The relationship between the olive fly population and epiphytic bacteria of the olive tree was investigated by carrying out a 1‐year survey in the field. The olive fly population affected the number of bacteria present on the olive surface. Scanning electron microscope observations demonstrated that bacteria may be ingested by the fly’s mouth apparatus through the midline of the pseudotracheae. DNA amplification of the oesophageal bulb content using 16S bacteria universal primers and DNA sequencing evidenced that Candidatus Erwinia dacicola was the predominant species present. The role of bacteria in olive fly biology is discussed.

The olive fly (OLF), Bactrocera oleae (Rossi), is an invasive tephritid fruit fly that causes extensive damage to olive crops around the world (especially in the Mediterranean basin and North America). Previous attempts to use the Sterile Insect Technique (SIT) for the OLF were not successful because of the inability to rear high quality OLF in the laboratory on an artificial diet. New improvements in rearing methods and additional understanding of the basic biology of the OLF have led to a renewal of interest in using SIT for OLF. This review discusses the history, difficulties, improvements and future directions of OLF mass‐rearing. Issues include: the design of cages and oviposition substrates, cost and quality of artificial diets, maintenance of endosymbiotic microbiota, control of pathogenic microbes, collection of pupae, the fitness of adults, and the competitiveness of sterilized laboratory males released to the field.

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Hippoboscidae flies parasitize various animal species. Knowledge about these insects remains sparse, although they are known to cause stress and damage to their hosts, and can also accidentally infest humans, causing different sanitary risks. Research conducted in Tuscany assessing the biology and distribution of Lipoptena cervi (Linnaeus, 1758) (Diptera: Hippoboscidae), the most common ectoparasite of ungulates in Italy, revealed the presence of Lipoptena fortisetosa Maa, 1965 in Italy for the first time. This study includes a morphological comparative description of L. cervi and L. fortisetosa, emphasizing the peculiar differences between the two species to facilitate their accurate identification. The most pertinent morphological differences between the two species are highlighted, such as the external features of the antennae, distribution of bristles, and different features in the external genitalia. In both species, scanning electron microscopy of mouthparts revealed strong adaptive convergence in the feeding apparatus. Modified palps and a very thin proboscis are described in relation to feeding behaviour.

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The relationship between Bactrocera oleae (Rossi 1790) and its endosymbiont Candidatus Erwinia dacicola is important to achieving effective control of the olive fly population in the field. This bacterium plays a crucial role in the life of B. oleae and is necessary for its fitness. Thus, in the absence of the endosymbiont, B. oleae wild populations in the field might decrease considerably. Copper is one of the most used antimicrobials for horticultural crops worldwide, and its efficacy against Ca. E. dacicola has been demonstrated in field trials. Propolis is another natural antimicrobial compound largely used for its activity in several fields. If propolis and copper prove to be efficient against wild populations of the endosymbiont B. oleae in the field, such a biological restraint might improve sustainable agriculture. We evaluated, under laboratory conditions, the effect of two different copper products (at two different concentrations, 5% and 20%) and propolis on the content of Ca. E. dacicola in the eggs and in the adult oesophageal bulbs of B. oleae. Bulbs were extracted twice, after 2 and 5 weeks of exposure. Real‐time PCR on the bulbs showed a reduction in Ca. E. dacicola content in flies treated with copper (at both 5% and 20%), and from the first to the second extraction, while flies treated with propolis showed an increment of the relative abundance of Ca. E. dacicola. Both copper products (5% and 20%) reduced the egg production after 2 and 5 weeks in comparison with the control and propolis treatments. Moreover, adult mortality was significantly higher with propolis compared with the other treatments. Thus, our results encourage further research in order to develop new tools for the control of the olive fly in the framework of an integrated pest management strategy.

Lipoptena cervi (Linnaeus, 1758), Lipoptena fortisetosa Maa, 1965, Hippobosca equina Linnaeus, 1758, and Pseudolynchia canariensis (Macquart, 1840) (Diptera: Hippoboscidae) are haematophagous ectoparasites that infest different mammal and bird species and occasionally attack humans. They are known for the health implications they have as vectors of pathogens to humans and animals, and for the injuries they inflict on their host's skin. This study focused on the morphological structures evolved by parasites in terms of their biology and the different environment types that they inhabit. To this aim, we examined four hippoboscid species, as well as their hosts' fur (ungulate and horse), and feather (pigeon) through light and Scanning Electron Microscopy (SEM) observations in order to highlight the main morphological features that evolved differently in these flies and to explain the effect of hosts' fur/feather microhabitats on the morphological specializations observed in the investigated ectoparasites. The studied species showed main convergent characters in mouthparts while remarkable differences have been detected on the antennal sensillar pattern as well as on the leg acropod that displayed divergent characters evolved in relation to the host.

BackgroundThe olive fly, Bactrocera oleae, is the most important insect pest in olive production, causing economic damage to olive crops worldwide. In addition to extensive research on B. oleae control methods, scientists have devoted much effort in the last century to understanding olive fly endosymbiosis with a bacterium eventually identified as Candidatus Erwinia dacicola. This bacterium plays a relevant role in olive fly fitness. It is vertically transmitted, and it benefits both larvae and adults in wild populations; however, the endosymbiont is not present in lab colonies, probably due to the antibiotics and preservatives required for the preparation of artificial diets. Endosymbiont transfer from wild B. oleae populations to laboratory-reared ones allows olive fly mass-rearing, thus producing more competitive flies for future Sterile Insect Technique (SIT) applications.ResultsWe tested the hypothesis that Ca. E. dacicola might be transmitted from wild, naturally symbiotic adults to laboratory-reared flies. Several trials have been performed with different contamination sources of Ca. E. dacicola, such as ripe olives and gelled water contaminated by wild flies, wax domes containing eggs laid by wild females, cages dirtied by faeces dropped by wild flies and matings between lab and wild adults. PCR-DGGE, performed with the primer set 63F-GC/518R, demonstrated that the transfer of the endosymbiont from wild flies to lab-reared ones occurred only in the case of cohabitation.ConclusionsCohabitation of symbiotic wild flies and non-symbiotic lab flies allows the transfer of Ca. E. dacicola through adults. Moreover, PCR-DGGE performed with the primer set 63F-GC/518R was shown to be a consistent method for screening Ca. E. dacicola, also showing the potential to distinguish between the two haplotypes (htA and htB). This study represents the first successful attempt at horizontal transfer of Ca. E. dacicola and the first step in acquiring a better understanding of the endosymbiont physiology and its relationship with the olive fly. Our research also represents a starting point for the development of a laboratory symbiotic olive fly colony, improving perspectives for future applications of the Sterile Insect Technique.