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Biological control remains unutilized as yet in the framework of Drosophila suzukii Matsumura management. Although several parasitoid species attack the pest under laboratory conditions, information is lacking on their host-finding and dispersal capabilities in natural environments. We tested the effect of repeated parasitoid releases on D. suzukii populations in infested orchards. The pupal parasitoid Trichopria drosophilae (Perkins) was released on different crops at eight sites. Parasitism was monitored using traps placed at various distances from the parasitoid release point (RP). A second experiment was carried out under semi-field conditions to evaluate augmentation of the parasitoid. In both experiments, D. suzukii infestation was evaluated through fruit samplings, both from the plant, and from the ground. In the open field trials, T. drosophilae attacked D. suzukii in traps up to 40 m away from the RP, and pest emergence was significantly reduced within a radius of 10 m at seven out of eight sites. In the semi-field trials, parasitoid releases significantly reduced D. suzukii emergence from ground-sampled fruit, and augmentation enhanced parasitism, increasing the numbers of parasitoids emerging from host pupae. Although further field studies are required, these results suggest that T. drosophilae may be considered a potential biocontrol agent for D. suzukii . [ABSTRACT FROM AUTHOR]

Two generalist pupal drosophilid parasitoids, Pachycrepoideus vindemiae (Rondani) (Hymenoptera: Pteromalidae) and Trichopria drosophilae Perkins (Hymenoptera: Diapriidae), are sympatric and among only a few parasitoid species attacking the invasive Drosophila suzukii Matsumura (Diptera: Drosophilidae) in many regions of the world. In this study, we evaluated their foraging efficiency when attacking D. suzukii infesting cherry fruit in a laboratory cage experiment; and we examined their potential interspecific interactions, including outcomes of intrinsic competition, host discrimination, and the impact of their interaction on pest control. We show that both parasitoids readily parasitized D. suzukii pupae located inside fruit or buried in soil. However, T. drosophilae was more efficient than P. vindemiae and that parasitism by either parasitoid species was higher in the fruit than in the soil. Generally, the parasitoid species that oviposited first in the host out-competed the later parasitoid in multi-parasitized hosts, we assume, through physiological suppression. Both parasitoids discriminated against hosts parasitized previously by the other species. In an additive-series design experiment with single ( D. suzukii ) or two ( D. suzukii and Drosophila melanogaster Meigen) host species, T. drosophilae performed similarly regardless of the presence of a competitor, while P. vindemiae achieved a higher parasitism when alone. The observed parasitism when the two parasitoid species were present together was always lower than the expected one, assuming each species acted independently. This indicates a negative effect by P. vindemiae on interspecific competition on host suppression. [ABSTRACT FROM AUTHOR]

[Display omitted] • Biocontrol agents can alter insect-fungus mutualistic interactions in Xylosandrus compactus. • Trichoderma and Bacillus spp. exhibited antagonistic activity against Ambrosiella xylebori. • Mycoparasitic fungi and antagonistic bacteria affect the development of beetle progeny. • Biofungicides have the potential to act as a novel tool for managing X. compactus. Xylosandrus compactus (Eichhoff) (Coleoptera: Curculionidae: Scolytinae) is among the most invasive ambrosia beetles causing severe damage to host plants belonging to various ecosystems. Foundress females excavate galleries into the plant xylem introducing mutualistic ambrosia fungi which are the exclusive food source for their offspring. The cryptic habits of this fungus-farming insect and its wide host range facilitated its rapid spreading worldwide. Despite several advances in deepening the bio-ecology of this beetle, there is still a general lack of information about effective control strategies. In this context, microbials, such as antagonistic bacteria and mycoparasitic fungi, can have the potential to act as alternative management tools. Here, we evaluated, for the first time, the potential of commercially available microbial agents for suppressing the growth of the main beetle mutualist, Ambrosiella xylebori, and consequently to hamper the beetle progeny development. The antagonistic activity of five Trichoderma and two Bacillus -based biofungicides was first evaluated in vitro by means of dual-culture experiments in Petri dishes. Then, beetle bioassays were conducted by exposing carob twigs, previously treated with different concentrations of each biofungicide, to beetle foundresses. Tested microbial antagonists significantly suppressed the growth of A. xylebori on Petri dishes. A significant reduction of the beetle progeny was observed in galleries of treated twigs compared to controls. The higher reduction in mutualist growth and brood production was obtained within galleries of T. atroviride treated twigs. Our results show the potential of the tested microbials to suppress the beetle mutualist growth within galleries and consequently to affect the development of its progeny. [ABSTRACT FROM AUTHOR]

• Pachycrepoideus vindemiae and Trichopria drosophilae are cosmopolitan pupal parasitoids of Drosophila suzukii. • Host range studies showed remarkable of plasticity in parasitoids' body growth and development. • Parasitoids benefited from attacking larger hosts, with increased progeny size and fecundity. Pachycrepoideus vindemiae and Trichopria drosophilae are cosmopolitan pupal parasitoids of Drosophilidae that attack the invasive Drosophila suzukii. This study investigated one aspect of their plasticity – host acceptance and offspring fitness on 25 Drosophila species in a phylogenetic framework. Each parasitoid's key biological and ecological traits were compared among the different host species. Results demonstrate that both parasitoid species successfully parasitized and developed from all tested host species. Although the parasitoids' efficiency and offspring fitness varied among host species, effects on life-history characteristics or ecological traits appeared to be unrelated to the phylogenetic position of tested host species. Both parasitoids benefited from attacking larger hosts, with body size of emerging progeny positively correlated to host size and an increased fecundity (mature egg load) of female wasps. Achieving larger body size came at no significant costs in immature development time. Results show remarkable levels of plasticity in the parasitoids' body growth and development. Body size plasticity in T. drosophilae and P. vindemiae could improve biological control by increasing variation in parasitoid body sizes. Large size may not be advantageous under all conditions, however, and the parasitoids' ecoservice impacts will be influenced not only by their plasticity to hosts but by environmental limitations such as temperature tolerances, habitat location, and host searching behaviors. [ABSTRACT FROM AUTHOR]

• Four European ant species exhibited potential in predating Xylosandrus compactus juveniles. • Temnothorax mediterraneus is able to enter galleries and prey beetles. • Dispersing beetle females avoid infesting twigs previously patrolled by ants. • Biocontrol services provided by the tested ants need consideration in further field studies. Due to their ubiquity and their nature as generalist predators, ants have long been used as biological control agents in forest and agricultural systems. Several exotic ambrosia beetles (Coleoptera: Curculionidae: Scolytinae, Platypodinae) are considered emerging widespread pests of various trees and shrubs growing in forests, nurseries, orchards, and urban areas. Among them, the Scolytinae Xylosandrus compactus (Eichhoff) is an invasive fungus-farming species native to Asia and able to cause serious damage to a broad range of natural and cultivated plants worldwide, exerting significant ecological and economic costs. Its biology makes conventional control strategies often ineffective, while little is known about natural enemies. We explored the potential of native European predators as natural enemy of this pest, conducting laboratory tests with four widespread ant species using chestnut and laurel as beetle hosts. In particular, we evaluated the interactions between X. compactus and four species of native Euro-Mediterranean ants that usually forage on plants: Crematogaster scutellaris (Olivier), Tapinoma magnum Mayr, Temnothorax affinis (Mayr), and Temnothorax mediterraneus Ward, Brady, Fisher & Schultz. Results indicate that ants may significantly limit the reproductive success of X. compactus , increasing the mortality of the beetle foundresses and reducing their offspring. Smaller ant species may also invade X. compactus nests, killing larvae, pupae and adults, while female beetles avoid nesting in twigs previously visited by ants. These results encourage to explore possible applications of ants in the biological control of X. compactus and the ecological implications of these interactions in the field. [ABSTRACT FROM AUTHOR]