EFFECT OF PHOTOPERIODIC REGIMES ON THE OVIPOSITION OF ARTIFICIALLY OVERWINTERED BOMBUS-TERRESTRIS L QUEENS AND THE PRODUCTION OF SEXUALS

Bombus terrestris queens which had been overwintered in artificial con ditions were transferred to small wooden boxes in a climate room at 28 -degrees-C and 65% RH; the bees were supplied with food and subjected to one of four photoperiodic regimes (L24 : D0; L8 : D16; L16 : D8; L0 : D24. The photoperiodic regimes were applied until the queens had pr oduced 10-15 workers, after which colonies were transferred from the s mall initiation boxes to larger ones to allow nests to increase in col ony size. The proportion of queens in each treatment which founded col onies ranged from 42% to 61%, but no significant difference was detect ed between photoperiodic regimes. Delays to oviposition were significa ntly shorter in the L8 : D16 regime compared with constant dark and co nstant light: 33.4 +/- 4.9 days, 47.3 +/- 4.8 days and 58.9 +/- 6.7 da ys 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 signific antly reduced by the L8 : Dl 6 regime (5.4 +/- 0.9 days) compared to c onstant light, constant dark or L16 : D8 (9.0 +/- 1.0, 10.1 +/- 1.4, a nd 10.2 +/- 1.4 days respectively). In the L8 : D16 and L16 : D8 regim es the proportion of queens that did not produce progeny queens was si gnificantly higher if oviposition was retarded.