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Factors influencing pathogen resistance in Lepidopteran crop pests

Background

There is a growing desire to replace environmentally-damaging chemical pesticides with novel biocontrol agents, such as microbial pesticides (entomopathogenic bacteria, viruses and fungi). However, in order to gain a better understanding of the circumstances influencing the efficacy of microbial pathogens, it is necessary to determine the factors generating variation in host resistance to these pathogens. As part of this remit, we have been examining the impact of genetic and environmental factors (e.g. larval density and diet) on resistance to microbial pathogens, using Spodoptera caterpillars and their pathogens as model systems.

Our work to date has demonstrated that pathogen resistance may increase under conditions of larval crowding and suggests a key role for dietary protein in constraining insect resistance to entomopathogens, mediated in part by the immune system’s dependence on this key macronutrient. It also suggests that when challenged with entomopathogens, insects are capable of self-selecting diets rich in this key limiting resource (i.e. insects appear to ‘self-medicate’).

Publications

  1. Lee K.P., Cory, J.S., Wilson, K., Raubenheimer D. & Simpson S.J. (2006) Flexible diet choice offsets protein costs of pathogen resistance in a caterpillar. Proc. Roy. Soc. B. 273: 823-829.
  2. Cotter, S.L., Kruuk, L.E.B. & Wilson, K. (2004) Costs of resistance: genetic correlations and potential trade-offs in an insect immune system. J. Evol. Biol: 17: 421- 429.
  3. Wilson, K., Cotter, S.C., Reeson, AF, & Pell, J.K. (2001) Melanism and disease resistance in insects. Ecology Letters 4: 637-649.
  4. Reeson, AF, Wilson, K, Cory, J.S., Hankard, P, Weeks, JM, Goulson, D & Hails, RS (2000) Effects of phenotypic plasticity on pathogen transmission in the field in a Lepidoptera-NPV system. Oecologia 124: 373-380.
  5. Reeson, AF, Wilson, K, Gunn, A, Hails, RS & Goulson, D (1998) Baculovirus resistance in the noctuid Spodoptera exempta is phenotypically plastic and responds to population