By Nick Gutkin
Throughout the history of agriculture, farmers have faced a common foe in agricultural pests. These pests take many forms, such as weeds, animals, and diseases, but all in some way reduce the productivity and survival of crop species. The annual impact of pests on crops varies depending on world region but ranges from crop losses of 14% in Europe to 35% in parts of Africa, Asia, and Oceania. As the growing issues of biodiversity loss and ecosystem degradation limit the possibilities for land use change, scientists and farmers must look for new ways to control pests and thus raise crop productivity to provide for a growing human population. Often, the go-to method of controlling pests relies on pesticide application. These synthetic chemicals are mass-produced with either specificity to a particular pest species, or more generally targeted to a class of organisms, for example the use of DDT as a general insecticide.
As agrochemical companies have developed novel forms of pesticide, their use worldwide has also increased in the past decades. For example, the usage of one of the most common pesticides, glyphosate (commonly known by its commercial name “Roundup”) increased over 1200% between 1995 and 2014, with over 826 million kilograms applied to crops worldwide in 2014. However, despite a large increase in pesticide use from the 1960s to the 2000s, crop productivity on a worldwide scale was hardly affected, and the efficacy of pesticides has been dropping in recent decades in part due to pest species developing resistance to pesticides over time. Pesticides also play a key role in the destruction of other, non-pest species. This is particularly important as many of these non-target species are involved in complex food-webs, where they may even act as predators against the pest species themselves.
This predator-prey interaction is at the foundation of another form of pest control – biological control. In a laboratory setting, this method involves an analysis of the tropic structure surrounding a target pest species, followed by the selection of an appropriate predator or parasite species to inoculate or inundate the crop field. Despite a growing scientific interest in the use of biological control methods, various such practices have been used by humans for millennia, while natural biological control has been at the heart of every well-functioning ecosystem for hundreds of millions of years. Prior to the discovery and subsequent soaring popularity of pesticides for pest control starting in the 1950s, farmers worldwide were well-versed in different forms of biological pest control, and often incorporated various techniques to manipulate food webs to their advantage. Many of these practices continue, particularly in developing countries, where income levels can restrict the purchase of synthetic pesticides. The significance of such practices has done little to shift the direction of research and development: spending on chemical control outweighs spending on biological control by a factor of 90, despite biological controls being up to 10,000 times more likely to succeed at pest management. Biological control has been praised as much more ecologically sustainable, due in part to the fact that synthetic chemicals are not involved and thus there is no pollution to harm surrounding ecosystems or communities.
This paper aims to investigate the negative impacts of pesticide usage in developing countries and consider the traditional practices of biological control as an alternative method. This paper will also consider the implications of both methodologies on rapidly increasing food demands, especially concerning countries of the Global South, and make a case for a wider implementation of traditional methods of biological control across the world.
Pesticides: simple, effective, and dangerous
Although pesticide production and usage has been increasing on a global scale since the 1960s, the dynamics of specific chemical consumption on a national scale are very difficult to identify, as specific data is largely unavailable or obscured through generic labelling methods. However, with agricultural intensification comes an increase in application of both fertilizers and pesticides to increase crop yields. Pesticides are so popular because, generally, they are effective at reducing pest populations and thus crop losses. Particularly in developing countries, subsistence farmers may feel the pressure to use pesticides in order to grow enough food to feed themselves and their families. As pesticides are rarely produced directly in developing countries, there is also the external pressure of manufacturers, importers, government agencies, and aid organisations who frame pesticide shipments as forms of “aid” or support for ailing subsistence farmers. Thus, small-scale farmers in developing countries use pesticides because they are widely available, relatively easy to use, and bring easily visible reductions in pest populations and crop losses.
However, pesticide use in developing countries is also plagued by a host of problems: improper application and protection, pesticide accumulation in soils and waterways, and inefficient use leading to lack of productivity gains. The lack of information available to local farmers and especially the lack of regulation can lead to detrimental health effects on the general population. While information concerning the dangers to health posed by pesticide use is easily accessible in developed countries, that is not the case in the developing world, where advertising companies seize the opportunity to proclaim the benefits of pesticides to an otherwise uninformed public. A lack of education or literacy is also tied to improper pesticide usage, as is a lack of personal protective equipment (PPE) appropriate for the chemical in question. Farmers in developing countries often are not educated or aware of the dangers of pesticide or lack the resources to buy PPE and take proper precautions to prevent exposure. The negative health effects of pesticide exposure are not negligible; pesticides account for over 200,000 acute poisonings per year, with developing countries accounting for 99% of the victims. This is further exacerbated by the sales of illegal pesticides – either mislabelled or banned chemicals – which leads to further damage to both public and environmental health. Often, the market for such pesticides exists precisely due to a lack of governmental regulation.
The negative impacts of pesticides have also been shown to disproportionately affect poorer workers and have indirect effects on pregnant women and children. Further complicating the issue is that even when the negative effects of pesticides are known, farmers in developing countries may be forced to continue using pesticides due to economic factors and a lack of alternatives. Beyond their human impacts, pesticides are also detrimental to the environment. Pesticides have been found in low concentrations in groundwater all over the world and are proven to have negative effects on various animal species. They also reduce biodiversity not only on the farms where they are applied, but in surrounding areas as droplets drift with the wind and surface runoff carries pesticide residues through stream systems. Even when properly applied, pesticides have detrimental effects on non-target species, and have been directly linked to the massive decline in insect populations worldwide over the past few decades. This decline has been strongest in developed countries where pesticide application is also the highest. In the context of agriculture in developing countries, pesticides have the potential to improve livelihoods through increased crop production and income. However, when weighed against their negative effects on the environment and human health, exacerbated by poverty conditions and a lack of investment in safety awareness by agribusiness, the benefits of pesticides are much less clear.
Biological control: a tried-and-true solution?
Methods of biological control, involving the use of natural predators to reduce pest populations, have shown a lot of promise over the past few decades. Particularly promising is the potential for biological control to increase production yields in developing countries, while also reducing the harmful impacts of pesticide application. Wyckhuys and colleagues note the ecological degradation wrought by pesticides in the few decades since their adoption into pest control regimes in developing countries. The same study also notes the historical precedent for biological control, which is that such strategies have in fact been used for millennia by farmers and continue to be used in areas where farmers lack the financial resources to access pesticides. For instance, Chinese farmers practice a traditional method of raising ducks in rice paddies, wherein the ducks feed on pests and weeds (reducing costs for feed) and fertilize the water with their droppings (increasing rice production). This example, along with many other traditional agricultural practices, shows the value of traditional knowledge for pest control solutions.
In countries across the world, farmers use traditional cultural practices to increase the effectiveness of natural pest predators and improve crop outcomes. For example, the pruning and addition of organic material to the soil surrounding crops is an effective way to increase the populations of natural insect predators such as spiders and earwigs. Such strategies play a big role in the growing field of agroforestry, but are also beneficial for subsistence farmers, who may not have the financial means to access chemical fertilizers. Pruning leaves and fertilizing the soil with organic matter, besides increasing the populations of pest predators, also allow for higher nutrient concentrations leading to increased crop yields. The promotion of such strategies over the use of chemical fertilizers and pesticides could be a viable way of decreasing reliance on agrochemicals, as well as decreasing their negative health effects in developing countries.
Even in countries with strong biological control traditions, the use of chemical inputs has been promoted to the degree that such traditions have been put aside. Governments in Africa promote the usage of pesticides as part of a general package of interventions meant to increase crop production. This is driven in part by shipments from developed countries of pesticides that are obsolete or banned in those same countries, which are disposed of through the charitable act of donation. In some developing countries, governments are motivated to provide pesticides free of charge to farmers, which then shifts the responsibility of pest management from farmers to the government and can reduce the application of traditional pest control techniques. Nevertheless, developing countries are hotspots of traditional methods of pest control. Traditional practices of crop rotation, polycultures, and low soil disturbance foster increased biodiversity and attract natural enemies to farmers’ fields, helping to naturally reduce pest populations.
Whereas biological control in developed countries is often oriented around the introduction of predator species from laboratories and production sites to crop fields, a more traditional approach to biological control involves transcending a purely agricultural viewpoint to a more agroecological one. Viewing crop systems as an intersection of agriculture and ecology allows farmers to support both through strategies that increase diversity and reduce chemical inputs. The cultural practices that are used in lower income, developing countries are not only effective at reducing pests and increasing crop yield, but also protect the health of communities from the adverse effects of pesticide use. A shift in focus by research and development teams (including increased financial investment) to investigating traditional practices of biological control could improve not only crop yields and health outcomes in developing countries, but also provide an alternative to the pesticide addiction that has become a key component of intensive crop systems in developed countries.
As our understanding of the negative effects of chemical inputs to agriculture grows, it is time to turn our attention to time-tested methods of biological controls. Particularly in developing countries, where financial means limit access to agrochemicals, farmers have a wide variety of biological control techniques to implement. Increasing the supply and application of pesticides in developing countries risks negative outcomes not only for the environment, but especially for the health of local people and communities. The traditional practices of pest control should be not only strengthened through increased scientific research but also shared amongst farmers in developing and developed countries alike. With incredibly high pesticide application rates, developed countries have a lot to learn from traditional techniques that have remained in use despite the introduction of pesticides. Issues such as a worldwide decline of insect populations and the looming pollinator crisis make it ever more important to consider novel techniques of pest control and reduce worldwide pesticide usage. Perhaps it is time for agriculture to look to its past and learn from traditional methods to bring about the pest management of the future.
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