The considerable adult size variability in wood feeders is optimal

Abstract

1. The life history of wood feeders was modelled in order to explain the multiseasonality of development and the great variability of adult size in this group.2. The model was parameterised with experimental bioenergetic and reproductive data for the xylem feeder Aredolpona rubra (Coleoptera: Cerambycidae).3. The length of the developmental period, which together with food quality directly determines adult size and indirectly determines the number of eggs laid, was optimised.4. The results show that multi-seasonal larval development maximises fitness under conditions of low food quality, relatively low predation pressure, and the presence of hostile periods during the year.5. The variability of the number of seasons needed to complete development within a wood-feeder population is a consequence of development time optimisation and the unavoidable extension of the egg-laying period. These insects have an evolutionary dilemma: to eclose late in a given season at smaller size, bringing about low egg production and low offspring value, or to grow bigger to the next season, jeopardising their lives.6. The results of the model predict wood-feeder developmental patterns that depend on the tree tissue inhabited.

Influence of Host Tree Condition on the Performance ofTetropium fuscum(Coleoptera: Cerambycidae)

“…A second year of development inherently reduces Þtness by half and increases exposure time to natural enemies and to harsh winter weather. However, multiyear generation times appear to optimize Þtness for some cerambycids, especially when food quality and natural enemy pressure is low (Walczyń ska et al 2010), similar to healthy trees in this study. In an independent study, larvae dissected from healthy trees were smaller (earlier instar) than larvae dissected from girdled trees after one summer of development in the Þeld (L. F., unpublished data).…”

2.4. Cerambycidae Latreille, 1802

“…Variable numbers of instars were also firmly established for the cerambycine Semanotus japonicus (Togashi 1985, and references therein). The develop mental strategy of most cerambycids allows consid erable to extreme variability of adult size (Andersen & Nilssen 1983;Walczyń ska et al 2010), primarily dependent on food quality and availability (e.g., Munyiri et al 2003;Shintani et al 2003). On the low side, four instars are common in some quickly developing Lamiinae in laboratory rearing and three are possible, albeit in a minor portion of the population (Pershing & Linit 1989;Shintani et al 1996 b).…”

Gradients of season length and mortality risk cause shifts in body size, reserves and reproductive strategies of determinate growers

“…(Hirche, ; Morewood & Ring, ; Walczyńska, Dańko, & Kozłowski, ). Such semivoltine (i.e., with juvenile period longer than 1 year) determinately growing arthropods are represented by thousands of species of crustaceans and insects; many members of copepods (Copepoda), damselflies (Odonata), mayflies (Ephemeroptera), butterflies (Lepidoptera), beetles (Coleoptera) and stoneflies (plecoptera) are semivoltine (Corbet, Suhling, & Soendgerath, ; Lillehammer, Brittain, Saltveit, & Nielsen, ; Tammaru & Haukioja, ; Varpe, ; Walczyńska et al., ). Furthermore, we must aim to explain intraspecific variability of age at maturation in semivoltine species such as the beetle Aredolpona rubra (Walczyńska, ), damselflies Coenagrion johanssoni and C. pulchellum (Śniegula, Johansson, & Nilsson‐Ortman, ; Śniegula, Nilsson‐Ortman, & Johansson, ) or copepods Calanus glacialis and Calanoides acutus (Daase et al., ; Tarling, Shreeve, Ward, Atkinson, & Hirst, ).…”

“…Furthermore, we must aim to explain intraspecific variability of age at maturation in semivoltine species such as the beetle Aredolpona rubra (Walczyńska, ), damselflies Coenagrion johanssoni and C. pulchellum (Śniegula, Johansson, & Nilsson‐Ortman, ; Śniegula, Nilsson‐Ortman, & Johansson, ) or copepods Calanus glacialis and Calanoides acutus (Daase et al., ; Tarling, Shreeve, Ward, Atkinson, & Hirst, ). In only a couple of theoretical studies considering time constraints as triggers of life‐history trade‐offs, the juvenile period is allowed to last for longer than 1 year (e.g., McNamara, Welham, Houston, Daan, & Tinbergen, ; Walczyńska et al., ) and only few investigate how differences in adult size affect fitness. Altogether, current theory does not show how interaction between season length and mortality rate affects body size evolution in organisms that spend more than 1 year in juvenile stages.…”