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

Abstract

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 pestCeratitis 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 SanJuan Biofactory, both sterile medfly males and the exotic larval parasitoid Diachasmimorphalongicaudata (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 fieldcage (semi-field) conditions. Trials were conducted during the summer, from 31 Januaryto 26 April 2019, at a fruit farm in the Rawson district of San Juan. Each mesh-coveredcylindrical iron field cage enclosed five exposure devices, each holding three semi-ripe figsused 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 medflyrelease alone (fertile flies and sterile males released simultaneously), and (4) combinedtechniques (fertile and sterile medflies released first, followed by parasitoids). The resulting dataset includes the number of recovered puparia and non-hatching puparia, adultflies and parasitoids, as well as the benefit proportion and Abbott’s effectiveness for eachexperimental condition. Combining both methods produced an additive suppression ofthe pest population, achieving 96% suppression of the medfly population, a value closeto a near-eradication effect. These results support the use of both control techniques in anarea-wide integrated medfly management approach.