Polistes nimpha

Appearance

The ''Polistes nimpha'' is usually more black-patterned compared to ''Polistes dominula'', but it is very difficult to morphologically differentiate between the females of ''Polistes nimpha'' and ''dominula''. In females, the color of the malar area is yellow and the 6th gastral sternum is black. In males, the clypeus has lateral ridges and the antennal segments are dark at the tips.
The venom gland of ''Polistes nimpha'' has a muscular poison sac in the shape of an oval. The tip of the stinger is curled at the peak towards the middle, and the palps are shorter than the stinger. The terminal palps are covered with substantial feathers.The nests are beige and grey with dark grey lines. Their sizes vary, with measurements ranging from 8.5 x 9.6 cm to 3.8 x 5 cm. The central cells are oriented in relation to the ground morphology. ''Polistes nimpha'' usually nest in trees and sometimes in cavities. A nest consists of a single resinous pedicel and a comb not covered by envelope. Since there are no envelopes on ''Polistes'' nests, the temperature is not internally maintained inside the nest. Thus, outer temperatures must coincide with the species needs for offspring development. Watch how the ''Polistes nimpha'' thermoregulate their nests .

The species uses a mixture of oral secretions and plant fibers, called paper pulp, to build their nests. These chewed plant fibers from weathered wood and other sources constitute the nest's make-up. The fibers are gathered from areas proximate to the nesting site. The oral secretions ensure the durability of the nest during rain and weathering. The duration of chewing ultimately determines the absorbency of the nest paper. The chewing period of pulps may differ amongst individual colonies.

The nests also consist of organic and inorganic materials; nitrogen is used for the production of the oral secretion, while oxygen, carbon, silisium, calcium, aluminum, potassium, and iron are found in fragments of the nest and within its walls. The amount of protein incorporated into the construction of nests may depend on environment conditions. Correspondingly, the amount of oral secretion used for the nest is positively correlated to the nest’s exposure to rainfall.

Distribution

''Polistes nimpha'' prefer low and relatively warm, uncultivated lands. The wasps prefer to nest on plants, under eaves of roofs and buildings, and in closed areas. Colonies with only one female foundress reside on vegetation, while colonies with two or more female foundresses are usually found in covered and sheltered areas.

Behavior

Colonies may either be haplometrotic or pleiometrotic. Haplometrotic colonies have a single foundress female, while pleiometrotic colonies have two or more foundress females. The fertile foundresses live through the winter and build a nest in the beginning of May. They raise the first generation of workers, which emerge in the first half of June. Over the summer the colony develops and switches from rearing workers to raising sexual individuals; these sexual individuals include males and future foundresses. In August, there is a mass emergence of the male species, and only after this, do the future foundresses appear. The colony begins to disintegrate in late summer and declines throughout autumn. Once the reproductive individuals mate, the males and workers die. By the end of autumn, only the future foundresses are left to survive the winter and begin the cycle again in June.
''Polistes'' colonies found in Turkey are found to be univoltine . ''Polistes nimpha'' colonies are small, averaging less than 100 workers per colony.In the late summer, males patrol and defend small areas of territory, usually around hedges and bushes. A male generally lands with his head directed towards the upper edge of the leaf. Then he rotates in a circle while dragging the ventral part of his abdomen, ending with his head facing in the opposite direction. Rotational direction is the same for a given wasp, and he usually cleans his posterior legs and abdomen afterwards. This movement may enable sexual pheromones to be deposited over territorial perches. The exocrine glands, found in the sternal gastral hypodermis of males, are the site for biosynthesis and storage of various excretions. These secretory glands are involved in the production of a wide range of substances, such as repellent, venom in females, and potentially sexual pheromones in males.
Resident males attack anything that flies near their territories, including other males, flies, other insects, and even paper models attached to the tips of grass stalks. Territorial males assault and bite the head and legs of intruders, sometimes leading to permanent impairment of the antennae and legs. Males can take on aggressive postures before attacking; they exhibit open mandibles and raised wings and antennae. Butting wasps typically hover in the air, and fights between neighboring territories are quite common. Territories of male ''Polistes nimpha'' seem to be purely symbolic and are comparable to leks of vertebrates, as well as the pheromone-marked sites of many bees.

Habitat

''Polistes nimpha'' prefer low and relatively warm, uncultivated lands. The wasps prefer to nest on plants, under eaves of roofs and buildings, and in closed areas. Colonies with only one female foundress reside on vegetation, while colonies with two or more female foundresses are usually found in covered and sheltered areas.

Reproduction

The nests are beige and grey with dark grey lines. Their sizes vary, with measurements ranging from 8.5 x 9.6 cm to 3.8 x 5 cm. The central cells are oriented in relation to the ground morphology. ''Polistes nimpha'' usually nest in trees and sometimes in cavities. A nest consists of a single resinous pedicel and a comb not covered by envelope. Since there are no envelopes on ''Polistes'' nests, the temperature is not internally maintained inside the nest. Thus, outer temperatures must coincide with the species needs for offspring development. Watch how the ''Polistes nimpha'' thermoregulate their nests .

The species uses a mixture of oral secretions and plant fibers, called paper pulp, to build their nests. These chewed plant fibers from weathered wood and other sources constitute the nest's make-up. The fibers are gathered from areas proximate to the nesting site. The oral secretions ensure the durability of the nest during rain and weathering. The duration of chewing ultimately determines the absorbency of the nest paper. The chewing period of pulps may differ amongst individual colonies.

The nests also consist of organic and inorganic materials; nitrogen is used for the production of the oral secretion, while oxygen, carbon, silisium, calcium, aluminum, potassium, and iron are found in fragments of the nest and within its walls. The amount of protein incorporated into the construction of nests may depend on environment conditions. Correspondingly, the amount of oral secretion used for the nest is positively correlated to the nest’s exposure to rainfall.

Predators

The ''Polistes nimpha'' is prey to not only parasitoids, but also to entomophages, such as the parasitic wasp ''L. argiolus'', the hornet ''Vespa crabro'', and ants. Pleiometrotic colonies are better protected from invertebrate predators, and they can usually rebuild their nests if it is destroyed. The most vulnerable time in the wasp’s life cycle is the interval between nest foundation and worker emergence.

Defense

The behavior and process of nest building consists of foragers delivering the paper material to the construction place; the foundress moving over the area and sometimes exhibiting wagging and/or trapping movements with its abdomen; the foundress grasping the entire amount of materials or some part of it; and the construction of the petiole, cell base, or cell wall. The foundresses wag their abdomens while keeping the batch of pulp in their mandibles. They continue this wagging movement until they find a suitable place to apply the pulp. The foundress may sometimes take the nest material from the foragers who brought it to the nest. This particular behavior is more common amongst foundresses who occupy larger nests. Foundresses may exhibit dominant behavior towards workers whenever workers attempt to lay eggs. If this happens, the worker’s wing tips can become damaged from the foundress’s aggressive attacks.