About Polybia paulista Ihering, 1896
Polybia paulista Ihering, 1896 is a species of eusocial wasp native to Brazil, Paraguay, and Argentina. Its venom contains a peptide called Polybia-MP1 that has potential use as a chemotherapeutic substance, and this peptide kills cancerous cells while leaving healthy cells unharmed. This wasp occurs in tropical regions of Argentina and Paraguay, and is especially prevalent in São Paulo, Brazil. It typically nests and colonizes in sites that provide protection from weather damage. Up to three colonies can occupy the same location, and swarms appear periodically. Initial nest development starts with swarming or absconding, where the first comb anchors the nest to a substrate. The first comb develops envelopes but holds no eggs, due to its low survival rate. During this early stage, a large portion of the colony remains outside the nest because of limited interior space, forming a tight cluster of wasps around the nest that blocks access to predators such as ants. The external swarm disperses around the 10-day mark, though this timing can vary with season: warmer temperatures increase the wasps’ work rate, leading to faster nest construction. Nest construction pauses to allow for larval emergence, so resources can be allocated to larval development. After larvae emerge, a final comb is built around 12 days, resulting in a total final count of 5 to 6 combs. Colony size changes over the course of nest development: during the energizing phase, a colony holds around 4500 wasps, and can reach up to 13,000 wasps during the period when males are produced. Queen numbers also shift throughout colony development. P. paulista is polygenic, meaning young queens are constantly recruited, so queen counts in a nest can range from 10 to 94 over the full colony cycle. This species is a swarm-founding paper wasp, so its colonies hold multiple queens at different stages of the colony cycle. Young queens are generally morphologically similar to workers, though older queens can be distinguished by their larger physical size. Queens can live up to 1 year, while workers have a 30-day life cycle, with their first flight occurring around the 6th day of life. Queen social dominance is a behavioral trait that is thought to shift a colony from polygyny to monogyny. Younger queens replace older queens based on increases in physical size. Queens can store sperm in their spermatheca, and use this stored sperm to fertilize their eggs when needed. Envelopes are built over combs to protect brood cells during oviposition. Envelope development also helps address the common issue of egg water loss, which would cause embryogenesis to become dormant. Eggs develop into workers throughout the year, during intermediate seasonal periods. P. paulista has 5 larval instars, which support the growth and development of multiple morphological features. Head size typically increases with each instar, but the amount of growth depends on both biotic and abiotic influences. Each instar brings an increase in body weight, as well as growth of the salivary glands and mandibular glands, and developmental changes are linked to the social relationships and tasks an individual will perform in the colony. Specific morphological developments per instar include: opening of the body spiracles in the second instar, development of the lateral tooth on the mandibles in the fourth instar, and the appearance of spines on the maxilla after the fifth instar.
