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Artificial larval diets affect Q-fly microbiome

Insects, including fruit flies, commonly host a large variety of microbes, especially bacteria, that can influence their physiology, behaviour and health. These microorganisms are generally abundant in their digestive system.

Fruit Fly ITTC member Dr Rajib Majumder explains that variation in the diet nutritional composition (protein, carbohydrate and lipids) can influence both the gut microbiome biodiversity and community structure in fruit flies, and that this can in turn affect fly quality and performance in mass rearing and release strategies to control pest populations. In his recent studies, Rajib has demonstrated that the Queensland fruit fly (Q-fly) microbiome is affected by the adoption of different artificial diets that are commonly used in laboratory settings (to rear flies for research purposes), or at a factory level in Sterile Insect Technique (SIT) programs. By adopting high-throughput Illumina sequencing, Rajib investigated the Q-fly microbiome after rearing wild flies for 5 generations on carrot and gel larval diets and found that the resulting bacterial communities were significantly different.

We would like to congratulate Rajib and his coauthors for publishing their research in Frontiers in Microbiology and we hope you will enjoy reading more about it.

"Artificial larval diet mediates the microbiome of Queensland fruit fly"

Rajib Majumder, Brodie Sutcliffe, Saleh Mohammad Adnan, Bishwo Mainali, Bernard C. Dominiak, Phillip W. Taylor & Toni A. Chapman


Larval diets used for artificial rearing can have a significant effect on insect biology. The Queensland fruit fly (aka “Qfly”), Bactrocera tryoni (Froggatt) (Diptera: Tephritidae), is one of the greatest challenges for fruit growers in Australia. The sterile insect technique (SIT) is being developed to manage outbreaks in regions that remain free of Qfly and to reduce populations in regions where this species is endemic. Factory scale rearing is essential for SIT; however, artificial larval diets are known to affect the microbiome of Qfly, which may then affect fly performance. In this study, high-throughput Illumina sequencing was used to assess the Qfly microbiome in colonies reared, for five generations from nature, on two common artificial diets (carrot and gel). At generation five (G5), the microbiome was assessed in larvae, pupae, adult males and adult females and standard fly quality control parameters were assessed together with additional performance measures of mating propensity and survival under nutritional stress. At the genus level, bacterial communities were significantly different between the colonies reared on the two larval diets. However, communities converged at Phyla to family taxonomic levels. Bacterial genera of Morganella, Citrobacter, Providencia, and Burkholderia were highly abundant in all developmental stages of Qfly reared on the gel diet, when compared to the carrot diet. Despite abundance of these genera, a greater percentage of egg hatching, heavier pupal weight and a higher percentage of fliers were found in the Qfly reared on the gel diet. Mating propensity and survival under nutritional stress was similar for adult Qfly that had been reared on the two larval diets. Overall, our findings demonstrate that the artificial larval diet strongly influences the microbiome and quality control measures of Qfly, with likely downstream effects on performance of flies released in SIT programs.

Read Rajib's publication.

Dr Rajib Majumder conducting fruit fly research at Applied BioSciences, Macquarie University.