Influence of Mating Type and Oviposition Period on Mandibular ...

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9-0DA, HOB, <strong>and</strong> HVA in the QMS bouquet, while Africanized mated queens have significantly higher proportions <strong>of</strong> (+) <strong>and</strong> (-) 9- HDA. Virgin European queens have a higher proportions <strong>of</strong> 9-0DA, while mated European queens have roughly equal proportions <strong>of</strong> 9- ODA <strong>and</strong> 9-HDA. The average amount <strong>of</strong> the QMP found in a pair <strong>of</strong> m<strong>and</strong>ibular gl<strong>and</strong>s <strong>of</strong> a European mated queen was found to be: 200 I.l 9-0DA, 80 I.lg9-HAD, 20 I.lgHOB, <strong>and</strong> 2 I.lg HVA (Pankiw et al., 1996). Functions <strong>of</strong> queen m<strong>and</strong>ibular pheromones include both primer <strong>and</strong> releaser effects on worker bees. As a primer pheromone, it was found to inhibit queen rearing by workers (Butler, 1954, 1960; Butler <strong>and</strong> Simpson, 1958; Winston et al., 1989, 1990; Pettis et al., 1995), stimulate pollen foraging <strong>and</strong> brood rearing in small, newly founded colonies (Higo et al., 1992), inhibit worker juvenile hormone OH) biosynthesis in laboratory experiments (Kaatz et al., 1992), <strong>and</strong> regulate the transition <strong>of</strong> worker activity from within-hive to foraging duties by lowering their juvenile hormone titers in colonies (Pankiwe et al., 1998). Contrary to earlier findings, Willis et al., (1990) reported that QMP does not affect ovarian development in worker bees. The releaser effects <strong>of</strong> QMP include attraction <strong>of</strong> workers to form retinue around the queen inside the colony (Velthuis, 1967; Winston et al., 1982, 1989; Slessor et al., 1988; Kaminski et al., 1990), attraction <strong>of</strong> workers during swarming outside the colony (Velthuis <strong>and</strong> Van Es, 1964; Butler <strong>and</strong> Simpson, 1967; Winston et al., 1989), <strong>and</strong> attraction <strong>of</strong> drones to the queen during mating flights (Butler <strong>and</strong> Fairey, 1964; Loper et al., 1996). As the main channel <strong>of</strong> communication, queen pheromones have critical importance during introduction <strong>of</strong> a new mated queen to a queenless colony. Beekeepers are advised to replace their queens annually to maintain goodquality performance for their queens <strong>and</strong> colonies <strong>and</strong> to maintain low levels <strong>of</strong> Africanization in commercial colonies. Superseded queens that have mated with Africanized drones can result in colonies with non-commercial properties (Guzman-Nova et al., 1998) such as high defensive proclivity, high rate <strong>of</strong> swarming <strong>and</strong> probability to abscond (Collins et al., 1982; Otis, 1982; Winston et al., 1979). Colonies that are led by young queens « 1 yr. old) produce more honey than colonies led by old queens (Kostarelou-Demianidou et al., 1995). Old queens' progenies could also have undesirable characteristics (e.g. high succeptibility to diseases <strong>and</strong> strong defensive behavior), which prompts beekeerpers to replace them with younger ones (Free, 1987). This regularly performed procedure requires a period <strong>of</strong> queenlessness on workers bees prior to introducing a new queen to the colony. However, worker bees in a queenless colony become more excited <strong>and</strong> sensitive to examinations as the queenlessness period continues. They aggressively attack a foreign introduced queen by the act <strong>of</strong> mounting, biting, pulling, <strong>and</strong> stinging. Eventually, this initiates the balling behavior when workers start to form a cluster <strong>of</strong> bees around the queen, usually resulting in queen elimination (Yavada, 1970;Boch <strong>and</strong> Morse, 1974;Pettis et al., 1998). In spite <strong>of</strong> reducing workers' rejection by caging foreign queens during introduction for 24 hr, this natural behavior <strong>of</strong> workers was found to be more frequent towards instrumentally inseminated queens (II) than naturally mated queens (NM). II queens have been reported to have problems with initial introduction <strong>and</strong> acceptance, <strong>and</strong> with early supersedure (Smith et al., 1993; Harbo <strong>and</strong> Szabo, 1984). II queens were also found to have lower oviposition rates than NM queens (Harbo, 1986a). Nevertheless, the use <strong>of</strong> instrumental insemination for honeybee queens is <strong>of</strong> great value to the beekeeping industry as a tool for bee breeders <strong>and</strong> queen producers to increase the quality <strong>of</strong> honeybee races. Natural
mating can result in bees with undesirable characters that might come from drones <strong>of</strong> unknown origin. The study was carried during Spring, 2000 to ascertain the effect <strong>of</strong> mating type <strong>and</strong> oviposition period <strong>of</strong> queens on the levels <strong>of</strong> m<strong>and</strong>ibular pheromone. It was hypothesized that NM queens have higher amounts <strong>of</strong> m<strong>and</strong>ibular secretion or a different proportion <strong>of</strong> components than II queens, a difference that might contribute to the reported lower acceptance <strong>and</strong> survival rates <strong>of</strong> II queens in field colonies. European Apis mellifera carnica queens were reared by commercial queen rearing method (Doolittle, 1989) from a Carniolan Gene Pool (New World Carniolan) maintained by he Rothenbuhler Honeybee Research Laboratory at the Ohio State University, Columbus, Ohio. A group <strong>of</strong> identical mature queen cells were treated as follows: one half <strong>of</strong> the mature queen cells ready for emergence were introduced to 5- frame nucleus colonies containing young queenless workers with sealed brood, honey <strong>and</strong> pollen. After emergence, virgin queens were allowed to mate naturally. The other half <strong>of</strong> the mature queen cells were kept in an incubator at 34°C <strong>and</strong> 75-80% RH until emergence. After 5-days <strong>of</strong> storage in queen banks, they were instrumentally inseminated with 8 III<strong>of</strong> semen per queen (Harbo, 1968b) on the same day on which NM queens are expected to mate. After inseminatioin, II queens were caged individually <strong>and</strong> left in queen banks for 24 hr. The following day, they were narcotized using C02 so they would lay eggs earlier (Mackensen, 1947), then they were introduced to nucleus colonies similar to those described earlier <strong>and</strong> were released after 48 hr. Both NM <strong>and</strong> II queens observed 7-10 days for oviposition. Once eggs were found, 7queens from each group were collected individually after one <strong>and</strong> two weeks <strong>of</strong> oviposition for dissection <strong>and</strong> extraction. After collection, queens were partially narcotized to reduce body movements <strong>and</strong> the possibility <strong>of</strong> releasing pheromone. Heads <strong>of</strong> queens were separated using fine scissors, then a small opening was made on the cuticle <strong>of</strong> each side in the area between the eye <strong>and</strong> the articulation <strong>of</strong> the m<strong>and</strong>ible with a fine blade (No. 11) fixed on a dissecting knife h<strong>and</strong>le (No.4). The gl<strong>and</strong> was grasped by its duct with fine-tipped forceps <strong>and</strong> removed intact. Gl<strong>and</strong>s were immediately extracted in vials containing 500 III <strong>of</strong> methylene chloride <strong>and</strong> stored at - 20°C for behavioral bioassays <strong>and</strong> chemical analysis. To examine the possibility <strong>of</strong> differences between madibular extract <strong>of</strong> NM <strong>and</strong> II queens, a retinue bioassay was conducted following the procedure <strong>of</strong> Kaminski et al. (1990). Bioassay arenas were prepared using 9- cm diameter plastic Petri dishes. Young workers aged 1-5 days were individually selected from the brood frames <strong>of</strong> honey bee colonies headed by A.m. queens. Upon collection, workers were temporarily frozen <strong>and</strong> 10 were placed in each bioassay arena. Pseudoqueens were prepared from glass rods (7-cm length X 0.6-cm diameter) with one end heated for smooth surface to receive the pheromone sample. The optimal amount <strong>of</strong> extract for bioassay was determined by preliminary tests <strong>of</strong> retinue behavior elicited by 0.004, 0.003, <strong>and</strong> 0.002 queen equivalents <strong>of</strong> QM extracts (unpublished data). The lowest concentration that could elicit a clear response was found to be 0.002 Qeq (3 Ill). The 3 III was applied on the smoothed tip <strong>of</strong> the glass rod using a microsyringe <strong>and</strong> the solvent was allowed to evaporate before introducing the pseudoqueen to the queenless workers. A total <strong>of</strong> 28-replicates (dishes) for each treatment were tested. The response <strong>of</strong> workers to the introduced pseudoqueens was videotaped under red light in a temperaturecontrolled room (25°C) for 15 minutes to allow
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Influence of Mating Type and Oviposition Period on Mandibular ...

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