Biology of the potter wasp Delta esuriens (Fabricius, 1787) (Hymenoptera: Vespidae: Eumeninae) with details on its nesting and mating behaviours, development, and ecology

[Display omitted] •The biology of Delta esuriens is studied in detail.•The potter wasp builds its mud nests in numerous different sites.•Several important insect pests on vegetables are used as prey.•Mating of the eumenine is taken place at flowers.•Developmental mortality ratio of immature stages is 54.4% The biology of the potter wasp Delta esuriens (Fabricius) is studied in Vietnam. The eumenine built its mud nests in numerous sites, usually in shaded locations. The nest consisted of 1–8 pot-shaped cells and was sometimes covered with a lay of mud after it was provisioned completely. The egg was laid before provisioning. The female stored 3–10 caterpillars of Noctuidae, Geometridae, Pieridae, and Plutellidae per nest cell, and left nest cells open during egg-laying and provisioning. The developmental time from the egg to the emergence of the adult wasp was 20–30 days under laboratory conditions. Mating of D. esuriens was taken place at flowers of Bidens pilosa L. and Celosia cristata L., usually in the morning. The male seized a female, grasped her pronotum with his forelegs and quickly copulated with her for 4–10 s. Delta esuriens overwintered as prepupae and occurred in the wild for about eight months a year. The sex ratio was 1.17. The developmental mortality ratio was 25 % under laboratory conditions and 54.4 % under natural conditions. Chrysis dissimilis Dahlbom, Chrysis sp., Trichrysis lusca (Fabricius), Melittobia sosui Dahms, two Sarcophagidae satellite flies, and small red ants were predators of the eumenine. This study provides a better understanding of the biology and ecology of D. esuriens, can be used to aid in studies of phylogeny and evolution of the nesting behaviour in Delta, and can help in developing measures to exploit this potter wasp in the biocontrol of insect pests in vegetable crops.