Ropalidia marginata

Ropalidia marginata is an Old World species of paper wasp. It is primitively eusocial, not showing the same bias in brood care seen in other social insects with greater asymmetry in relatedness. The species employees a variety of colony founding strategies, sometimes with single founders and sometimes in groups of variable number. The queen does not use physical dominance to control workers; there is evidence of pheromones being used to suppress other female workers from overtaking queenship. R. marginata was originally described by Johan Christian Fabricius in 1793 under the name Vespa ferruginea, but that name was previously applied to a different species, so the oldest available name for the species was given by Amédée Louis Michel le Peletier in 1836. One of its subspecies, R. marginata jocund from New Guinea and Australia, was described in 1898, and two others, R. marginata rufitarsis from Myanmar and R. marginata sundaica from Indonesia and the Malay Peninsula, were described in 1941. R. marginata is an insect, having six legs. It is in the order Hymenoptera, containing wasps, ants and bees. It is in the family Vespidae, with wasps, yellow jackets, and hornets. It is in the subfamily Polistinae, containing eusocial wasps and it is in the tribe Ropalidiini. On the Indian subcontinent, there are 22 recognized species of the genus Ropalidia. The species R. travancorica, once thought separate, was determined synonymous with R. marginata after intensive specimen comparisons in 1989. R. marginata is most closely related to R. spatulata and R. brevita. The male antenna and genitalia are similar between R. brevita and R. marginata. R. marginata are a dark reddish color (slightly lighter than Ropalidia revolutionalis), with yellow spots on some joints and a yellow ring around the lower abdomen. Males differ from females by having a weaker mandible and lacking a stinger. The female workers are not morphologically different from the queen and are more distinguishable by behavior. Females are hard to distinguish morphologically except for their level of ovary development, which generally increases with their age. Females are the default workers of R. marginata, but they may also rise to queenship by taking over a resident queen, founding a new colony, or adopting an abandoned one. Female workers forage to feed themselves and non-foragers, such as the queen, larvae, and males. They help to build the nest and care for the larvae. Workers may mate with males and remain inseminated even if they are never able to attain queenship and produce offspring. Worker-worker relatedness is not asymmetrically higher than relatedness between workers and males or workers and the queen. This is because of overlapping matrilines and patrilines within the colony which decreases relatedness overall between individuals. When a queen is lost, a worker has the ability to take her place. The mechanism by which the next-in-line-queen is chosen is cryptic; neither age nor dominance accurately predicts the successor. The potential queen may or may not be inseminated or have developed ovaries. The only certainty is that after the queen is gone, the worker who is the potential queen will become very aggressive. The aggressiveness subsides after about two days.The potential queen seems to require this heightened aggression in order to boost her own development. Primitively eusocial societies are typically headed by behaviourally aggressive queens, who use aggression to suppress worker reproduction. However, the queen in R. marginata is a 'docile sitter' who does not use physical aggression to maintain her reproductive monopoly in the colony. The queens are suspected to control workers through pheromones. She uses these pheromones to signal her presence and fecundity to her workers, who perceive these signals and refrain from reproducing. The tenure length, age, and productivity of a queen vary greatly on a case by case basis. The exact mechanisms by which the queen is recognized by her colony are not fully understood. One possibility is that there are chemicals in the queen's Dufour's glands that signal her queen status and influence workers who are on the nest with those chemicals. A potential queen who is acting aggressively can be experimentally subdued by applying the old queen's Dufour's gland's chemicals to the nest.