Nesting biology of Pareumenes quadrispinosus (de Saussure, 1855) (Hymenoptera: Vespidae: Eumeninae) in trap nests in North Vietnam

Nests of Pareumenes quadrispinosus (de Saussure, 1855) were obtained at Me Linh Station for Biodiversity (323 nests) and Tam Dao Town (283 nests), Vinh Phuc Province, as well as at Phu Luong, Thai Nguyen Province (9 nests) and Kim Boi, Hoa Binh Province (62 nests). The wasps nested in segments of bamboo canes and reed stems, 5 to 18 mm in internal diameter. Each nest consisted of a linear series of one to four cells, separated by mud partitions. Brood cells were provisioned with caterpillars and eggs were attached to the ceiling of the cells by thin threads. The life history and sex ratio of this species nesting in trap nests in North Vietnam were recorded from mid-April to last October. The species is multivoltine, with likely up to four generations per year. It has two alternative life histories (diapause and direct development) and overlapping generations. The sex ratio is strongly female-biased. Only 46% of the provisioned cells were successful; the others were damaged by nine parasitoid species or died during development for unknown reasons.