Microbial composition affects the performance of an artificial Tephritid larval diet

Abstract

The present study investigated the patterns of microorganisms in an artificial larval diet during Dacus ciliatus (Diptera; Tephritidae) larval development. Microbial population contents in the diet of total heterotrophic bacteria, yeast and molds, coliform and lactobacilli, and their dynamics during development, were monitored. Initially, the microbial composition in diet trays failing to produce viable pupae and in trays successfully producing pupae and adult flies was characterized. The failing diet trays contained large populations of lactobacilli that increased during larval development, and low populations of coliforms. In contrast, the successful diet showed an increasing population of coliforms and a low, or undetected, population of lactobacilli. To study the hypothesis that lactobacilli affect D. ciliatus larval development, we conducted controlled inoculation experiments in which Lactobacillus plantarum was added into fresh diet at the time of egg seeding. L. plantarum inoculated trays showed no production of D. ciliatus. Control trays without lactobacilli inoculation showed variable results. One tray successfully produced viable pupae and adults, and showed a slight and slow increase in the indigenous populations of lactobacilli. The second tray, however, failed to produce pupae and showed a fast increase of the indigenous lactobacilli to very high levels. Monitored pH trends in L. plantarum-inoculated diet showed a sharp pH decrease during the first 4 days of larval development from 5 to less than 4 units, while successful diet, producing viable D. ciliatus pupae and adults, showed a moderate pH drop during most of the larval development period. The paper discusses the possible ecological interactions between D. ciliatus larvae, the microbial content of the diet and the physical properties of the diet. The discussion also points out at the usefulness of this approach in understanding and managing mass production parameters of tephritid fruit flies industrial diets used for Sterile Insect Technique.

Taxonomy, Diet, and Developmental Stage Contribute to the Structuring of Gut-Associated Bacterial Communities in Tephritid Pest Species

“…Many problems arise from the suboptimal conditions regarding the initial steps of laboratory domestication as well as mass rearing, including artificial diet and artificial substrates for oviposition. In some cases, such constraints can modify the behavior of laboratory strains, affecting therefore the efficiency of SIT (Dyck et al, 2005; Estes et al, 2012b; Rempoulakis et al, 2018). The changes that can happen in the symbiotic communities of laboratory populations due to long established domestication and artificial conditions are worth investigating.…”

Wild bacterial probiotics fed to larvae of mass‐reared Queensland fruit fly [Bactrocera tryoni (Froggatt)] do not impact long‐term survival, mate selection, or locomotor activity

“…In the current study, we did not add citric acid to the carrot diet due to the known production of lactic acid by lactic acid bacteria and the potential negative effects of low pH on insect growth and development. In a previous study, the addition of the lactic acid bacterium Lactobacillus plantarum , to the larval diet of mass‐reared curcurbit fly had deleterious effects likely due to the reduction of pH of the diet to < 4 within 4 d of larval development (Rempoulakis et al ., ). Therefore the diet ingredients as well as the effects of the bacteria added to the diet need to be considered.…”

“…Firmicutes, and particularly members of the order Lactobacilliales, have known positive gut associations in a diversity of animal species including insects, birds, rodents and humans (Million et al ., ; Stevenson et al ., ; Morimoto et al ., ). Of the few studies testing Firmicutes on tephritids, a recent study testing a lactic acid bacterial species, Lactobacillus plantarum , on mass‐reared larvae of the tephritid Dacus ciliatus (cucurbit fly) showed no fly production, while control trays without inoculation showed variable results (Rempoulakis et al ., ). This was likely due to the reported reduction the pH of the larval diet to <4 within 4 d of larval development.…”

Symbiosis in Sustainable Agriculture: Can Olive Fruit Fly Bacterial Microbiome Be Useful in Pest Management?

“…Olive fruit fly larvae are monophagous, feeding exclusively on the tissue of olive fruits, while adults are polyphagous generalists, feeding on various substrates such as nectar, honeydew, fruit and plant exudates, bacteria and even bird faeces (e.g., [106,107,108,109]). Olive fruit flies share diverse bacterial relationships with other fruit flies (Tephritidae, subfamilies Dacinae and Trypetinae), and traditional microbiological approaches have identified other bacteria of the genera Lactobacillus , Micrococcus , Pseudomonas , Streptococcus , Citrobacter , Proteus , Providencia , Enterobacter , Hafnia , Klebsiella , Serratia , Pantoea and Xanthomonas [110,111,112,113,114]. Putatively important in the olive fruit fly life cycle, their role requires confirmation and they are mostly considered facultative [115].…”