DOI: 10.2478/v10289-012-0022-x Vol. 56 No. 2 2012 Journal of Apicultural Science 37 A TEST OF Bombus terrestris COCOON AND OTHER COMMON METHODS FOR NEST INITIATION IN B. lapidarius AND B. hortorum Alena Buč ánková1,2, Vladimír Ptáč ek1 1Agricultural Research, Ltd. Troubsko, Czech Republic 2Research Institute for Fodder Crops, Ltd. Troubsko, Czech Republic e-mail: [email protected] Received 11 April 2012; accepted 21 November 2012 Summary Several methods for stimulating nest initiation (particularly the use of the Bombus terrestris cocoon) in queen bumblebees of the species B. lapidarius and B. hortorum were compared. For B. lapidarius, it was determined that the percentage success rate for establishing the fi rst egg cell on a cocoon of B. terrestris is similar to that on a conspecifi c cocoon. Nest establishment, however, was signifi cantly slower on the cocoon of B. terrestris. Moreover, it was determined that queens of B. lapidarius are able to initiate a nest without hibernation. Queens hibernated in the laboratory displayed a similar percentage success rate in establishing an egg cell during stimulation with the cocoon of B. terrestris as did the outdoor queens, but the lab queens established it signifi cantly more slowly. Queens of B. hortorum did not incubate the cocoon of B. terrestris, nor did they establish an egg cell on it. Keywords: bumblebee, cocoon, colony initiation, Bombus terrestris, Bombus lapidarius, Bombus hortorum. INTRODUCTION (1985) and Ptáček (2000); the method Bumblebees are important pollinators of an added worker, later mentioned by of many agricultural crops. During the Alford (1975); and the use of interspecies past century, great advances have been cooperation to initiate nesting of the queen made in research concerning bumblebee and rearing of a brood (Ono et al., 1994). domestication. Today, several species are Bumblebees’ willingness to accept already being reared in commercial hives a brood or an individual of another species (Velthuis and Doorn, 2006). is very advantageous. This permits the The first important attempts at rearing breeding of those bumblebee species not yet bumblebees were made by Sladen(1912). domesticated and for which a conspecific He published his experience in the now brood or worker is usually not available. legendary book, “The Humble-bee”. The For interspecies cooperation, callow basis for certain stimulatory methods used workers or male cocoons of the species today for stimulating queens’ oviposition Bombus (Bombus) terrestris L. are most in the laboratory, can be traced to his frequently used due to their easy breeding experiments. These methods include, and availability. To date, the stimulatory for example, the stimulatory effect effect of the B. terrestris cocoon has of providing a brood, which today is most been detected in the species B. hypocrita frequently used in the form of a male hypocrita P., B. (Bombus) ignitus S., B. h. cocoon (Duchateau, 1994; Kwon et sapporoensis C. (Yoneda, 2008), Bombus al., 2003); the method of two queens, (Bombus) lucorum L. (Bučánková and later more developed by Plowright and Ptáček, 2010) and Bombus (Bombus) Jay (1966), Alford (1975), Duchateau cryptarum F. (Bučánková et al., 2011). Yet, not all bumblebee species seem 38 to accept the cocoon of B. terrestris. replaced daily. The containers were placed In 1998, Přidal and Hofbauer in a dark room at a temperature of 27°C published a study in which the cocoon with 60-80% humidity. of B. terrestris was not accepted by the Stimulation and breeding of queens of B. (Megabombus) pascuorum B. lapidarius queens S. or B. (Pyrobombus) hypnorum. It was Queens from nature also stated by Yoneda (2008) that queens A total of 80 queens captured outdoors of other subgenera (B. (Pyrobombus) were tested. Twenty queens were offered ardens S., B. (Diversobombus) diversu a B. lapidarius (BL) cocoon, 43 queens S. and B. (Thoracobombus) schrenkii M.) were offered a B. terrestris (BT) cocoon, were much less stimulated by the cocoon 10 queens were placed in a free pair, of B. terrestris. Unfortunately, more 2 queens were kept alone, and 5 queens details about the influence of phylogenetic had three callow honeybee workers added. relatedness on cooperation are not known. Cocoons were replaced as needed with In the first half of the 1980s, Ptáček fresh cocoons. The queens were inspected reported another stimulatory method every day. The establishment and location for the species B. terrestris which uses (on the cocoon/not on the cocoon) callow honeybee workers. In other species of the first egg cell, emerging of the first (B. (Pyrobombus) lapidarius, B. lucorum, worker, death and behaviour (incubation, B. hypnorum, B. (Pyrobombus) pratorum L., aggression, antennae contact, lack B. pascuorum, B. (Megabombus) hortorum of interest) and eventually the emergence and B. (Megabombus) ruderatus F.) this of the first young queen were checked. method did not work well (Ptáček, 1983, After the first workers emerged, 1985). the colony was transferred into For our study, we decided to test a 26.5×20×20 cm wooden hive lined with the possibilities of using the cocoon a newspaper, then kept at a temperature of B. terrestris and certain other stimulatory of 23-25°C with 40-50% humidity. For methods, in laboratory breeding of the easier manipulation, the top of the hive was species B. lapidarius L. and B. hortorum covered with plastic film. An opening was L. These species were selected because cut in the centre of the plastic film. The top they have longer tongues than B. terrestris of the hive with plastic film was covered (Hanski, 1982). B. lapidarius L. and with a wooden lid. The queen colonies B. hortorum L. are therefore suitable for that had been captured outdoors, were fed pollinating plants with a long flower tube mostly with fresh pollen. which the B. terrestris cannot pollinate. Young queens emerged in the hive, Breeding proficiency would therefore, be attempted to leave it after several days. a welcome advantage. These queens were seen on the hive walls beneath the plastic film, trying to leave. MATERIALS AND METHODS They were collected and transferred Experiments were performed during into a glass box together with unrelated the 2008-2011 time period. Queens were males. The glass box was covered with captured in the spring when they had netting and placed out in the daylight. not yet established nests at several sites The individuals had both pollen and sugar in Moravia (the Czech Republic). On the solution available. After mating they were same day as their capture or one day after, either removed from the glass box and they were placed into plastic containers placed together into a breeding container that were 14×19×7 cm. The bottom in the dark at room temperature with sugar of the container was covered with a piece solution or marked and placed back into of cardboard. They were provided with the vivarium to mate again. The queens a 60% sugar solution (90% sucrose and were then hibernated in a refrigerator at 10% fructose) and fresh pollen which was a temperature of 4-7°C. Vol. 56 No. 2 2012 Journal of Apicultural Science 39 Artificially hibernated queens homogeneity of variances, Welch’s t-test After 3-4 months, 16 hibernated queens was used. If the data did not conform to the were activated. Thirteen queens were conditions of parametric testing, even after given a B. terrestris cocoon, 2 queens had being logarithmically transformed, they a B. lucorum cocoon, and 1 queen was kept were evaluated using the Kruskal-Wallis alone. one-way analysis of variance or the Mann- Queens without hibernation Whitney U test. After being removed from the vivarium, 31 B. lapidarius queens were not RESULTS hibernated, but were placed into a breeding Comparison of stimulation methods space. of these, 6 queens were stimulated and breeding success rate for with a cocoon of B. lapidarius, 22 with B. lapidarius a cocoon of B. terrestris, and 3 queens Queens from the outdoors were kept alone. In the case of the BL cocoon variant, Non-hibernated and hibernated queens 60% of the queens established an egg cell were kept using the same methods as were on the cocoon, and 85% of the queens the queens from outdoors, but, since they established an egg cell - this includes egg were generally bred out of season, they cells on as well as not on the cocoon. In the were provided mostly with dried or frozen group of queens with a BT cocoon, 60% pollen. of the queens also initiated on the cocoon, Stimulation and breeding of the while 88% of the queens established B. hortorum queens an egg cell. No queen of the ten free pairs The capture and breeding of B. hortorum established an egg cell. of the two queens were similar to those for the aforementioned kept alone, neither initiated a nest. of the B. lapidarius. five queens kept with honeybees, three A total of 46 queens were tested. of these, initiated a nest. The significant difference 21 were offered a cocoon of B. terrestris, among these groups (p<0.001) was due to 6 queens were placed in separate pairs the unsuccessfulness of the pair-method, (queens were separated by a double mesh as the difference in the success rate which allowed odour contact but prevented of establishing an egg cell between the physical attack), 12 queens were kept queens stimulated by various cocoons is alone, and 7 queens had three callow insignificant (χ2=0.14; df=1; p=0.708). honeybee workers added. Queens with BL cocoons had The colonies of B. hortorum were reared significantly shorter intervals in during the season, so they were provided comparison to queens with BT cocoons. with fresh pollen in a tiny bowl.