Engineering natural enemy shelters to enhance conservation biological control in field crops

Conserving natural enemies has become the cornerstone for sustainable pest management. Conservation is often attained through habitat manipulation in order to create suitable conditions for supporting the populations of natural enemies. In this context, creating natural enemy shelter is an important tactic for enhancing the conservation biological control of pests. In this article, I have reviewed several aspects of sheltering natural enemies, including the ecological mechanisms that promote conservation biological control, potential negative interactions, and directions for creating shelters, in addition to indicating challenges and recommendations for future work. Shelters may bolster natural enemy abundance/diversity by providing them with suitable microclimate, alternative prey/host, and non-prey food, in addition to providing protection from intraguild predators and pesticides. However, a shelter may interact negatively with natural enemies in some instances by hampering their movement, diverting their attack, and/or promoting antagonistic intraguild interactions. Some of the most common forms of shelters include beetle banks, shelterbelts, hedgerows, flower strips, intercropping, and selective conservation of arable weeds. Nonetheless, while these habitat manipulations have been proven to be beneficial, many challenges still lie ahead. We need to promote adoption of conservation biological control by farmers, especially by scientifically linking its implementation to profitability (i.e., crop yield). Additionally, an interdisciplinary research approach is necessary for the development of an applied knowledge concerning how the interplay between local management, landscape complexity, and arthropod community will affect conservation biological control of herbivorous pests. Because this type of knowledge is important for the environment and sustainable agriculture, more programs that foster conservation biological control should be in-centivized by governments.