Use of environmental niches to understand interactions among Botrytis cinerea, biocontrol agents, and the environment

The use of Integrated Pest Management (IPM) and of alternative approaches or techniques, such as non-chemical alternatives to pesticides, are promoted by Directive 2009/128/EC. Alternatives to chemical pesticides include biological control agents (BCA). Some commercial BCAs are available for the control of Botrytis bunch rot (BBR) on grapevines, caused by Botrytis cinerea, but their practical use is still limited. One likely reason is the inconsistent efficacy of BCAs under field conditions, which may be related to several factors, including the variability of the environmental conditions affecting both, BCA fitness and B. cinereadevelopment. The colonization rate and the efficacy of a specific BCA, as well as B. cinereagrowth and infection, are all influenced by weather conditions, such as temperature and moisture. To achieve an effective integration of BCAs in a disease management program is then relevant to know: i) the life cycle of both, the pathogen and the BCA; ii) the mode of action of the BCA against the target pathogen; and iii) how the two are influenced by the environment. The concept of “environmental niches” is proposed to understand how the environment influence the BCA-pathogen interaction. Environmental niches are defined as the environmental conditions necessary for the presence of a species and the maintenance of its population. In this work, this concept was used to study the temperature and humidity conditions under which different commercially BCA-based products prevails over B. cinerea, and to define the extent of environmental niche sharing between each BCA and the target pathogen.