuta, the release magnitude and field persistence of Phymastichus coffea varied between 2023 and 2024 in the colonization plots at the La Catalina coffee farm. In 2023, with an average parasitism of 64.3% and 4.2 individual borers on average per parasitized grain, an estimated 604,934 wasps were released, while in 2024, 729,960 wasps were released due to a greater number of released grains, a higher parasitism rate (70%), and a slightly higher average number of borers per grain.
Despite the greater number of parasitoids released in 2024, inverse patterns in the field were observed in the persistence and magnitude of parasitism. In 2023, the parasitism rate exceeded 70% in September and remained relatively high for several months before declining to zero, whereas in 2024, the maximum observed rate was close to 40%, with greater fluctuations in the dynamics and an earlier disappearance of the species. This decrease in parasitism in 2024 coincides with an increase in temperature due to the El Niño event, and it appears that maximum temperatures exceeding 30 °C are not beneficial to
P. coffea. In addition, as documented by Benavides et al. [
16],
P. coffea’s inability to establish permanently in the field is confirmed, with parasitism dropping to zero five months after the last release.
The discrepancy between the number of
P. coffea released and their persistence in the field could be caused by abiotic and biotic factors. Benavides et al. [
16] point out that climatic events such as La Niña, featuring high rainfall, can negatively affect the availability and condition of infested fruits, reducing the window for borer colonization and, therefore, the oviposition opportunities for
P. coffea. Furthermore, the variability in the initial density of
Hypothenemus hampei in the colonization plots and the synchrony between the release of parasitoids and the availability of CBB females entering coffee berries are decisive factors in maximizing the impact of this measure, since this species exclusively parasitizes adults during the fruit-penetration phase.
The strategy of applying entomopathogenic fungus at La Catalina coffee farm was framed within a sustainable pest management program for Hypothenemus hampei, with applications focused on the critical attack period, defined by infestations greater than 2% and by more than 50% of individuals positioned at coffee berry entrances. This approach aligns with Cenicafé’s recommendations to maximize efficacy and reduce unnecessary chemical inputs.
During the evaluation period (2023–2024), applications were sporadic, with a general tendency toward 1 intervention per 1 ha plot per year; the highest number was recorded in August 2023 (7 plots, 7.54 ha treated). This pattern reflects the population dynamics of the borer and their association with climatic and phenological factors, previously documented by Bustillo et al. [
35], who highlighted that high humidity and rainfall stimulate mass emergence from fallen fruits.
Jaramillo et al. [
20] validated the virulence effect of a mixture of different strains of
B. bassiana and
Metarhizium anisopliae (Metschn.). Sorokīn on the insect’s oviposition in the laboratory and on infestation and population levels in field plots. In the laboratory, the mixed strain resulted in mortality rates of 91–94%, reducing oviposition capacity by up to 87%. In the field, infestation was reduced by 18–47%. Meanwhile, Benavides et al. [
21] evaluated the effects of cultural, chemical, and biological control using
B. bassiana on coffee berry borers under field conditions, finding that cultural control was the most crucial component of IPM, leading to higher coffee production, income, and economic contribution margins.
Field efficacy is determined by the quality of the inoculum and the formulation used. Bustillo and Posada [
36] established minimum standards for concentration (≈2 × 10
10 spores L
−1), viability (>90%), and purity (>95%) to maintain yields, and also emphasized the importance of activating the fungus on the coffee berry borer before use to preserve pathogenicity. Comparing these parameters with those used at La Catalina coffee farm would allow for identifying potential areas for improvement.
Finally, the low application frequency used in this study suggests that the monitoring and threshold system employed is effective in containing the pest with minimal intervention, reducing costs and preserving the activity of natural enemies. However, the evidence supports exploring complementary strategies, such as strain mixtures and formulations with greater persistence, to improve control during population peaks and during adverse weather conditions.
Economic analysis using the partial budget method showed that implementing the sustainable CBB management program generated a net income per hectare of USD 9981, 26% higher than under the chemical control scheme (USD 7868). This difference is mainly explained by a 2.5% increase in farm productivity and a 20% higher coffee sale price, both of which were driven by lower berry borer infestation in the coffee parchment. In contrast, in the conventional chemical system, the average penalty was USD 82.48/ha for higher coffee parchment infestation levels.
Although labor costs under the sustainable pest management program were 49% higher than under chemical management, due to greater demand for activities such as trimming, monitoring, and trap management, these costs were offset by a 49% reduction in input costs and a higher net income. Previous studies have indicated that the transition to sustainable pest management with less reliance on chemical insecticides may initially entail an increase in labor demand, but in the medium term, they generate sustainable economic and environmental benefits.
In this study, the marginal analysis yielded a rate of return of USD 18.06, meaning that for every additional USD 1 invested in switching from chemical control to sustainable pest management, the investment is recovered, and an additional benefit of USD 18.06 is obtained. This result demonstrates that investment in sustainable practices is economically viable and highly profitable, consistent with studies that have documented improvements in competitiveness and access to differentiated markets when sustainable agricultural practices are implemented free of chemical residues.
This result is significantly higher than the typical minimum acceptable marginal rate of return for agricultural technology adoption, which typically ranges from 1.5 to 2.0. Furthermore, the robustness of this profitability is confirmed by the threshold sensitivity analysis. The economic advantage of the sustainable pest management program is not a fragile outcome dependent on specific market peaks; instead, it remains the superior financial choice even under extreme stress scenarios. Specifically, sustainable pest management would remain more profitable than historical conventional control unless labor costs increased by more than 422% or the coffee selling price decreased by more than 20.1%. These safety margins suggest that the shift toward sustainable practices serves as a structural de-risking strategy for coffee production units, enhancing competitiveness by preserving grain quality rather than relying on fluctuating external premiums.
Taken together, these results support the view that using a sustainable pest management program for controlling CBB is not only environmentally friendly but also enhances profitability. However, additional challenges include resistance to pruning among farmers, limited availability of biofactories for mass rearing African parasitoids, ensuring the quality of biocontrol agents, and increased labor costs associated with these practices. To address these limitations, the use of
P. nasuta as a specific predator to reduce CBB dispersal could be replaced by native predators such as
C. quadricollis and
A. advena, applied in larger numbers as suggested by Constantino et al. [
37]. Moreover,
P. coffea releases could be substituted with preventive applications of
B. bassiana to reduce colonization in newly established coffee crops. Ensuring bioinput quality will require simple, field-friendly tests to verify the germination of
B. bassiana conidia. Labor demands for bioinput spraying could be reduced through technologies such as uncrewed aerial vehicles (UAVs). Finally, using native predators may also help lower CBB populations on the ground, thereby decreasing labor intensity during cultural control practices.
The sustainable pest management program for coffee berry borer evaluated in this study was implemented on a coffee farm covering 41.47 ha, which demonstrates its feasibility for application at larger spatial scales under an Area-Wide management approach, as previously reported by Benavides et al. [
16]. In this context, coordinated actions across contiguous coffee areas facilitate the optimization of monitoring efforts, labor organization, and biological control implementation. For smaller farms, the SPM components evaluated in this study are also adaptable. Cultural control practices and biological control can be readily implemented at the smallholder level, and in situations where access to mass-reared parasitoids is limited, native natural enemies, particularly predators, may serve as viable alternatives, as documented [
18,
37].