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Deficiency of food resources in ontogeny is known to prolong an organism's developmental time and affect body size in adulthood. Yet life-history traits are plastic: an organism can increase its growth rate to compensate for a period of slow growth, a phenomenon known as 'compensatory growth'. We tested whether larvae of the greater wax moth Galleria mellonella can accelerate their growth after a fast of 12, 24 or 72 h. We found that a subgroup of female larvae showed compensatory growth when starved for 12 h. Food deficiency lasting more than 12 h resulted in longer development and lower mass gain. Strength of encapsulation reactions against a foreign body inserted in haemocoel was the weakest in females that showed compensatory growth, whereas the strongest encapsulation was recorded in the males and females that fasted for 24 and 72 h. More specifically, we found sex-biased immune reactions so that females had stronger encapsulation rates than males in one group that fasted for 72 h. Overall, rapidly growing females had a short larval development period and the shortest adult lifespan. These results suggest that highly dynamic trade-offs between the environment, life-history traits and sex lead to plasticity in developmental strategies/growth rates in the greater wax moth. [ABSTRACT FROM AUTHOR]

Harmful parasite infestation can cause energetically costly behavioural and immunological responses, with the potential to reduce host fitness and survival. It has been hypothesized that the energetic costs of infection cause resting metabolic rate ( RMR) to increase. Furthermore, under terminal investment theory, individuals exposed to pathogens should allocate resources to current reproduction when life expectancy is reduced, instead of concentrating resources on an immune defence. In this study, we activated the immune system of Tenebrio molitor males via insertion of nylon monofilament, conducted female preference tests to estimate attractiveness of male odours and assessed RMR and mortality. We found that attractiveness of males coincided with significant down-regulation of their encapsulation response against a parasite-like intruder. Activation of the immune system increased RMR only in males with heightened odour attractiveness and that later suffered higher mortality rates. The results suggest a link between high RMR and mortality and support terminal investment theory in T. molitor. [ABSTRACT FROM AUTHOR]

Blood parasites are often considered as indicators of immunity in birds, and data on parasite prevalence and intensity of infections are essential to reveal information about the condition of both individuals and populations. We prevented parasite vectors from biting and infecting nestling great tit Parus major by using insect repellent inside nest boxes. We found that in the absence of blood parasites, great tit nestlings had higher concentrations of haemoglobin, and they survived at significantly higher rates through the nestling phase and also during the first weeks of their fledgling period. This is the first demonstration so far of the impact these parasites have on haemoglobin levels of the hosts, which reveals one mechanism of adverse impact by blood parasites. This study shows that the effects of blood parasites can be assessed without using anti-malaria drugs, which can cause additional risk of oxidative stress. [ABSTRACT FROM AUTHOR]