Field-Cage Assessment of the Neotropical-Native Parasitoid Ganaspis pelleranoi as a Biocontrol Agent of the Invasive Pest Ceratitis capitata

Abstract

Ceratitis capitata (Diptera: Tephritidae) is an invasive pest inhabiting urban and rural non-crop areas throughout Argentina, where standardized management strategies, such as cultural and chemical controls, are commonly implemented. The success in controlling medfly populations depends on implementing preventive, sustainable, long-term, and eco-friendly eradication/control strategies across all invaded environments. One of those actions may involve augmentative biological control using parasitoids adapted to local conditions, such as Ganaspis pelleranoi (Brèthes), a Neotropical-native parasitoid that mostly forages on tephritid larvae in a broad range of fallen fruit. Two hypotheses were tested in the current study: (1) G. pelleranoi are more efficient in controlling medfly larvae infesting different fruits as the density of released females progressively increases, and (2) such host-killing capacity remains when host density is increased. Field-cage trials were performed to assess the G. pelleranoi-induced host mortality in two medfly multiplier host fruit species, namely sour orange and peach, under a natural free-foraging condition and variation in both parasitoid release and host larval densities. From those trials, two major findings were highlighted. Firstly, G. pelleranoi females performed satisfactorily once released under uncontrolled environmental conditions and successfully killed host larvae on the two tested fruit species. Secondly, medfly mortality significantly increased in both peach and sour orange relative to the gradual increase of released G. pelleranoi females, regardless of the increase in host density offered to parasitoids. Such outcomes may provide relevant information for implementing augmentative biological control against medfly using indigenous parasitoid species within an eco-friendly pest management approach.