Limiting factors of mycopesticide development

Phytosanitary crop protection products have shown their impact on the environment. They may not be very selective and their excessive use in agriculture causes pollution of soil and groundwater, destruction of many beneficial insects and the emergence of resistant pests. Hence there is strong public and political pressure driven by consumers to implement phytosanitary alternatives that are less aggressive to the environment, such of biopesticides. Biopesticides and, in particular, mycopesticides are frequently used as an environmentally friendly tools to reduce plant diseases by inhibiting the growth of pathogens and inducing resistance in plants.<br /><br />In this review, we will first analyze the current evolution of the global market of biopesticides. Boosted by different political initiatives all over the world, this market has increased 6-fold between 2005 and 2016. In 2016, it represented 6% of the global pesticide market with a compound annual growth rate (CGAR) of 14.1%. The mycopesticides accounted for only 10% of the global biopesticide market of 2016.<br /><br />We then focused on two main factors which should contribute to the future development of mycopesticides: the large panel of their modes of action and the physiological state of the active product. Indeed, several modes of action could, in some instances, increase the efficacy of a biopesticide and postpone the emergence of resistance mechanism. The broad set of mechanisms use by Trichoderma harzianum and T. atroviride to reduce plant diseases: nutrient competition, direct antagonism, mycoparasitism and induction of resistance mechanism in plants were developed as an example. Stability of the active substance is another essential factor for creating competitive mycopesticides. For this, the choice of propagule types could be a major factor in enhancing their stability. This choice was discussed highlighting the advantages of conidia or sporidia from solid-state fermentation.<br /><br />To end with, the registration process in European Union was described revealing another limiting factor that delays the development of mycopesticides in this zone.