PSZCZELNICZE ZESZYTY NAUKOWERok XL, Nr 1 1996

THE PARENTAL EFFECT ON THE PROGENY BROODPOST-CAPPING STAGE DURATION •

Maciej Siuda, Jerzy WildeAcademy of Agriculture and Technology, Apiculture Division, 10-957 Olsztyn, POLAND

Summary

The post-capping developmental stage (peS) of queens, drones and workers was determined.The queens with known pes were inseminated with sperm of one drone with a shorter orlonger pes or with doses of 8 mm' mixed semen. The queens were kept in .kirchhainer" m~csand the pes of the progeny of the crossing were determined. The correlation between thequeens and their sons was highly significant (r= 0.54, p<0,01) but the correlation calculatedbetween quee'ls and their queen daughters was only r= 0.29, p<0.07. The regressioncoefficient of the mother-queens on their daughters was b=0.78, and that of the' sons-droneswas 2.34. The estimated coefficients of the pes heritability amounted h2=0.6 for thedaughter-queens and h2=0.45 for the sons. The correlation between the workers and theirmothers and their drone fathers we re similary low (r=0.26 and r=O.28 respectively), but bothwere highly signiticant (p<0.01). According to these results queens have a greater intluenceon the postcapping duration of their sons than on that of their daughters. The pes of theworker correlated significantly with that of both parents. Because of the low correlationcoefficient, a rapid process of selection for low pes in workers, and the appearance of beestolerating varroatosis because of this trait, appears unlikely.Keywords: breeding, selection, resistance, Va"oa jacobsoni, post capping period, correlation,

heritability.

INTRODUCTION

Since 1991, the Division of Apiculture of University of Agriculturaland Technnology in Olsztyn (NorthEast Poland) has been working onbreeding out the honey be es with a short post-capping developmental stage(PCS). Attempts to obtain such bee strains are one example of work thathas been carried out in order .o create bee lines resistant against Varroajacobsoni. This kind of resistance against the parasite invasion was found toexist in South-African bee Apis mellifera capensis. Its workers emerge asearly as 10-11 days after the duration of the postcapping stage, and the stillimmature Varroa parasite progeny dies (M o r i t z, M a u t z 1990). Itwas supposed that a short period of the host's post-Iarval development

* This research was supported by the KBN Grant Nr. :; S311 01007.

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would restrain the mite reproduction to only a direct reproduction level andtherefore would enable us to limit or completely restrict the introduction ofacaricides, which should thus not only free the honey-bee colonies fromVarroa jacobsoni but also free the bee products from the remains ofacaricide substances.

In our Division, we have been breeding bees with a short PCS withinthe carniolan bee race, and also, in co-operation with The ApicultureInstitute of Oberursel (Germany), within hybrids of Apis mellifera capensisx Apis mellifera camica, crossing them back with carniolan drones. TheL a n ge n b a c h method (1991) was most often used when selecting theworker be es for a short pesoThe time of cełł sealing of 60 cełłs on averagewas determinated by marking individual cells on a plastic sheet at ~-hrsintervals. Approximately 10 hrs before hatching, the cappings of these cellswere marked by attaching numbered queen marking disk. By the time theworker bees emerged, celi capping had been removed. The marking disksfeli through a grid attached to the bottom of the hive and through a tunnełon a circular register plate. This plate was subdivivided into 24 segments,and revolved once in 24 hrs. The time ot' emergence could be read from theposition ot' the marking disks. The celi was identivied from the num ber onthe disk, and the duration ot' the sealing period was caIculated from therespective sealing time. In the conditions of NorthEast Poland, thisprocedure permits us to rear three generations of queens and their workerprogeny but only two of them can be tested in the same season. New, moreefficient methods are therefore desired. It appears that one possible waycould be by establishing the correlation coefficients between the pesduration in the differenthoney bee castes. Such an approach could possiblyenable us to avoid the time-consuming determination ot' workers' pesduration and ensure instead that we obtain five - six generations ot' queensannually.

MATERIALS AND METHODS

The experiment was carried in the apiary of the Apiculture Divisionof the U niversity of Agricultural and Technnology of Olsztyn in 1992-1994.In 1992, the carniolan honey bee race was used, and since 1993 its hybridswith Apis mellifera capensis (F5 and the further generations), crossing themback with the carniolan drones. The queens were reared continuously in thequeenless rearing colonies. The time of the queens pes duration wasdetermined by the authors own method (W i I d e 1994, W i I d e andS i u d a 1992). The time of queen cełł sealing of all cells was determinatedindividual at 4-hrs intervals by inspection of rearing colonies. Approximately10 hrs before hatching, the cappings of these queen cells in the incubator atl-h intervals were observed. Once emerged, the queens were introduced to

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the newly settled smali mating hives (made of foamy polystyrene) andfollowing two days of holding them in a cellar (temp. 10°C) they were placedin an api ary. The very moment of the comb's cells capping was detected bymarking a sample of 60-100 cells on a transparent plastic sheet. Theduration of the workers pes was estimated using the method by L a n g en b a c h (1991). As for drones, the authors own method was elaborated(W i Id e and S i u d a 1992). A number of queens were inseminated withsemen taken from one drones with known duration time for their pes,individually selected and different for each queen. The remaining queenswith known pes were inseminated with semen of one drone with shorter arlonger PCS or with single dosis of 8 mm' mixed semen. The queens werekept in "kirchhainer" nucs and the PCS of the progeny of the crossing weredetermined.

In 1992, the time of PCS duration was determined for 40 queens,327 drones and 1300 workers of the camica F2 generation (tab. 1 and 2). Ofthis number, five queens started the regular oviposition following theirinsemination with the semen from an individually selected drone. In 1993the pes durations were determined for 14 - daughter-queens of hybrid F6generation, for 246 carniolan drones and for 128 workers, and in 1994 for223 carniolan workers - the progeny of queens that had been inserninatedwith mixed semen. The results of these experiment, were statistically testedusing the "Statgraphics" computer package procedure (D ą b k o w s k i1992).

RESULTS

In 1992, the queens emerged between 161.0 and 186.0 hours, onaverage after 175.0 hrs of the pes development, while the sons-dronesbetween 288.0-356.0 hrs, on average after 328.2 hrs (tab. l). The correlationcoefficients were calculated between the pes durations in the mother-queens and their progeny - daughter queens and sons (tab. 3). A moderate,however highly significant correlation was found between the mothers andtheir sons postlarval development time (r= 0.54, p<O.Ol). Correlationcoefficient for the mother- and daughter-queens was low (r= 0.29) and wasat the margin of significance limits (p<0.07). The regression coefficient formother andtheir daughter-queens on was b=0.78, and for mother and sons-drones was 2.34. The estimated coefficients of the PCS heritability was toh2=0.6 for the daughter-queens and h2=0.45 for sons (tab. 3).

In 1992, the workers originating from queens inseminated withsemen of a single drone emerged after 284.5 to 310.5 hrs, on average after294.1 hrs of the post-capping development (tab. 2). The correlationcoefficients between workers and their mothers, and between workers and

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their fathers were r=0.26 and r=0.28 respectively (tab. 3). Both the valueswere highly significant (p<0.01). The obtained regression coefficients wereto b=0.33 and b=0.12 respectively, while the heritability coefficient wereh2=0.37 for mother-queens and workers, and h2=0.24 for fathers and wórkerbees.

Table 1

PCS duration in daughter-queens and sons (hours)Długość OCZ matek-córek i synów (w godzinach)

n range - rozstęp x

daughter-queens 199240 161.0 - 186.0 175.0

matki-córki 1992

daughter-queens 199314 176.0 - 205.0 184.3

matki-córki 1993

sons - synowie 128 288.0 - 356.0 328.2

In 1992, the workers, originating from queens inseminated with themixed semen, had the PCS ranging from 274.5 to 310 hours, on average284.2 hrs (n= 1088; tab. 2). The estimated correlation coefficient betweenthe mother-queens and workers was r= -0.14 and it was statisticallysignificant (p<0.05) and that of heritability h2= 0.37 (tab. 3).

Table 2

Workers' and drones'PCS duration in successive generations and years of experiment (hours)Długość OCZ robotnic i trutni w kolejnych pokoleniach i latach doświadczenia (w godzinach)

I IGeneration I I range - rozstęp I IPokolenie n x

workers - robotnice 1992 F2 1088 274.5 - 310.0 284.2

workers - robotnice 1992- F2 212 284_) - 310.5 294.1

workers - robotnice 1993- F6* 128 268.5 - 306.0 279.7

drones - trutnie 1993 P 246 321.0 - 357.4 343.6

workers - robotnice.t 994 Fj 223 262.5 - 303.5 279.4

- workers from mother-queens inseminated by a single drune* robotnice od matek unasienianych pojedynczymi trutniami

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In 1993, the daughter-queens emerged between 176.0 and 205 hours,on average 1R4.3 hrs after brood celi capping (tab. 1). The correlationcoefficient between the PCS durations of the mother-queens and daughter-queens of the hybrid F6 generation was high (r= 0.73) and statisticallyhighly sigrufieant (p<O.01), the regression coefficient of the daughter-queenson their mother was to b=3.51; whereas the heritability coefficient had beenoverestimated (h"> 1; tab. 3). Three queens from that F6 generation lai deggs regularly after being inseminated with semen from an individuallyselected drone. In this case, the workers emerged between 268.5 and 306.0hrs, on average 279.7 hrs after brood celi capping. The correlationcoefficient between the PCS ofworkers and their mother-queen was high tor= 0.83. It was ais o high between the PCS of workers and drones orginatingfrom the same queen to r= 0.97 (tab. 3). Both the last coefficients were

, Table 3

Coefficients ot" regression (b). correlation (r) and heritability (h2)

Współczynniki regresji (b). korelacji (r) i odziedziczalności (lr')

I I b I r I p I h2 Imother-queens/daughter-queens 1992

0.78 0.29 p(0.07 0.6matki/matki-córki 1992

mother-queens/daughter-queens 19933.51 0.73 P (0.01 1.64

matki/matki-córki 1993

mother-queens/drones 1992 2.34 0.54 p(O.OI 0.45matki/trutnie 1992

mother-queens/workers 1992 -0.18 -0.14 p(0.05 0.37matki/robotnice 1992

mother-queens/workers 1992*0.33 0.26 p(0.01 0.66

matki/robotnice 1992*

mother-queens/workers 1993* 1.03 0.83 P (0.01 1.61matki/robotnice 1993*

mother-queens/workers 1994-0.19 -0.14 P (0.05 0.60matki/robotnice 1994

father-drones/workers 1992*0.12 0.28 P(0.01 0.24ojcowie/robotnice 1992*

father-drones/workers 1993" 1.75 0.97 p(0.01 0.63ojcowie/robotnice 1993*

•. workers from mother-queens inseminated by a single drone•. robotnice od matek unasienianych pojedynczymi trutniami

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highly significant (p-cfl.Ol ). The workers on their parents regressroncoefficients were b= 1.03 and b= 1.75 respectively. The heritabilitycoefficient of the mother-queens' PCS duration by workers appeared to beoverestimated (h"> l), while for the parent-drones and workers it amountedto h2= 0.63.

In 1994, the workers ernerged after 262.5-303.5 hrs, on average 279.4hrs after brood celi capping (tab. 2). The respective coefficients were ofsimilar values in the case of the progeny of the rnother-queens inseminatedin 1992. The correłation coefficient was low and negative r = -0.14.However it was statistically significant (p<0.05), the regression coefficientof workers on their mothers was b= -0.19, and the heritability coefficientwas to h2= 0.6 (tab. 3).

DISCUSSION

The heritability coefficients obtained in the year 1993 for the mother- daughter-queens, and for the workers and their mothers, was over-estimated. The low genetic variation, estimated at 5.23%, was probably thecause of such results.

In the years 1992 and 1994, the coefficient of correłation andregression for the workers originating from mother-queens inseminated withSmnr' of the mixed semen, were negative. In the remaining cases they werepositive. The values of the caJculated coefficients for the workers originatingfrom mother-queens in 1992 we re comparable to those obtained byB u c h l e r and D r e s c h e r (1990). The negative values.of theconsidered coefficients can point to evidence of the drones' considerableinfluence in determining the PCS in bees. M o r i t z and Jor d a n(1992) came to a similar concłusion. However, they obtained high erheritability coefficients (h2= 0.76) than those in our own experiment.

The heritability coefficients estimated for workers in the 1992 seasonwere simiłar to those reported by B u c h I e r and D r e s c h e r (1990)and by L e C o n t e et al. (1994). In 1994, the coefficient obtained in ourinvestigations was of simiłar value (h2= 0.6) to that reported by H a r b o(1992). The increase in the heritability coefficient value was accompanied bythe investigated trait ranging towards the lower values and by the mean PCSvalue decreasing. Similarly to heritability coefficients evolved the remainingparameters estimated in our own experiment. This suggests that geneticfactors are an increasing influence on the trait of the short duration of thecapped brood period.

It is, however, difficult to explain why, regardless of the highcorrelation and heritabiłity indexes, onły smali breeding progress, asconcerns the seIection trait, was achieved. Most probably, some impact onthis situation exerts the rełatively smali number of the bred and sełection

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individuals which is limited by the pes monitoring possibilities. Betterresults could possibly be obtained, using the estimated coefficients andchanging the selection procedure. lt would be advisable to abandon thedetermination of the pes of each individual and in each generation and toconcentrate efforts instead on breeding out and selecting the morenumerous materiał.

REFERENCES

B li c h I e r R., D r e s c h e r W. (1990) - Variance and heritability of the cappeddeveloprnental stage in EuropeanApis mellifera L. and its correlation with increasedVarroa jacobsoni Oud. infestation. J.Apic.Res., 29:172-176.

H a r b o J.R. (1992) - Breeding honey bees (Hymenoptera: Apidae) for more rapiddevelopment of larvae and pupae. J.Econ.Entomol., 85:2125-2130.

D ą b k o w s k i L, (1992) - Statgrafics - System statystycznego opracowania danych.Komputerowa Oficyna Wydawnicza "Help", 1-240 s.

L a n g e n b a c h K. (1991) - Bestimmung der Zellverdeckelungsdauer verschiedenerBienenherkunfte. Apidologie, 22:448-450.

L e C o n t e, B r u c h o u C; B e n h a m o u d a K., G a u t h i e r c., C o r -n u e t l.M. (1994) - Heritability of the queen brood post-caping stage duration inApis mellifera mellifera L. Apidologie, 25:513-519.

M o r i t z R.F.A., Jor d a n K (1992) - Selection of resistance against Varroa jacobsoniacross caste and sex in the honeybee (Apis mellifera L.. Hymenoptera: Apidae).Exp.Appl. Acarol .• 16:345-353.

M o r i t z R.F.A., M a u t z D. (1990) - Development ol' Varroa jacobsoni in colonies Apismełli/era capensis and Apis mełlifera camica. Apidologie, 21:53-58.

W i I d e l. (1994) - Hodowla pszczół o skróconym okresie postlarwalnym. odpornych naVarroa jacobsoni. Acta Acad. Agricult. Tech Olst., Zootechnica, 39B: 1-43.

W i I d e J., S i u d a M. (1992) - Próba selekcji na skrócenie stadium czerwia zaskle-pionego u pszczoły miodnej Apis mellifera camica. Ann. UMCS. Sectio DD, 47: 137-140.

WPŁYW RODZICÓW NA OKRES CZERWIU ZASKLEPIONEGO POTOMSTWA

M. S i u d a, J. W i I d e

Streszczenie

Od roku 1991 prowadzone są w Zakładzie Pszczelnictwa AR-T w Olsztynie pracehodowlane prowadzące do wyhodowania pszczół o krótkim okresie czerwiu zasklepionego(OCZ). Poszukuje się nowych bardziej efektywnych metod selekcji. Wydaje się, iż jedną znich może być zastosowanie współczynników korelacji pomiędzy rozwojem czerwiuzasklepionego poszczególnych kast pszczelich. Pozwoli to być może na zaniechanieczasochłonnego określania OCZ robotnic, a tym samym na wyhodowanie 5-6 pokoleń w ciąguroku.

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W 1992 roku do hodowli użyto pszczół rasy kraińskiej, a od 1993 roku równieżmieszańce A. m. capensis x A. m. camica (Fj i dalsze pokolenia) krzyżowanych wypierającotrutniami kraińskimi. Okres trwania stadium zasklepionego matek określano metodą własną(W i l d e i S i u d a 1992). Moment zasklepiania komórek pszczelich określano posługującsię metodą znakowania 60-100 komórek na przykładanej do plastra folii. Przy określaniuOCZrobotnic posługiwano się metodą opracowaną przez L a n g e n b a c h (1991). Dookreślenia OCZ trutni posłużono się metodą własną (W i l d e i S i u d a 1992). Częśćmatek pszczelich unasieniano nasieniem pobranym od jednego trutnia o znanym OCZ,pozostałe matki - jednorazowo dawką 8 mm! nasienia.

Porniędzy matkami a ich synami stwierdzono umiarkowaną lecz wysoko istotnąkorelację (r=0.54 p<0,01) (tab.3). Współczynnik korelacji dla matek i matek-córek był niski(r=0,29), lecz bliski istotności (p <0,07). Współczynnik regresji matek-córek na matki wynosiłb=0,78 a synów b=2,34. Współczynnik odziedziczalności OCZ dla matek-córek wynosiłh2=0,6 a dla synów h2=0.45 (tab.3).

Współczynniki korelacji oszacowane w 1992 roku wynosiły. pomiędzy robotnicamia ich matkami r=0.26 p<O.Ol i r=-0.14 p<0.05 oraz ich ojcami r=0,28 p-cu.Ol (tab.3).Współczynniki regresji wynosiły odpowiednio: b=0,33 i b=-0.14 oraz b=0.]2. Natomiastwspółczynnik odziedziczalności wynosił h2=0.66 i h2=0.37 pomiędzy matkami a robotnicamioraz hZ=0,24 pomiędzy ojcami i robotnicami.

Współczynnik korelacji pomiędzy matkami a matkami-córkami pokolenia F6mieszańców był wysoki (r= 0,73) oraz wysokoistotny statystycznie (p< 0.01), współczynnikregresji matek-córek na matki wynosił b=3,51, natomiast współczynnik odziedziczalnościzostał przeszacowany h2> 1 (tab.3). Współczynnik korelacji pomiędzy robotnicami a ichmatkami wynosił r=0,83 p<O,Ol oraz ich ojcami r=0,28 p<O.01 (tab.3). Współczynnikiregresji wynosiły odpowiednio: b= 1.03 oraz b=O.12. Współczynnik odziedziczalnościpomiędzy matkami a robotnicami natomiast wynosi! h2> 1 oraz h2=0.63 pomiędzy ojcamij robotnicami (tab.3).

W ]994 roku współczynnik korelacji wynosił r=-0,]4 i był statystycznie istotny(p<0,05), współczynnik regresji robotnic na matki wynosił b=-0.19 a współczynnikodziedziczalności h2=0.6.

W 1993 roku pomiędzy matkami dla matek-córek i robotnic od strony matekprzeszacowano współczynniki odziedziczalności. Przypuszczać należy. iż powodem była małazmienność genetyczna oszacowana na 5,23%.

W 1992 roku oraz 1994 współczynniki regresji oraz korelacji pomiędzy matkamiunasienionymi 8 mm" nasienia jednolicie mieszanego a robotnicami. były ujemne. Świadczyćto może o dużym wpływie trutni na kształtowanie się OCZ u pszczół. Do podobnego wnioskudoszli M o r i t Z i Jor d a n (1992). Jednak oszacowane w doświadczeniu współczynnikiodziedziczalności były niższe niż uzyskane przez tych autorów (0,76).

W naszym doświadczeniu współczynniki odziedziczalności były podobne jak uB li c h l e r a i D r e s c h e r a (1990) oraz L e C o n t e i in. (1994). Natomiast w1993 i 1994 współczynnik ten osiągnął podobną wartość (0.6) jak u H a r b o (1992). Wzwiązku z uzyskaniem tak różnorodnych wynikóww poszczególnych latach badań, wydaje się.iż na obecnym etapie prowadzonych prac nad uzyskaniem pszczół o krótkim OCZ możliwejest ograniczone wykorzystanie tych współczynników w dalszej hodowli. W pracachselekcyjnych należy więc opierać się nadal na bardzo pracochłonnym określaniu OCZkażdego hodowanego pokolenia.Słowa kluczowe: hodowla, selekcja, odporność. Varroajacobsoni, okres czerwiu zasklepionego,

korelacja, odziedziczalność.

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