Geostatistical characterization of fruit damage caused by Anarsia lineatella (Lepidoptera: Gelechiidae) in organic fruit orchards and implications for its management

The peach twig borer Anarsia lineatella is the most common pest threat of peaches worldwide. This work studies for the first time, the fruit damage patterns inside organic peach orchards using geostatistical methods. A linear semivariogram model provides the best fit among candidates’ linear and non-linear models based on the RSS and r². Moreover, the shape of the linear model approaches the pure nugget effect model, with a very low correlation between samples regardless of the distance of separation. This suggests either that the caused damage is to a high degree randomly or uniformly distributed, or, that autocorrelation may be present in distance lower than the measured distance of the study orchards. The linear model has been used for Kriging interpolation to simulate the spatial distribution of fruit damage and to indicate hot spots of high pest activity. According to the linear interpolation model, the simulated percentage of damage ranged from 12% to 28% during an observation period of three years. Moreover, slight border effects were observed during the first two years of observation suggesting possible entry of individuals from nearby orchards.