Effect of Photoperiodic regimes on the oviposition of artificially overwintered Bombus terrestris L. queens and the production of sexuals.
Jean-Noel Tasei; Pierrick Aupinel
Bombus terrestris queens which had been overwintered in artificial conditions were transferred to small wooden boxes in a climate room at 28°C and 65% RH; the bees were supplied with food and subjected to one of four photoperiodic regimes (L24 : D0; L8 : D16; L16 : D8; LO : D24. The photoperiodic regimes were applied until the queens had produced 10-15 workers, after which colonies were transferred from the small initiation boxes to larger ones to allow nests to increase in colony size. The proportion of queens in each treatment which founded colonies ranged from 42% to 61 %, but no significant difference was detected between photoperiodic regimes. Oelays to oviposition were significantly shorter in the L8 : 016 regime compared with constant dark and constant light: 33.4 ± 4.9 days, 47.3 ± 4.8 days and 58.9 ± 6.7 days respectively. In the L16 : D8 regime the delay (42.4,± 5.6 days) was not significantly different from that in the L8 : D16 regime. The period from the start of brooding attitude to oviposition was significantly reduced by the L8 : D16 regime (5.4 ± 0.9 days) compared to constant light, constant dark or L16 : 08 (9.0 ± 1.0, 10.1 ± 1.4, and 10.2 ± 1.4 days respectively). In the L8 : D16 and L16 : D8 regimes the proportion of queens that did not produce progeny queens was significantly higher if oviposition was retarded.