Combined Effect of Sterile Insect Technique and Augmentative Biological Control Use for Ceratitis capitata Control Under Field Cage Conditions

Biological control using parasitoid wasps and the sterile insect technique (SIT) are environmentally sustainable strategies that can be integrated into fruit fly management programs. Both eco-friendly techniques have been applied independently against the invasive pest Ceratitis capitata (Wiedemann), commonly known as the Mediterranean fruit fly or medfly, in irrigated fruit-growing areas of San Juan Province, central-western Argentina. At the San Juan Biofactory, both sterile medfly males and the exotic larval parasitoid Diachasmimorpha longicaudata (Ashmead) are mass-reared using the Vienna-8 temperature-sensitive lethal (tsl) genetic sexing strain. The aim of this study was to assess the effectiveness of controlling the medfly by combining releases of D. longicaudata and sterile male flies under field cage (semi-field) conditions. Trials were conducted during the summer, from 31 January to 26 April 2019, at a fruit farm in the Rawson district of San Juan. Each mesh-covered cylindrical iron field cage enclosed five exposure devices, each holding three semi-ripe figs used as oviposition substrates. The experimental treatments were as follows: (1) control (no parasitoid or sterile fly releases), (2) parasitoid release alone (fertile flies from a biparental medfly strain which were released first, followed by parasitoids), (3) sterile medfly release alone (fertile flies and sterile males released simultaneously), and (4) combined techniques (fertile and sterile medflies released first, followed by parasitoids). The resulting dataset includes the number of recovered puparia and non-hatching puparia, adult flies and parasitoids, as well as the benefit proportion and Abbott’s effectiveness for each experimental condition. Combining both methods produced an additive suppression of the pest population, achieving 96% suppression of the medfly population, a value close to a near-eradication effect. These results support the use of both control techniques in an area-wide integrated medfly management approach.