ACIDIlY OF THE RECTUM CONTENT IN WORKER BEES

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1 PSZCZELNICZE ZESZYTY NAUKOWE Rok XXXVI 1992 ACIDIlY OF THE RECTUM CONTENT IN WORKER BEES Janina Muszyńska,Barbara Leżnicka Institute oc Pomology and Aoriculture, Division of Apiculture Kazimierska 2, Puławy, Poland Warsaw University, Faculty oc Biolog)', Zoolog)' Institute Krakowskie Przedmieście 26(113, Warszawa, Poland Summary The ph oc the rectum of worker bees was measured. The bees were sampled Crom the edge oc the nest during the productive season and wintering. The ph was measured using Merc lacmoid papers graded from 0,5 lo 13.The acidity of the rectum of bees was Coundto vary subslanlially in either of the opposite seasons. Under eonditions of Ihe active season that make purging flights possible worker bees with a ph below to 5,5 are the prevalent c1ass whereas loward the end of winrering (January, February) Ihe bees with a distinclly higher ph ranging from 5,6 to 6,5 are in majority. Keywords: bee condition, acidity, rectum, worker bees, wintering. INTRODUCTION AND REVIEW OF LITERATURE It is weu known that worker bees do not excrete faeces during wintering. Undigested food remnants and waste products of nitrogen metabolism as well as mineral parts are accumulated in the rectum thus creating an environment for a numerous and diverse intestinal flora (K I u g e 1963, C r u s 1972). Further studies are required to learn about the role played in the bee organism by bacleria and fungi and the compounds that they produce (P o I t e v, E g o r o v a 1966, G i I i a m, P r e s t 1972, G iiia m 1989). Acidity is one of the factors that determine the type of the flora of a given environment including the rectum eontent of worker bees. Acidity also effects the activity of rectum enzymes bot h exogenous and those produced by the bees. In addition, the ph of the rectum eontent plays an important role in the processes of active transport in the rectum. 4 The rectum flora is known to be different during the active (productive) season from that present during wintering (C r u s 1972). However, there are no data on the acidity of that rectum segment in different seasons of the year. MATERIAL AND METHODS The acidity of the rectum eontent was determined in the years 1986 and 1987 in wintering bees and in 1989 and 1990 in active season bees. In each year bees were 109

2 taken from the produetive eolonies with naturally inseminated qucens of thc carniolan raee (Apis mellifica camica).. The bees were sam pled, several celonies at a time, once a month in the wintering season and during the active season from mid-may through September sporadically, two or three colonies at a time. They were workers reared on the last comb in the nest fairly well characterized during the wintering season (M u s z y ó- s k a, B o r n u s 1981) and the most representative of the entire colony during the produetive season (M u s z y ń s k a et al. 1975). In the productive season, in addition to the workers from the edge of thc comb workers from the sugar powder feeders were also taken. That food is carried exclusively by workers older than 15 days (M u- s z y ń s k a - unpublished data). The acidity of rectum eon tent was determined in bees using a method developed in this laboratory. Lacmoid papers manufactured by Mcrc with the ph range from 0,5 to 13 and accuracy of 0,5 were used. Thc dcterminations were made after the bees were killed with a temperatur e of minus twenty degrees (-20 C) and the alimentary canals were dissected. The canals were plaeed on the microscope slide. Next the rectum was incised and the lacmoid paper was immersed in its content. The ph value was read on the colour scale. The results were examined statisticaliy using the analysis of varianee and Duncan test. RESULTS The results of the study indicate that bot h during the active season and during wintering worker bees may differ substantially from one another with rectum acicidty. In spite of that variation (variation coefficients of more than 15%) a close relationship was demonstrated between rectum acidity of the bces and the conditions in whieh they live. The highest average ph values i.e. the lowest acidity of the reetum eontent was found in wintering bees in January. In March, after first spring flights the acidity of the rectum eontent is increased and reaehes a value close to that observed in workers sampled in December. It should be stressed that among the aetive season bees the acidity of the reetum eontent ranges from 4,5 to 5,5 in 30% of the individuals whereas in the January and February bees those having the rectum ph of 6,1 to 6,5 account for more than 30% of the total number. The begining and the end of the wintering season (December and March) are characterized by an intermediate paltern of the reetam eontent acidity (Table 2). Interestingly, the lowest ph values were found in workers examined in April (Table l). Also in that group the individuals with rcetum ph from 4,0 to 4,5 were the most numerous (Table 2). DISClJSSION AND CONCLUSIONS The acid ph of the recturn eontent was found in bccs after the spring f1ights and during the productive season when the faeces do not remain in the rcctum for a long time. The acidity of the rectum declines during wintering. In January and February, the coldest months of the year, the organisms of the worker be es undcrgo 110

3 Table l Average values of the pił of the worker bees rectum Średnie wartości ph treści jelita prostego charakteryzowanych pszczół Group of bees Number ph of bees V% Grupa pszczół Liczba bad. averages from- to pszczół średnie przedział last comb Active ostatni plaster 197 5,28 be 4,0 6,0 29,73 season Sezon sugar aktywny cukier puder 254 4,94 ab 3,5 6,0 31,78 December grudzie d 136 5,57 cd 3,5 7,5 28,19 Wintering January. styczed 171 6,39 e 5,1 8,0 24,57 season February łuty 110 5,93 d 4,0 7,5 26,48 Okres zimowania March- marzec 158 5,71 cd 4,0 6,5 27,50 Aprił kwiecied 75 4,85 a 3,5.6,5 32,37 after the first spring flight po pierwszym wiosennym oblocie Means foliowed by the same letter are not significantly different Te same litery przy cyfrach oznaczają brak różnic istotnych między cyframi important changes. A eoincidenee was observed between low ambient temperatures and the inerease of the amount of water and inorganie substanees in the alimentary duets of bees (L e 1;n i c k a et al a, b). That rise was atributed to the need of maintaining the eoneentration of the alimentary duet eontent at a defined level thus proteeting the vital fluids against freezing. Thus one of the funetions of the alimentary duet seems to be to maintain the eonstancy of the internal environment. Those suggestions are in agreement with the data on changes in the level of such osmotieally active element s as sodium and potassium. As soon as the ambient temperature falls below zero potassium and sodium eontent s in the alimentary duet of the bee are raised whije they remain stable in the tissues (L e 1;n i c k a, M u- s z y ń s'k a 1986). However, the excessive increase in sodium and potassium levels in the reetum may eause the bees to die as was demonstrated by H o r n and E b e r s- p a c h e r (1976). Presumbly, keeping the stability of the internal environment and the proteetion of the body against freezing may involve a risk of unfavourable changes buijding up in the rectum such as a drop in acidity. The shift of the rectum from acid to alkaline mayaiso be brought on by the aecumulation of considerable amounts of ealcium (L e 1;n i c k a, M u s z Yń s k a 1986). Of note is the particularly low acidity of the reetum eontent found in the April worker bees. It canot be exluded to be the result of some kind of selection pressure brought about by an increased mortality of the bees with high reetum ph at that time. 111

4 ... N T a b l e 2 Percent of bees in each range of ph value Procentowy udzia] pszcz6j o określonej wartości ph w stosunku do og6lnej liczby badanych osobnik6w Group of bees Grupa pszcz6] ph of the rectum - ph treści jelita prostego i3,9 4,0+4,4 4,5+5,0 5,1+5,5 5,6+6,0 6,1+6,5 6,6+7,0 17,1.~ _ _._ _ _ _, _. _.", _ _ _ _ M _ H. _ _ Active last comb season ostat. piast. O 10,66 37,06 25,38 16,24 6, Sezon sugar feeders prod. cukier puder 5,11 13, ,78 15,75 3, ,54 0,79,..._-_._-_.._---_._.._----_._--_.._._--_._..,-_..-_..._,._._._-_..._...", December Grudzień 0,74 12,50 17,65 22,06 16,18 15,44 11,76 3,68 January Wintering Styczeń O O O 9,94 25,73 36,26 11, season February Luty O 1,82 3,64 17,27 31,82 36,36 10,00 O Okres March zimowania Marzec O 6,33 24,64 39,24 22,78 6,96 O O April Kwiecień 2,67 24,00 46,67 17,33 6,67 2,67 O O - after the first spring flight - po pierwszym oblocie wiosennym

5 The examination of the ph oc the rectum in bees can be used to predict the changes of the intestinal flora. The method used in this study allows to eonduet such surveys in the field as weu. REFERENCES C r u s L. (1972) - Note on a special association between bacteria and rectal wall in overwintering worker honeybees. J.Apic.Res. 11(1):23-26 G i I i a m M., P r e s I D. (1972) - Fungi isolated from intestinal contents or roraging worker honey bees, Apis melłifera, J.lnvertebr.Palhol. 20(1): G i I i a m M., P r e s I D., L o r e n z B. (1989) - Microbiolo&y of pollen and bee bread: laxonomyand enzymolog}' or molds. Apidologie 20(1):53-68 H o r n H., E b e r s p a c h e r J. (1976) - Die waldtrachlkrankheit der Honigbiene 11. Nachweis von Bakterien in der Hamolymphe Waldlrachlkranker Bienen und der Zusalzliche Einfluss der Fullerung aur die Waldlrachlkrankheil. Apidologie 17(4): K I u g e R. (1963) - Untersuchungen uber die Oarmflora der Honigbiene. Z.Bienenforsch. 6(6): L e i n i e k a B., M u s z y ń s k a J., Q a n u c h a K., S I a c h e raz. (1984 a) - Changes in the eontent or waler, organie and inorganic substances in the wintering worker honeybees (Apis mellifica caucasiea Gorb.) Pszczeln.Zesz.Nauk. 28:29-38 Le i n i e k a B., M u s z y ń s k a J., K w i e e i ń s k a M., S z c z u k a A. (1984 b) - Changes in the waler and organie and inorganie substances contents in the worker honeybee hybrids.of Apis mellifica eaueasiea Gorb. from a eluster and a winter fali. Pszczeln.Zesz.Nauk. 28:39-48 L e i n i c k a B., M u s z y ń s k a J. (1984) - The eontent of elements in Ihe body of wintering honey - bees from eluster and winler fall. I. The eontenlor calcium, magnesium and phosphorus. Pszczeln.Zesz.Nauk. 28:49-60 L e ź n i c k a B., M u s z Y ń s k a J. (1986) - The eontent of elements in the body of wintering honey - bees Irom a eluster and winter fall, II. The eon tent of potassium and sodium. Pszczeln.Zesz.Nauk. 30:49-61 M u s z Y ń s k a J., B o r n u s L. (1981) - Niektóre zmiany w organizmie robotnic z zimowego kłębu, Pszczeln.Zesz.Nauk.2'):15-3O M u s z Y ń s k aj., K o n o r a c k a Z., S z e z e p a ń s k i K. (1975) - Przydatność prób z różnych części gniazda dla charaklerystyki rodziny pszczelej w okresie letnim. Pszczeln.Zesz.Nauk. 19:53-64 p o I t e v V., E g o r o v a A. (1966) - L'origine et le role de la microflore chez les colonies d'abeilles. Bull.Apic.9(2):I KWASOWOŚĆ TREŚCI JELITA PROSTEGO PSZCZÓŁ Janina Muszyńska,Barbara Leźnicka Streszczenie Oznaczono kwasowość treści jelita prostego pszczół robotnic w dwóch przeciwstawnych okresach roku: podczas zimowli oraz w czasie sezonu aktywnego, produkcyjnego. Badania prowadzono w latach 1986 i (pszczoły zimujące) oraz 1988 i (pszczoły sezonu produkcyjnego) na ogólnej liczbie 1100 pszczół robotnic, z których po zabiciu przez wychłodzenie, wypreparowywano przewód pokarmowy. Kwasowość jelita prostego oznaczano metodą wskaźnikową, stosując papierki firmy Merc o skali od 0,5 do 13. Przeprowadzone badania wykazały, że zarówno podczas zimowli jak i w sezonie produkcyjnym wyslę:puje znaczne zróżnicowanie pszczół pod względem kwasowości treści ich jelita prostego. Mimo tego 113

6 zróżnicowania wykazano jednakże ścisły związek między odczynem jelita prostego robotnic a warunkami w jakich one przebywają. Najmniejszą kwasowość stwierdzono w styczniu i lutym, a więc w warunkach długotrwałego zamknięcia pszczół. Po obłocie wiosennym w marcu, kwasowość treści jelita prostego pszczół jest zbliżona do stwierdzanej w grudniu. W kwietniu odpowiada ona typowej dla sezonu produkcyjnego w czasie którego pszczoły mają możliwość dokonywania oblotów oczyszczających (Tab. 1i2). Kwasowość jest jednym z czynników określających typ nory bakteryjnej i grzybowej danego środowiska, decyduje także między innymi o aktywności enzymów. Ocena ph jelita prostego pszczół może by<! zatem wykorzystywana do prognozowania kierunku zmian zachodzących we norze jelita prostego pszczół robotnic pod wpływem różnych czynników. Zastosowana w niniejszych badaniach metoda oznaczeri ph treści jełita pszczół pozwala na prowadzenie obserwacji również w warunkach terenswych. Słowa kluczowe: kondycja pszczół, kwasowość, jelito proste, pszczoła robotnica, zimowanie. 114