Sex-Specific Effect of Juvenile Diet on Adult Disease Resistance in a Field Cricket

Abstract

Food limitation is expected to reduce an individual’s body condition (body mass scaled to body size) and cause a trade-off between growth and other fitness-related traits, such as immunity. We tested the condition-dependence of growth and disease resistance in male and female Gryllus texensis field crickets by manipulating diet quality via nutrient content for their entire life and then subjecting individuals to a host resistance test using the live bacterium Serratia marcescens. As predicted, crickets on a high-quality diet eclosed more quickly, and at a larger body size and mass. Crickets on a high-quality diet were not in better condition at the time of eclosion, but they were in better condition 7–11 days after eclosion, with females also being in better condition than males. Despite being in better condition, however, females provided with a high-quality diet had significantly poorer disease resistance than females on a low-quality diet and in poor condition. Similarly, males on low- and high-quality diets did not differ in their disease resistance, despite differing in their body condition. A sex difference in disease resistance under diet-restriction suggests that females might allocate resources toward immunity during development if they expect harsh environmental conditions as an adult or it might suggest that females allocate resources toward other life history activities (i.e. reproduction) when food availability increases. We do not know what immune effectors were altered under diet-restriction to increase disease resistance, but our findings suggest that increased immune function might provide an explanation for the sexually-dimorphic increase in longevity generally observed in diet-restricted animals.

Intra‐ and trans‐generational effects of larval diet on susceptibility to an entomopathogenic fungus, Beauveria bassiana, in the greater wax moth, Galleria mellonella

“…Results of several other studies on insects and other animals are concordant with our finding (e.g. McVean et al ., ; Klemola et al ., ; Oarada et al ., ; Kelly & Tawes, ). On the other hand, the hypothesis that stress due to poor nutritional conditions promotes disease is also well established, as numerous studies have found poor developmental nutrition to have negative effects on an individual's ability to resist parasites and pathogens (e.g.…”

Evaluating indices of body condition in two cricket species

“…We used data presented in Kelly and Tawes () to compare the performance of the scaled mass index with that of two other commonly used approaches (residual index and ANCOVA). Kelly and Tawes () examined the interaction between nutritional quality (poor vs. good diet) during development and sex on various fitness‐related traits, including body condition, at adulthood. This data set comprised information on the body size (pronotum length, mm) and body mass (g) at eclosion for n = 82 females and n = 92 males (see Kelly and Tawes for details).…”

“…) or using residual body mass (Wagner and Hoback ; Andrade and Mason ; Whattam and Bertram ; Harrison et al. ), with only a few adopting the newly developed scaled mass index (e.g., Kelly and Tawes ; Stahlschmidt et al. ; Kelly et al.…”

“…), (Peig and Green , ), and ANCOVA (Garcia‐Berthou ). We achieve the latter goal using data previously presented in Kelly and Tawes () on the effect of sex and nutritional conditions during development on body condition at adulthood in G. texensis . An additional goal of this study is to add invertebrate taxa to the vertebrate‐dominated list of animals in which condition indices have been verified.…”

Independent and interactive effects of immune activation and larval diet on adult immune function, growth and development in the greater wax moth (Galleria mellonella)

“…A phenotype characterized by effective immune defence, often accompanied by relatively long development time and/or small body size, is frequently observed in insects in challenging nutritional conditions (Sheldon & Verhulst, ; McVean et al ., ; Klemola et al ., ; Kelly & Tawes, ; Krams et al ., ). Accordingly, in the present study, poor larval diet had a positive effect on adult encapsulation response in female moths, whereas having negative effects on development speed and body mass in both sexes.…”