BACKGROUND AND AIMS The lack of studies assessing the simultaneous expression of tolerance and resistance traits during seedling development and overall seedling defences as compared with adult plants, in general, constitutes a significant research need that can greatly improve our understanding of overall investment in defences during plant ontogeny. METHODS Using two seedling and two juveni...

Phytopathogens and herbivores induce plant defences. Whereas there is evidence that some pathogens suppress these defences by interfering with signalling pathways involved in the defence, such evidence is scarce for herbivores. We found that the invasive spider mite Tetranychus evansi suppresses the induction of the salicylic acid and jasmonic acid signalling routes involved in induced plant de...

The costs and benefits of parasite virulence are analysed in an evolutionarily stable strategy (ESS) model. Increased host mortality caused by disease (virulence) reduces a parasite's fitness by damaging its food supply. The fitness costs of high virulence may be offset by the benefits of increased transmission or ability to withstand the host's defences. It has been suggested that multiple inf...

Social organisms face a high risk of epidemics, and respond to this threat by combining efficient individual and collective defences against pathogens. An intriguing and little studied feature of social animals is that individual pathogen resistance may depend not only on genetic or maternal factors, but also on the social environment during development. Here, we used a cross-fostering experime...

Microbial diseases are important selective agents in social insects and one major defense mechanism is the secretion of cuticular antimicrobial compounds. We hypothesized that given differences in group size, social complexity, and nest type the secretions of these antimicrobials will be under different selective pressures. To test this we extracted secretions from nine wasp species of varying ...

Obligate avian brood parasites show dramatic variation in the degree to which they are host specialists or host generalists. The screaming cowbird Molothrus rufoaxillaris is one of the most specialized brood parasites, using a single host, the bay-winged cowbird (Agelaioides badius) over most of its range. Coevolutionary theory predicts increasing host specificity the longer the parasite intera...

The negative cross-talk between induced plant defences against pathogens and arthropod herbivores is exploited by vectors of plant pathogens: a plant challenged by pathogens reduces investment in defences that would otherwise be elicited by herbivores. This negative cross-talk may also be exploited by non-vector herbivores which elicit similar antiherbivore defences in the plant. We studied how...

Ecologists have recently shown great interest in using physiological markers as indicators of the health of animal populations. In this context, the measurement of markers of oxidative balance, such as antioxidant defences and oxidative damage, may be a valuable tool. Indeed, at the individual level, antioxidant defences are positively associated with fertility and survival probability, while e...

The waterflea Daphnia is a model to investigate the genetic basis of phenotypic plasticity resulting from one differentially expressed genome. Daphnia develops adaptive phenotypes (e.g. morphological defences) thwarting predators, based on chemical predator cue perception. To understand the genomic basis of phenotypic plasticity, the description of the precedent cellular and neuronal mechanisms...

Many seaweeds and terrestrial plants induce chemical defences in response to herbivory, but whether they induce chemical defences against competitors (allelopathy) remains poorly understood. We evaluated whether two tropical seaweeds induce allelopathy in response to competition with a reef-building coral. We also assessed the effects of competition on seaweed growth and seaweed chemical defenc...