Interacting pest control and pollination services in coffee systems

Abstract

Biodiversity-mediated ecosystem services (ES) support human well-being, but their values are typically estimated individually. Although ES are part of complex socioecological systems, we know surprisingly little about how multiple ES interact ecologically and economically. Interactions could be positive (synergy), negative (trade-offs), or absent (additive effects), with strong implications for management and valuation. Here, we evaluate the interactions of two ES, pollination and pest control, via a factorial field experiment in 30 Costa Rican coffee farms. We found synergistic interactions between these two critical ES to crop production. The combined positive effects of birds and bees on fruit set, fruit weight, and fruit weight uniformity were greater than their individual effects. This represents experimental evidence at realistic farm scales of positive interactions among ES in agricultural systems. These synergies suggest that assessments of individual ES may underestimate the benefits biodiversity provides to agriculture and human well-being. Using our experimental results, we demonstrate that bird pest control and bee pollination services translate directly into monetary benefits to coffee farmers. Excluding both birds and bees resulted in an average yield reduction of 24.7% (equivalent to losing US$1,066.00/ha). These findings highlight that habitat enhancements to support native biodiversity can have multiple benefits for coffee, a valuable crop that supports rural livelihoods worldwide. Accounting for potential interactions among ES is essential to quantifying their combined ecological and economic value.

Keywords: biodiversity; coffee production; economic valuation; ecosystem services; synergies.

Fig. 1.

Study area and experimental design. (A) Location of the VCTBC (red silhouette) proportional to Costa Rica and main land uses present within the VCTBC. Yellow circles with black centers show individual location of coffee farms (n = 30). (B) Full-factorial experimental design of bee and bird exclosure treatments to assess the potential interacting contributions of pollination and pest control. By selecting eight coffee plants and excluding a group of four coffee plants from birds, and two branches in each plant from bees, we set up four exclosure treatments at the branch level: i) in which only birds were allowed access (bird activity alone), ii) where only bees were allowed access (bee activity alone), iii) where both were allowed access (bird and bee activity, i.e., control treatment), and iv) where birds and bees were both excluded (neither activity). In branches 1 to 4, we assessed fruit set (i.e., pollination service) and the proportion of bored fruits (i.e., pest control service). In branches 5 to 8, we further assessed only the proportion of bored fruits.

Fig. 2.

Interacting effects of bee and bird activity on coffee production. (A and B) Effects of bee and bird activity on fruit set and fruit weight. (C) Effects of bee activity and fruit condition (i.e., bored vs. not bored) on fruit weight, and (D) effects of bee and bird activity on fruit weight CV as a measure of fruit uniformity. Statistics are presented in Table 1. Different letters denote statistically significant differences.

Fig. 3.

Interacting effects of bee activity, bird activity, and time on the proportion of bored fruits. Fruit counts were conducted every 2 mo postflowering (May) until main harvest (November). Statistics are presented in Table 1. Different letters denote statistically significant differences within each time.