Quantitative Differences in Nourishment Affect Caste-Related Physiology and Development in the Paper Wasp Polistes metricus

Abstract

The distinction between worker and reproductive castes of social insects is receiving increased attention from a developmental rather than adaptive perspective. In the wasp genus Polistes, colonies are founded by one or more females, and the female offspring that emerge in that colony are either non-reproducing workers or future reproductives of the following generation (gynes). A growing number of studies now indicate that workers emerge with activated reproductive physiology, whereas the future reproductive gynes do not. Low nourishment levels for larvae during the worker-rearing phase of the colony cycle and higher nourishment levels for larvae when gynes are reared are now strongly suspected of playing a major role in this difference.Here, we present the results of a laboratory rearing experiment in which Polistes metricus single foundresses were held in environmental conditions with a higher level of control than in any previously published study, and the amount of protein nourishment made available to feed larvae was the only input variable. Three experimental feeding treatments were tested: restricted, unrestricted, and hand-supplemented. Analysis of multiple response variables shows that wasps reared on restricted protein nourishment, which would be the case for wasps reared in field conditions that subsequently become workers, tend toward trait values that characterize active reproductive physiology. Wasps reared on unrestricted and hand-supplemented protein, which replicates higher feeding levels for larvae in field conditions that subsequently become gynes, tend toward trait values that characterize inactive reproductive physiology. Although the experiment was not designed to test for worker behavior per se, our results further implicate activated reproductive physiology as a developmental response to low larval nourishment as a fundamental aspect of worker behavior in Polistes.

Queen Dominance May Reduce Worker Mushroom Body Size in a Social Bee

“…Larval nutrition affects brain morphology in honeybees, with queens having larger and more rapidly growing brains in the larval stage (Moda et al , ), and reduced larval nutrition results in smaller MB calyces at emergence in workers (Steijven et al , ), but this has not been studied in primitively eusocial groups. Variation in larval nutrition can affect reproductive physiology and behavior in other sweat bee species (Richards and Packer, ; Brand and Chapuisat, ) as well as other species of primitively eusocial insects (Judd et al , ; Lawson et al , ; ; Kapheim, ). Our previous work on this species suggests that queens manipulate larval pollen resources to create small, subordinate worker daughters (Smith et al , ; ; Kapheim et al , ; ).…”

A Nutritional Profile of the Trap-Nesting Wasp Trypoxylon lactitarse (Hymenoptera: Crabronidae): Comparison of Sexes and Overwintering and Non-Overwintering Generations

“…Although Polistes and Trypoxylon are not extremely phylogenetically close within Aculeata [47], the similarities between the worker- and gyne-destined larvae of P. metricus and the G1 and G2 larvae of T. lactitarse , respectively, are striking. Several studies have pointed to the fact that cues during larval development can influence caste development in social wasps such as Polistes [6,48,49,50,51]. Here, we see some nutritional differences that Polistes castes and G1 and G2 generations of Trypoxylon share.…”

“…Newer hypotheses on the evolution of sociality, such as the diapause ground plan hypothesis [3,4] and the ovarian ground plan hypothesis [5], point to solitary ancestors that are either bivoltine or serial egg laying. Because nutrition plays a large role in caste determination in wasps and bees [6,7], a better understanding of the nutritional ecology of solitary species will provide better model systems to test the aforementioned models. Unfortunately, we know very little about the basic nutritional ecology of most solitary wasps and bees beyond the prey they collect.…”

Morphological Differences between Reproductive and Non-reproductive Females in the Social Wasp Mischocyttarus consimilis Zikán (Hymenoptera: Vespidae)

“…Larger females are therefore more likely to assume colony reproductive functions, suggesting that attributes established during immature development are relevant for the adult behavioral phenotype (Zanette & Field, 2009). Recent studies have shown that preimaginal caste determination can occur in IF polistine wasps, and that subtle morphological differences can be decisive in establishing the reproductive division of labor among foundresses (Fukuda et al, 2003;Judd et al, 2015;Montagna et al, 2015). These results provide evidence that body size affects the reproductive organization in pleometrotic foundations of M. consimilis.…”

“…In the case of IF polistine wasps, Judd et al (2010) showed that the development of larvae of Polistes metricus into either workers or gynes was significantly influenced by the levels of nutrients in the hemolymph, including lipids, carbohydrates, and proteins, and that the differences were associated with possible variations in nutritional quality. In studies of the same species, Judd et al (2015) showed that an increase in the quality of larval nutrition led to the development of larger females. In M. consimilis, workers and gynes emerge in different phases of the colony cycle, so the conditions for development of the immature are different .…”