Geostatistical analysis as essential information for efficient decision making in Anastrepha fraterculus (Diptera: Tephritidae) control in apple orchards

Abstract

Anastrepha fraterculus Wiedemann (Diptera: Tephritidae) is a key pest in apple orchards (Malus domestica Borkh.). Decision making for fruit fly management relies on the mean number of flies captured per trap. The number of flies captured depends on trap distribution in the orchards and climatic conditions that explain population density patterns as a function of space and time. Knowledge of A. fraterculus spatial distribution patterns and climatic conditions in apple orchards may help to plan control measures, develop efficient monitoring plans and improve management by targeting specific sites and periods when A. fraterculus occurrence is highest. Therefore, our aim in this study was to determine the seasonal variation and spatial distribution patterns of A. fraterculus in commercial apple orchards using geostatistical analysis. Anastrepha fraterculus density was higher during the warmer periods of the year and when apple trees had fruit. The spatial distribution pattern for this pest varied over the years and between orchards. Pest outbreaks were initially small however, they subsequently spread throughout the entire orchard. The adults of A. fraterculus colonized the orchard during the reproductive phase of apple trees, initiating at the edge of the orchard. The different occurrence sites of the pest foci and their fast growth underline the importance of locating and controlling these foci at the initial stage. Still, basing decision making on mean pest density values when implementing control measures can lead to unnecessary applications. The information found in this study provides useful information to initiate methods for timely management, prevention and control during periods of high favorability in orchard sites with high A. fraterculus incidence, thereby reducing production costs and harmful effects of pesticide use.