Hernández Penadés, P., Rodríguez Reina, J.M., & García-Marí, F. 2002 Economic threshold for the diaspidid scales [Aonidiella aurantii, Cornuaspis beckii and Parlatoria pergandii (Homoptera: Diaspididae) in citrus orchards.] Umbrales de tratamiento para cóccidos diaspídidos en cítricos.. Boletín de Sanidad Vegetal, Plagas 28(4): 469-478.

Notes: A quantitative economic threshold determination for the diaspidid armored scales A. aurantii, C. beckii [Lepidosaphes beckii] and P. pergandii was conducted in 34 commercial citrus plantations in Spain during 1998, 1999 and 2000. At each orchard, 300 mature fruits from a group of 15 to 30 trees were observed for scale infestation. The trees were not sprayed with insecticides for scale control during the three years. The flight activity of A. aurantii males was also measured in nine of these orchards in 1999 and in 20 in 2000, using pheromone traps. A positive correlation was found in fruit infestation at harvest between consecutive years in the three diaspidid species. The coefficient of correlation was high and consequently, the fruit infestation in the previous years could be used to predict the present year's infestation. Without chemical sprays to control the scales, the overall percentage of fruit infestation in the three species increased on average in individual orchards by a factor of two to three, and at most by a factor of six to seven. Infestation levels below 2% guarantee that no economic injury will happen at harvest next year. A high correlation was found between two or three deg male flights and infestation by A. aurantii at harvest. Male daily catches below ten per trap guarantee that no economic injury will appear on fruits at harvest. Daily catches above ten per trap can cause economic injury depending on the climate of the year and parasitism levels.