HOW LONG DO HONEY- BE ES^^^;^;

Transcription

1 HOW LONG DO HONEY- BE ES^^^;^;, CARRY GERMINABLE POLLEN -. ON THEM? t% 'ttn 3/ ~,'f",.-l -' INSTITUUT VOOR DE VEREDELING VAN TUINBOUWGEWASSEN WAGENINGEN (NEDERLAND)

2 Euphytim (962): HOW LONG DO HONEY-BEES CARRY GERMINABLE POLLEN ON THEM? A. KRAAI Xnstitute of Horticultural Plant B ding -Wageningen With 2 figures Received J Nov. 96 Bees are used to pollinate plants in isolation cages. Usually the bees have previously flown about freely in the open air and may have gathered pollen from the same plant species. Now the question arises whether the bees can contaminate with this pollen plants with whick they are enclosed in an isolation cage. In this connection a number of experirnents were undertaken to find out how Iong becs are loaded with germinable pollen. Tt appeared that the risk of contamination was practicaliy elirninated by keeping the bees in a house or empty isolation cage for 2 hours. In the breeding of various crops bees can be used to advantage to do the pollination work in isolation cages (KRAAI, 954). The bees may previously have flown about freely in nature, visiting flowering plants that are closely related to the isoiated specimens, and consequently they rnay carry pollen that wilt cause undesired cross-fertilization. To determine the extent of this danger a number of experiments were carried out during the years 953 to 959. MATERIALS AND METHODS First the bees were enclosed for 8 to 72 hours in an isolation cage containing flowering plants with easiiy rrecognjzable dominant characters. Then they were returned for one night to 8 days to a very smali bee-hive specially designed for these experiments, or they were put in a poliination cage without flowers, where they were fed sugar water. Next they were placed for one day in another isolation cage housing or 2 fiowering plants of the same species, but now with readily recognizable recessive characters. The seed of the latter plants was aftemards harvested, sown out and inspected for contamination. The number of seeds per combination annuaily sown for this purpose was usudly over 00. The following plants were used for these experiments : With dominant characters: Red cabbage - Langedijker Rode bewaar Borecale - Westlandse hatf hoge Brussels sprouts - Roodnerf Round red radish - Ronde Scharlakenrode

3 TAE3.E. PLANTS USED FûR THE CONTAMTNATION EWERlMENTS 2 I Number of years tated Plants with dominant characters which were visited fint Borecale Brussels sprouts Round red radish Blue comiiower Reddish brown wallflower Begonia semperfloreni, rid Duration of subsequent enclosure without flowers 2 hours 2 hom 20 hours 36 houn 84 hours 90 hours UW) hours 2 hours 2 hours 2 hours 20 hom 36 hourî i 2 hours 20 hours 2 hours! 20 hours M) hours 2 houm 20 hours Plants with recessive characters which were visited afterwards Species Number Totalnumber Of planrs inspected % contaminated White cabhage White cahbage Savoy cahbage Lone white radish ~ong white radish Long white radish 350 O and 0 () O ~ong white radish White wmflower White wmflower White wmiiower White wmflower Yellowish white walüiower Yellowish white walüiower Yellowish white wallflower Yellowish white walmower Yellowish white walüiower Begonia semperflorens, white Begonia. semmrflorens, white Begonia semperflorens, white Begonia semperfloreus, white () one of the plants gave 0 % wntamination in the off-spring (see text)

4

5 A. KRAAI Blue cordower Reddish brown wdlflower Begonia sewperfiorens, diploid red - Centaures c,vanus - Cheii-anihu,~ cheiri - Ball's Rode With recessive characters: - Langedijker Witte Bewaar Savay cabbage - Langedijker Gele Bewaar Long white radish - IJskegel (Icicle) White cornfiawer - Centaures cyanus Yellowish white wallflower - Cheiranth~~~ cheiri (White Gem) Regonia ~emperjîorens, dipl oid white - Snowbank The results are shown in table. Only in one case, in the progeny of one of the three savoy plants, did 0 % contamination occur (4 of the 40 plants). Presumably the piant in question partly already flowered and had been pollinated with pollen of red cabbage before being placed in the isolation cage. In later experinents special care was taken to remove such Rowers as were aiready open before the plants were isolated. Further contamination did not occur. From this it may be concluded that there is generally no risk in allowing bees that have visited plants of a certain crop to visit other plants of the same crop after one night's enclosure in a bee-house. Apparently, after being enclosed for 2 liours, they no longer carry germinable pollen on them. Hos Iang dragen byen kiemkrachrig stuifvzeel hg zich? Voor het bestuiven van planten in geïsoleerde ruimten worden bijen gebruikt. Meestal hebben deze voordien in het vrije veld gevlovgen en daar wellicht op dezelfde plantensoort stuifmeel verzaineld. De vraag was of zij daarmee op de planten in de isoiatieruirnte waaraan zij worden toegevoegd verbastering kunncn veroorzaken. In verband hiermee zijn enige proeven genomen om na te gaan hoe lang bijen kiemkrachtig stuifineel bij zich dragen. Hierbg bieek dat dit al niet meer het p al was, wanneer de bijen gedurende een periode van 2 uur opgesloten werden in hun kast of in een isolatiekamer zonder bloemen. Het Iijkt dus wel verantwoord voor bestuivingsdoeleinden bijen te gebruiken die een nacht opgesloten zijn geweest.. KRAAI, A., 954. The use of honey-bees and bumble-bem in hreeding work. Euphytica 3: 97-07

6