Effect of Dietary Components on Larval Life History Characteristics in the Medfly (Ceratitis capitata: Diptera, Tephritidae)

Background: The ability to respond to heterogenous nutritional resources is an important factor in the adaptive radiation of insects such as the highly polyphagous Medfly. Here we examined the breadth of the Medfly’s capacity to respond to different developmental conditions, by experimentally altering diet components as a proxy for host quality and novelty. Methodology/Principal Findings: We tested responses of larval life history to diets containing protein and carbohydrate components found in and outside the natural host range of this species. A 40% reduction in the quantity of protein caused a significant increase in egg to adult mortality by 26.5%±6% in comparison to the standard baseline diet. Proteins and carbohydrates had differential effects on larval versus pupal development and survival. Addition of a novel protein source, casein (i.e. milk protein), to the diet increased larval mortality by 19.4%±3% and also lengthened the duration of larval development by 1.93±0.5 days in comparison to the standard diet. Alteration of dietary carbohydrate, by replacing the baseline starch with simple sugars, increased mortality specifically within the pupal stage (by 28.2%±8% and 26.2%±9% for glucose and maltose diets, respectively). Development in the presence of the novel carbohydrate lactose (milk sugar) was successful, though on this diet there was a decrease of 29.8±1.6 µg in mean pupal weight in comparison to pupae reared on the baseline diet. Conclusions: The results confirm that laboratory reared Medfly retain the ability to survive development through a wide range of fluctuations in the nutritional environment. We highlight new facets of the responses of different stages of holometabolous life histories to key dietary components. The results are relevant to colonisation scenarios and key to the biology of this highly invasive species

Life history evolution in a globally invading tephritid: Patterns of survival and reproduction in medflies from six world regions

Comparisons among populations from different localities represent an important tool in the study of evolution. Medflies have colonized many temperate and tropical areas all over the world during the last few centuries. In a common garden environment, we examined whether medfly populations obtained from six global regions [Africa (Kenya), Pacific (Hawaii), Central America (Guatemala), South America (Brazil), Extra-Mediterranean (Portugal) and Mediterranean (Greece)] have evolved different survival and reproductive schedules. Whereas females were either short-lived [life expectancy at eclosion (e0) 48-58 days; Kenya, Hawaii and Guatemala] or long-lived (e 0 72-76 days; Greece, Portugal and Brazil], males with one exception (Guatemala) were generally long-lived (e0 106-122 days). Although males universally outlived females in all populations, the longevity gender gap was highly variable (20-58 days). Lifetime fecundity rates were similar among populations. However, large differences were observed in their age-specific reproductive patterns. Short-lived populations mature at earlier ages and allocate more of their resources to reproduction early in life compared with long-lived ones. In all populations, females experienced a post-reproductive lifespan, with this segment being significantly longer in Kenyan flies. Therefore, it seems plausible that medfly populations, inhabiting ecologically diverse habitats, have evolved different life history strategies to cope with local environmental conditions. © 2009 The Linnean Society of London

Ancestral populations perform better in a novel environment: domestication of Mediterranean fruit fly populations from five global regions

Geographically isolated populations of a species may differ in several aspects of life history, morphology, behaviour and genetic structure as a result of adaptation in ecologically diverse habitats. We used a global invasive species, the Mediterranean fruit fly (medfly), to investigate whether adaptation to a novel environment differs among geographically isolated populations that vary in major life history components, such as life span and reproduction. We used wild populations from five global regions (Kenya, Hawaii, Guatemala, Portugal and Greece). Adult demographic traits were monitored in the F(2), F(5), F(7) and F(9) generations in captivity. Although domestication in constant laboratory conditions had a different effect on the mortality and reproductive rates of the different populations, a general trend of decreasing life span and age of first reproduction was observed for most medfly populations tested. However, taking into account the longevity of both sexes, age-specific reproductive schedules and average reproductive rates, we found that the ancestral Kenyan population kept the above life history traits stable during domestication compared with the other populations tested. These findings provide important insights into the life history evolution of this model species, and suggest that ancestral medfly populations perform better than the derived, invasive ones in a novel environment. (C) 2011 The Linnean Society of London, Biological Journal of the Linnean Society, 2011, 102, 334-345