Nesting biology of the trap-nesting Neotropical wasp Trypoxylon (Trypargilum) awifrons Shuckard (Hymenoptera, Crabronidae)

摘要

Nesting biology of the trap-nesting Neotropical wasp Trypoxylon (Trypargilum) aurifrons Shuckard (Hymenoptera, Crabronidae). The present study was carried out in three localities of the state of Sao Paulo, Brazil: Araras (Dec/03-Dec/06), Sao Carlos (Nov/04-Nov/06) and Rifaina (Jul/04-Dec/06). Trap-nests were distributed among sites in the sampling areas and were collected every 35 days. Data from 295 nests indicate that T. aurifrons is a multivoltine species, with higher rates of nest building and cell production in the warm, rainy season. The trap-nests used by the females ranged from 117 to 467 mm in length and 3.1 to 16.6 mm in diameter. All nests showed deep plugs and a vestibular cell was found in 37% of the complete nests. The number of cellsper nest ranged from one to 12. Females were larger than males, emerged from longer cells and their cocoons were significantly larger. A secondary 1:1 sex ratio was found in Araras and Rifaina. No correlation was observed between the diameter of the trap-nest and sex ratio. Males were usually oviposited in the first brood cells. Male and female developmental time from egg to adult was longer in the cold, dry season. Trypoxylon aurifrons provisioned their nests mainly with orb-spiders from the family Araneidae. The most important mortality factor was the death of immature forms, probably due to development failure. The most important parasitoid was Melittobia sp.