Dr Kévin Malod

PhD Entomology, Pretoria

MSc Neurosciences, Behavior and Animal Cognition, University Paul Sabatier, Toulouse , France

Honours Ecology & Evolution, University Paul Sabatier, Toulouse, France

BSc Organismal Biology, University Montpellier II, France

 

UP Externally Funded Postdoctoral Fellow

Office: 2-8.1, Ground Floor, Zoology Building

Email: [email protected]

 


Fruit fly ageing, diet and nutritional ecology

In insects, lifespan and reproduction are highly linked with nutrition. The ratio of nutrients consumed throughout life, directly impacts life expectancy and available resources for reproduction. The geometric framework is a nutritional model that explores how animals regulate the intake of multiple nutrients and the correlation with life history traits. It is a powerful method for assessing the effect of dietary manipulation on life history strategies, and has been extensively used in insects. Several studies using tephritid flies have highlighted trade-offs between longevity and reproductive effort in relation to the protein to carbohydrate ratio consumed. In Ceratitis capitata and Anastrepha ludens, as well as in Bactrocera tryoni, lifespan is extended at low proteins to carbohydrates ratios (P:C). In contrast female fecundity is increased at higher P:C ratios, highlighting the importance of protein for reproductive development. Flies are able to regulate nutrient intake when given the opportunity to do so, and females tend to self-regulate nutrient intake to achieve high life-time egg production. Despite its status as a pest in southern Africa, the marula fly, Ceratitis cosyra (Walker) (Diptera: Tephritidae), is relatively understudied. In contrast with other tephritids for which nutritional landscapes have been determined, C. cosyra is a host specialist, with females normally ovipositing in the fruit of only a few plant species.

For my PhD I:

  • Determined the nutritional requirements of C. cosyra and how P:C ratios influence reproductive performance and longevity in this relatively host-specialised species.
  • Investigated the effects of changes in life-history strategy on nutrient intake by using strains selected for age of reproduction (5, 15 and 25 days) over several generations.
  • Measured body nutrient composition (protein, lipids, carbohydrates and glycogen), oxidative damage as well as antioxidant capacity in fruit flies selected for age of reproduction and evaluate how it is related to their nutrient intake.
  • Determined how age of reproduction, nutrition and oxidative damages affect age-related cognitive impairments in females and males.

I am now broadening the scope of my research to include the applied consequences of dietary intake in tephritid flies. In particular, I am investigating how feeding on a range of plant secondary metabolites affects response of the oriental fruit fly, Bactrocera dorsalis, to the lures used to monitor them. This will provide useful information for development of sterile insect programmes for B. dorsalis.


Publications

Published by Christopher Weldon

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