Osmia Cornuta Research Articles

Body size as an estimator of production costs in a solitary bee

Abstract 1. Body weight is often used as an estimator of production costs in aculeate Hymenoptera; however, due to differences between sexes in metabolic rates and water content, conversion of provision weight to body weight may differ between males and females. As a result, the cost of producing female progeny may often have been overestimated.2. Provision weight and body weight loss throughout development were measured in a solitary bee, Osmia cornuta (Latreille), to detect potential differences between sexes in food weight/body weight conversion.3. Male O. cornuta invest a larger proportion of larval weight in cocoon spinning, and presumably have higher metabolic rates than females during the larval period; however, this is compensated by a slightly longer larval period in females.4. Overall, body weight loss throughout the life cycle does not differ significantly between sexes. As a result, cost production ratios calculated from provision weights and from adult body weights are almost identical.5. The validity of other weight (cocoon, faeces) and linear (head width, intertegular span, wing length, cocoon length, and cell length) measures as estimators of production costs is also discussed.6. Valid estimators of production costs vary across species due to differences in sex weight ratio, cocoon shape, provision size in reference to cell size, and adult body size.

Weather-Dependent Pollinator Activity in an Apple Orchard, with Special Reference toOsmia cornutaandApis mellifera(Hymenoptera: Megachilidae and Apidae)

The foraging activity of pollinator insects in relation to weather factors (ambient temperature, solar radiation, relative humidity, and wind speed) was studied in an apple orchard with special reference to two managed bee species, Osmia cornuta (Latreille) and Apis mellifera L. Over the range of observed weather values, A. mellifera activity was significantly dependent on temperature, solar radiation, and wind speed; O. cornuta activity was dependent on solar radiation and wind speed. These results were confirmed through video recordings at one O. cornuta nesting shelter and one A. mellifera hive. For both species, daily activity started at lower temperatures than it ceased, whereas solar radiation did not differ between these two events. In general, O. cornuta was active from 10 to 12°C and 200 w/m2, and A. mellifera from 12 to 14°C and 300 w/m2. O. cornuta was the only bee species seen visiting apple flowers under strong wind or light rain. Because of its greater tolerance to inclement weather, O. cornuta pollinated apple flowers for longer periods (both daily and seasonally) than other flower visitors.

Pollinating Efficacy of <I>Osmia cornuta</I> and <I>Apis mellifera</I> (Hymenoptera: Megachilidae, Apidae) on ‘Red Delicious’ Apple

The foraging behavior and pollinating efficacy of Osmia cornuta (Latreille) and Apis mellifera L. were studied in an orchard of ‘Delicious’ apple, Malus domestica Borkh, in northeastern Spain. Yields after one single visit were more than five times higher in flowers visited by O. cornuta than in those visited by A. mellifera nectar gatherers. This is attributed to the lower rate of stigma contact in A. mellifera visits, rather than to insufficient deposition of compatible pollen when the stigmas are contacted. A. mellifera pollen collectors had very high rates of stigma contact, but they were very scarce (3%) on ‘Delicious’ flowers despite the presence of abundant brood in their hives. One single visit per flower by O. cornuta produced commercial fruit set (27.4%) and fruit size (>70 mm diameter). Based on cell production, average number of trips required to provision a male and a female cell, and flower visiting rates, it is estimated that a mean of 22,252 apple flower visits per female O. cornuta were made during the 15-d flowering period. This result indicates that 530 nesting O. cornuta females per hectare are enough to provide adequate apple pollination.

Nest Site Orientation and Relocation of Populations of the Orchard PollinatorOsmia cornuta(Hymenoptera: Megachilidae)

Moving actively nesting populations of the orchard pollinator Osmia cornuta (Latreille) from a pollinated crop to one beginning to bloom could increase both the number of flowers pollinated and the number of bee progeny produced. This study investigates the possibility of moving actively nesting O. cornuta populations, and evaluates the effects of moving distance and nest site artificial visual landmarks on orientation and establishment of moved females. Nesting shelters with known numbers of nesting females were nocturnally relocated for distances ranging from 0 to 240 km, and the numbers of nesting females were counted after each move. Nearly all females continued to nest at shelters that were moved short (0–3 m) distances. Moves of intermediate distances (135–235 m) resulted in considerable (30–76%) bee loss (dispersal), and many females flew back to the original nesting site. At long distances (3–240 km), dispersal was higher (63–78%) and no bees were seen hovering at the original site. Moving distance was correlated positively with dispersal and with orientation (zigzagging) flights made by females when they first exited their nests after the moves. The addition or removal of supplementary visual landmarks (2 by 1.5-m banner with colored patterns) at the nesting shelter did not affect dispersal rates. Bees appeared to respond to supplementary landmarks but used other signals as primary orientation cues. An additional experiment showed that O. cornuta populations can be removed and stored at low temperature for up to 4 d (e.g., to avoid pesticide treatments) and then reinstalled at their nesting site, without affecting female orientation or nesting.

Comparison of Nesting Materials for the Orchard Pollinator Osmia cornuta (Hymenoptera: Megachilidae)

A population of the orchard pollinator Osmia cornuta (Latreille 1805) was released in an almond orchard in NE' Spain to test the attractiveness of 4 diff.erent man-made nesting materials. Wood blocks are found most attractive, followed by grooved boards, reed sections, and milk-carton nesting units. Bamboo reeds are much more attractive than Phragmites or Arundo reeds. No significant differences in the number of cells built per nest or in mortality rates are found between nesting materials. On the other hand, the sex ratio ( MM / FF)) of progeny differs between nesting materials, and tends to be higher in the least attractive ones. The highest cell production and female cell production is obtained in wood blocks, and therefore, these are considered the most suitable nesting materials for pollination operations with O. cornuta.

Pollens collected by wild and managed populations of the potential orchard pollinator Osmia cornuta (Latr.) (Hym., Megachilidae)

AbstractPollen samples of provisions of the potential orchard pollinator Osmia cornuta were analyzed. Bee populations studied (from NE Spain) were of 4 different origins: A. wild populations of almond‐growing areas; B. wild populations of non‐almond‐growing areas; C. managed populations released in almond (Prunus dulcis) orchards; D. managed populations released in apple (Pyrus malus) orchards. Although pollen grains of 19 plant families were identified in the samples, Prunus pollen was the dominant pollen type in all wild populations (A populations: 77–99%; B populations: 55–85%). Pollen of other Rosaceae was very scarce (A populations: 0.03–12.3%; B populations: 1–5.5%). Prunus pollen was also the dominant pollen type in samples from C populations (78–99 %), and pollen of other Rosaceae was again very scarce (0–5%). When bees were released in apple orchards (D populations), they overwhelmingly collected Pyrus pollen (92–94%), and hardly any Prunus pollen was found in the samples (0–0.01 %). These results are positive from the point of view of the potential use of O. cornuta as a pollinator of orchard crops, since they indicate that the species preferentially collects Prunus pollen but, will switch to Pyrus pollen when this is more readily available.ZusammenfassungÜber die Pollensammel‐Tätigkeit von wilden und gezüchteten Populationen der Obstbaumbestänberin Osmia cornuta (Latr.) (Hym., Megalichidae)Es wurde die Pollenaufsammlung der Obstbestäubenden Biene Osmia cornuta analysiert. Die aus Nordostspanien stammenden Bienen hatten 4 Herkünfte: A. Wildpopulationen von Mandelbaumarealen, B. Wildpopulationen von Arealen ohne Mandel, C. Zuchtpopulationen, die in Mandel‐Beständen (Prunus dulcis) freigelassen wurden, D. Zuchtpopulationen, die in Apfelbeständen freigelassen wurden. Von den 19 Pflanzenfamilien, die als Pollenquellen ermittelt wurden, dominierte Prunus bei allen Wildpopulationen (A‐Population 77–99 %; B‐Population 55–85 %). Der Pollenanteil anderer Rosaceen war dagegen sehr begrenzt (A 0,93‐12,3 %; B 1–5,5 %). Prunus‐Pollen dominierte auch bei den C‐Populationen (78–99%), wobei auch hier der Pollenanteil anderer Rosaceen sehr gering war (0–5 %). Wurden die Bienen in Apfelplantagen freigelassen (D‐Populationen), trugen sie ganz überwiegend Pyras‐Pollen ein (92–99%), während Prunus‐Pollen einen äußerst geringen Anteil hatten (0‐0,01 %). Diese Ergebnisse sind unter dem Gesichtspunkt einer möglichen Verwendung von O. cornuta als Bestäuberin in Obstplantagen positiv zu bewerten, da sie zeigen, daß die Biene je nach Angebot bestimmte Obstarten bevorzugt bestäubt.

Effect of over-wintering and incubation temperatures on adult emergence in Osmia cornuta Latr (Hymenoptera, Megachilidae)

On etudie actuellement en Espagne l'utilisation d'Osmia cornuta comme pollinisateur alternatif des vergers. La synchronisation de l'emergence des adultes avec la floraison de la culture cible est essentielle pour utiliser au mieux le potentiel pollinisateur de cette abeille solitaire, principalement lorsque les floraisons sont courtes. Dans cette etude, des cocons mâles et femelles d'O. cornuta ont ete places dans des recipients en verre et exposes a differents regimes de temperatures d'hivernage et a diverses modalites d'incubation. Les abeilles qui ont partiellement ou totalement hiverne dans un entrepot d'une region de vergers d'amandiers ont emerge sur une periode beaucoup plus longue (fig 1) que celles qui avaient hiverne dans des refrigerateurs (figs 2 a 5)

The nesting behaviour of the mason bee Osmia cornuta (Latr) with special reference to its pollinating potential (Hymenoptera, Megachilidae)

On a etudie le comportement de nidification d'Osmia cornuta sur des populations introduites dans des vergers d'amandiers. Le temps passe par les femelles a l'interieur et a l'exterieur du nid a ete mesure. Les parois en boue des cellules et les charges de boue transportees par les abeilles ont ete rassemblees et pesees. Les voyages des femelles pour recolter la boue duraient en moyenne 2,72 min et le dechargement 1,87 min (tableau I). Le nombre de voyages necessaires pour construire une paroi en boue etait de 6,88 pour les premieres parois, de 4,41 pour les parois intermediaires, de 11,88 pour les parois du vestibule et de 21,09 pour les bouchons terminaux (tableau II)

Parasitism in wild and managed populations of the almond pollinatorOsmia cornutaLatr. (Hymenoptera: Megachilidae)

SUMMARYThe potential threat of parasites to Osmia cornuta populations managed for almond pollination was analysed. Rates of parasitism were measured in both managed and wild trapnested populations. Only two parasites, the drosophilid fly Cacoxenus sp., and the cleptoparasitic mite Chaetodactylus osmiae, were found in wild populations, but their rates of parasitism rarely exceeded 10%. Cacoxenus was never found in managed populations, but the torymid wasp Monodontomerus obsoletus caused serious damage in some populations when bee cocoons were made accessible by extricating them from nesting materials in the laboratory. Chaetodactylus osmiae was also present in managed populations but in low numbers. In 1991, a population of O. cornuta was released in an almond orchard. As opposed to other releases in which ‘clean’ populations were used, in this release some cells infested with C. osmiae, Cacoxenus sp., and M. obsoletus were intentionally introduced with the bee population. No cell was reparasitized by Caco...

Introduction of the European Bee, Osmia cornuta, into California Almond Orchards (Hymenoptera: Megachilidae)

A population of Osmia cornuta Latr. was trapped in northern Spain during 1984, transported to the United States, quarantined, exposed to various temperature regimes through summer months, and placed in California almond orchards through winter months. Results of this study demonstrated that bees overwintered in commercial almond orchards emerged in synchrony with almond bloom; gregarious nesting was expressed; immatures developed normally on provisions composed mostly of almond pollen and nectar resources; prewintering temperatures affected winter survival of parent bees; and populations that had the highest rates of winter mortality produced the fewest number of cells per emerged female.

Chromosome Number in the Leaf-Cutter Bee, Megachile rotundata1

Determination of the chromosome number of the leafcutter bee, Megachile rotundata (F.), an important pollinator of alfalfa in the Pacific Northwest, is reported hero. A previous summary (Kerr and Laidlaw 1956) of apoid chromosome numbers lists Osmia cornuta Latreille, the only representative of the family Megachilidae reported, as having an n number of 16.