Risk assessment of pea moth Cydia nigricana infestation in organic green peas based on spatio-temporal distribution and phenology of the host plant

Abstract

1 A method for area-wide risk assessment of pea moth infestation in commercial pea-growing areas based on spatial and temporal analyses of pea moth abundance and the phenological distribution of pea fields was investigated. 2 In a commercial pea-growing region in Saxony, Germany, all pea fields were identified, mapped and characterized, recording the pea plant phenology, pea moth flight and larval infestation of each field in the years 2006–2008. 3 The relationship between pea moth flight and pea plant phenology was studied in detail in small-scale field experiments in Hesse, Germany, using different pea cultivars and sowing dates. 4 In the study area, the abundance of Cydia nigricana Fabricius (Lepidoptera: Tortricidae) in organic green peas increased linearly with the pea-cropping area of the previous year in the surroundings of the current fields according to the continuous abundance index. 5 Considering solely the early flowering period (= early pea sowing dates) of the organic green peas, we calculated that a minimum distance of the current pea field to the nearest pea field of the previous year of 500 m was necessary to significantly reduce pea moth flight and larval infestation. 6 In small-scale field experiments, a correlation between pea moth flight and larval investation, as well as the importance of the pea flower for the pea moth occurrence, was demonstrated. 7 The spatio-temporal findings are discussed in relation to the development of a coincidence avoidance strategy in pea-growing areas.