Jean-Noël Tasei

Nutritive value of 15 single pollens and pollen mixes tested on larvae produced by bumblebee workers (Bombus terrestris, Hymenoptera: Apidae)

AbstractLaboratory trials were performed at 27 °C on micro-colonies comprised of three Bombus terrestris workers. They were fed with syrup and pollen paste ad libitum. The micro-colonies were terminated on the 14th day after egg-laying. Two bioassays tested the nutritive value of 6 pure pollens and 9 commercial pollen mixes on bumblebee larvae. Among 10 criteria tested, the most sensitive to the different pollens were the mean weight of larvae and the rate of discarded larvae. Differentiation between treatments was easier with single pollens that ranged from 14.4% to 24.9% crude protein for Helianthus and Castanea respectively, than with mixes that ranged from 12.9% to 17.6%. The best performance ranking was assigned to Castanea, Papaver and Rubus, which produced larvae weighing 110–150 mg, the lowest to Helianthus and Cistus which resulted in larvae of 20–50 mg. The largest larvae (240 mg) were produced with the mix at 96% Brassica and 15.9% protein and the smallest with the mix at the lowest protein content (12.9%) assembling Picris, Hedera, Amaranthus, Solanum, Helianthus and graminaceae.ZusammenfassungDer Nährwert von Pollen, der von Honigbienen gesammelt wurde, stellt einen Schlüsselfaktor für die kommerzielle Hummelzucht dar. Wir wollten eine einfache, schnelle und empfindliche Methode entwickeln, mit der man routinemäßig den Nährwert verschiedener Pollen vergleichen kann. Die Ziele unserer Studie waren: (i) Ein Vergleich der Empfindlichkeit der vorhandenen Kriterien zum Test der Nährwerte von Pollen bei der Produktion von Larven in weisellosen Mikro-Völkern mit Arbeiterinnen; (ii) Ein Test der Qualität von 6 Pollen, die zu verschiedenen Pflanzenfamilien gehören und von 9 kommerziellen Pollengemischen, die derzeit von Hummelzüchtern benützt werden.Für die Tests wurden Mikro-Völker mit drei Bombus terrestris Arbeiterinnen in kleinen Kästen (11 × 5 × 5 cm) benutzt, die bei 27 °C, 70 % RF und einem Dunkel-Licht-Rhythmus von D8 : L16 gehalten wurden. Pollen und Zuckerwasser wurden ad libitum angeboten. Der Pollen wurde als Paste in 1–2g-Bällchen angeboten. Neun Diäten mit kommerziellen Pollengemischen, die aus Honigbienenvölkern gesammelt wurden und 6 Diäten mit nur einer Pollensorte wurden den Mikro-Völkern gefüttert und die Versuche 10 bis 13 mal wiederholt. Die Hauptpollen in den Gemischen waren: Salix, textit-Picris, Brassica, Prunus, Quercus (Tab. I).Einzelpollen waren: Castanea, Actinidia, Cistus, Papaver, Helianthus und Rubus. Über folgende Kriterien wurde der Nährwert bestimmt: (i) Eiweißgehalt anhand der Stickstoff-Bestimmung, (ii) Anzahl und Größe der Larven (Gewicht der Larven pro Mikro-Volk, mittleres Gewicht der Larven), (iii) Verluste (Arbeiterinnenmortalität, ausgeräumte Larven, Oophagie und Zerstörung von Eizellen), (iv) Pollenaufnahme und Effektivität der Pollenverwendung (Pollenaufnahme durch Arbeiterinnen während der 5 Tage vor Eiablage, Pollenaufnahme während der 14 Tage nach Eiablage, Polleneffektivität, Eiweißeffektivität). Die Pollen- und Eiweißeffektivität wurden durch den Quotienten „Gewicht der produzierten lebenden Larve / Pollen- bzw. Eiweißaufnahme“ bestimmt.Zwei aus Einzelpollen gebildete Pasten wiesen den höchsten Stickstoffgehalt auf: Papaver (3,98 %) und Castanea (3,25 %). Pasten aus Cistus und Helianthus (2,31 % und 2,30 %) hatten den geringsten Gehalt, während Rubus (3,08 %) und Actinidia (2,91 %) dazwischen lagen. Der Stickstoffgehalt von gemischten Pasten reichte von 2,06 % für Mix B, bis 2,82 % für Mix G. (Tabs. II und III). Castanea, Papaver und Rubus produzierten die größten Larven (0,15 g, 0,12 g and 0,11 g), während Actinidia, Cistus und Helianthus die kleinsten hervorbrachte (0,09 g, 0,05 g bzw. 0,02). Die höchsten Larvenausräumraten wurden bei Fütterung mit Papaver (27 %) und Helianthus (22,4 %) beobachtet, die geringsten bei Fütterung mit Castanea (4,5 %) und Rubus (6 %). Darüber hinaus gab es bei 4 weiteren Kriterien Unterschiede (Tab. IV).Bezüglich einiger der 9 Mischungen traten nur bei drei Parametern Unterschiede auf: durchschnittliches Larvengewicht, Entfernen von Larven und Futterverbrauch durch die Arbeiterinnen. Obwohl keine klare Rangordnung bezüglich der Qualität der Mischungen aufgestellt werden konnte, scheint es, dass Mischungen mit hohem Anteil an Picris oder Quercus einen Effekt auf die Larven haben (Tab. V). Die wichtigsten Parameter in einem solchen Bruttest sind das durchschnittliche Larvengewicht und die Ausräumrate der Larven 14 Tage nach Eiablage. Einzelpollen sind leichter zu vergleichen als Mischungen. Pollen von Compositae ist von eindeutig schlechter Qualität. Es muss geprüft werden, ob Tests in Mikro-Völkern eine Vorhersage bezüglich des Nährwertes von Pollen in weiselrichtigen Völkern erlauben.

Sub-lethal effects of imidacloprid on bumblebees, Bombus terrestris (Hymenoptera: Apidae), during a laboratory feeding test

A laboratory feeding test was conducted on queenless micro-colonies of three bumblebee workers (Bombus terrestris L) to study the effects of low doses of imidacloprid on pollen and syrup consumption, worker survival, brood size and larval development. Two doses were used: D1 = 10 µg AI kg−1 in syrup and 6 µg AI kg−1 in pollen; D2 was 2.5 times higher in syrup and 2.7 higher in pollen. During 85 days 27, 30 and 29 micro-colonies were reared for control, D1 and D2 treatments respectively. Food consumption was not affected by either dose. During the 5-day pre-oviposition period the mean insecticide intake was 4.8 ng per day per worker in treatment D2. Both doses slightly but significantly affected worker survival rate by 10% during the first month, without any dose-effect relationship. Brood production was significantly reduced in D1 treatment and larval ejection by workers was significantly lower in D1 and D2 than in control. No significant effect of D1 and D2 treatments on the duration of larval development was revealed. No residue could be detected in workers still alive after 85 days. It was concluded that the survival rate and reproductive capacity of B terrestris was not likely to be affected by prolonged ingestion of nectar produced by sunflower after seed-dressing treatment with imidacloprid (Gaucho), since honey or pollen collected by honeybees foraging treated sunflower never revealed concentrations of imidacloprid higher than 10 µg kg−1. © 2000 Society of Chemical Industry

Hazards of Imidacloprid Seed Coating to Bombus terrestris (Hymenoptera: Apidae) When Applied to Sunflower

Abstract Seed coating treatments of sunflower by the systemic insecticide imidacloprid was suspected of affecting honey bees and bumblebees. The hypothesis raised was whether imidacloprid could migrate into nectar and pollen, then modify flower attractiveness, homing behavior, and colony development. Our greenhouse and field experiments with Bombus terrestris L. were aimed at the following: the behavior of workers foraging on treated and control plants blooming in a greenhouse, the homing rate of colonies placed for 9 d in a treated field compared with colonies in a control field, and the development of these 20 colonies under laboratory conditions when removed from the fields. In the greenhouse, workers visited blooming heads of treated and control plants at the same rate and the mean duration of their visits was similar. In field colonies, analysis of pollen in hairs and pellets of workers showed that in both fields 98% of nectar foragers visited exclusively sunflowers, whereas only 25% of pollen gatherers collected sunflower pollen. After 9 d, in the control and treated field, 23 and 33% of the marked foragers, respectively, did not return to hives. In both fields, workers significantly drifted from the center to the sides of colony rows. During the 26-d period under field and laboratory conditions, the population increase rate of the 20 colonies was 3.3 and 3.0 workers/d in hives of the control and treated field, respectively. This difference was not significant. New queens were produced in eight colonies in either field. The mean number of new queens per hive was 17 and 24 in the control and treated field, respectively. Their mating rate was the same. It was concluded that applying imidacloprid at the registered dose, as a seed coating of sunflowers cultivated in greenhouse or in field, did not significantly affect the foraging and homing behavior of B. terrestris and its colony development.

Territorial biodiversity and consequences on physico-chemical characteristics of pollen collected by honey bee colonies

Pollen resources may become a constraint for the honey bee in cereal farming agrosystems and thus influence honey bee colony development. This survey intended to increase knowledge on bee ecology in order to understand how farming systems can provide bee forage throughout the year. We conducted a 1-year study to investigate the flower range exploited in an agrarian environment in western France, the physico-chemical composition of honey bee-collected pollen, the territorial biodiversity visited by the bee at different periods, and the relationships between these three datasets. Palynological analyses showed the importance of maize among crop pollens and that of weeds during the food shortage period. Pollen protein varied from 16% to 29% and lipids from 7% to 24%. The contribution of different habitats to pollen harvest, was from crops (62%), woods (32%), grasslands (4%), and gardens (1%).

Relationship between aging, mating and sperm production in captive Bombus terrestris

SUMMARYMating behaviour of Bombus terrestris, its sperm production and sperm transfer to queens were studied in parallel, under controlled conditions. The mean value of the age of mating was 6.1 days (s.e. = 0.4 days) for queens and 12.1 days (s.e. = 1.3 days) for males. The average sperm content of vasa deferentia ranged between 4000 and 230 000 spermatozoa per male. It increased from emergence up to the sixth day. The age at which males mated extended from the sixth day to day 27. Chances to cause queens to mate dropped dramatically after day 11. Spermatheca contents varied from 5800 to 36 200 spermatozoa after a single copulation with virgin males. The efficiency of mating in terms of sperm transfer to spermatheca was not affected by the age but was reduced by previous copulations of the male.

Effect of photoperiodic regimes on the oviposition of artificially overwintered Bombus terrestris L. queens and the production of sexuals

SUMMARYBombus terrestris queens which had been overwintered in artificial conditions were transferred to small wooden boxes in a climate room at 28°C and 65% RH; the bees were supplied with food and subjected to one of four photoperiodic regimes (L24: DO; L8: D16; L16: D8; LO: D24. The photoperiodic regimes were applied until the queens had produced 10–15. workers, after which colonies were transferred from the small initiation boxes to larger ones to allow nests to increase in colony size. The proportion of queens in each treatment which founded colonies ranged from 42% to 61 %, but no significant difference was detected between photoperiodic regimes. Delays to oviposition were significantly shorter in the L8: D16 regime compared with constant dark and constant light: 33.4 ± 4.9 days, 47.3 ± 4.8 days and 58.9 ± 6.7 days respectively. In the L16: D8 regime the delay (42.4 ± 5.6 days) was not significantly different from that in the L8: D16 regime. The period from the start of brooding attitude to oviposit...

Validation of a method using queenless Bombus terrestris micro-colonies for testing the nutritive value of commercial pollen mixes by comparison with queenright colonies.

Abstract The nutritive value of pollen blends purchased by bumble bee producers from beekeepers is a key factor of successful mass rearing. We have already devised a method for quality ranking of pollen diets. It was a 1-mo bioassay using queenless micro-colonies of three callow workers (Bombus terrestris L.; Apidae: Bombinae). In the current study, we tested three pollen diets through the micro-colony method and compared the results to the development of queenright colonies supplied with the same diets. The three diets were “A,” a spring blend with a protein rate of 15.7% and a dominance of Corylus avellana L.(46%) and Buxus sempervivens L. (35%); “B,” a summer assemblage with a lower crude protein content (14.4%), with a dominance of Helianthus annuus L.(37%), Zea mays L. (35%), and Poaceae (21%); and “C,” a 50/50 mixture by weight of A and B, with a crude protein content of 15.8%. In micro-colonies, the more sensitive parameter for diet ranking was the mean weight of a larva, whereas in queenright colonies, the discrimination between treatments was enabled by considering the body size of new queens (weight and length of the radial cell) and the slope of the sigmoidal curve of the pollen consumption at the inflection point reflecting brood growth. Both testing methods assigned the lower rank to diet B compared with diet A. Despite the closeness of the three diets in terms of nitrogen content, we concluded that micro-colonies were a good estimate of colony development when nutritive value of pollen was tested.

PREMIÈRES OBSERVATIONS SUR LA POLLINISATION ET LA COULURE DES FLEURS DE LUZERNE EN CHARENTES (MEDICAGO SATIVA L.)

HAL is a multi-disciplinary open access archive for the deposit and dissemination of scientific research documents, whether they are published or not. The documents may come from teaching and research institutions in France or abroad, or from public or private research centers. L’archive ouverte pluridisciplinaire HAL, est destinée au dépôt et à la diffusion de documents scientifiques de niveau recherche, publiés ou non, émanant des établissements d’enseignement et de recherche français ou étrangers, des laboratoires publics ou privés. PREMIÈRES OBSERVATIONS SUR LA POLLINISATION ET LA COULURE DES FLEURS DE LUZERNE EN CHARENTES (MEDICAGO SATIVA L.) Alain Delaude, Jean-Noël Tasei, Pierre Blanchard