Biocontrol agents against diseases

International audienceBiological control against plant diseases has been extensively studied in recent decades, leading to the identification and development of a significant number of biocontrol agents with various modes of action. Considerable scientific and industrial investments are needed for the development and the commercialization of these protection tools. One of the main issue for the adoption of biocontrol by farmers is the reliability and stability of its efficacy in field conditions including greenhouses. Efficacy of biocontrol agents (especially that of microbes) is managed by complex factors linked to the changeable environmental conditions encountered in the field (e.g. microclimatic variations) and to farming practices (e.g. compatibility with other control methods, plant fertirrigation). Efficacy is also linked to the biological properties of the biocontrol agent (e.g. ecological competence, quality of the products, mode of application, mechanism of action, persistence of its efficacy) and of the plant pathogen (e.g. type of disease, inoculum pressure, diversity of sensitivity). In this chapter, examples of biocontrol agents used against soil-borne and foliar diseases, their modes of action as well as the factors of their efficacy will be addressed

Mollusc harvesting in the Pre - European contact Pacific Islands: investigating resilience and sustainability

Mollusc shells, which are often quite numerous in archaeological sites throughout the Pacific Islands, offer good proxies for assessing environmental change as well as human impact. Documented changes in species size, richness, and abundance have often been interpreted as evidence of resource abuse by shellfish gatherers. While this may be valid in some cases, archaeologists need to consider other variables to explain change (or stability) in shell distribution. A better understanding of ecological and biological (life history) characteristics associated with shell midden deposits, as well as greater awareness of ethnographic and ethnoarchaeological data on the interaction between people and varieties of marine resources, may result in a reinterpretation of past human behavior. A growing interest in indigenous resource management among contemporary Pacific Island communities has led some archaeologists to seek tangible evidence of community resilience and sustainable use of resources in the past. This chapter draws primarily from direct observations and semi-structured interviews among mollusc gatherers in Kiribati, eastern Micronesia, and examines selected case studies of archaeological shell deposits from the Pacific Islands that could shed new light on marine resource management to complement the more widespread research conclusions that depict human impact in largely negative terms