Ecosystem services valuation of integrated pest management practices in cotton agro-ecosystems

Introduction

The hidden economy of farm biodiversity far outweighs the price tag on a bottle of pesticide. Global ecosystem services from agricultural landscapes have been valued at €1.5 trillion annually, yet conventional pest control strategies that rely on broad-spectrum chemicals systematically erode this natural capital [1] . Cotton, one of the world's most pesticide-intensive crops, receives roughly 16% of global insecticide applications despite occupying just 2.4% of arable land [2] . This disproportionate chemical load suppresses beneficial arthropod populations, disrupts pollination networks, and degrades soil microbial communities [3] . IPM offers an alternative framework that combines biological control agents, cultural practices, pheromone traps, and targeted chemical applications to keep pest damage below economic thresholds [4] . Several researchers have measured IPM's effect on pest suppression and yield, but far fewer have attempted to place a monetary value on the broader ecological benefits that IPM sustains [5,6] . Benefit transfer valuation which adapts existing ecosystem service values from comparable sites provides a practical method for monetizing services like pollination and natural pest control where direct market prices don't exist [7] . European cotton production is concentrated in Greece, Spain, and, to a smaller extent, northern Italy. The Po Valley supports a niche cotton sector alongside major cereal and horticultural crops [8] . This research aimed to: (a) compare arthropod biodiversity between IPM and conventional cotton farms, (b) assign monetary values to five ecosystem service categories, and (c) model the relationship between IPM adoption intensity and total service value [9] .

Study Area Description

The research was conducted in the Po Valley of northern Italy (44°50′-45°30′N, 8°40′-10°20′E), within Lombardy and Emilia-Romagna provinces. The area features deep alluvial soils with a silty clay loam texture, pH 6.8-7.4, and organic matter of 2.1-2.9%. Cotton is grown as a warmseason row crop between April and October, with fields typically bordered by hedgerows, drainage ditches, and cereal rotations that serve as reservoirs for beneficial arthropods [8] .

Climatic Conditions during the Research Period

From April to October 2023, mean monthly temperatures ranged from 14.2°C (April) to 26.8°C (July). Total rainfall was 487 mm, slightly below the 10-year average of 523 mm. A 19-day dry spell in July coincided with peak bollworm pressure. Relative humidity averaged 68-82% across the growing season. No hail events or frost events occurred during the trial [9] . insecticides, and conservation headlands. Conventional farms relied on scheduled calendar-based insecticide applications [4,5] .

Material and Methods

Material

Methods: Arthropod sampling used pitfall traps (five per farm) and yellow sticky traps (three per farm) deployed biweekly from May to September. Specimens were sorted to family level and classified as pests, natural enemies, or pollinators. Ecosystem services were valued across five categories: pollination support, natural pest regulation, soil biodiversity maintenance, water quality protection, and carbon sequestration. Values were assigned through benefit transfer using unit values from a European meta-analysis adjusted for purchasing power parity [7,10] . IPM adoption intensity was scored on a 0-100 scale based on the number and frequency of IPM practices. Linear regression modeled the relationship between adoption score and total service value. Group comparisons used independent t-tests at p<0.05 in R version 4.3 [11] .

Results

Discussion

The 2.71-fold difference in ecosystem service value between IPM and conventional farms exceeds the 1.8-2.3 range reported in comparable European cereal systems [5,6] . Cotton's higher pesticide intensity likely amplifies the biodiversity gap, making the contrast sharper than in less chemically dependent crops.

The R² of 0.964 between IPM adoption and total service value suggests a near-linear relationship, though this may flatten at very high adoption levels where marginal biodiversity gains become smaller [10] . Natural pest regulation (€294.8 ha⁻¹ yr⁻¹) dominated the service portfolio, consistent with meta-analytic findings that biological control is the highest-value regulating service in annual cropland [11] . The pollination estimate (€201.4 ha⁻¹ yr⁻¹) may seem high for a self-pollinating crop like cotton, but cotton yields benefit from insect-mediated outcrossing that increases boll weight by 12-18% [12] . The benefit transfer method carries inherent uncertainty because source values were generated under different climatic and landscape conditions. However, adjustment for purchasing power and crop type mitigates the largest sources of bias [7,13] .

Conclusion

IPM practices in Po Valley cotton farms generated ecosystem services worth €847.3 ha⁻¹ yr⁻¹, compared to €312.6 ha⁻¹ yr⁻¹ on conventional farms. Natural pest regulation and pollination support were the two largest contributors, accounting for 34.8% and 23.7% respectively. A strong linear relationship (R² = 0.964) linked IPM adoption intensity to total service value. Arthropod diversity was substantially higher on IPM farms, with 2.7 times more natural enemy species and 3.1 times more pollinators. These monetary values represent hidden returns that current farm accounting systems overlook. Incorporating ecosystem service payments into agricultural policy could strengthen the economic incentive for IPM adoption in cotton and other pesticide-intensive cropping systems across southern Europe.

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