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Updated: Aug 6, 2026
Systemic Bacterial Infection and Immune Defense Phenotypes in Drosophila Melanogaster
Published on: May 13, 2015
Bacterial entomopathogens from the Drosophila paulistorum semispecies complex
S G Miller1, B C Campbell, J Becnel
1USDA/ARS, Insect Attractants, Behavior, and Basic Biology Research Laboratory, Gainesville, Florida 32608.
Abstract:
Bacteria which are infectious by inoculation in lepidoptera have been isolated and characterized from semispecies comprising the Drosophila paulistorum complex. These microorganisms are pathogenic toward lepidopteran hosts such as Heliothis virescens when introduced by injection of Drosophila tissue extracts and have been given the trivial name DpLE (D. paulistorum lepidopteran entomopathogen). The DpLE from two of the semispecies, Transitional and Andean, were determined to be related to Proteus vulgaris based upon nucleotide sequence comparisons of 16S rDNA genes. Infectivity and 16S rDNA-based PCR assays showed the bacterium to be localized in a number of drosophilid tissues except adult heads and thoraces. Based upon similar experiments, the DpLE in transinfected Heliothis larvae were found in all tissues assayed prior to the onset of mortality. Stocks of Drosophila which had spontaneously lost DpLE continued to produce sterile sons when crossed with incompatible semispecies' females, confirming that the bacilliform DpLE is not the causative agent of the Drosophila paulistorum intersemispecific hybrid male sterility. Acquisition of the sequences of the 16S rDNA molecules of DpLE from all six semispecies permitted the construction of a phylogenetic tree in which the groupings were found not to be congruent with the phylogenies of their insect hosts.
Insights
Researchers identified bacteria, DpLE (D. paulistorum lepidopteran entomopathogen), pathogenic to lepidopteran hosts. These bacteria, related to Proteus vulgaris, were not the cause of hybrid male sterility in Drosophila paulistorum.
Area of Science:
- Microbiology
- Entomology
- Genetics
Background:
- The Drosophila paulistorum complex exhibits intersemispecific hybrid male sterility.
- Bacteria infectious to lepidoptera were isolated from D. paulistorum semispecies.
Purpose of the Study:
- To characterize the isolated bacteria, termed DpLE (D. paulistorum lepidopteran entomopathogen).
- To determine the role of DpLE in D. paulistorum hybrid male sterility.
- To investigate the phylogenetic relationship between DpLE and their insect hosts.
Main Methods:
- Isolation and characterization of bacteria from D. paulistorum semispecies.
- 16S rDNA gene sequencing for bacterial identification and phylogenetic analysis.
- Infectivity assays in lepidopteran hosts (Heliothis virescens).
- PCR assays to determine DpLE localization in insect tissues.
- Analysis of D. paulistorum crosses to assess DpLE's role in sterility.
Main Results:
- DpLE bacteria were identified and found pathogenic to Heliothis virescens.
- DpLE from Transitional and Andean semispecies were related to Proteus vulgaris.
- DpLE localized in various drosophilid and heliothid tissues.
- DpLE was confirmed not to be the causative agent of D. paulistorum hybrid male sterility.
- Phylogenetic analysis of DpLE 16S rDNA did not align with host insect phylogenies.
Conclusions:
- DpLE are entomopathogenic bacteria related to Proteus vulgaris, isolated from D. paulistorum.
- These bacteria are not responsible for the hybrid male sterility observed in D. paulistorum.
- The phylogenetic divergence of DpLE from their hosts suggests complex evolutionary interactions.
