Insights of Caste Determinations in Social Insects

Abstract

Eusocial insects display caste structures in which reproductive ability is possessed by a single or a few queens while all other colony members act as workers. In social insects like ants, bees, and termites, vital physiological processes are regulated at the colony scale. Females in social insects have at least one reproductive caste and one nonreproductive caste; many termites have at least two male castes. The castes have considerable anatomical, physiological, and behavioural differences in higher social insects. Organismal systems, such as pheromone sensing, hormone signaling, and brain signaling pathways, are deployed in novel circumstances to impact nestmate and colony behaviours due to physiological decentralization over evolutionary time. Significant morphogenesis with region-specific cellular proliferation and degradation occurs during soldier development through two moulting via a presoldier stage in termite. JH action has been developed, in which a high JH titer causes soldier differentiation and a low JH titer causes alate differentiation. A monogamous pair of primary reproductives (one king and one queen) generated from alates normally establishes termite colonies (winged adults). The nymph-alate pathway (sexual pathway) or the worker pathway differentiates larvae in Reticulitermes termites (neuter pathway). Haplo-diploid sex determination controls the first developmental transition, in which unfertilized (haploid) embryos become males and fertilized (diploid) embryos become females in the case of Cataglyphis ant genus. The queen’s mandibular gland secretion, a mix of fatty acids and aromatic chemicals, is critical for maintaining the reproductive division of labour in honeybees (Apis mellifera), suppressing ovary growth in workers. Besides this, the brood produced by the queen also inhibits ovary development in workers by emitting two pheromones: the brood pheromone (BP), mainly composed of esters, and the highly volatile E-b-ocimene.

Hierarchical Porous Activated Carbon from Wheat Bran Agro‐Waste: Applications in Carbon Dioxide Capture, Dye Removal, Oxygen and Hydrogen Evolution Reactions

“…The existence of broad peaks indicates that the crystalline structures of WB (Figure S1) have disappeared after carbonization and activation, which are reflected in the amorphous domain. [37] The WB-AC with large dspacing comparable with WB-RC proves that small primary mesopore sizes and considerable amounts of micropores. Moreover, the peak at 42°in WB-RC completely disappeared, and the relative intensity for the peak at 21°is slightly weaker than the WB-AC.…”

“…It is clearly observed that both the materials displayed a diffused curve lacking significant peak intensity around 23° and 42°, corresponding to the (002) and (100) crystal planes, respectively. The existence of broad peaks indicates that the crystalline structures of WB (Figure S1) have disappeared after carbonization and activation, which are reflected in the amorphous domain [37] . The WB‐AC with large d‐spacing comparable with WB‐RC proves that small primary mesopore sizes and considerable amounts of micropores.…”

Social administration of juvenile hormone to larvae increases body size and nutritional needs for pupation

“…As shown in solitary species, juvenile hormone delays moulting and pupation, and combined with sufficient nutrition, leads to larger adult body size [30]. Various studies have shown that juvenile hormone III, the most common form of juvenile hormone in social Hymenoptera [31], affects adult size and morphology in ants [7,22,27,32,33]. In the ant Harpegnathos saltator, treating larvae with juvenile hormone increases their likelihood of developing into larger adults or into queens [33].…”

“…Proteins that make up these jellies are synthesized by nurse workers who feed the larvae [19] and adapt quantitatively and qualitatively the composition of their jelly diet [17,20]. Although there is evidence for a role for nutrition in caste determination in social insects other than in honeybees [11,12,18,[21][22][23][24], the molecular and social mechanisms of caste fate determination and adult body size are far less understood.…”