• An assessment of the antibacterial activity in larval excretion/secretion of four species of insects recorded in association with corpses, using Lucilia sericata Meigen as the marker species

      Barnes, Kate M.; Gennard, Dorothy E.; Dixon, Ron A.; University of Lincoln (Cambridge University Press, 2010-03-22)
      The relative antibacterial activities of excretion/secretion (ES) from two carrion-feeding insects, Calliphora vicina Robineau-Desvoidy and Dermestes maculatus DeGeer, and a detritivore, Tenebrio molitor Linnaeus, were compared to that of Lucilia sericata Meigen, a species with ES of known antibacterial capacity, in order to explore the antimicrobial potential of other carrion and detritivore species. Viable counts were used to assess time-kill of ES against five bacterial species, Staphylococcus aureus, Escherichia coli, Bacillus cereus, Pseudomonas aeruginosa and Proteus mirabilis. Antibacterial activity was recorded in all four insect species although T. molitor and D. maculatus were the most effective in controlling growth of P. mirabilis. The blowflies were more effective in controlling a wider range of both Gram-positive and Gram-negative bacteria. The larval ES from all species was shown to reduce bacterial growth rate although differences in antibacterial spectrum were noted and the degree of potency varied between the four species. These differences may be explained ecologically by the different colonisation times of each insect species on the corpse. Overall, this study demonstrates that research into other carrion-feeding insect species has potential to provide an increased source of antimicrobial chemicals to broaden the range of bacterial species beyond that currently controlled using L. sericata.
    • The effect of bacterially-dense environments on the development and immune defences of the blowfly Lucilia sericata

      Barnes, Kate M.; Gennard, Dorothy E.; University of Lincoln (Wiley, 2010-11-01)
      Competitive interactions between insects and microbes and the associated cost of development in bacterially-dense environments are investigated using the blowfly Lucilia sericata (Meigen) (Diptera: Calliphoridae) as a model. The effects of developing in a bacterially-dense environment are measured by assessing the fitness consequences of competition using the pathogen Staphylococcus aureus. Fitness is quantified in terms of larval survival, puparial development and adult emergence.The influence of bacteria on larval immune defences is investigated using optical density to assess whether antibacterial potency of the larval excretion/secretion changes in response to the degree of contamination of the larval environment. The results obtained demonstrate that bacterial presence has no detrimental effect on survival of L. sericata from egg to adult eclosion, or on puparial size. Additionally, the level of microbial contamination of larvae has no effect on the antibacterial potency of the larval excretion/secretion. These findings confirm that larval antibacterial activity is not induced by the presence of environmental bacteria but is produced constitutively.
    • Rearing bacteria and maggots concurrently: a protocol using Lucilia sericata (Diptera: Calliphoridae) as a model species

      Barnes, Kate M.; Gennard, Dorothy E.; University of Derby; University of Lincoln (Springer, 2013-04-07)
      Maggot debridement therapy using live Lucilia sericata (Meigen) larvae is an efficient and cost-effective way to treat chronic wounds. The recent increase in studies to assess the antibacterial properties of L. sericata has created a need for a simple, low-cost, and comprehensible rearing and investigative method for researchers with little or no entomological experience. This paper describes and evaluates a reproducible protocol for sterilising and rearing blowfly larvae utilising two sterile artificial diets (blood–yeast agar and pre-prepared blood agar plates) that is suitable for directly investigating the effect of larvae on microbial growth. Using Lucilia sericata as a model, the results show that larval growth on the pre-prepared blood agar diet is detrimental to larval growth and survival, whereas larval growth and survival on the blood–yeast agar diet are comparable to those of larvae raised on porcine liver. This diet is proposed as a standard for blowfly and bacteria interaction studies investigating clinical microbial strains. Developmental data are provided for L. sericata larvae raised on both sterile and nonsterile diets so that researchers can determine the effect of treatment based on the length of time for larvae to reach the required life stage at 25 ± 2 °C. Information on larval ageing (instars at an average of 1, 2, 3 and 4 days), oviposition times (4–5 days after adult emergence) and adult longevity on the diets (102–116 days) is also given.