Evaluation of a chemosterilization strategy against Ceratitis capitata (Diptera: Tephritidae) in Mallorca island (Spain)

A pest management programme using the chemosterilant lufenuron against the Mediterranean fruit fly, Ceratitis capitata in Mallorca (Spain) is reported. The aim of this field trial was to monitor the reduction on C. capitata population and fruit infestation during the second and third years of an overall pest control programme. The insect growth regulator lufenuron (a phenylbenzoylurea) was placed within a Sevep device baited with the synthetic, female attractants (ammonium acetate, putrescine and amines), as well as the male attractant trimedlure (TML). A total of 7200 devices were placed on 300 ha within the municipalities of the Soller Valley, at a density of 24 devices/ha. In order to measure the effectiveness of the chemosterilization, the C. capitata population was evaluated by Probodelt traps, baited either with the synthetic food attractants or TML, placed in three citrus orchards located at different altitudes. Fruit infestation was also evaluated. Results showed an average of 20% reduction in adult medfly population (37.2% for males vs. 2.7% for females). However, high differences were observed among the different orchards. In Site 1, where fallen oranges fruits were removed and phytosanitary treatments were applied, female captures decreased by 63.28%. Whereas at Site 2, where fallen fruits were neglected and no insecticide was applied, female captures increased by 19.90%. Ceratitis capitata population increase placed in Site 2 was probably due to the presence of unmanaged or mismanaged surrounding orchards. Summing up, it seems that the method based on lufenuron applied in the Soller Valley was successful in decreasing medfly population, but the presence of the nearby improperly managed citrus orchards, as well as other hosts fruit trees for C. capitata, decrease the efficacy of the method.