Morphometric Analysis of the Hard Parts of Pseudodactylogyrus anguillae and Pseudodactylogyrus bini (Monogenea: Dactylogyridae) on the Gill Apparatus of the European Eels ( Anguilla anguilla ) from the Freshwaters of Latvia.

We investigated the spatial distribution and measured the hard parts of the attachment apparatuses and reproductive organs of the 2 eel-specific monogenean species Pseudodactylogyrus anguillae and Pseudodactylogyrus bini. Comparative analysis focused on parasite microhabitats within the gill apparatus. Additionally, we compared the morphometric characteristics of the monogeneans based on geographical locality and seasonality.

Male mealworm beetles increase resting metabolic rate under terminal investment.

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.

Previous encapsulation response enhances within individual protection against fungal parasite in the mealworm beetle Tenebrio molitor.

Immune defenses of insects show either broad reactions or specificity and durability of induced protection against attacking parasites and pathogens. In this study, we tested whether encapsulation response against nylon monofilament increases between two attempts of activation of immune system in mealworm beetles Tenebrio molitor, and whether previous exposure to nylon monofilament may also increase protection against an entomopathogenic fungus. We found that survival of beetles subjected to immune activation by nylon implant and subsequent fungal exposure a week later was significantly higher than survival of beetles which had been subjected to fungal infection only.

Senescence in immune priming and attractiveness in a beetle.

Age-related decline in immune activity is referred to as immunosenescence and has been observed for both the adaptive immune response of vertebrates and the innate immune system of invertebrates. Because maintaining a basic level of immune defence and mounting an immune response is costly, optimal investment in immune function should vary over a wide range of individual states such as the individual's age. In this study, we tested whether the immune response and immunological priming within individuals become less efficient with age using mealworm beetles, Tenebrio molitor, as a model organism.

Female choice reveals terminal investment in male mealworm beetles, Tenebrio molitor, after a repeated activation of the immune system.

Increasing evidence suggests that secondary sexual traits reflect immunocompetence of males in many animal species. This study experimentally investigated whether a parasite-like immunological challenge via a nylon implant affects sexual attractiveness of males in Tenebrio molitor L. (Coleoptera: Tenebrionidae) Although a single immunological challenge significantly reduced sexual attractiveness and locomotor activity of males, it had no adverse effect on their survival.