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Updated: Jun 8, 2026
Drosophila melanogaster Larva Injection Protocol
Published on: October 19, 2021
Lethality and developmental delay in Drosophila melanogaster larvae after ingestion of selected Pseudomonas
Marika H Olcott1, Marcella D Henkels, Kise L Rosen
1Department of Zoology, Oregon State University, Corvallis, Oregon, United States of America.
Background:
The fruit fly, Drosophila melanogaster, is a well-established model organism for probing the molecular and cellular basis of physiological and immune system responses of adults or late stage larvae to bacterial challenge. However, very little is known about the consequences of bacterial infections that occur in earlier stages of development. We have infected mid-second instar larvae with strains of Pseudomonas fluorescens to determine how infection alters the ability of larvae to survive and complete development.
Methodology/Principal Findings:
We mimicked natural routes of infection using a non-invasive feeding procedure to study the toxicity of the three sequenced P. fluorescens strains (Pf0-1, SBW25, and Pf-5) to Drosophila melanogaster. Larvae fed with the three strains of P. fluorescens showed distinct differences in developmental trajectory and survival. Treatment with SBW25 caused a subset of insects to die concomitant with a systemic melanization reaction at larval, pupal or adult stages. Larvae fed with Pf-5 died in a dose-dependent manner with adult survivors showing eye and wing morphological defects. In addition, larvae in the Pf-5 treatment groups showed a dose-dependent delay in the onset of metamorphosis relative to control-, Pf0-1-, and SBW25-treated larvae. A functional gacA gene is required for the toxic properties of wild-type Pf-5 bacteria.
Conclusions/Significance:
These experiments are the first to demonstrate that ingestion of P. fluorescens bacteria by D. melanogaster larvae causes both lethal and non-lethal phenotypes, including delay in the onset of metamorphosis and morphological defects in surviving adult flies, which can be decoupled.
Insights
Fruit fly larvae infected with Pseudomonas fluorescens bacteria experienced lethal and non-lethal developmental issues. Specific strains caused distinct outcomes, including delayed metamorphosis and adult morphological defects, highlighting early-stage infection impacts.
Area of Science:
- Developmental Biology
- Microbiology
- Immunology
Background:
- Drosophila melanogaster is a key model for adult immunity.
- Early-stage larval bacterial infection consequences remain largely unknown.
- Investigating Pseudomonas fluorescens impact on larval development is crucial.
Purpose of the Study:
- To determine how Pseudomonas fluorescens infection affects Drosophila melanogaster larval survival and development.
- To analyze the distinct toxicities of different P. fluorescens strains on fruit fly larvae.
Main Methods:
- Infection of mid-second instar Drosophila melanogaster larvae with three P. fluorescens strains (Pf0-1, SBW25, Pf-5) via feeding.
- Observation of larval survival, developmental trajectory, and adult morphology.
- Assessment of the role of the gacA gene in P. fluorescens toxicity.
Main Results:
- Distinct lethal and non-lethal phenotypes observed across P. fluorescens strains.
- SBW25 induced mortality and melanization; Pf-5 caused dose-dependent mortality and adult defects.
- Pf-5 infection led to delayed metamorphosis, with a functional gacA gene required for toxicity.
Conclusions:
- Ingestion of P. fluorescens by D. melanogaster larvae results in both lethal and non-lethal outcomes.
- Delayed metamorphosis and adult morphological defects are separable phenotypes.
- This study reveals critical impacts of early-stage bacterial infections in a model organism.
