Drivers of and Barriers to the Implementation of Integrated Pest Management in Horticultural Crops

Integrated pest management (IPM) aims to protect plants using methods that limit the use of pesticides, as well as other interventions, to levels that are economically and ecologically justified, thus reducing the negative impact of crop protection on humans and the environment [1]. The adoption of IPM has been successful in fruit and protected crops, but remains marginal in other crops [2].

The routine monitoring of pests, the application of pest population thresholds, and the rational use of pesticides are the major pillars upon which IPM is based. Adequate pest monitoring systems using innovative tools, such as automated insect/spore traps [3] or forecasting systems [4], are currently available and are critical for the correct implementation of IPM. Tools predicting the dynamics of harmful organisms, including epidemiological models, have been developed to provide decision support systems (DSSs) that integrate intervention thresholds, and should thus promote the implementation of IPM programs that are adaptable to specific needs [5,6].

Biological control (BC) is a key ecosystem service and can become a pillar of IPM, for example, in case of protected crops as well as the control of invasive pests through the introduction of their natural enemies. Indeed, climate change as well as intensification of trade have favored the introduction of new invasive pests and their establishment in new territories on a global scale [7]. Drosophila suzukii [8] and Hyalomorpha hyalis [9] are two recent examples of this trend and the potential of BC. Nevertheless, while it was estimated that approximately 230 natural enemies are available from over 500 suppliers [10], biological control is still adopted on a relatively small scale world-wide. Reasons for this include the need for technical knowledge about the conditions for the successful large-scale release of natural enemies (e.g., the determination of the opportune time for their release, when there is an abundance of the target pest population on which the predator or parasitoid feeds) as well as the ecological and behavioral aspects of the natural enemy [11,12].

On the other hand, the exploitation of conservation- BC and crop management practices to increase the abundance and activity of autochthonous natural enemies is becoming increasingly relevant considering the decrease in biodiversity recorded in recent decades [13]. In this regard, landscape modification at the farm [14] and/or territorial level [15] has had a favorable impact on the whole control strategy and positive long-term results have also demonstrated favorable economic returns on investment [16]. Shelters or food sources for natural enemies can be provided by specific plant structures, groups of plants, or plant litter, as well as through artificial structures. Interconnectivity among these structures could improve the movement of natural enemies within and between fields [17], with large distances between these structures affecting the efficiency of BC [18].

Understanding the economic value of the key ecosystem services supplied by BC could encourage the adoption of IPM practices and increase awareness among decision makers supporting funding measures. The relationship between the composition of the surrounding landscape and biodiversity in crop fields has been found to impact ecosystem services (e.g., pollination) as well as pest regulation through conservative BC [19,20]. For example, an estimation of the monetary value of ecosystem services derived from the introduction of living mulches, a practice commonly recommended to increase biodiversity in orchards, demonstrated the potential for additional income also due to the reduced need for pest control treatments [21]. The latter is particularly relevant considering that pest management decisions can generate externalities (i.e., costs or benefits that are not directly reflected in economic transactions), such as long-term effects on environmental health, water quality, or workers’ health, with ecosystem-level estimates showing significant value [22]. However, if growers cannot directly benefit from the externalities provided by BC, they may under-adopt IPM practices. Considering that the economic threshold is a key component of IPM, which incorporates population dynamics into an economically based framework supporting control decisions, the limited research evaluating BC or conservative BC makes difficult to convince farmers to adopt such practices [23]. In this case, public support could help promote IPM implementation. Nevertheless, despite the strong policy support for IPM, particularly in advanced economies in the last few decades, its adoption has been inconsistent [24,25].

Although most technological constraints representing potential obstacles to the adoption of IPM have been overcome by recent technological progress (i.e., image analysis for insect identification, meteorological data acquisition, internet access, simple phone-based applications, etc.) [26], the translation of these innovative methods into practice is still hampered by socio-economic constraints and farmers’ perceptions of IPM being a complex, technically demanding practice, not always ensuring economic advantages with respect to conventional or organic farming [27,28].

Nevertheless, the introduction of precision farming techniques (which can reduce the input of PPPs only to areas of fields where the economic threshold is reached) in combination with artificial intelligence could also represent an important technological innovation in terms of reduced costs [29]. Moreover, the reduction in environmental impact achieved through the application of pesticides using spraying systems, which allows farmers to recover product that has not reached the plant canopy or dynamically modifying the amount applied to different parts of the tree canopy using sensors and IT systems in their tractors, are innovations also associated with economic benefit [30]. Nonetheless, the efficiency of precision farming systems depends on the accuracy of the monitoring method selected for the specific pest, as well as information on population dynamics and their associated ecological factors. In this regard, the introduction into practice of self-organized networks of traps that collectively report data on local, regional, and even country scales using the Internet of Things (IoT) [31] could lead to a breakthrough in the adoption of IPM on a larger scale.

The Special Issue entitled “Integrated Pest Management in Horticulture” encompasses several of the above-mentioned topics, and the data and research presented should further encourage the implementation of pest management methods to reduce the application of synthetic plant protection products via a system approach.