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Title: Studies on microbes, including potential human pathogens, from insects and other invertebrates
Author: Al Dahi, Amer
ISNI:       0000 0004 5993 3980
Awarding Body: University of Sheffield
Current Institution: University of Sheffield
Date of Award: 2017
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A wide range of bacteria were obtained from the exterior, and from the body fluids, of insects collected locally, and Lepidoptera species obtained from an Entomological supplier. The insects were found to contain a wide range of bacteria, both internally and externally including Bacillus thuringiensis, a bacterium used in the biocontrol of larval pests. Although not major pathogens, many of the bacterial isolates can cause infection in immune-compromised patients, a possibility which is discussed. Larvae of the Peacock butterfly (Vanessa io) were fed nettle leaves which were deliberately covered with a range of bacteria. Feeding with B. thuringiensis not surprisingly, lead to the death of all of the larvae after 4 hours. The results show that feeding with B. subtilis and E. coli can lead to larval death, while MRSA was shown to be less toxic. Feeding the larvae with the other bacteria killed some larvae, with the death rate after feeding B. subtilis and E. coli being identical. Bacillus cereus was isolated from the larvae fed B. thuringiensis and B.subtilis. Bacteria were isolated from the Dermestidae (beetle larvae) obtained from human cadavers. The dominant species of bacteria was Enterococcus faecalis which was isolated from inside the larvae extracted from a human corpse. Two species of Clostridium were also isolated; Clostridium cochlearium was isolated from the Dermestid larva, the other, Clostridium paraputrificum was isolated from inside the larva. Brevibacterium ravenspurgense, Staphylococcus hominis, Lishizhenia tianjinensis and Bacillus safensis, were also isolated from inside larvae, extracted from human body. The biocontrol agents Bacillus thuringiensis and Paenibacillus popiliae were shown to be capable of mediating in vitro, transformations which are important in the major environmental mineral cycles These bacteria are likely to reach the agriculture soils following treatment and, on germination can presumably participate in mineral cycling Both bacteria were shown to be capable in vitro hydrolysis of urea, and were shown to oxidize ammonium and elemental sulphur and also to solubilize a source of insoluble phosphate. It is not clear however, to what extent the ability of these bacteria to participate in these reactions in vitro correlates with the same activity in soils and other environments. Insects were sampled at a height of 120 meters using a drone–towed fabric sleeve and their microbial content studied. The major point of interest behind this work is the use of a drone-towed sleeve to sample the insects. As far as can be determined, this is the first reported use of this approach to sample high flying insects in relation to a study of their microbiology. The use of a drone was shown to be ideal for the high altitude sampling of insects since it proved to be both powerful and highly manoeuvrable and there is no doubt that the drone used could have been used to sample at greater heights than the 120 m used here. The results relating to the microbiology of the insects sampled using the drone are not surprisingly similar to those obtained using other sampling methods, since the drone, of course, does not necessarily sample insects which differ from those obtained using more traditional approaches. An octanol-based midge sampler (Predator) was used to obtain large numbers of midges from the air, in relations to studying their microbiology this approach appears to be novel. The midge-biomass collected was found to contain microbes and was shown to break down in an agricultural soil to release ammonium and nitrate. The potential use of this material as an agricultural or home fertilizer is discussed. Finally, larger moths were trapped using a Robinson UV light trap. The moths were found to carry filamentous fungi on their bodies, some of which are plant pathogens, notably of trees.
Supervisor: Wainwright, Milton Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available