Angela Douglas

Professional Overview & Objectives

I am interested in how insects work. My research area is insect nutritional physiology (how insects process food for growth and reproduction), including the contribution of symbiotic microorganisms to insect nutrition. The three current research foci in the laboratory are:

The obligate intracellular symbioses in insects. We focus almost entirely on the symbiosis between aphids and the bacterium Buchnera, which is supported by excellent genomic resources and is amenable to nutritional physiological techniques. We have demonstrated that Buchnera provide aphids with essential amino acids, nutrients in short supply in the aphid diet of plant phloem sap. Currently, we are seeking to identify key genes mediating the interactions between insect and bacteria and to establish their mode of action. This involves mining genomes for candidate genes, metabolic reconstruction, post-genomics (e.g. analysis of transcript profiles, proteomics, RNAi) and the physiology of nutrient utilization. We are motivated by the fundamental problem of how the bacteria have become integrated into the physiological system of the insect, and by the potential of key genes as targets for insect pest management.

Carbon nutrition and osmoregulation in phloem-feeding insects. A major challenge for phloem-feeding insects is the high osmotic pressure of their sugar-rich diet that they are bound to ingest at high rates in order to extract sufficient nutrients other than sugar. We have established that the aphid gut is a major osmoregulatory organ through sugar transformations in the gut lumen and the controlled movement of water across the gut wall. Our research on the molecular physiology of the aphid gut is revealing genes, including an α-glucosidase and aquaporin, that play important roles in aphid carbon nutrition and osmoregulation. The key research problem is to establish how the functions of these genes are integrated to guarantee the sustained sugar supply and osmotic homeostasis in insects feeding on phloem sap of very variable sugar content. One goal of this research is to develop novel pest management strategies based on the disruption of osmoregulation in phloem-feeders.

Drosophila-gut microbe interactions. We have established that the commensal microbiota in Drosophila guts is beneficial for the insect under standard laboratory conditions. Our purpose is to identify how the microbiota interacts with insect nutrition and how it is managed by the insect immune system, as a general model system for animal-gut microbe interactions.

Education

1975-1978     BA in Zoology         University of Oxford
1978-1981     PhD in Microbiology University of Aberdeen

Publications

Refereed Journal Articles
Chandler SM, Wilkinson TL and Douglas AE, 2008. Impact of plant nutrients on the relationship between a herbivorous insect and its symbiotic bacteria. Proceedings of the Royal Society of London B 275, 565-570.

Price DRG, Karley AJ, Ashford DA, Isaacs HV, Pownell ME, Wilkinson HS, Gatehouse JA and Douglas AE, 2007. Molecular characterisation of a candidate gut sucrase in the pea aphid, Acyrthosiphon pisum. Insect Biochemistry and Molecular Biology 37, 307-317

Douglas, AE, Francois, CLMJ and Minto LB, 2006. Facultative ‘secondary’ bacterial symbionts and the nutrition of the pea aphid, Acyrthosiphon pisum. Physiological Entomology 31, 262-269

Pescod KV, Quick WP and Douglas AE, 2007. Aphid responses to plants with genetically manipulated phloem nutrient levels. Physiological Entomology 32, 253-258.

Douglas AE, Price DRG, Minto LB, Jones E, Pescod, KV, Francois CLMJ, Pritchard J and Boonham N, 2006. Sweet problems: insect traits defining the limits to dietary sugar utilisation by the pea aphid, Acyrthosiphon pisum. Journal of Experimental Biology 209, 1395-1403.

Prickett MD, Page M, Douglas AE and Thomas GH, 2006. BuchneraBASE: a post-genomic resource for Buchnera sp. APS. Bioinformatics 22, 641-2

Karley AJ, Ashford DA, Minto LB, Pritchard J and Douglas AE, 2005. The significance of gut sucrase activity for osmoregulation in the pea aphid, Acyrthosiphon pisum. Journal of Insect Physiology 51, 1313-1319.

Darby AC, Chandler SM, Welburn SC and Douglas AE, 2005. Symbiotic bacteria of aphids cultured in insect cell lines. Applied and Environmental Microbiology 71, 4833-4839.

Tosh CR, Morgan D, Walters KFA and Douglas AE, 2004. The significance of overlapping plant range in the aphid species complex Aphis fabae Scop. Ecological Entomology 29, 488-497.

Birkle LM, Minto LB, Walters KFA and Douglas AE, 2004. Microbial genotype and insect fitness in an aphid-bacterial symbiosis. Functional Ecology 18, 598-604.

Ferrari J, Darby AC, Daniell TJ, Godfray HCJ and Douglas AE, 2004. Linking the bacterial community in pea aphids with host-plant use and natural enemy resistance. Ecological Entomology 29, 60-65.

Haynes S, Darby AC, Daniell TJ, Webster G, van Veen FJF, Godfray HCJ, Prosser JI and Douglas AE, 2003. The diversity of bacteria associated with natural aphid populations. Applied and Environmental Microbiology 69, 7216-7223.

Cloutier C and Douglas A, 2003. Impact of a parasitoid on the bacterial symbiosis of its aphid host. Entomologia Experimentalis et Applicata, 109, 13-19.

Darby AC and Douglas AE, 2003. Elucidating the transmission patterns of an insect-borne bacterium. Applied and Environmental Microbiology 69, 4403-4407.

Karley AJ, Pitchford JW, Douglas AE, Parker WE and Howard JJ. 2003. The causes and processes of the mid-summer population crash of potato aphids. Bulletin of Entomological Research 93, 425-437.

Darby AC, Tosh CR, Walters KFA and Douglas AE, 2003. The significance of a facultative bacterium to natural populations of the pea aphid Acyrthosiphon pisum. Ecological Entomology 28, 145-150.

Wilkinson TL and Douglas AE, 2003. Phloem amino acids and the host plant range of the polyphagous aphid, Aphis fabae. Entomologia Experimentalis et Applicata 106, 1-11.

Johnson SN, Douglas, AE, Woodward, S and Hartley, SE, 2003. Microbial impacts on plant-herbivore interactions: the indirect effects of a birch pathogen on a birch aphid. Oecologia 134, 388-396.

Birkle LM, Minto LB and Douglas AE, 2002. Relating genotype and phenotype for tryptophan synthesis in an aphid-bacterial symbiosis. Physiological Entomology 27, 1-5.

Karley AJ, Douglas AE and Parker WE, 2002. Amino acid composition and nutritional quality of potato leaf phloem sap for aphids. Journal of experimental Biology 205, 3009-3018.

Johnson, SN, Mayhew PJ, Douglas AE and Hartley SE, 2002. Insects as leaf engineers - can leaf miners alter leaf structure for birch aphids. Functional Ecology 16, 575-584.

Wilkinson TL, Adams D, Minto LB and Douglas AE 2001. The impact of host plant on the abundance and function of symbiotic bacteria in an aphid. Journal of experimental Biology 204, 3027-38

Raymond B, Searle JB and Douglas AE, 2001. On the processes shaping reproductive isolation in aphids of the Aphis fabae (Scop.) complex (Aphididae: Homoptera). Biological Journal of the Linnean Society 74, 205-215.

Wilkinson TL, Minto LB and Douglas AE, 2001. Amino acids as respiratory substrates in aphids: an analysis of Aphis fabae reared on plants and diets. Physiological Entomology 26, 225-8.

Darby AC, Birkle LM, Turner SL and Douglas AE, 2001 An aphid-borne bacterium allied to the secondary symbionts of whitefly. FEMS Microbiology Ecology 36, 43-50.

Tosh CR, Walters KFA and Douglas AE, 2001. On the mechanistic basis of plant affiliation in the black bean aphid (Aphis fabae) species complex. Entomologia Experimentalis et Applicata 99, 121-125.

Douglas AE, Minto LB and Wilkinson TL, 2001. Quantifying nutrient production by the microbial symbiosis in an aphid. Journal of Experimental Biology 204, 349-358.

Raymond B, Darby AC and Douglas, A. E, 2000. Intraguild predation and the spatial distribution of a parasitoid. Oecologia 124, 367-72.

Douglas AE, 2000. Reproductive diapause and the bacterial symbiosis in the sycamore aphid Drepanosiphum platanoidis (Schr.). Ecological Entomology 25, 256-61.

Raymond B, Darby AC and Douglas AE, 2000. The olfactory responses of coccinellids to aphids on plants. Entomologia Experimentalis et Applicata 95, 113-7.

Ashford DA, Smith WA and Douglas AE, 2000. Living on a high sugar diet: the fate of sucrose ingested by a phloem-feeding insect, the pea aphid Acyrthosiphon pisum. Journal of Insect Physiology 46, 335-342

Review articles
Douglas AE, in press. The microbial dimension in insect nutritional ecology. Functional Ecology

Douglas AE, 2008. Conflict, cheats and persistence of symbioses. New Phytologist 177, 849-858.

Douglas AE, 2007. Symbiotic microorganisms: untapped resources for insect pest control. Trends in Biotechnology 25, 338-342.

Douglas AE, 2006. Phloem sap feeding by animals: problems and solutions. Journal of Experimental Botany 57, 747-754.

Karley, AJ, Parker WE, Pitchford JW and Douglas AE, 2004. The mid-season crash in aphid populations: why and how does it occur? Ecological Entomology 29, 383-388.

Douglas AE and Raven JA, 2003. Genomes at the interface between bacteria and organelles. Philosophical Transactions of the Royal Society of London B 358, 5-17

Douglas AE, 2003. Nutritional physiology of aphids. Advances in Insect Physiology 31, 73-140. Academic Press.

Book Chapters
Douglas AE in press. Mutualism and Commensalism: endosymbionts and intracellular parasites. In Encyclopedia of Microbiology (3rd edition). Academic Press.

Douglas AE and van Emden HF, 2007. Nutrition and symbiosis. In: Aphids as Crop Pests (ed van Emden H and Harrington R). CABI International, UK.

Douglas AE, 2004. Strategies in antagonistic and cooperative interactions. In: Microbial Evolution: Gene Establishment, Survival and Exchange (ed. RV Miller & MJ Day), pp. 275-289. American Society for Microbiology.

Douglas AE, 2003. Buchnera bacteria and other symbionts of aphids. In Insect Symbiosis, ed. K. Bourtzis and T.A. Miller. pp 23-38. CRC Press, Boca Raton.

Douglas AE, Darby AC, Birkle LM and Walters KFA, 2002. The ecological significance of symbiotic micro-organisms in animals - perspectives from the microbiota of aphids. In Genes in the Environment, ed. RM Hails, J Beringer and HCJ Godfray, pp. 306-325.
Blackwell Scientific Publishers.

Mittler TE and Douglas AE, 2002. Honeydew. In Encyclopedia of Insects, ed. VH Resh and RT Carde. Academic Press, New York.

Douglas AE, 2002. The functions of symbiotic micro-organisms in insects. In Symbiosis: Mechanisms and Model Systems, ed. J. Seckbach, pp. 675-684. Kluwer Academic Publishers, The Netherlands.

Douglas AE, 2001. Symbiosis. In Encyclopedia of Evolution, ed. M Pagel, pp. 1093-1099. Oxford University Press, New York.

Douglas AE, 2000. Symbiotic micro-organisms in insects. In Encyclopedia of Microbiology (2nd edition). Academic Press, 526-537.