A walk on the wild side: gut bacteria fed to mass-reared larvae of Queensland fruit fly [Bactrocera tryoni (Froggatt)] influence development

Abstract

BackgroundThe Queensland fruit fly, Bactrocera tryoni (Froggatt) (Diptera, Tephritidae) is the most significant insect pest of Australian horticulture. Bactrocera tryoni is controlled using a range of tools including the Sterile Insect Technique (SIT). Mass-rearing and irradiation of pupae in SIT can reduce the fitness and quality of the released sterile insects. Studies have also showed reduced microbial gut diversity in domesticated versus wild tephritids.ResultsTransmission electron microscopy confirmed the presence of the bacterial isolates in the mid-gut of mass-reared larvae, and plate counts from individual larval guts showed increased numbers of bacteria in supplemented larvae. Several developmental and fitness parameters were tested including larval development time (egg-hatch to pupation), pupal weight, emergence, flight ability, sex-ratio, and time to adult eclosion (egg-hatch to adult eclosion). Enterobacter sp. and Asaia sp. shortened larval development time, while this was delayed by Lactobacillus sp., Leuconostoc sp. and a blend of all four bacteria. The mean time from egg hatch to adult eclosion was significantly reduced by Leuconostoc sp. and the blend for males and females, indicating that the individual bacterium and consortium affect flies differently depending on the life stage (larval or pupal). There was no impact of bacterial supplemented larvae on pupal weight, emergence, flight ability, or sex ratio.ConclusionsOur findings show that bacteria fed to the larval stage of B. tryoni can impart fitness advantages, but the selection of probiotic strains (individual or a consortium) is key, as each have varying effects on the host. Bacteria added to the larval diet particularly Leuconostoc sp. and the blend have the capacity to reduce costs and increase the number of flies produced in mass-rearing facilities by reducing time to adult eclosion by 1.3 and 0.8 mean days for males, and 1.2 and 0.8 mean days for females.

Fruit host-dependent fungal communities in the microbiome of wild Queensland fruit fly larvae

“…Furthermore, use of Leuconostoc sp. in artificial larval diet significantly reduced the mean time from egg hatch to adult emergence of the Qfly 42 . In addition, significant variation in bacterial communities and their abundance has been found across developmental stages of the Qfly 43,44 .…”

“…and Asaia sp. were supplemented with artificial larval diet shortened the development time of the Qfly larvae 42 . Furthermore, use of Leuconostoc sp.…”

“…Bacterial community structure of Qfly larvae is dominated by vertical transfer of the microbiome during egg laying from adult female to larvae, with comparatively minor contributions from the host fruit (diet) microbiome 34,40 . Qfly development and fitness traits were also observed using an artificial diet supplemented with microbes 41,42 . Bacterial isolates, Enterobacter sp.…”

New Insights on the Zeugodacus cucurbitae (Coquillett) Bacteriome

“…In this way, they provide their hosts with the nitrogen resources required to synthesize essential amino acids that they are otherwise unable to receive from their nitrogen-poor diet [ 64 , 65 , 80 ]. Some strains have also probiotic properties when provided as food supplements in mass-rearing facilities and could be used for improving important fitness parameters of hosts [ 5 , 6 , 8 , 81 , 82 , 83 , 84 , 85 ]. On the other hand, certain Providencia bacteria exhibit pathogenicity in insects [ 86 , 87 ].…”

Comparative genomics of Klebsiella michiganensis BD177 and related members of Klebsiella sp. reveal the symbiotic relationship with Bactrocera dorsalis

“…Gut microbiota affects insects in several ways, such as aiding food digestion and detoxification [16], providing essential nutrients [17], and protecting against infectious pathogens [18]. Much recent research of Tephritids suggests that gut microbiota reduced larval development time [19,20], increased pupal weight [21], larger males [22], improved male performance [13,23], increased female fecundity [24], increased longevity [23,25] and increased chilling resistance [26]. Mass rearing and irradiation processes affect the gut microbial community structure in the Tephritids [13,23,27,28].…”