One of the biggest benefits of biological control is that it offers an additional control option in IPM Systems that serves to reduce the impact of pest management on the environment. By implementing biological control, we can target specific pests and thus mitigate the unintentional harm to non-target species that can result from control tactics with a broader range like insecticides. However, it is important to note that the specificity of biological control is dependent on the host breadth of the natural enemy. Biological control tactics are becoming more popular due in part to the increasing awareness of the impact of pesticides on the environment and other organisms. Biological control is a movement toward sustainability and also addresses the growing problem of pesticide resistance. This can have added benefits for farmers since products grown under organic or sustainable practices command a higher market price and demand for these products' growing. With the increasing costs of new pesticides, as well as the stricter rules governing the use of chemical controls, biological control may be economically justifiable in many situations. It's also less likely to negatively impact plant quality which can occur with repeated pesticide applications to some perennial crops. Other advantages to the implementation of biological controls are environmental and economic sustainability. Classical biological control is costly in the short term as it can be expensive and time-consuming to produce, evaluate, and transport biological control agents to release sites. However, if populations of natural enemies become self-sustaining in a new habitat, the cost of control decreases. In comparison, the cost of augmentative biological control remains about the same over time as augmentative biological control generally involves multiple introductions of the control agent. Conservation bio-control can be quite affordable as the measures taken in this approach do not include direct manipulation of the population of natural enemies. Overall, the future of biological control seems bright. New technologies that make biological control more economical are constantly being developed. These include the use of mechanized applicators as well as banker plants which provide additional resources to support populations of beneficial insects. In addition, the development of new highly specific insecticides allows the integration of biological controls with chemical controls and promote the integration of bio-control into IPM Systems. Despite the many advantages of biological pest control, this approach is not without its limitations. First, like most integrated pest management tactics, biological control requires a thorough understanding of the biology and ecology of all species within the habitat prior to implementation. Understanding these factors is necessary to ensure the efficiency of biological control. For example, annual cycles of temperature and day length may affect the ability of a natural enemy to control pests in the year-round crop production of many greenhouses. A short day length may limit the efficiency of visual predators, while some natural enemies have obligatory diapause requirements and can only be suitable control agents at specific times of the year. Lack of information about the target pest and its natural enemies can inadvertently result in unintentional and unexpected damage to both natural and managed systems. Unfortunately, there are several instances where a lack of research has resulted in a biological control system that has backfired on the manager. Take, for instance, the case of the Asian Ladybird Beetle. This predator was originally imported into North America as a biological control agent for aphid pests throughout the 20th century. The beetle helped to suppress aphid populations. But they also ended up competing with native ladybird beetles. Due to the Asian ladybird beetles high reproductive capacity and resilience to environmental extremes, this introduction has resulted in an ecological shift. The Asian ladybird beetle is now one of the predominant ladybird species in many regions of North America. If a biological control agent has abroad diet range, its impact on the past can be diluted through the consumption of non-pest species. Parasitoids and predators that are host-specific are generally more effective as biological control agents as they will efficiently search out and attack specific pests with little impact on non-target species. On the other hand, the use of biological control agents with a restricted host range may mean that multiple species are required to control a pest complex which can increase the cost of management. The diversity of plants grown in some agroecosystems can further complicate the use of biological controls. Many nurseries can have over 1,000 cultivars of different plants growing in the same facility. This means there will be a greater diversity of pests to be controlled. Many of which may not be controlled by commercially available agents. The release of multiple biological control agents needs to be specifically timed in response to pest phonology and population densities. If other types of control tactics are used to control some of the pest species, they will need to be compatible with the biological control agents. Natural enemies of different species can also interfere with each other. They may compete for resources or be vulnerable to predation by the other natural enemies. These interactions get more complex as plant and pest diversity increases. Another major limitation of biological control is that its effects are not as instantaneous as chemical methods, although some microbial insecticides can act quite quickly. It takes time for populations of the biological control agents to reach levels that provide effective pest management. This lagging effect is particularly concerning in the management of high-value crops or extremely damaging pests. Biological control agents are often well-suited for using greenhouse systems, as they can be contained within the enclosed spaces and because biological control agents are often commercially available for common greenhouse pests. The lag of bio-controls can disrupt plant growth in these systems, however, as pest populations can build up quickly in the ideal conditions of a greenhouse and pest may move in from external environments. For example, there may be an influx of pests into a greenhouse as pests disperse away from harvested agricultural fields nearby. These large pest populations can be difficult to manage with biological control alone. Biological control agents are living organisms and commercially available agents have a short shelf life and cannot be stored indefinitely, unlike some chemical insecticides. These control agents must be delivered or released soon after they are produced for optimal effect, which can be tricky if they must be transported to distant sites for release. There also many restrictions governing the international movement of biological control agents. So only a limited number may be available in a certain region. These hurdles must be overcome for biological control to become a regular part of integrated pest management systems. As we have discussed so far, biological control can have many advantages. It aids in conservation efforts and environmental protection and is also environmentally and economically sustainable in the long-term. However, biological control can be expensive, particularly in the short-term and its effects are not as instantaneous as chemical control. The key to effective biological control is to educate the users and the public. It requires a more informed approach than chemical control to be successful but can be more sustainable and economical in the long run. Now that we have explored the concepts of biological control, in the next lesson we'll turn our attention to another approach used in IPM, cultural control.
