Osmia Cornifrons Research Articles

Distribution Status of Mason Bees, Osmia spp.(Hymenotpera: Megachilidae) in Apple Orchard of Korea

2006년부터 3년 동안 전국 32개 사과원에서 서식하는 뿔가위벌류의 종별 분포와 성비 및 뿔가위벌류의 천적과 경쟁종을 조사하였다. 뿔가위벌류 유인트랩의 평균 영소율은 14.0±}1.7%였고, 지역별로는 충주와 영주가 평균 영소율의 2배로 가장 높았다. 영소된 트랩의 비율은 뿔가위벌류 66.7%, 천적 및 경쟁종이 34.3%로 나타났다. 사과원에서는 머리뿔가위벌, 뿔가위벌, 붉은뿔가위벌, 사토외뿔가위벌, 꼬마민뿔가위벌 등 총 5종이 채집되었다. 뿔가위벌류 중 우점종은 머리뿔가위벌로 69.6%를 차지하였고, 뿔가위벌이 13.0%, 붉은뿔가위벌 11.2%순이었다. 3년간 뿔가위벌류의 분포비율은 유의미한 차이를 보였고, 지역에 따른 머리뿔가위벌의 분포비율도 유의미한 차이가 있었다. 성비의 경우, 뿔가위벌류의 평균 암수성비는 1:2.9였으며, 머리뿔가위벌은 1:1.9, 뿔가위벌은 1:5.1, 붉은뿔가위벌은 1:2로 나타났다. 성비는 채집연도에 따라 채집지역에 따라 성비가 통계적으로 유의미한 차이를 보였다. 뿔가위벌류의 천적은 7종이 채집되었고, 세줄알락수시렁이(48%)와 응애류(38%)의 비율이 가장 높았다. 뿔가위벌의 경쟁종은 9종이 채집되었고, 황슭감탕벌(38.6%)로 가장 높은 비율을 보였다.

Modeling spring emergence of Osmia cornifrons Radoszkowski (Hymenoptera: Megachilidae) females in Korea

The Japanese hornfaced bee, Osmia cornifrons Radoszkowski (Hymenoptera: Megachilidae), is an important pollinator of apple. It overwinters as diapausing adult in cocoon and the synchronization of the adult emergence in spring with apple blossom is critical for successful pollination, specifically in the environment with variable climate. To this end, prediction model of adult emergence would help manage O. cornifrons populations for planed pollination. In this study, by using temperature-dependent emergence data of O. cornifrons, emergence rate were mathematically described using linear and Lactin's nonlinear regression methods. The lower emergence thresholds estimated from linear regression for female was 7.98°C and the thermal constant (DD, degree days) was 112.43DD. Pattern of emergence completion was described by using Weibull function and prediction of spring emergence was modeled based on functions of emergence rate and distribution. The model predicted the emergence of O. cornifrons between 100–130 Julian date and the observation fell between 108–129 Julian date. The prediction ranges of O. cornifrons emergence were wider than that of observation. This model could help predict spring emergence of O. cornifrons in the field and optimize planed pollination program for pollination service in agricultural systems in the climate change era.

Comparative Toxicities and Synergism of Apple Orchard Pesticides to Apis mellifera (L.) and Osmia cornifrons (Radoszkowski)

The topical toxicities of five commercial grade pesticides commonly sprayed in apple orchards were estimated on adult worker honey bees, Apis mellifera (L.) (Hymenoptera: Apidae) and Japanese orchard bees, Osmia cornifrons (Radoszkowski) (Hymenoptera: Megachilidae). The pesticides were acetamiprid (Assail 30SG), λ-cyhalothrin (Warrior II), dimethoate (Dimethoate 4EC), phosmet (Imidan 70W), and imidacloprid (Provado 1.6F). At least 5 doses of each chemical, diluted in distilled water, were applied to freshly-eclosed adult bees. Mortality was assessed after 48 hr. Dose-mortality regressions were analyzed by probit analysis to test the hypotheses of parallelism and equality by likelihood ratio tests. For A. mellifera, the decreasing order of toxicity at LD50 was imidacloprid, λ-cyhalothrin, dimethoate, phosmet, and acetamiprid. For O. cornifrons, the decreasing order of toxicity at LD50 was dimethoate, λ-cyhalothrin, imidacloprid, acetamiprid, and phosmet. Interaction of imidacloprid or acetamiprid with the fungicide fenbuconazole (Indar 2F) was also tested in a 1∶1 proportion for each species. Estimates of response parameters for each mixture component applied to each species were compared with dose-response data for each mixture in statistical tests of the hypothesis of independent joint action. For each mixture, the interaction of fenbuconazole (a material non-toxic to both species) was significant and positive along the entire line for the pesticide. Our results clearly show that responses of A. mellifera cannot be extrapolated to responses of O.cornifrons, and that synergism of neonicotinoid insecticides and fungicides occurs using formulated product in mixtures as they are commonly applied in apple orchards.

Bee pollination of the endangered orchid Calanthe discolor through a generalized food-deceptive system

Calanthe discolor is a Japanese terrestrial orchid that is cultivated for its beautiful flowers arranged in racemose inflorescences. Although its propagation for horticultural purposes has been studied extensively resulting in the successful production of seedlings, little is known about the pollinators and breeding system of C. discolor in its natural habitat. The current study, which combined field observations and pollination experiments, was conducted to gain further insight into the reproduction of this important orchid species. Three bee species: Eucera nipponensis, Osmia cornifrons and Apis cerana japonica, were found to be effective pollinators, transferring the pollinaria on their heads. Pollination experiments also revealed that this species was self-compatible, although it was neither autogamous nor apogamous. The fruit set for the open-pollinated flowers was less than 10 %, suggesting a high degree of pollinator limitation, possibly as a result of the deceptive nature of this species. These results provide evidence that pollinator specificity is the primary mechanism of reproductive isolation between C. discolor and its close relative Calanthe striata, because the latter species is known to be exclusively pollinated by carpenter bee.

An immunomarking method to determine the foraging patterns of Osmia cornifrons and resulting fruit set in a cherry orchard

The foraging patterns of Osmia cornifrons (Radoszkowski) (Megachilidae, Hymenoptera) were determined with an immunomarking method and correlated with fruit set in a commercial tart cherry orchard in Pennsylvania. Adults of O. cornifrons were self-marked with chicken egg-white protein powder from a dispenser nest box placed at the center of the study orchard at early bloom. Flower samples were collected from randomly selected trees (n = 30) located at different distances from the nest box. Flowers were analyzed for the presence of immunomarker protein with enzyme-linked immunosorbent assay. Foraging patterns were determined by measuring the distance and direction of marked flowers from the nest box. While marked flowers were found out to 55 m (maximum distance sampled), most marked flowers were found within 35 m from the nest and the percentage of marked flowers declined rapidly beyond that distance. Fruit density per limb cross-sectional area (cm2) in the study orchard was significantly higher than in the orchard without O. cornifrons, indicating the value of O. cornifrons as pollinators in increasing fruit yield in tart cherries.

Outcome of the First Round of Public Consultation on the draft Guidance Document on the Risk Assessment of Plant Protection Products on Bees (Apis mellifera, Bombus spp. and Solitary Bees)

Outcome of the First Round of Public Consultation on the draft Guidance Document on the Risk Assessment of Plant Protection Products on Bees (Apis mellifera, Bombus spp. and Solitary Bees)

Distribution of Chaetodactylus krombeini (Acari: Chaetodactylidae) within Osmia cornifrons (Hymenoptera: Megachilidae) nests: implications for population management

Chaetodactylus krombeini (Baker) (Acari: Chaetodactylidae) is a cleptoparasitic mite that negatively affects propagation of Osmia spp. (Hymenoptera: Megachilidae) for orchard pollination in the USA. This study was conducted to determine the effect of C. krombeini on mortality of male and female Osmia cornifrons, the Japanese hornfaced bee. A total of 107 O. cornifrons nests were examined to determine within-nest distribution of C. krombeini with regression analyses. A total of 30 mite-free O. cornifrons nests were observed and within-nest distribution of male and female O. cornifrons was determined with non-linear regression analyses. In addition, cocoons from 20 mite-infested O. cornifrons cells were examined to determine whether C. krombeini could be found inside cocoons of O. cornifrons. The results of this study showed that female O. cornifrons and C. krombeini were found more frequently in the inner part of the nest, and male O. cornifrons were found mostly in the center of the nest. No C. krombeini were found inside O. cornifrons cocoons. These results indicate that C. krombeini have a greater negative impact on mortality in the egg and larval stages of female O. cornifrons than in male O. cornifrons. Implications for management of C. krombeini and O. cornifrons populations for orchard pollination are discussed in this article.

The hymenopterous pollinators of Himalayan foot hills of Pakistan (distributional diversity)

Studies were undertaken to explore the diversity of hymenopterans pollinators from a diverse agroecosystems of Himalayan foot hills comprising the orchards of pome and stone fruits at different altitudes from 2200 to 3000 m from sea level. Field experiments were conducted on seven commercial fruit orchards at five various localities. Out of the total 448 specimens, 60.94% were found in an antemeridian (A.M.) phase and 39.06% specimens were found in post-meridian (P.M.) indicating their activity both diurnal and crepuscular. Rank abundance values revealed that 9 species in 5 genera belonged to four families of order Hymenoptera comprising the diversity of Osmia cornifrons Panzer, Anthophora niveo-cincta (Smith), Anthophora himalayensis Rad., Anthophora crocea Bangham , Bombus tunicatus (Smith), Xylocopa dissimilis Lepel., Xylocopa rufescens Smith, Andrena harrietae Bangham and Andrena anonyma Cam. The calculated values of all diversity indices showed that the lowest diversity was found in a monoculture fruit habitat with well weeded orchards, whereas the diversity of pollinators was found greater in multiple cultures with partially weeded orchards particularly during the successional stage of full bloom in both pomes and stone fruits. A significant difference in the pollinators’ population was seen in the orchards with undisturbed surroundings. The natural ecosystem offers more opportunities of refuges for the insect pollinators compare to those orchards with clean cultivation. Key words : Diversity, agro-ecosystem, fruit orchards, hymenopterans pollinators, monoculture.

Influence of repeated pollination on seed number and fruit shape of ‘Fuji’ apples

Lopsided apple fruits were found in an orchard consisting of a single commercial cultivar Fuji and pollinizers of crab-apples under conditions of natural pollination. Speculating that it was caused by inadequate partial pollination, we devised an appropriate model. We artificially pollinated one out of five pistils of apple gynoecium, and then investigated the correlations among inadequate partial pollination, seed number, distribution, and fruit shape.It was speculated that a decrease in seed number and an increase in the rate of lopsidedness were caused by inadequate partial pollination. A deviation in seed distribution was also a factor in the occurrence of lopsided fruits. Since many of the main pollinator Osmia cornifrons visited a flower repeatedly at an orchard consisting of a single cultivar and pollinizers, we analyzed the effect of repeated pollination on increasing and improving seed number in fruits and fruit shape, respectively, using artificial pollination of a pollinizer and cultivars with various S-genotypes. Repeated pollination at 24-h intervals did not contribute to fertilization, but those at 4-h intervals contributed significantly as pollen parents of seeds in fruits. The ability of pistil fertilization was maintained until four days after flowering regardless of pollination, but once fertilization occurred, this pistil was not considered to contribute to seed production 24h after initial pollination. Those results suggested that pollinizers in full bloom be shifted more than a day seemed unnecessary at an orchard with single commercial cultivar, and repeated artificial pollination must be done within one day.

Assessment of Potential Fumigants to Control <I>Chaetodactylus krombeini</I> (Acari: Chaetodactylidae) Associated With <I>Osmia cornifrons</I> (Hymenoptera: Megachilidae)

With the recent decline of honey bees, Apis mellifera (L.) (Hymenoptera: Apidae), there is a need for alternative or supplemental crop pollinators, such as Osmia cornifrons (Radoszkowski) (Hymenoptera: Megachilidae). However, O. cornifrons propagation could be impeded by a cleptoparasitic mite, Chaetodactylus krombeini Baker. We investigated the effects of formic acid and wintergreen oil on mortality of C. krombeini hypopi and O. cornifrons adults by determining the lethal concentration of each compound on each species. On average, >4.8 and >1.8 h were required to cause mortality in O. cornifrons adults when <2,473.5 ppm of formic acid and wintergreen oil was applied as a fumigant, respectively. When the two chemicals were directly applied to the exoskeleton of O. cornifrons adults, 353.4 ppm of wintergreen oil caused bee mortality within 10 min; however, no mortality was found with any formic acid application attempted. Mortality of C. krombeini hypopi occurred 5 and 10 min after application of >176.7 ppm of formic acid and wintergreen oil, respectively. Estimates of LC50 for C. krombeini hypopi treated with formic acid and wintergreen oil were 54.3 and 271.3 ppm, respectively. This study showed that C. krombeini could be controlled effectively without inducing O. cornifrons adult mortality based on concentration and duration of fumigation.

Temperature-Dependent Emergence of &lt;I&gt;Osmia cornifrons&lt;/I&gt; (Hymenoptera: Megachilidae) Adults

Japanese hornfaced bees Osmia cornifrons (Radoszkowski) (Hymenoptera: Megachilidae) are used for pollination of spring blooming fruit crops such as apple, pear, and blueberry. Because O. cornifrons has a short adult life span, synchronization of bee emergence with bloom is critical to maximize crop pollination. This study was conducted to determine lower temperature thresholds (LTDs), optimum temperatures, and required degree-day accumulation for emergence of O. cornifrons adults. Patterns of temperature-dependent emergence of O. cornifrons adults at seven temperatures (3.9, 12.0, 18.6, 26.6, 30.3, 35.6, and 42.5 degrees C) were modeled and simulated with linear and nonlinear regression analyses. Results of this study showed that required degree-days (DD) for emergence of male and female O. cornifrons adults were 125.2 DD, with LTD of 8.9 degrees C and 179.8 DD, with LTD of 8.6 degrees C, respectively. The optimum temperatures for emergence were 36.5, 30.2, and 35.7 degrees C for male, female, and both sexes combined, respectively. This study indicated that emergence of O. cornifrons adults could be manipulated to synchronize with pollination periods of target fruit crops.

Evaluating Osmia cornifrons as Pollinators of Highbush Blueberry

The objective of this study was to investigate the use of Osmia cornifrons Radoszkowski (hornfaced bees) as a pollinator of Vaccinium corymbosum L. (highbush blueberry). Currently, there are no reports available on hornfaced bee use for commercial blueberry production. Five pollination treatments were compared in a 2-year evaluation (2005–06) including hornfaced bees, honeybees, bumblebees, native pollinators, and no pollinators. Enclosed pollination cages were constructed around mature, field-grown highbush blueberry plants to prevent mixing of pollination treatments. Each cage contained a single pollination treatment, except for the open pollination and no pollination treatments. The five pollination treatments were replicated three times inside separate pollination field cages on the farm. Three branches per plant were randomly selected that had a minimum of five fruiting buds and blossom number was recorded. After pollination occurred, the cages were removed to allow the berries to ripen. Ripe fruits were picked weekly over the fruiting season (July to August) in each year (2005 and 2006), with the fruit from each sample being counted and weighed. Blossom number was compared to fruit number and weight to determine efficiency of pollination as a result of the pollination treatments. The results showed that hornfaced bees can be a successful pollinator of commercial highbush blueberry under pollination field cage conditions.

Nest‐to‐nest dispersal of Chaetodactylus krombeini (Acari, Chaetodactylidae) associated with Osmia cornifrons (Hym., Megachilidae)

AbstractA cleptoparasitic mite, the Krombein’s hairy‐footed mite, Chaetodactylus krombeini Baker (Acari, Chaetodactylidae) became a key pest that affects the maintenance and propagation of Osmia spp. (Hym., Megachilidae), thus disrupting orchard pollination in the United States. Although hypopi, the dispersal stages of C. krombeini, are known to disperse from nest to nest by hitchhiking on Osmia cornifrons adults, we observed that they might disperse in other ways too in commercial orchards. This study was conducted to elucidate the nest‐to‐nest dispersal mechanisms of C. krombeini hypopi. We tested three potential dispersal mechanisms of C. krombeini other than phoresy by O. cornifrons: (1) dispersal by walking from nest to entrances of nearby nests, (2) dispersal by walking from nest to nest through emergence holes made by parasitic wasps on nests, and (3) dispersal by being unloaded and uptaken to and from flowers by O. cornifrons. Results of this study showed that C. krombeini hypopi could disperse from a nest to nearby nests by walking through nest entrances and holes made by parasitic wasps of O. cornifrons. Although 0.06% of C. krombeini hypopi on blueberry flowers were picked up by O. cornifrons, they were not able to be unloaded to flowers from O. cornifrons and no hypopi could inhabit or survive on blueberry flowers. This indicated no or very low chance of C. krombeini hypopi dispersal via blueberry flowers. Based on our findings of C. krombeini dispersal ecology, development of C. krombeini control strategies are discussed in this article.

Foraging behavior of Osmia cornifrons in an apple orchard

An apple orchard consisting of a single commercial cultivar and of pollinizers such as Crab apples under the condition of natural pollination needs pollinators for stable fruit production. We investigated the foraging behavior of pollinators, especially Osmia cornifrons Radoszkowski, in order to evaluate their use instead of honeybees. O. cornifrons showed strong flower constancy for 4–8 min during one pollen–nectar foraging trip, as observed in honeybees. However, the bees seemed to forage for different types of flowers, e.g. from a red to a white petal color, during their 16–22 pollen–nectar foraging trips based on the S-RNase allele and simple sequence repeat (SSR) analyses of pollen loaves made during those trips. After one pollen–nectar foraging trip, the bees brushed their abdomen with their hind legs at a nester tube, but ca. 10% of pollen was not brushed from their bodies. The remaining pollen on the body retained the ability for the fertilization of apple for 12 days, suggesting that the pollen on the pollinator's body from a pollinizer could be used for the fertilization of a commercial cultivar visited on their next foraging trip. O. cornifrons seems to be a useful pollinator in apple orchards consisting of a single cultivar, such as, ‘Fuji’, and of pollinizers of different types, such as the red petal color type, ‘Maypole’ or ‘Makamik’. Moreover, most pollen loaves investigated contained S 28 -RNase allele, which was specific for pollen of ‘Starking Delicious’ planted at a great distance (55.2 m) from the nestiny shelter, suggesting that O. cornifrons is a useful pollinator for ‘Delicious’, which is difficult for honeybees to use as a pollinator for its sideworking behavior.

Incidence of Wolbachia and Cardinium endosymbionts in the Osmia community in Korea

Sex ratio distorting endosymbionts induce reproductive anomalies in their arthropod hosts. They have recently been paid much attention as firstly texts of evolution of host-symbiont relationships and secondly potential biological control agents to control arthropod pests. Among such organisms, Wolbachia and Cardinium bacteria are well characterized. This study aims at probing such bacteria in the Osmia community to evaluate their potential utilization to control arthropod pests. Among 17 PCR tested species, Osmia cornifrons and a parasitic fly are infected with Wolbachia and a mite species is infected with Cardinium. Phylogenetic tree analyses suggest that horizontal transfer of the bacteria occurred between phylogenetically distant hosts.

The utilization and industrialization of insect resources in China

AbstractInsecta is the biggest group of animals on earth. The insects are thought to be one of the biggest biological resources that have not been fully exploited by humans. China is one of the earliest countries to exploit insect resources in the world and has been the top producer for over one thousand years of many insect‐related industrial products, such as silk, insect wax and Chinese gallnuts. The exploitation and industrialization of insect resources in China is generally classified into four different levels. The first level is the direct utilization of insect bodies and their secretions, the history of which can be traced back for thousands of years. This level includes the culture and utilization of the silkworm Bombyx mori, the Chinese honeybee Apis cerana cerana, the Chinese white‐wax scale Ericerus pela, the Chinese gall aphid Schlechtendalia chinensis, and the lac insects Kerria spp. Additionally, numerous other insects are typically used for Chinese traditional medicines and food, such as Eupolyphaga sinensis, Opisthoplatia orientalis, Aspongopus chinensis, Martianus dermestoides, Polyrhachis vicina, Hepialus spp, Vespa, Hydrillodes repugnalis, and Tenebrio molitor. Pollinators (Megachile rotundata, Osmia cornifrons, O. excavata) and ornamental insects like butterflies, katydids Gampsocleis grafiosa, and fighting crickets Scapsipedes micado are also among the insects included in this level. Accordingly, a related industry is insect‐breeding, including sericulture and apiculture, which lays the basis for all insect industrialization. The second level is the utilization of insects as enemies of pests and insect pathogens for biological control. The enemy insects, including the egg parasites tricogramma Trichogramma spp, the seven spotted lady beetle Coccinella septempunctata, the Chinese green lacewing Chrysopa sinica, and Anastatus sp. could be produced in large scale. The insect pathogens that have been extensively used for commercial biocontrol in China include Helicoverpa armigera Nucleopolyhedrovirus (HaSNPV), Ectropis oblique Nucleopolyhedrovirus (EcobNPV), Spodoptera exigua multicapsid nucleopolyhedrovirus (SeMNPV), Autographa californica multicapsid nucleopolyhedrovirus (AcMNPV), Plutella xylostella Granulosis (PxGV), Pieris rapae granulosis (PiraGV), and Bacillus thuringiensis (Bt). Related industries include the biopesticide industry and the enemy insect production industry. The third level of utilization is the extraction and synthesis of insect materials with diverse bioactivities. Some insect pheromones and hormones extracted from insect bodies or chemically synthesized have been used for insect pest control and for regulating the silkworm breeding. Toxins from honeybees and wasps have been used in medicine. Some insect materials from the larvae of honeybees, silkworms, tasar silkworms, and houseflies have been developed into health products. The fourth level is using the insects as bioreactors to produce peptides for medical and veterinary uses. Hundreds of foreign genes have been successfully expressed in the insect cells and larvae. The hGM‐CSF expressed in silkworm pupae is commercially available. In this article, we review the culture and utilization of important industrial insects in China.

Effect of distance from early flowering pollinizers ‘Maypole’ and ‘Dolgo’ on ‘Fiji’ fruit set

An apple orchard consisting of a single cultivar under the condition of natural pollination must have suitable pollinizers such as Crab apples to ensure stable fruit production. We selected ‘Maypole’ and ‘Dolgo’ as pollinizers for the cultivar ‘Fuji’, and investigated the rate of fruit and seeds in ‘Fuji’ fruits produced by pollen of the pollinizers. We developed a method for tracing pollen flow based on the leaf color of progeny and S-RNase allele of ‘Maypole’, and on Simple Sequence Repeat (SSR) analyses of ‘Maypole’ and ‘Dolgo’. These were powerful tools for determining the distance insects (mainly Osmia cornifrons) carry pollen from the pollinizers to ‘Fuji’. Although the fruit set of ‘Fuji’ apples was not reduced with increasing distance between ‘Fuji’ apple trees and pollinizers (probably due to pollen flow from other commercial cultivars planted outside the area), the rate of ‘Fuji’ apple fruit produced by the pollen of the pollinizers decreased with increasing distance. The rate of fruit produced by the pollinizers was 84% and 77% when ‘Fuji’ was 2.5 m from ‘Maypole’ and ‘Dolgo’, respectively, and 71% and 64% when ‘Fuji’ was 5 m from ‘Maypole’ and ‘Dolgo’, respectively, but was reduced to 47% and 39% when ‘Fuji’ was 10 m from ‘Maypole’ and ‘Dolgo’, respectively. However, the spacing could cause reduced fruit size, and require extra fruit thinning for producing large fruits. It could also cause reduction of the yield for increasing the planting area of pollinizers. We recommend that pollinizers should be planted not more than 10 m from ‘Fuji’.

Evaluating Hornfaced Bees (Osmia cornifrons) as Pollinators of Highbush Blueberry

The objective of this study was to investigate the use of hornfaced bees (Osmia cornifrons Radoszkowski) as a successful sustainable alternative for pollination of commercial highbush blueberry (Vaccinium corymbosum L.). The hornfaced bee is native to Japan and introduced to the United States in 1977 by the USDA. Hornfaced bees have been shown to be 300× more efficient in pollinating apples than honey bees. Hornfaced bees are active for 4–6 weeks (April to June), and then the adults die. The rest of the year (10 months), dormant hornfaced bees exist inside nest cells located in cardboard straws stored away from berry production areas. Currently, there are no reports on hornfaced bee use available for blueberry farmers. Five pollinator treatments were compared in 2005 including: hornedfaced bees; honey bees; bumble bees; natural pollinators; and no pollinators. Enclosed pollination cages were constructed around mature field-grown highbush blueberry plants to prevent mixing of pollinator treatments. Each cage contained a single pollinator treatment except for the natural pollinator treatment. The five pollinator treatments were replicated three times inside separate netted cages on the farm. Three branches per plant were randomly selected that had a minimum of five fruiting buds and blossom number recorded. After pollination occurred the cages were removed to allow the berries to ripen. Ripe fruit were picked weekly over the season (July to August), with the fruit from each sample being counted and weighed. Blossom number was compared to fruit number and weight to determine efficiency of pollination as a result of the pollinator treatments. The results showed that hornfaced bees pollinated blueberries as well as or better than the other pollinators.

Pollinating Efficacy of Osmia cornifrons and Osmia lignaria subsp. lignaria (Hymenoptera: Megachilidae) on Three Brassicaceae Species Grown Under Field Cages

Until 1997, honey bees, Apis mellifera L., were used to pollinate Brassicaceae grown in field cages at the North Central Regional Plant Introduction Station (NCRPIS), at Ames, IA. At this time, a solitary bee, Osmia cornifrons (Radoszkowski), was first employed to pollinate the crop in field cages; however, a native bee species, Osmia lignaria subsp. lignaria Say, out-competes O. cornifrons in central Iowa for artificial nesting sites erected for rearing. The purpose of this study was to investigate the efficacy of these two solitary bee species for producing Brassica napus, B. rapa, and Sinapis alba seed in field cages. There was no difference in seed production for the S. alba accession, PI 209022, or the B. rapa accession, PI 278766, between the two species of Osmia. But, the B. rapa accession, PI 392025, and the B. napus accession, PI 469944, produced significantly more seed when pollinated by O. lignaria subsp. lignaria than by O. cornifrons. Because the native bee is easier to rear and maintain, it will be the pollinator of choice for control pollinating collections of Brassicaceae species maintained at NCRPIS. The commercial use of O. lignaria subsp. lignaria or the related subspecies, O. lignaria subsp. propinqua, should be investigated for improving the production of canola and rapeseed.

The effects of bumblebees (Bombus terrestris L.) on fruit quality and yield of pepper (Capsicum annuum L.) grown in an unheated greenhouse

Bumblebees (Bombus terrestris L.) are commonly used as a pollinator in tomato, but for pepper, other bee colonies such as Osmia cornifrons (Radoszkowski), Megachile rotundata F., and Apis mellifera L. are used for the same purpose. Here we report on the possibility of using B. terrestris as a pollinator of long-type pepper (Capsicum annuum L.) cultivars. The effects of bee pollination were compared with natural self-pollination in terms of fruit quality and yield of plants grown in a long cycle from October to May in an unheated greenhouse. Number of pollen grains/flower and pollen viability were recorded at 15-day intervals during the experimental period. The results showed that the number of pollen grains/flower decreased from January to March, and pollen germination decreased to its lowest level in January. Despite the decrease in the number of pollen grains/flower and the pollen germination percentage, bumblebee pollination was found to have a positive effect on the fruit yield, fruit quality, and seed set. The bee-pollinated plants set more seeds/fruit, and the fruit was of better quality and heavier. These results indicate that B. terrestris can be considered an effective pollinator of long-type pepper cultivars under unheated greenhouse conditions.