An analysis of trade‐offs in immune function, body size and development time in the Mediterranean Field Cricket, Gryllus bimaculatus

Abstract

Summary 1.Immune defence has recently been viewed as a life-history trait that shows trade-offs with other life-history traits. However, studies exploring correlations between different components of immune defence and other life-history traits are scarce. 2. In this study, two measures of immune function, body size, and development time were studied in the Mediterranean Field Cricket, Gryllus bimaculatus. 3. We found no differences between the sexes, but differences in the correlation between the measure of immune function, development time, and body size. In both sexes, encapsulation rate was negatively correlated with body size and development time, whereas lytic enzyme activity was positively correlated with these two traits. Furthermore, encapsulation rate and lytic activity were themselves negatively correlated. 4. These results indicate that there is no single trait that can be termed 'immunocompetence' and that an understanding of trade-offs between the different types of immune function and life-history traits will require a more detailed analysis of the physiological basis of the traits.

Quantitative genetics of immunity and life history under different photoperiods

“…We found a significant positive phenotypic correlation between development time and body size: faster developers reached adulthood at a smaller size, confirming findings of Rantala and Roff (2005) in the same species. All phenotypic correlations between life history and immune traits were negative.…”

Foliar Phenolics are Differently Associated with Epirrita autumnata Growth and Immunocompetence

“…A possible explanation is that insect melanotic encapsulation is a resource-demanding process and may therefore trade off with insect traits relating to growth (Rantala and Roff 2005). The tannin composition of the larval diet could affect moth investment in growth and immune response.…”

“…The level of insect immune defense was estimated by a commonly used technique that measures the efficiency with which insect hemocytes encapsulate a foreign object in their hemocoel (see, e.g., Vainio et al 2004;Rantala and Roff 2005). We inserted an implant (a nylon monofilament, 2 mm long, 0.20 mm in diameter, rubbed with sandpaper) into the hemocoel of 1-wk-old pupae.…”

Inbred decorated crickets exhibit higher measures of macroparasitic immunity than outbred individuals

“…For example, the ability of an individual to mount an immune response may reflect their general health, such that one individual may be superior in multiple components of immunity to another individual. However, immune components often draw on the same pool of resources or exhibit negative genetic correlations, trading off against one another as do other life history traits (Cotter et al, 2004;Rantala and Roff, 2005). These trade-offs may be affected by inbreeding because inbreeding decreases the ability of individuals to use available resources, which can lead to a decrease in the maximal size and growth rates of individuals (Keller and Waller, 2002;Rantala and Roff, 2006).…”