Abstract

The World Health Organization (WHO), Food and Agriculture Organization (FAO), and other international organizations are now calling for the development of environmentally sustainable systems that are less reliant on chemical pesticides (CPs) as the primary management tool for pest control. However, at the moment, biological control alone cannot solve all pest problems and must be considered an instrument to be used in combination with other methods. The compatibility of CPs and biological pesticides (BPs) is a key factor for the implementation of Integrated Pest Management (IPM) programs. Testing the compatibility of CP and BP is essential if these two agents are to be applied together in integrated management as synergistic, neutral, and antagonistic responses have been reported for some commercial BPs used with chemical ones. Although the compatibility of such pest control methods has been outlined as being a contentious and complicated issue, they are being increasingly used in combination, or even in tandem, to control pests in agricultural and urban settings, as well as for the control of invasive species and insect vectors of human and animal diseases. It is not always possible to achieve compatibility, but combinations can sometimes result in an additive or even synergistic effect, improving pest control and reducing CP use. There has been some discussion on the need for a wider international standard to achieve a much needed formal compatibility with respect to environmental and human health. Although an approach combining CP and BP can provide a safer and more comprehensive management program, which results in reducing CP, an exhaustive and standardized method is still needed to evaluate the environmental risk assessment (ERA) of such combinations. Indeed, carrying out an ERA is important as synergism on a targeted pest can result in toxicological synergism for non-target organisms. Most of the information documenting adverse environmental effects comes from studies focused on exposure to single pesticides, but in normal agricultural practice, the use of only a single pesticide is rare. The combination of BP and CP is an example of when an ERA is needed. Such an ERA for CP–BP combinations could be useful to predict an outcome, also in cases where combination was not fully intended. Thus, future goals should be directed towards evaluating and standardizing the ERA and cost analysis of CP and BP compatibility.