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Flower and nectar attributes of pepper (Capsicum annuum L.) plants in relation to their attractiveness to honeybees (Apis mellifera L.)
Annals of Applied Biology
Abstract
Flower morphology, nectary structure, nectar traits and rates of honeybee foraging on pepper plants were studied. The nectary appears as swellings on the basal part of the ovary. The nectariferous cells are smaller and denser than the neighbouring parenchyma. Stomata are present in the nectary epidermis, but do not appear on the other parts of the ovary epidermis. Seven pepper breeding lines were grown near a bee yard in Rehovot. Five to six fold differences in nectar volume were found between the extreme genotypes. Nectar volumes were higher during noon and afternoon hours, as compared with morning hours. High correlation coefficients between nectar volume and sugar concentration were found. These were significant for the four high nectar yielding genotypes, ranging between r = 0.65 to r = 0.94. Male-fertile flowers produced more nectar and higher sugar concentration than sterile ones. Skewed distribution was observed in nectar volume of F2 populations, but relatively low heritability values were calculated.
Pepper nectar contains fructose and glucose only. The former occupies 52–82 % of the total sugar content. Pepper genotypes varied in frequency of honeybee visits and significant correlation between sugar quantity and number of honeybee visits per flower was evident. Fertile pepper flowers are not very attractive to honeybees and male-sterile flowers are even less so. The considerable variation in nectar characteristics can be exploited to increase attractiveness to honeybees, thus facilitating bee pollination in commercial production of F1hybrid seeds and improve fruit quality.
... Capsicum species exhibit a wide range of distinctive phenotypes, including variations in flower and fruit shape, size, color, and odor (Wahyuni et al., 2011;Zhigila et al., 2014;Sarpras et al., 2016;Jha & Bhowmick, 2021;Resmi, 2022). From an anthropologic perspective, Capsicum species are of great importance as they are cultivated for their culinary use, medicinal properties, ornamental value, and cultural significance (Palevitch & Craker, 1996;Mongkolporn & Taylor, 2011;Wahyuni et al., 2011;Khan et al., 2014). More notably, Capsicum baccatum, Capsicum eximium, and Capsicum pubescens are unique within the genus as they produce distinctive, yellow-colored nectars, whereas the remaining species appear to produce colorless nectars (Hansen et al., 2007); however, the chemical nature and function of the yellow pigment are unknown. ...
... Capsicum pubescens is found in mid-elevations to highlands in the Andes (500-3500 m) and blooms year-round, while C. baccatum is widely distributed in South America, occurring in dry or humid subtropical or tropical forests, especially in scrub forests, disturbed areas, or the edges of secondary forests (Barboza et al., 2022). Pollination of Capsicum has primarily been studied with cultivated varieties, but it is clear that bees are effective pollinators, including honey bees, solitary bees, and stingless bees (Rabinowitch et al., 1993). ...
... (c-e) Growth (OD 600 ) over a 2-d period of Acinetobacter nectaris (a common nectar bacterium), Metschnikowia reukaufii (a common nectar yeast), and E. coli on artificial nectars with or without riboflavin (0.5 mM) and either exposed to light or incubated in the dark. Error bars represent SD; two-way ANOVAs were used for statistical tests (significant interaction with riboflavin in the light for A. nectaris (Rabinowitch et al., 1993;Raw, 2000). Since Capsicum flowers are usually surrounded by vegetative tissue, leaves are assumed to be the primary background upon which floral reflectance (nectar and petals) resides. ...
A few Capsicum (pepper) species produce yellow‐colored floral nectar, but the chemical identity and biological function of the yellow pigment are unknown.
A combination of analytical biochemistry techniques was used to identify the pigment that gives Capsicum baccatum and Capsicum pubescens nectars their yellow color. Microbial growth assays, visual modeling, and honey bee preference tests for artificial nectars containing riboflavin were used to assess potential biological roles for the nectar pigment.
High concentrations of riboflavin (vitamin B2) give the nectars their intense yellow color. Nectars containing riboflavin generate reactive oxygen species when exposed to light and reduce microbial growth. Visual modeling also indicates that the yellow color is highly conspicuous to bees within the context of the flower. Lastly, field experiments demonstrate that honey bees prefer artificial nectars containing riboflavin.
Some Capsicum nectars contain a yellow‐colored vitamin that appears to play roles in (1) limiting microbial growth, (2) the visual attraction of bees, and (3) as a reward to nectar‐feeding flower visitors (potential pollinators), which is especially interesting since riboflavin is an essential nutrient for brood rearing in insects. These results cumulatively suggest that the riboflavin found in some Capsicum nectars has several functions.
... Capsicum annuum is autonomous selfing, but certain cultivars require a pollinator for fertilization. For example, C. annuum generates nectar with high fructose and glucose content, which attracts honey bees (Rabinowitch et al., 1993) and increases fruit size (Raw, 2000;Putra et al., 2014;Arpita et al., 2017). Moreover, flower traits of C. annuum are influenced by abiotic factors (e.g. ...
... The traits that were measured were stigma-anther separation, corolla diameter, nectar volume per flower, nectar sugar concentration, flower longevity, flowering onset time and the number of flowers per plant. All measurements were collected on three randomly selected, fully opened flowers per plant between 0800 and 1430 h (Rabinowitch et al., 1993). Corolla diameter was estimated by averaging two measurements taken across the flower from petal tip to petal tip as flowers were fully opened (to the nearest 0.1 cm; Supplementary Data Fig. ...
Background and aims:
It has been demonstrated that nitrogen addition alters flower morphology, floral rewards, and pollinator performance. However, little is known about the effects of nitrogen (N) addition on plant reproduction, including fruit set and seed set during selfing and outcrossing, floral and vegetative traits, and pollinator performance. We hypothesized that nitrogen addition would influence the fruit set, the seed set in selfed and outcrossed flowers, the relationship between vegetative and flower traits, and pollinator performance.
Methods:
A two-year pot experiment was conducted in which Capsicum annuum was exposed to three levels of relatively short-term nitrogen supplies, i.e., 0 g·m -2 (none of N addition, as the control), 4 g·m -2 (4N) and 16 g·m -2 (16N), which are equivalent to about 0-fold, 1-fold, and 4-folds of peak local nitrogen deposition. We measured flower rewards, flower morphology, flowering phenology, as well as pollinator visitation rate, fruit set, seed set by self- and outcross- fertilization of C. annuum.
Results:
4 levels of N addition increased plant biomass, biomass allocation to flowers, flower size, stigma-anther separation, nectar production, and pollen production, resulting in an increase in pollinator visitation and fruit set. Nevertheless, the control and 16 levels of N addition reduced plant biomass, biomass allocation to flowers, flower size and stigma-anther separation, nectar and pollen production, and consequently decreased pollinator visitation and fruit set. Exclusion of pollinators and hand-pollination experiments revealed that low levels of N addition were associated with high seed se in outcrossed flowers; however, this trend was reversed in flowers grown in the control and 16N treatments.
Conclusion:
Our results suggest that an optimal level of 4N can enhance the correlation between flower traits, pollinator performance, and plant reproduction. Our findings would cast new light on the underlying mechanisms of plant-pollinator interactions and plant adaptation to nitrogen deposition.
... Having no scent, hot pepper flowers were visited by a limited species of insects, the pollen-gathering bees. In addition, Rabinowitch et al. (1993) mentioned that the low sugar concentrations in the nectar makes the pepper flowers not attractive to honeybees. The most numerous and the most frequent visitor throughout the flowering period of hot pepper were the carpenter bee, Xylocopa sp. and stingless bee, T. biroi. ...
... Ants were considered as chance pollinators because they visited the flowers irregularly. They were present on hot pepper flowers only because the flowers produce nectar that accumulates in the nectary at the base of the ovary (Dewitt and Bosland 2009;Rabinowitch et al. 1993 Ants are nectar thieves, visiting flowers for nectar solely (Faegri and Pijl 1979;Byk and Del-Claro 2010). They were seen feeding at the base of the corolla of hot pepper flowers (Fig. 6D). ...
The floral biology and pollination of Red Hot F1 variety hot pepper, Capsicum frutescens x C. annuum, were studied in this paper. Its flowers are herkogamous and inodorous, and the pollen and nectar serve as rewards to visitors. Anthesis occurred during morning, from 0600 h to 1000 h and peaked on the second day. The pollen grains are simple and numerous with high viability, 96 ± 1.06%. Receptivity of stigma synchronized with pollen viability. This hot pepper variety is partially protogynous. The asynchronous flowering, dichogamy, and herkogamy in hot pepper are their adaptive strategies to promote outcrossing and for reproductive assurance. Four insect species visited the flowers but only the carpenter bee, Xylocopa sp., and the stingless bee, Tetragonula biroi (Friese), are the true pollinators. The foraging activity, which peaked at 0900 h, synchronized with anthesis. Fruit set in an open-pollinated (87 ± 13.12%) and hand-pollinated plants (84 ± 19.37%) were significantly higher than in the control (26 ± 14.30%). Open-pollinated plants produced fruits and seeds with significantly higher quantity and quality.
... Conversely, the assessed parameters of floral preference were significantly lower on the flowers from non-preferred trees compare to the flowers of preferred cashew trees. These results could probably be attributed at the disadvantageous climate factors (sunny, temperature and relative humidity) that are probably affect negatively reproduction phenology in these non-preferred trees, and consequently the availability of floral resources like nectar and pollen [43][44][45][46][47] . Indeed, we noted one late flowering and fruiting season per year (only in dry season from January to April) with low number of flowers per inflorescence (250 flowers/inflorescence) during the reproduction period of these trees. ...
... So, the results evidenced that this low diversity of bees on the flowers from these trees might probably suggest their potential low productivity. These results could probably due to the volume of nectar and the quantity of pollen that are probably low, and therefore affect negatively the attractiveness of flowers and consequently the bees 'diversity [42][43][44][45][46][47] . ...
In spite of the low agronomic performances of Ivorian cashew orchards, Côte d'Ivoire recently became the first worldwide producer and exporter of raw cashew nuts. To maintain this ringleader position, several factors should be understood including the ecological factors supporting this success. Pollination service due to bees was recognized to impact cashew production. Therefore, determining cashew trees that are more attractive to bees can contribute to promote pollination activities. To detect these cashew trees possessing the flowers preferred by bees, two types of investigations were undertaken: (1) a socioeconomic survey in 3167 cashew hectares belonging to 381 producers and (2) an experimental detection of the bees' floral preference. As results, 58 of the 381 interviewed producers had identified the bees' floral preference resulting in a detection of 681 cashew trees. The flowers of the preferred cashew trees were visited 5 times more and they attracted 3 times more bee foragers as compared to non-preferred cashew trees. These findings may be included in research programs focus on: (i) improvement of agronomic performances and (ii) effective management of bees' community.
... Conversely, the assessed parameters of floral preference were significantly lower on the flowers from non-preferred trees compare to the flowers of preferred cashew trees. These results could probably be attributed at the disadvantageous climate factors (sunny, temperature and relative humidity) that are probably affect negatively reproduction phenology in these non-preferred trees, and consequently the availability of floral resources like nectar and pollen [43][44][45][46][47] . Indeed, we noted one late flowering and fruiting season per year (only in dry season from January to April) with low number of flowers per inflorescence (250 flowers/inflorescence) during the reproduction period of these trees. ...
... So, the results evidenced that this low diversity of bees on the flowers from these trees might probably suggest their potential low productivity. These results could probably due to the volume of nectar and the quantity of pollen that are probably low, and therefore affect negatively the attractiveness of flowers and consequently the bees 'diversity [42][43][44][45][46][47] . ...
In spite of the low agronomic performances of Ivorian cashew orchards, Côte d'Ivoire recently became the first worldwide producer and exporter of raw cashew nuts. To maintain this ringleader position, several factors should be understood including the ecological factors supporting this success. Pollination service due to bees was recognized to impact cashew production. Therefore, determining cashew trees that are more attractive to bees can contribute to promote pollination activities. To detect these cashew trees possessing the flowers preferred by bees, two types of investigations were undertaken: (1) a socioeconomic survey in 3167 cashew hectares belonging to 381 producers and (2) an experimental detection of the bees' floral preference. As results, 58 of the 381 interviewed producers had identified the bees' floral preference resulting in a detection of 681 cashew trees. The flowers of the preferred cashew trees were visited 5 times more and they attracted 3 times more bee foragers as compared to non-preferred cashew trees. These findings may be included in research programs focus on: (i) improvement of agronomic performances and (ii) effective management of bees' community.
... Pollination benefits to Citrus species and cultivars vary, but nectar volume is correlated with honey bee visitation (and also flower size; Albrigo et al., 2012). Peppers and onions are both considered unattractive to bees and receive little direct benefit from pollinator visitation; however, bees are needed to produce hybrid seed, and increased honey bee visits are associated with increased nectar sugar or volume (Rabinowitch et al., 1993;Silva and Dean, 2000). ...
... Allium cepa (onion) Nectar volume + honey bee visits Silva and Dean, 2000 Brassica napus (oilseed rape) Nectar volume * + bumble bee visits Creswell, 1999 Brassica napus (oilseed rape) Absence of petals = /+ honey bee visits Pierre et al., 1996 Brassica rapa (field mustard) Ultraviolet patterning + pollinator visits Brock et al., 2016 Brassica rapa (field mustard) Floral volatiles + bumble bee visits Knauer and Schiestl, 2015 Capsicum annuum (pepper) Nectar volume × concentration + honey bee visits Rabinowitch et al., 1993 Citrus spp. (citrus) Nectar volume, flower size + honey bee visits Albrigo et al., 2012 Cucurbita pepo (zucchini) Nectar volume, sugar ratios + bumble bee visits Roldán-Serrano and Guerra-Sanz, 2005 ...
Floral nectar and other reward facilitate crop pollination, and in so doing, increase the amount and breadth of food available for humans. Though abundance and diversity of pollinators (particularly bees) have declined over the past several decades, a concomitant increase in reliance on pollinators presents a challenge to food production. Development of crop varieties with specific nectar or nectar-related traits to attract and retain pollinating insects is an appealing strategy to help address needs of agriculture and pollinators for several reasons. First, many crops have specific traits which have been identified to enhance crop–pollinator interactions. Also, an improved understanding of mechanisms that govern nectar-related traits suggest simplified phenotyping and breeding are possible. Finally, the use of nectar-related traits to enhance crop pollination should complement other measures promoting pollinators and will not limit options for crop production or require any changes by growers (other than planting varieties that are more attractive or rewarding to pollinators). In this article, we review the rationale for improving crop-pollinator interactions, the effects of specific plant traits on pollinator species, and use cultivated sunflowers as a case study. Recent research in sunflower has (i) associated variation in bee visitation with specific floral traits, (ii) quantified benefits of pollinators to hybrid yields, and (iii) used genetic resources in sunflower and other plants to find markers associated with key floral traits. Forthcoming work to increase pollinator rewards should enable sunflower to act as a model for using nectar-related traits to enhance crop–pollinator interactions.
... Vários trabalhos demonstraram a importância dos insetos na polinização de C. annuum (KRISTJANSSON e RASMUSSEN, 1991;SHIPP et al., 1994;MEISELS e CHIASSON, 1997;JARLAN et al., 1997), incluindo Apis mellifera, que foi efetiva tanto em estufas (DE RUIJTER et al., 1991;DAG e KAMMER, 2001) quanto em condições de campo (KUBISOVÁ e HÁSLBACHOVÁ, 1991;RABINOWITCH et al., 1993). O conhecimento da entomofauna visitante das flores de C. annuum no Brasil é escasso, restringindose aos trabalhos de CALMONA et al. (1989), RAW (2000) e CRUZ et al. (2005). ...
... Com relação à polinização de C. annuum, as informações tendem a ser contraditórias e o papel dos insetos na polinização desta cultura tem sido alvo de debate (FREE, 1970(FREE, , 1975MC GREGOR, 1976;RABINOWITCH et al., 1993). As flores são hermafroditas, autocompatíveis e normalmente autopolinizadas (MEISELS e CHIASSON, 1997). ...
LUIZ ROBERTO RIBEIRO FARIA JÚNIOR (2,3*); JULIANA DO NASCIMENTO BENDINI (2,4); LÍDIA MARIA RUV CARELLI BARRETO (5) RESUMO Este trabalho teve como objetivo identificar a entomofauna visitante das flores de Capsicum annuum L. var. Cascadura Ikeda, e avaliar os efeitos da polinização entomófila, mais especificamente de Apis mellifera L., nesta cultura. O estudo realizou-se em Taubaté (SP), a 21º01'S; 45º29'W; altitude de 570 m entre abril e setembro de 2002. Na ocasião, foram observadas 36 plantas de pimentão, das 6h às 17h (10 minutos/hora), durante quatro dias no período de floração máximo da cultura, sendo coletados os insetos visitantes florais. Doze parcelas receberam os seguintes tratamentos: (1) livremente visitadas por insetos; (2) isoladas em gaiolas de polinização; (3) parcelas em gaiolas de polinização contendo uma colméia de Apis mellifera. Foram observadas 12 espécies de insetos visitando as flores de pimentão, sendo as mais freqüentes espécies de abelhas do gênero Exomalopsis (53,9% das visitas). Os frutos produzidos nos tratamentos (1) e (3) tinham maior massa, diâmetro, espessura de pericarpo e número de sementes do que os produzidos no tratamento (2). Concluiu-se, assim, que a polinização por insetos influenciou na produção de frutos de maior qualidade que os produzidos na ausência destes quando se considera os parâmetros aqui avaliados. Ademais, conclui-se que Apis mellifera foi tão eficiente quanto os demais insetos na polinização deste cultivo. Palavras-chave: pimentão, Capsicum annuum L., Solanaceae, polinização, Apis mellifera, Apidae. (1) Recebido para publicação em 16 de outubro de 2006 e aceito em 23 de novembro de 2007. (2) Departamento de Biologia, Universidade de Taubaté. Av. Tiradentes, 500, Bom Conselho, 12030-010 – Taubaté (SP) (3) Programa de Pós-Graduação em Entomologia, Departamento de Zoologia, Universidade Federal do Paraná. Caixa Postal 19020, 81531-980 Curitiba (PR). E-mail: nuno@ufpr.br (*) Autor correspondente. (4) Programa de Pós-Graduação em Zootecnia, Faculdade de Medicina Veterinária e Zootecnia, UNESP Caixa Postal 560, 18618-000 Botucatu (SP).
... Vários trabalhos demonstraram a importância dos insetos na polinização de C. annuum (KRISTJANSSON e RASMUSSEN, 1991;SHIPP et al., 1994;MEISELS e CHIASSON, 1997;JARLAN et al., 1997), incluindo Apis mellifera, que foi efetiva tanto em estufas (DE RUIJTER et al., 1991;DAG e KAMMER, 2001) quanto em condições de campo (KUBISOVÁ e HÁSLBACHOVÁ, 1991;RABINOWITCH et al., 1993). O conhecimento da entomofauna visitante das flores de C. annuum no Brasil é escasso, restringindose aos trabalhos de CALMONA et al. (1989), RAW (2000) e CRUZ et al. (2005). ...
... Com relação à polinização de C. annuum, as informações tendem a ser contraditórias e o papel dos insetos na polinização desta cultura tem sido alvo de debate (FREE, 1970(FREE, , 1975MC GREGOR, 1976;RABINOWITCH et al., 1993). As flores são hermafroditas, autocompatíveis e normalmente autopolinizadas (MEISELS e CHIASSON, 1997). ...
The aim of this research was to identify the insects visiting flowers of sweet pepper and evaluate the effects of entomophilous pollination as a whole and, more especifically, of honeybees as pollinators of this crop. This study was carried out in the municipality of Taubaté, State of São Paulo, Brazil (21°01'S; 45°29'W; altitude: 570 m) from April to September, 2002. Insects were collected in thirty-six plants during 10 minutes/hour between 6:00 and 17:00h during days of maximum blooming. Twelve plots were subjected to the following treatments: (1) open-pollinated plots, freely visited by insects; (2) caged plots; (3) caged plots containing a hive of honeybees. Twelve species of insects visited the flowers. Exomalopsis spp. (Hymenoptera, Apidae) were the commonest ones (53,9% of visits). Fruits yielded in treatments (1) and (3) were heavier, presented higher diameter, thicker pericarp and more seeds per fruit than fruits in treatment (2). Results showed that fruits from insect pollinated plots presented better quality. Honeybeesas as pollinators were efficient as the other insects. sweet pepper, Capsicum annuum L., Solanaceae, pollination, Apis mellifera, honeybee.
... Plants, which provide around 35% of our diet, are directly or indirectly dependent on insect pollinators (Richards, 1993; Klein et al., 2007). Estimates by Martin (1975), Levin (1983), Robinson et al. (1989) and Southwick and Southwick (1992) on the value of pollination in the USA range up to US$ 40 billion per annum and, in Canada, up to CN$ 1.2 billion per annum. ...
... Globally, the benefits from non-Apis, native bee pollinators are increasing, as the honey bee industry continues to decline (Richards, 1993, Gallai et al., 2008). ...
... Vários trabalhos demonstraram a importância dos insetos na polinização de C. annuum (KRISTJANSSON e RASMUSSEN, 1991;SHIPP et al., 1994;MEISELS e CHIASSON, 1997;JARLAN et al., 1997), incluindo Apis mellifera, que foi efetiva tanto em estufas (DE RUIJTER et al., 1991;DAG e KAMMER, 2001) quanto em condições de campo (KUBISOVÁ e HÁSLBACHOVÁ, 1991;RABINOWITCH et al., 1993). O conhecimento da entomofauna visitante das flores de C. annuum no Brasil é escasso, restringindose aos trabalhos de CALMONA et al. (1989), RAW (2000) e CRUZ et al. (2005). ...
... Com relação à polinização de C. annuum, as informações tendem a ser contraditórias e o papel dos insetos na polinização desta cultura tem sido alvo de debate (FREE, 1970(FREE, , 1975MC GREGOR, 1976;RABINOWITCH et al., 1993). As flores são hermafroditas, autocompatíveis e normalmente autopolinizadas (MEISELS e CHIASSON, 1997). ...
The aim of this research was to identify the insects visiting flowers of sweet pepper and evaluate the effects of entomophilous pollination as a whole and, more especifically, of honeybees as pollinators of this crop. This study was carried out in the municipality of Taubaté, State of São Paulo, Brazil (21º01'S; 45º29'W; altitude: 570 m) from April to September, 2002. Insects were collected in thirty-six plants during 10 minutes/hour between 6:00 and 17:00h during days of maximum blooming. Twelve plots were subjected to the following treatments: (1) open-pollinated plots, freely visited by insects; (2) caged plots; (3) caged plots containing a hive of honeybees. Twelve species of insects visited the flowers. Exomalopsis spp. (Hymenoptera, Apidae) were the commonest ones (53,9% of visits). Fruits yielded in treatments (1) and (3) were heavier, presented higher diameter, thicker pericarp and more seeds per fruit than fruits in treatment (2). Results showed that fruits from insect pollinated plots presented better quality. Honeybeesas as pollinators were efficient as the other insects.
... As with tomatoes, in recent decades the practice of relocating sweet pepper cultivation from open fields to enclosures has become widespread. However, unlike tomatoes , sweet pepper flowers secrete nectar and the anthers are exposed, not hidden (Rabinowitch et al., 1993). Honeybee activity has been found to be correlated with the sugar quantity in nectar (Rabinowitch et al., 1993). ...
... However, unlike tomatoes , sweet pepper flowers secrete nectar and the anthers are exposed, not hidden (Rabinowitch et al., 1993). Honeybee activity has been found to be correlated with the sugar quantity in nectar (Rabinowitch et al., 1993). Bee pollination in enclosures was found to increase the number of seeds per fruit, as well as fruit weight, width, and wall thickness (Dag et al., 2007). ...
Most of the cultivated crops depend on animal pollination. Honeybees remain the most economically valuable pollinators of crops worldwide. The current review describes the research developments in crop pollination and crop–pollinator interactions in Israel in the last four decades. The review primarily discusses the honeybee as a pollinator but also refers to bumblebees, wasps, flies, and beetles. The interactions between these pollinators and a variety of crops (i.e., sweet pepper, tomato, watermelon, melon, cucumber, squash, apple, pear, apricot, sweet cherry, almond, Japanese plum, anona, citrus, fig, strawberry, cotton, sunflower, lychee, mango, alfalfa, avocado, and yellow pitaya) are discussed.
... In angiosperm-pollinator communities, bees typically are the dominant pollinators (Proctor et al. 1996). The ability to recruit hive mates efficiently gives honey bees (von Frisch 1967;Visscher and Seeley 1982;Seeley 1995) and stingless bees (Nieh et al. 2003) the capacity to quickly exploit productive nectar sources and accumulate nectar for future use. ...
... The greenhouse and field studies with bagged flowers demonstrated that, in the absence of insect visits, nectar volume in Summer Crookneck squash accumulates throughout anthesis but the greatest secretion rates occur during mid-anthesis (Figures 1, 2, and 4). Alternatively, if honey bee foragers base their behavior on sugar flow rates (Varju and Nuñez 1991;Greggers et al. 1993;Wainselboim et al. 2002) or sugar quantity (Giurfa and Núñez 1992;Rabinowitch et al. 1993), then they should schedule their visits to Summer Crookneck squash during mid-anthesis, when the rates of nectar sugar production (a product of both volume and concentration) are highest (Tables I and II). In the present study, honey bees foraged on squash flowers during mid-anthesis in two trials (Figure 4 and trial 1 of Figure 6) and 1-2 h later in another (trial 2 of Figure 6). ...
Most studies of foraging behavior in bees have been performed under artificial conditions. One highly neglected area is the
daily nectar secretion rhythm in flowers including how nectar properties may vary with time of day. As a first step in understanding
the connections between forager behavior and nectar presentation under more natural conditions, we examined nectar secretion
patterns in flowers of the squash Cucurbita pepo. Under greenhouse conditions, squash flowers exhibit consistent diel changes in nectar volume and concentration through anthesis.
These temporal patterns are robust, persisting under field conditions as well as simulated drought conditions in the greenhouse.
In the presence of active pollinators, diel patterns are evident but with highly variable, severely reduced volumes. The potential
consequences of these factors for pollinator behavior are discussed.
... Floral nectar is produced by plants to attract animal pollinators (Cruden et al. 1983). The number of pollinator visits is often greater in flowers that produce more nectar, both among species (Southwick et al. 1981; Lack 1982) and within species (Devlin and Stephenson 1985; Klinkhamer and de Jong 1990; Mitchell 1993; Rabinowitch et al. 1993; Williams 1997; Mitchell et al. 1998; Golubov et al. 1999). Nectarless flowers often rely on other tactics, such as deceit or increased pollen production, to obtain sufficient visits for fertilization of their ovules (Gross 1993; Alexandersson and A ˚ gren 1996). ...
... Sugars such as sucrose, glucose, and fructose are the most abundant nectar components (Baker and Baker 1983). A higher sugar concentration is usually preferred by flower visitors, presumably because of its higher energy content (Pyke and Waser 1981; Rabinowitch et al. 1993). However, a high sugar concentration can render the nectar too viscous to be extracted by some visitor groups (e.g., butterflies; 1 Present address: Unité d'Ecologie et de Biogéographie, Université catholique de Louvain, Croix du Sud 4-5, B-1348 Louvain-la-Neuve, Belgium. 2 Author for correspondence; e-mail arnold@ dogwood.botany.uga.edu. ...
Nectar is an important attractant for pollinators, and a plants success in sexual reproduction can be influenced by the amount and concentration of nectar produced by its flowers. We studied nectar production over flower lifetime in Iris fulva, Iris brevicaulis, and four classes of hybrids - reciprocal F1 s and back-crosses - between these species. Iris fulva produced less concentrated nectar than did I. brevicaulis, whereas I. brevicaulis flowers had a shorter life span. Hybrids were not intermediate, but they had the high nectar concentration of I. brevicaulis combined with the long life span of I. fulva flowers. Nectar production and concentration declined after the first day in all classes, but flowers continued to produce nectar until they were completely wilted. Backcrosses did not show a shift in mean or increased variation for the characters that distinguished the parental species; backcrosses toward I. fulva retained the high nectar concentration of I. brevicaulis, and backcrosses toward I. brevicaulis did not have a reduced flower life span. Overall, F1 hybrid flowers produced the highest amounts of nectar and nectar sugar over their life spans. These results, together with previously obtained data on pollinator choice in mixed arrays of the same flower classes, show that F1 hybrids between these species do not suffer from reduced attractiveness to pollinators. F1 individuals produced more nectar and nectar sugar than did their parents, and thus, they are possibly even more attractive to pollinators that forage for nectar.
... Nectar volume and sugar concentration have shown to directly impact pollinator visitation in several crops, including blueberry, pepper, citrus, raspberry, blackberry, and sunflower [35][36][37][38][39]. Early investigations found that nectar sugar concentration of lowbush blueberry (V. ...
Background
Pollination is crucial to obtaining optimal blueberry yield and fruit quality. Despite substantial investments in seasonal beekeeping services, blueberry producers consistently report suboptimal pollinator visitation and fruit set in some cultivars. Flower morphology and floral rewards are among the key factors that have shown to contribute to pollinator attraction, however little is known about their relative importance for improving yield in the context of plant breeding. Clarifying the relationships between flower morphology, nectar reward content, pollinator recruitment, and pollination outcomes, as well as their genetic components, can inform breeding priorities for enhancing blueberry production. In the present study, we measured ten flower and nectar traits and indices of successful pollination, including fruit set, seed count, and fruit weight in 38 southern highbush blueberry genotypes. Additionally, we assessed pollinator visitation frequency and foraging behavior over two growing seasons. Several statistical models were tested to optimize the prediction of pollinator visitation and pollination success, including partial least squares, BayesB, ridge-regression, and random forest.
Results
Random forest models obtained high predictive abilities for pollinator visitation frequency, with values of 0.54, 0.52, and 0.66 for honey bee, bumble bee, and total pollinator visits, respectively. The BayesB model provided the most consistent prediction of fruit set, fruit weight, and seed set, with predictive abilities of 0.07, -0.08, and 0.42, respectively. Variable importance analysis revealed that genotypic differences in nectar volume had the greatest impact on honey bee and bumble bee visitation, although preferences for flower morphological traits varied depending on the foraging task. Flower density was a major driving factor attracting nectar-foraging honey bees and bumble bees, while pollen-foraging bumble bees were most influenced by flower accessibility, specifically corolla length and the length-to-width ratio.
Conclusions
Honey bees comprised the majority of pollinator visits, and were primarily influenced by nectar volume and flower density. Corolla length and the length-to-width ratio were also identified as the main predictors of fruit set, fruit weight, seed count, as well as pollen-foraging bumble bee visits, suggesting that these bees and their foraging preferences may play a pivotal role in fruit production. Moderate to high narrow-sense heritability values (ranging from 0.30 to 0.77) were obtained for all floral traits, indicating that selective breeding efforts may enhance cultivar attractiveness to pollinators.
... Nectar volume and sugar concentration have shown to directly impact pollinator visitation in several crops, including blueberry, pepper, citrus, raspberry, blackberry, and sunflower (Jablonski et al., 1985;Rabinowitch et al., 1993;Albrigo et al., 2012;Schmidt et al., 2015;Mallinger and Prasifka, 2017). Early investigations found that nectar sugar concentration of lowbush blueberry (V. ...
Pollination is crucial to obtain optimal blueberry yield and fruit quality. Despite substantial investments in seasonal beekeeping services, blueberry producers consistently report suboptimal pollinator visitation and fruit set in some cultivars. Flower morphology and floral rewards are among the key factors that have shown to contribute to pollinator attraction, however little is known about their relative importance for improving yield in the context of plant breeding. Clarifying the relationships between flower morphology, nectar reward content, pollinator recruitment, and pollination outcomes, as well as their genetic components, can inform breeding priorities for enhancing yield. In the present study, we measured ten flower and nectar traits and indices of successful pollination, including fruit set, seed count, and fruit weight in 38 southern highbush blueberry genotypes. Additionally, we assessed pollinator visitation frequency and foraging behavior over two growing seasons. Several statistical models were tested to optimize the prediction of pollinator visitation and pollination success, including partial least squares, BayesB, ridge-regression, and random forest. Random forest models obtained high predictive abilities for pollinator visitation frequency, with values of 0.54, 0.52, and 0.66 for honey bee, bumble bee, and total pollinator visits, respectively. The BayesB model provided the most consistent prediction of fruit set, fruit weight, and seed set, with predictive abilities of 0.07, -0.08, and 0.42, respectively. Variable importance analysis revealed that genotypic differences in nectar volume had the greatest impact on honey bee and bumble bee recruitment, although preferences for flower morphological traits varied depending on the foraging task. Flower density was a major driving factor attracting nectar-foraging honey bees and bumble bees, while pollen-foraging bumble bees were most influenced by flower accessibility, specifically corolla length and the length-to-width ratio. Corolla length and the length-to-width ratio were also identified as the main predictors of fruit set, fruit weight, and seed count, suggesting that bumble bees and their foraging preferences may play a pivotal role in fruit production. Moderate to high narrow-sense heritability values (ranging from 0.30 to 0.77) were obtained for all floral traits, indicating that selective breeding efforts may enhance cultivar attractiveness to pollinators.
... Simultaneously, a hand refractometer with 0.5% precision was used to measure nectar concentration (Eclipse, Stanley and Bellingham, Basingstoke, UK). When the flowers were fully open, measurements were taken between 08:00 and 14:30 (Rabinowitch et al., 1993). Our experience indicated that pale to white anthers emerging from flowers indicated maximum nectar volume production in male-phase flowers (Mu et al., 2014), whereas the opening of stigmatic lobes indicated maximum nectar volume production in female-phase flowers (Fig. S1). ...
It is believed that grazing has an effect on the functioning and performance of flowers, as well as their association with pollinator preferences and plant reproduction. However, the effects of grazing time on nectar secretion and pollen removal are still not fully understood. We hypothesized that seasonal grazing influences pollinator visitation and pollen removal by altering above-ground biomass and nectar secretion. In this study, we conducted field experiments to measure above-ground biomass, flower number per capitulum and capitulum number per plant, nectar volume and concentration, pollinator visitation of male-and female-phase flowers, pollen removal (e.g., number of pollens exported and deposition on a pollinator body and stigma), seed set ratio, and seed number between summer and winter grazing pastures of Saussurea stella. Our findings demonstrated that summer grazing reduced the above-ground biomass, nectar secretion, and pollinator visitation of male-phase flowers, thereby decreasing pollen export. There was a positive correlation between nectar secretion and above-ground biomass, as well as between pollinator visitation and nectar secretion, the number of pollens exported, and pollinator visita-tion of male-phase flowers. Experiments involving the removal of leaves revealed that a decrease in above-ground biomass was associated with a decrease in nectar secretion, pollinator visitation of male-phase flowers, and pollen removal. However, plants growing in summer and winter grazing pastures had comparable nectar secretion, pollinator visitation of female-phase flowers, seed number, and seed set ratio. Our results suggested that seasonal grazing influences nectar rewards, pollinator preferences, pollen removal, and male fitness. These findings would shed new light on the influence of herbivores on plant-pollinator interactions in the Tibetan meadow.
... Even though nectar ducts are elaborate systems, such mechanism of nectar presentation, as an easily accessible reward, would lead to generalist pollinators (Vogel 1998), such as bees. Bees have been documented as effective pollinators of Capsicum (Kristjansson and Rasmussen 1991;Rabinowitch et al. 1993;Cauich et al. 2006;Cruz and Olivera de Campos 2007;Palma et al. 2008). ...
Capsicum L. (tribe Capsiceae, Solanaceae) is an American genus distributed ranging from the southern United States of America to central Argentina and Brazil. The genus includes chili peppers, bell peppers, ajíes, habaneros, jalapeños, ulupicas and pimientos, well known for their economic importance around the globe. Within the Solanaceae, the genus can be recognised by its shrubby habit, actinomorphic flowers, distinctive truncate calyx with or without appendages, anthers opening by longitudinal slits, nectaries at the base of the ovary and the variously coloured and usually pungent fruits. The highest diversity of this genus is located along the northern and central Andes. Although Capsicum has been extensively studied and great advances have been made in the understanding of its taxonomy and the relationships amongst species, there is no monographic treatment of the genus as a whole. Based on morphological and molecular evidence studied from field and herbarium specimens, we present here a comprehensive taxonomic treatment for the genus, including updated information about morphology, anatomy, karyology, phylogeny and distribution. We recognise 43 species and five varieties, including C. mirum Barboza, sp. nov. from São Paulo State, Brazil and a new combination C. muticum (Sendtn.) Barboza, comb. nov. ; five of these taxa are cultivated worldwide (C. annuum L. var. annuum, C. baccatum L. var. pendulum (Willd.) Eshbaugh, C. baccatum L. var. umbilicatum (Vell.) Hunz. & Barboza, C. chinense Jacq. and C. frutescens L.). Nomenclatural revision of the 265 names attributed to chili peppers resulted in 89 new lectotypifications and five new neotypifications. Identification keys and detailed descriptions, maps and illustrations for all taxa are provided.
... Pepper nectar contains fructose, glucose, and sucrose. Therefore, the sugar metabolism pathway plays an important role in the biosynthesis of pepper nectar (Rabinowitch et al., 1993;Roldán-Serrano and Guerra-Sanz, 2004;Greco et al., 2011;Pereira et al., 2015). ...
The measurement of gene expression can provide important information about gene function and the molecular basis for developmental processes. We analyzed the transcriptomes at three different developmental stages of pepper flower [sporogenous cell division, stage (B1); pollen mother cell meiosis, stage (B2); and open flower (B3)]. In the cDNA libraries for B1, B2, and B3: 82718, 77061, and 91491 unigenes were assembled, respectively. A total of 34,445 unigene sequences and 128 pathways were annotated by KEGG pathway analysis. Several genes associated with nectar biosynthesis and nectary development were identified, and 8,955, 12,182, and 23,667 DEGs were identified in the B2 vs B1, B3 vs B1, and B3 vs. B2 comparisons. DEGs were involved in various metabolic processes, including flower development, nectar biosynthesis, and nectary development. According to the RNA-seq data, all 13 selected DEGs showed similar expression patterns after q-PCR analysis. Sucrose-phosphatase, galactinol-sucrose galactosyltransferase, and sucrose synthase played very important roles in nectar biosynthesis, and CRABS CLAW could potentially be involved in mediating nectary development. A significant number of simple sequence repeat and single nucleotide polymorphism markers were predicted in the Capsicum annuum sequences. The new results provide valuable genetic information about flower development in pepper.
... Honey bees, Apis mellifera, have the remarkable ability to remember the time of day when food sources are most profitable. This time-memory, also described as circadian time-place learning (cTPL), has been shown repeatedly in A. mellifera (Butler, 1945;Corbet and Delfosse, 1984;Edge et al., 2012;Giurfa and Núñez, 1992;Kleber, 1935;Rabinowitch et al., 1993) and has now been demonstrated in the ants Ectatoma ruidum (Schatz et al., 1999) and Paraponera clavata (Harrison and Breed, 1987) and in the stingless bees Melipona fasciculata (de Jesus et al., 2014), Trigona amalthea (Breed et al., 2002) and Trigona fulviventris (Murphy and Breed, 2008). Evidence that honey bee time-memory is driven by a circadian clock comes from (1) experiments showing a free-running period of foraging behavior close to 24 h under constant conditions (Frisch and Aschoff, 1987;Renner, 1955Renner, , 1957, (2) phase shifts, with transients, in response to phase changes in light-dark (LD) cycles (Beier, 1968;Renner, 1959) and (3) a limited range (20-26 h) of entrainment under LD cycles (Beier, 1968). ...
Honey bee (Apis mellifera) foragers can remember both the location and time of day food is collected and, even in the absence of a reward, reconnoiter the food source at the appropriate time on subsequent days. This spatiotemporal memory (time-memory) is linked to the circadian clock and enables foragers to synchronize their behavior with floral nectar secretion rhythms, thus eliminating the need to rediscover productive food sources each day. Here, we asked if the establishment of one time-memory influences the formation of another time-memory at the same time of day. In other words, can two time-place memories with the same “time-stamp” coexist? We simultaneously trained two groups of foragers from a single hive to two separate feeders at the same restricted time of day. After five days of training, one feeder was shut off. The second feeder continued being productive four more days. Our results showed that (1) foragers with high experience levels at the first source were significantly more likely than low-experience foragers to maintain fidelity to their original source and resist recruitment to the alternative source, (2) nearly one-third of foragers demonstrated multiple, overlapping time-memories by visiting both feeders at the correct time, and (3) significantly more high-experience than low-experience foragers exhibited this multitasking behavior. The ability to maintain and act upon two different, yet contemporaneous, time-memories gives the forager bee a previously unknown level of versatility in attending to multiple food sources. These findings have major implications for understanding the formation and management of circadian spatiotemporal memories.
... La polinización del pimiento dulce por insectos ha sido estudiada previamente. Un claro ejemplo de esto es el uso de abejas (Rabinowitch et al. 1993, Dag & Krammer 2001, por moscas (Kristjansson & Rasmussen 1991, Jarlan et al. 1997 o por abejorros de la especie Bombus terrestris (Roldan & Sanz 2003), con el objeto de incorporarlo como una forma de manejo para producción de pimiento para consumo. ...
Durante la última década el consumo de hortalizas y frutas, tanto frescas como
procesadas, ha aumentado en forma sostenida en Chile. En la actualidad, el
consumo per cápita es de 103 Kg de hortalizas al año, uno de los más altos en
Latinoamérica. Esto ha sido provocado por cambios en los hábitos de consumo
de la población y por la preferencia del consumidor por productos con menor
contenido de carbohidratos, menos grasas saturadas y con mayor contenido de
fibra, vitaminas y compuestos asociados a una alimentación saludable.
Entre las hortalizas, el pimiento, que cuenta con sólo 1.000 ha plantadas, es una
especie que tiene un alto potencial para mejorar su competitividad y recuperar su
participación en el mercado internacional. Esto se fundamenta en que el pimiento
es una importante materia prima para la producción de jugos y extractos, tanto
líquidos como en polvos, por su alto contenido de antioxidantes y de carotenoides
específicos como la capsantina/capsorubina. Estos compuestos son sustancias
que le otorgan el picor a los pimientos picantes ampliamente utilizados en la
industria de alimentos, farmacéutica y cosméticos, teniendo alta demanda en
países como Estados Unidos, Japón, Corea y Europa. Así, la agregación de valor
y diversificación de productos a partir de pimiento podrían no sólo mejorar su
competitividad, sino mejorar el abanico de productos para el mercado de exportación,
ya sea en las categorías de semi procesados, procesados y refinados
como ingredientes y aditivos especializados. Esta condición pone al pimiento
en sintonía con las metas que se ha planteado nuestro país de diversificar y
sofisticar la oferta de exportaciones agrícolas y específicamente de alimentos.
En el presente boletín se aborda la situación del pimiento en Chile, la tendencia
de mercados y avances en el mejoramiento genético y manejo, con el fin de potenciar
no sólo la producción de pimiento para el mercado fresco, sino también
como materia prima para la industria de alimentos e ingredientes.
... Both manual and open pollinated methods are being practiced for pollen transfer for large scale hybridization. Capsicum flowers produce both pollen and nectar; hence, are attractive to honeybees, Rabinowitch et al. [79] reported that pepper genotypes varied in frequency of honeybee visits and there was significant correlation between sugar quantity in nectaries and honeybee visit per flower. Increasing number of visits increased the number of seeds in the pepper fruits. ...
BSTRACT Male-sterility in chili was documented for the first time in the 1950’s. Since then, considerableknowledge has been accumulated on the nature of the trait, the means of its identification, induction,inheritance of genetic and cytoplasmic genetic male-sterility, maintenance of inbreds, and their potentialfor breeding hybrid cultivars. Heterosis for various economic traits like maturity, fruit weight, size, numberand total yield have been utilized. Today, several internationally known seed companies and research instituteuse the genetic mechanism [msms] on a large scale for producing hybrids of sweet pepper, whereas thecytoplasmic genetic sterility [(S) rf rf] is used mainly for breeding pungent hybrids. The possibilities ofexploitation of male sterility for crop improvement as well as production of F1 hybrids have been reviewedand discussed in the present paper. Biochemical as well as biotechnological aspects of this phenomenon hasalso been vividly reviewed.
... The odourless flowers are visited by insects both for sugary nectar, which is mostly hexoses and low in daily amount (greatest on the day of anthesis), and also for their pollen (Rabinowitch et al., 1993;Vogel, 1998;Roldán-Serrano and Guerra-Sanz, 2004;Raw, 2000). Solitary bees, honeybees, bumblebees, aphids and thrips are likely to transfer the pollen grains, especially those that obtain pollen by buzz pollination, shaking the anthers (Andrews, 1995;Raw, 2000;de Ruijter et al., 1991;Kubišová and Háslbachová, 1991;Shipp et al., 1994;Dag and Kamer, 2001;Kristjansson and Rasmussen, 1991). ...
A review of the biology and taxonomy of Capsicum, with emphasis on the Capsicum annuum complex in agriculture.
... The circadian clock responsible for the time memory is a continuously consulted oscillator (as defined by Pittendrigh 1958) since the bee can be trained to collect food at virtually any time of day and return to the source at the appropriate time on subsequent days, even in the absence of food (Beling 1929;Wahl 1932;Moore and Rankin 1983;Moore et al. 1989; Moore and Doherty 2009). The time memory allows a bee to time its visits to match the source's highest nectar concentration (Wahl 1933;Kleber 1935;Butler 1945;Corbet and Delfosse 1984) or the source's highest total available sugar (Giurfa and Núñez 1992;Rabinowitch et al. 1993;Edge et al. 2012). ...
The honey bee time memory enables foragers to return to a profitable food source in anticipation of the time of day at which they previously collected food from that source. The time memory thus allows foragers to quickly resume exploiting a source after interruption, at the appropriate time of day, without the costs associated with having to rediscover it. A portion of a foraging group (the persistent foragers) will reconnoiter a previously profitable source and may do so for several days. The remaining bees (the reticent foragers) await confirmation of availability before revisiting the source. Recent work has shown that both persistent and reticent bees make extracurricular flights to alternative sources when one food source ceases being productive. Little else, however, is known about reticent foragers. In the present study, we determined that reticent bees congregate near the hive entrance in anticipation of the learned foraging time as do persistent foragers. We then confirmed that the food-anticipatory clustering takes place on the waggle dance floor, as suspected, but also found differences in the number of days that persistent and reticent foragers continue clustering. Finally, we found that persistent foragers had significantly more rewards per day at the source than did reticent foragers, supporting the hypothesis that experience at a food source influences a forager’s decision to become either persistent or reticent. Our findings demonstrate that persistence and reticence are not immutable characteristics of foragers themselves but rather strategies they employ toward different food sources.
Significance statement
Much has been learned in recent years about the honey bee time memory and foraging behavior. Receiving scant attention, however, is the phenomenon of forager bees gathering near the hive entrance, anticipating the time of day when previously productive food sources become available. We show that both persistent and reticent bees (foragers that do and do not investigate the source, respectively) congregate on the waggle dance floor at the appropriate time of day, but, in the absence of food at the source, persistent bees continue to show this behavior a day or two longer than reticent bees do. We also show that experience with the source influences the decision to become persistent or reticent. Our results reveal how foraging experience influences the individual bee’s decision making, thereby providing insights into how foragers are reallocated efficiently among different resources in the environment.
... Further studies would be necessary to determine sunflower traits which are responsible for attractiveness and their prevalence. But, if linked to melliferous potential, as some studies suggests (Rabinowitch, 1993;Shykoff et al., 1995;Southweek et al., 1981), sunflower attractiveness would be a major lever to activate in order to increase the capacity of a territory to host pollinators and especially Apis mellifera L. Indeed, in certain areas where semi-natural habitats are little represented, mass flowering crops such as sunflower are of particular interest. As a result, maximizing nectar resource at a territory scale by cultivating melliferous sunflower cultivars would have positive implications by increasing honey production and viability of apicultural economic activity and as well as food sources available for all pollinators in the global context of their decline. ...
In France, sunflower honey production has decreased since the nineties and professional beekeepers report important honey yield variability between years and locations. Consequently, melliferous potential of current sunflower cultivars is questioned as it is not part of traits held in breeding programs. To investigate this question, a 3-years study was conducted on two sites and attractiveness for honeybees of 13 current sunflower cultivars was assessed under natural conditions. The number of honeybee visits per plant was recorded daily during blooming period on cultivars randomly distributed on experimental plots. Sunflower genetic was a major factor influencing honeybee attendance on plots and discrepancy between most and least visited cultivars reached a factor of 3. Cultivars relative attractiveness was consistent between years and sites. Potential link between sunflower attractiveness for honeybees and its melliferous characteristics is discussed. If confirmed, farmers' choice concerning cultivars at a territory scale could contribute to enhance nectar resource for pollinators and to increase viability of apicultural activity.
... In pepper plants, nectar functions as a pollinator attractor, and therefore any variation in nectar characteristics (e.g. sugar quantity and nectar volume) can potentially increase attractiveness to pollinators, consequently enhancing cross pollination and improving fruit quality and crop yield 29 . Any variability in nectar traits is important to document since it can clearly affect crop success. ...
Global climate change is likely to increase maximum temperatures and atmospheric CO2 concentrations. High temperatures can alter plant reproductive phenology, resulting in earlier or later flowering. High atmospheric CO2 levels have a positive fertilizing effect in plants, producing higher biomass and flower number. The objectives of this research work were to quantify the effects of higher maximum temperature (Experiment 1) and atmospheric CO2 concentration (Experiment 2) on reproductive phenology in the tropical crop Habanero pepper (Capsicum chinense Jacq.). Three growth chambers were used in each experiment. In Experiment 1, different diurnal maximum temperatures (30, 35 and 40deg;C) were used in each chamber. In Experiment 2, diurnal maximum temperature was set at 30°C and different atmospheric CO2 concentrations (380, 760 and 1140 μmol mol-1) were used in each chamber. Relative humidity, maximum photosynthetic photon flux density (PPFD) and photoperiod were the same in all chambers of both experiments. Variables were flowering days, fruiting days, flower production, flower abortion, fruit production and flower morphology traits. A maximum temperature increase from 30 to 35°C caused flowering to be 6 days earlier, but at 35°C fruiting was 27 days later than at 30°C. When comparing plants grown at 380 μmol mol-1 CO2, those grown at 1140 μmol mol-1 flowered 18 days earlier and fruited 37 days earlier. Both maximum temperature and CO2 concentration had significant effects on flower abortion and fruit production. Overall, Habanero pepper responded negatively to higher diurnal maximum temperatures and positively to higher CO2 concentrations.
... In Montiniaceae, the inferior ovaries of female flowers show a massive nectary at the summit around the style (Decraene et al., 2000b). Nectar-secreting Solanaceae (considered basal) presents an annular gynoecial nectary at the base of the ovary, which may be either conspicuous or inconspicuous externally (see " Solanaceae " on page 51 for a detailed dis- cussion; Bernardello, 1987; Vogel, 1991 Vogel, , 1998b Rabinowitch et al., 1993; Mione & Serazo, 1999). ...
... Le nectar constitue la seule ressource butinable dans les fleurs MS et les différences entre lignées pourraient refléter des différences de production nectarifère, d'accessibilité du nectar dans la longue corolle tubullaire, ou de composition du nectar. Des variations concomitantes de la production nectarifère et de l'attractivité vis-à-vis des abeilles domestiques ont déjà été mises en évidence entre lignées MS, par exemple chez le piment (Rabinowitch et al., 1993). Une étude fine de la morphologie des nectaires d'artichaut n'a pas révélé de différence marquée entre fleurs des capitules MS et MF, mais elle a mis en évidence une variabilité importante selon les lignées au sein de chaque groupe (Lannuzel, 1999; Delpierre et al., 2000). ...
Advantages and difficulties resulting from the use of F 1 hybrid seeds in artichoke are reported. After the limited success of clonal selection of the cultivar Violet de Provence, INRA launched a program on seed-propagated F 1 hybrids starting in 1974 in Montfavet (Provence) and Plougoulm (Brittany). Preliminary trials showed the possibilities to improve significantly yields and head quality. The genetic base was broadened by creating 2 sources populations corresponding to the two main head types of the French market, each of these was subsequently divided into early and late lines. After Prencipe (1984), the male sterility was used to enable the production of many experimental F 1 as well as hybrid seed. To date, five F 1 crosses proved of interest and further development of the program was taken by Nunhems. Two remaining problems which still prevent the widespread use of F 1 hybrid seeds in artichoke are (1) the management of the cultural cycle for seed-propagated plants and (2) the economical production of F 1 hybrid seed as adequate pollination of male-sterile plants remains difficult to achieve.
... The importance of insect-pollination for bell peppers is supported by the presence of floral nectaries (Dag and Kamer 2001); however, the quality of the nectar and other flower attributes are not very attractive to bees (Rabinowitch et al. 1993). The IC with basil increased the bee visitation on the pepper flowers, and our results suggest that low flower attractiveness in plants of agricultural importance can be compensated by IC with a highly attractive flowering plant. ...
Enhancements of floral resources in surrounding landscape and in local crop fields are expected to mitigate adverse human impacts on pollinator diversity and pollination services. We evaluated whether intercropping with flowering basil (Ocimum basilicum) increases the local abundance and richness of bees and improves fruit and seed production of bell pepper (Capsicum annuum). Fields of bell pepper were divided into intercropping (basil mixed with pepper) and single-cropping plots (only pepper). We also grew bell peppers in protected greenhouse in the presence and absence of beehives. The richness and abundance of visiting bees to pepper flowers were greater in the intercropped plots than the single-cropping plots. The increase in the number of bees visiting the peppers was due to the stronger attraction of Paratrigona lineata, Apis mellifera and Tetragonisca angustula to basil in the inter-cropping plots. The pepper fruits produced in the inter-cropping were wider, longer, and heavier and developed more seeds than the fruits produced by single-cropping. The same differences were observed between the fruits grown in greenhouse with and without beehives of P. lin-eata. We demonstrate that agricultural systems designed to attract and retain pollinators are more productive than growing pure stands. Our results also highlight the role of provisioning floral resources to enhance bee conservation and management in anthropogenic ecosystems.
... In pepper plants, nectar functions as a pollinator attractor, and therefore any variation in nectar characteristics (e.g. sugar quantity and nectar volume) can potentially increase attractiveness to pollinators, consequently enhancing cross pollination and improving fruit quality and crop yield 29 . Any variability in nectar traits is important to document since it can clearly affect crop success. ...
Global climate change is likely to increase maximum temperatures and atmospheric CO2 concentrations. High temperatures can alter plant reproductive phenology, resulting in earlier or later flowering. High atmospheric CO2 levels have a positive fertilizing effect in plants, producing higher biomass and flower number. The objectives of this research work were to quantify the effects of higher maximum temperature (Experiment 1) and atmospheric CO2 concentration (Experiment 2) on reproductive phenology in the tropical crop Habanero pepper (Capsicum chinense Jacq.). Three growth chambers were used in each experiment. In Experiment 1, different diurnal maximum temperatures (30, 35 and 40ºC) were used in each chamber. In Experiment 2, diurnal maximum temperature was set at 30°C and different atmospheric CO2 concentrations (380, 760 and 1140 μmol mol-1) were used in each chamber. Relative humidity, maximum photosynthetic photon flux density (PPFD) and photoperiod were the same in all chambers of both experiments. Variables were flowering days, fruiting days, flower production, flower abortion, fruit production and flower morphology traits. A maximum temperatura increase from 30 to 35°C caused flowering to be 6 days earlier, but at 35°C fruiting was 27 days later than at 30°C. When comparing plants grown at 380 μmol mol-1 CO2, those grown at 1140 μmol mol-1 flowered 18 days earlier and fruited 37 days earlier. Both maximum temperature and CO2 concentration had significant effects on flower abortion and fruit production. Overall, Habanero pepper responded negatively to higher diurnal máximum temperatures and positively to higher CO2 concentrations.
... In male fertile (MF) plants, pollen grains could be seen sticking to the anther lobes, whereas, in MS plants, the anther lobes were devoid of pollen grains. ms mutants have been widely used for hybrid production in pepper (Breuils and Pochard, 1975;Csillery et al., 1987;Daskalov, 1972;1976;Hirose, 1965;Hirose and Fugime, 1980;Miladinovic and Stevanovic, 1977;Rabinowitch et al., 1993;Shifriss and Pilowsky, 1993a;Shifriss and Sacks, 1980;Velazquez, 1983;Yu, 1990). Despite the need for early identification, the 50% of MF plants can be identified at anthesis and are then removed. ...
Pepper belongs to the genus Capsicum, of which five species are cultivated (C. annuum L., C. chinense Jacq., C. frutescens L., C. baccatum L. Ruiz. & Pavon, and C. pubescens). C. annuum L., which includes both hot pepper and bell pepper, is the most widely cultivated species. Commercial hybrid pepper seed is produced manually or by exploiting male sterility (MS). Both nuclear (NMS) and cytoplasmic (CMS) MS are available in pepper. Due to recessive gene control, the development of NMS lines through conventional breeding is tedious and time-consuming. Molecular markers linked to the NMS genes ms-1 and ms-8 have been developed. This will facilitate the development of new NMS lines, identify MS plants at the seedling stage, and test the purity of F1 hybrid seed. To reduce hybrid seed costs further, and to improve seed yields, there is a need to identify seedling markers to facilitate the removal of fertile plants in nursery blocks. Most reports have indicated that CMS is sensitive to low temperatures. Restorer-of-fertility genes are common in hot pepper and rare in bell pepper cultivars. Despite conflicting reports, it has been concluded that a single dominant gene (Rf) along with a modifier gene (Pr), controls the restoration of fertility in pepper. Molecular markers linked to the Rf and Pr genes and the mitochondrial CMS genes coxII and atp6 have been developed. These will facilitate the rapid screening of inbred pepper lines for Rf/rf alleles, accelerate the transfer of the rf gene in female hot pepper parents (maintainer breeding), and the Rf gene in male sweet pepper parents (restorer breeding). We have compiled up-to-date information on both NMS and CMS systems in pepper and discuss the prospects for their use in breeding for heterosis. © 2014 Journal of Horticultural Science & Biotechnology. All rights reserved.
... Since the relative amounts of these sugars may be important for the attraction and fitness of flower visitors (Baker and Baker 1983;Fonta et al. 1985;Wäckers et al. 2006) these differences might also have influenced sweet alyssum's higher attractiveness to S. rueppellii adults. Sweet pepper flowers, on the other hand, provide large pollen and nectar volumes, and floral rewards are also within easy access to pollinators (Rabinowitch et al. 1993). However, previous works have also reported a low attractiveness of sweet pepper flowers to honeybees and other Apoidea, presumably due to the poor sugar concentrations found in the flower nectar (McGregor 1976;Baker and Baker 1983) which could also explain the low attractiveness towards the syrphid fly found in this work. ...
Provision of additional floral resources in the crop is a successful strategy of conservation biological control for attracting several natural enemies including predatory syrphids. However, the selection of flower species is mainly based on visiting preferences, paying little attention to the link between preference and performance. In this study, we assess the influence of feeding on flowers of two insectary plants (sweet alyssum and coriander) and flowers of a crop species (sweet pepper) on performance of the parental and first generation of the syrphid Sphaerophoria rueppellii (Wiedemann) (Diptera: Syrphidae). We found that floral preference of the adults was linked to developmental performance of their offspring. Sweet alyssum was the flower most frequently visited by syrphid adults, enhancing adult body size and egg-to adult survival of the F1 generation.
... Pollinators of chili peppers, such as thrips (Thripidae spp.), honeybees and syrphid flies (Syrphidae spp.) were observed during the study, however, their abundance was not measured. Pepper flowers are not attractive to honeybees, possibly due to the low sugar concentrations in the nectar [30]. Although flowers of cucurbits, sunflower, onion, etc. are preferred, pollinators visit chili pepper flowers because they flower throughout seasons when flowering of other crops is limited [7]. ...
Gene flow from genetically modified (GM) chili pepper (Capsicum annuum L.), containing the CMVP0-CP (cucumber mosaic virus pathotype 0 – coat protein) gene to a non-GM control variety ‘P915’ and two commercial F1 hybrids, ‘Manidda’ and ‘Taesan’, was assessed over two growing seasons in the field. Seeds were collected from non-GM chili peppers at a range of distances from the GM chili pepper plot, and hybrids between GM and non-GM plants were screened using the kanamycin assay. Event-specific PCR was performed to confirm the presence of transgenes in the kanamycin-resistant seedlings. From a total of 11,194 ‘P915’ seeds, there were 67 hybrids; there were 40 hybrids of 7499 seeds, and 102 hybrids of 5340 seeds for ‘Manidda’ and ‘Taesan’, respectively. The gene flow frequency was as high as 17.89% between GM and ‘Taesan’ chili pepper at the closest distance from the GM plot.
... A honey bee forager will remember the time of day it exploited a profitable food source and will return to that source at approximately the same time on the following day (von Buttel-Reepen, 1900;Beling, 1929;Wahl, 1932;Wahl, 1933;Renner, 1955;Renner, 1957;Beier, 1968;Beier and Lindauer, 1970;Frisch and Aschoff, 1987; Moore and Rankin, 1983; Moore et al., 1989). This time memory enables bees to match their foraging efforts with nectar secretion rhythms of flowers by cuing on either the time of highest nectar concentration (Butler, 1945;Corbet and Delfosse, 1984;Kleber, 1935) or highest total sugar (Giurfa and Núñez, 1992;Rabinowitch et al., 1993;Edge et al., 2012). This means that many foragers do not start their day as novices: the time memory eliminates the need to expend excess energy required to rediscover the same food sources each day. ...
Honey bee foragers form time-memories that enable them to match their foraging activity to the time of day when a particular food source is most productive. Persistent foragers show food-anticipatory activity by making reconnaissance flights to the previously productive food source and may continue to inspect it for several days. In contrast, reticent foragers do not investigate the source but wait for confirmation from returning persistent foragers. To determine how persistent and reticent foragers might contribute to the colony's ability to rapidly reallocate foragers among sources, we trained foragers to collect sucrose from a feeder at a restricted time of day for several days and then observed their behavior for three consecutive days during which the feeder was empty. In two separate trials, video monitoring of the hive entrance during unrewarded test days in parallel with observing reconnaissance visits to the feeder revealed a high level of activity, in both persistent and reticent foragers, thought to be directed at other food sources. This "extracurricular" activity showed a high degree of temporal overlap with reconnaissance visits to the feeder. In some cases, inspection flights to the unrewarded feeder were made within the same trip to an extracurricular source, indicating that honey bees have the ability to manage at least two different time memories despite coincidence with respect to time of day. The results have major implications for understanding flower fidelity throughout the day, flower constancy within individual foraging excursions, and the sophisticated cognitive management of spatiotemporal memories in honey bees.
... In pepper plants, nectar functions as a pollinator attractor, and therefore any variation in nectar characteristics (e.g. sugar quantity and nectar volume) can potentially increase attractiveness to pollinators, consequently enhancing cross pollination and improving fruit quality and crop yield 29 . Any variability in nectar traits is important to document since it can clearly affect crop success. ...
Background:
The effects of the increase of atmospheric CO2 on agricultural productivity have been mainly analyzed through its impact on biomass yield, and little attention has been directed to quality traits, such as nutritional or organoleptic attributes. For this study, plants of hot Habanero pepper (Capsicum chinense Jacq.) were grown in growth chambers under three different CO2 levels: 380 (normal atmospheric value), 760 and 1140 µmol mol(-1), and their effects on pod yield, size, color and pungency, were monitored.
Results:
The total number of pods per plant increased by 88.5% at the highest CO2 , in comparison to plants grown at normal CO2 conditions. Pod size and yield per plant also increased when plants were grown at the highest CO2 concentration (partial pressure). Furthermore, total capsaicinoids contents in ripe peppers under a high CO2 atmosphere were 27% higher than those from plants under lower concentrations, but it was not the case for immature pods.
Conclusion:
These data suggest that the increase of atmospheric CO2 could modify specific routes of secondary metabolism as well as others desirable traits, thus affecting the quality of Capsicum pepper products.
... In Montiniaceae, the inferior ovaries of female flowers show a massive nectary at the summit around the style (Decraene et al., 2000b). Nectar-secreting Solanaceae (considered basal) presents an annular gynoecial nectary at the base of the ovary, which may be either conspicuous or inconspicuous externally (see "Solanaceae" on page 51 for a detailed discussion; Bernardello, 1987;Vogel, 1991Vogel, , 1998bRabinowitch et al., 1993;Mione & Serazo, 1999). ...
... Because wind or rain is not directly associated with the cross-pollination of chili peppers (Bosland 1993; Free 1993; Delaplane and Mayer 2000), wind speed may not be an important environmental factor contributing to gene flow from those GM to non-GM plants. Bumble bees, honeybees, and thrips are potentially effective pollinators of both chili and sweet peppers (Rabinowitch et al. 1993; Shipp et al. 1994; Saxena et al. 1996). Among them, thrips and honeybees were observed in our fields, although their abundances were not quantified. ...
We conducted a 2-year field assessment of the gene flow from genetically modified (GM) chili pepper (Capsicum annuum L.), containing the PepEST (pepper esterase) gene, to a non-GM control line “WT512” and two commercial hybrid cultivars, “Manidda” and “Cheongpung Myeongwol
(CM).” After seeds were collected from the pollen-recipient non-GM plants, hybrids between them and the GM peppers were screened
by a hygromycin assay. PCR with the targeting hpt gene was performed to confirm the presence of transgenes in hygromycin-resistant seedlings. Out of 7,071 “WT512” seeds and
6,854 “Manidda” seeds collected in 2006, eight and 12 hybrids, respectively, were detected. In 2007, 33 hybrids from 3,456
“WT512” seeds and 50 hybrids from 3,457 “CM” seeds were found. The highest frequency of gene flow, 6.19%, was observed in
that 2007 trial. These results suggest that a limited isolation distance would be sufficient to prevent gene flow from GM
to conventionally bred chili peppers.
... It is assumed that the time-memory allows honey bees to schedule their foraging flights in anticipation of speciesspecific rhythms of nectar secretion, although a direct connection between the time-memory and foraging behavior has not been established under natural conditions. It is known, for instance, that honey bees forage most actively at the time of day that coincides with the highest nectar concentrations for each flower species (Kleber 1935;Butler 1945;Corbet and Delfosse 1984) or with the highest total available sugar (Giurfa and Núñez 1992;Rabinowitch et al. 1993). However, the role of the time-memory in these temporal foraging patterns has not been differentiated from other factors that may bring foragers to the flower patch, such as discovery of the patch by scouts, reactivation of foragers with previous experience at the patch, or recruitment of new foragers to the patch by those foragers already exploiting it. ...
Classical experiments demonstrated that honey bee foragers trained to collect food at virtually any time of day will return to that food source on subsequent days with a remarkable degree of temporal accuracy. This versatile time-memory, based on an endogenous circadian clock, presumably enables foragers to schedule their reconnaissance flights to best take advantage of the daily rhythms of nectar and pollen availability in different species of flowers. It is commonly believed that the time-memory rapidly extinguishes if not reinforced daily, thus enabling foragers to switch quickly from relatively poor sources to more productive ones. On the other hand, it is also commonly thought that extinction of the time-memory is slow enough to permit foragers to 'remember' the food source over a day or two of bad weather. What exactly is the time-course of time-memory extinction? In a series of field experiments, we determined that the level of food-anticipatory activity (FAA) directed at a food source is not rapidly extinguished and, furthermore, the time-course of extinction is dependent upon the amount of experience accumulated by the forager at that source. We also found that FAA is prolonged in response to inclement weather, indicating that time-memory extinction is not a simple decay function but is responsive to environmental changes. These results provide insights into the adaptability of FAA under natural conditions.
Crop–pollinator interactions are essential for world food security. Studying crop pollination from a network approach allows identification of target pollinators for conservation and management, and gaps in our knowledge. Solanaceae represents the third highest ranked family based on economic value, and its production is highly improved by animal pollination. This study aimed to integrate global data on solanaceous crop pollination and analyse the interaction patterns using a meta‐network approach. Our questions were: (i) how are interactions structured and what are the structuring roles of species; and (ii) what are the main gaps in our knowledge?
Data were obtained through a systematic review of the main scientific databases. The network structure was described using connectivity and modularity calculations, and the role of species using centrality metrics.
The 251 pollinator species reported were in seven orders, mainly Hymenoptera (84.9%). The generalists Bombus and Apis species were the most common pollinators. The meta‐network was modular, and all modules mostly included bees. Most species were peripherals, around 12% were connectors, and there were no module hubs. Apis mellifera was the only network hub (supergeneralist).
The most important pollinators are the most managed pollinators worldwide; however, many native species play a role in structuring the meta‐network. Main gaps include species of importance to pepper pollination, lack of species‐specific identification, and the need for more robust experimental studies evaluating the pollination efficiency of native, manageable bees.
Pollinator nutrition is a highly complex subject that we are just starting to unravel, from the multidimensional nature of bee forage (pollen and nectar) to how the abiotic environment can affect the resources available to bees. Doing so is of utmost importance, as improving pollinator resource availability and nutrition is one of the proposed mechanisms to improve populations and pollinator health. However, landscape change has changed the resources naturally available for pollinators. Farmland and cropping systems create a unique nutritional landscape for pollinators, with agroecosystems typically containing few crops dominating a landscape along with natural corridors containing noncrop plants. The types of crops planted and the surrounding landscape will ultimately affect the nutritional landscape bees have access to. Even the management practices in agriculture and how pests are controlled will, directly and indirectly, affect bee health and nutrition. Hence, a better understanding of bee nutrition in agricultural ecosystems is warranted. This review synthesizes research on bee nutritional ecology and the agricultural landscapes to advance our understanding of bee health in agriculture.
Herbivory can induce changes in flower traits influencing the community of flower-visiting insects and ultimately impacting the plant’s reproductive output. Here, we investigated how leaf herbivory on sweet pepper plants, Capsicum annuum L., by Diabrotica speciosa (Germar) adults influences the community of insect floral visitors and alters plant reproduction. In an experimental field, we found that flowers of herbivore-infested plants were less visited by insects than those of uninfested plants. A similar pattern was found for the abundance of the three most common species of floral visitors in the collections, Apis mellifera (Linnaeus), Toxomerus sp.1, and Trigona spinipes (Fabricius). The insect community associated with the flowers of herbivore-infested plants was distinct, less rich, and diverse than that of uninfested plants. Leaf herbivory also impacted flower abundance that likely influenced the visual attraction of insects. The changes in flower-visiting insect community associated with herbivore-infested plants coincided with a reduced number of fruits, which were smaller and contained fewer seeds than those from uninfested plants. Our results suggest that leaf herbivory by D. speciosa results in direct and indirect costs to the plants through modifications in abundance and composition of flower-visiting insect community.
Bal arılarının nektar ve polen kaynaklarını tercihi bitki türlerine göre farklılık gösterebilmektedir. Bu durum aynı zamanda nektar ve polen kaynağının yakınlık, miktar, kalite ve varyetesine bağlı olarak da
değişebilmektedir.
Bu makalede, arıcılıkta koloni gelişimi ve verimliliği açısından önemli karbonhidrat ve protein kaynaklarını oluşturan nektar ve polen bakımından bitki tercihinde etkili olan bazı faktörlerin incelenmesi amaçlanmıştır.
This chapter describes the need for pollination in greenhouses due to its special agro-ecological conditions and unique constraints. The advantages that greenhouses hold for both achieving pollination of particular crops and for safeguarding managed pollinators are compared with open air cultures. The traits of the two main greenhouse pollinators - bumble bees and honey bees - are discussed according to their relevance for pollination in this horticultural system. Finally, some examples of pollination of greenhouse cultures and predictions for the future development of pollination in greenhouses are described.
To identify the foraging plants by honeybees and determine apicultural potential, a sample collection of species was carried out with the commencement of rangeland plants at 6 different stations in the Freidan summer rangelands during 2010. Attractive index (AI) of each plant was determined by direct observations based on the average number of bees visiting and the length of time that each bee spents on the flowers. By using ordinate method, the AI data were classified into four main groups. The most import vegetation families utilized by the bees in the area were Compositae Labiatae, Umbeliferae, Cruciferae, Gramineae, Liliaceae and Caryophyllaceae. The results of the assessment carried out on the plant diversity showed that between 88 plant species, 70 species were utilized by the bees. These species were unpalatable for grazing animals and were dominant in degraded rangelands. The Class I group comprised of Papaver dubium, Onobrychys sativa, Astragalus gossipianus, Thymus kotschyanus, Eryngium billardieri, Echinops cephalotes and Alhagi camelorum. The Class II group comprised of Eremurus persicus, Peganum harmala, Astragalus sp., Centaurea sp., Scariola orientalis, Medicago lupulina, Ferula gummosa and Mentah longifolia. The Classes III and IV comprised of the species, Euphorbia, Tragopagon caricifolius, Centaurea, Salvia sp, Acantholimon erinaceum, Convolvulus arvensis, Achillea falcate and Cynodon dactylon. The results indicated that the more extensive uses of the pollen of these plants by the honeybees were associated with the higher attractiveness of the flowers and the presence of more nutritive materials in the pollen and nectar.
In landscape studies conducted in 2002 and 2003, Lantana camara (L.) ‘New Gold’ and ‘Radiation’ were visited by native butterflies to a greater extent than the remaining eight lantana in the studies. Other lantana visited preferentially but not as consistently included L. camara ‘White Doves’, ‘Firewagon’, ‘Confetti’, and Lantana montevidensis (Spreng.) ‘Weeping Lavender’. In general, the lowest visitation was experienced by L. camara ‘Cherry’ and ‘Carlos’. Total visit duration by one randomly selected butterfly was greater for ‘New Gold’, ‘Radiation’, ‘Firewagon’, and ‘White Doves’ than the remaining lantana. Plant characteristics including inflorescence number, number of flowers per inflorescence, percentage of yellow flowers per inflorescence, growth index, flower morphology, and flower color characteristics differed among cultivars. Cultivar differences that consistently correlated with visitation preferences were inflorescence number in 2002 and 2003, flower number per inflorescence in 2003, percentage of yellow flowers per inflorescence in 2002 and 2003, and growth index in 2003. Flower lightness and flower chroma correlated sporadically with visitation in late September and October 2002 and 2003. Percentage light reflectance of flowers for the wavelengths of green, yellow, orange, and red correlated with visitation in 2003. Based on correlation analysis, the cultivar characteristics that did not contribute to visitation differences included inflorescence width, corolla width, and corolla tube length.
In a separate study conducted in 2003 using the same lantana as in the visitation study, nectar volume, carbohydrate composition, and sucrose and fructose concentrations differed among inflorescences. Of ten Lantana evaluated, ‘Carlos’ and ‘Confetti had the largest inflorescence nectar volumes combined from nine flowers while ‘New Gold’, ‘White Doves’, and ‘Weeping Lavender’ had the smallest. The ratio of sucrose to hexose (fructose and glucose) in nectar from ‘Weeping Lavender’, ‘White Doves’, and ‘New Gold’ was greater than that of the remaining Lantana. The lowest ratios of sucrose to hexose were found for ‘Irene’, ‘Hot Country’, and ‘Carlos’, while similar to ‘Cherry’ and ‘Radiation’. The sucrose to hexose ratio for recently opened inner flowers was double that of middle and outer flowers. Sucrose and total sugar concentrations were greatest in recently opened inner flowers compared to middle and outer flowers. While direct comparison to the 2002 and 2003 studies of butterfly visitation preferences was not possible due to experimental design, data trends suggest a possible relationship between sugar composition, inflorescence nectar production and visitation from native butterfly species.
Globe artichoke is currently multiplied mainly by vegetative means, but the planting of seeds could lead to easier cropping practices and improved yields. This is especially true with hybrid seeds which could be produced using the two genetic male-sterility systems available. For two years, we studied the effectiveness of honey bees as pollinators to produce hybrid seeds of globe artichoke under insect-proof enclosures. We used two adjacent 10 x 6 m tunnels covered with 1-mm mesh screen and planted with 2 male- fertile (MF) and 7 male-sterile (MS) lines (Tab. I). Each tunnel was provided with a colony of 3,500 bees at the onset of MF flowering. Flowering of MS and MF lines was well synchronized (Fig. 1), and the number of flower heads per plant was similar for all lines. Yet, there were over 10-fold differences in both years in the density of foragers that visited the various lines with extremes of 0.04 to 1.18 honey bees per head (Fig. 2). Some foragers collected pollen, but these were rarely seen on MS heads. The ranking of MS lines in terms of forager density was similar over both seasons, which suggests that the differences in attractiveness among these lines were of genetic origin and probably resulted from differences in nectar availability or composition. Yield of achenes per plant also varied significantly among lines (Fig. 3). The proportion of heads that were empty ranged from 23% to 100% among MS lines, and for each season was negatively correlated with the average forager density on each line (Fig. 4). The number of achenes per head in the flower heads which were not empty did not vary significantly among MS lines (Tab. II), which suggests that the pollination effectiveness of honey bee visits was similar among these different lines. This achene content was greater in MF heads, which is consistent with a greater pollination effectiveness of honey bees in this inflorescence due to the presence of pollen and some self-fertility in MF lines. The overall forager density was similar between the two seasons as was the proportion of empty MS heads, but the achene content of non-empty MS heads was significantly greater in the second year than in the first one (Tab. II). This suggests that the pollination effectiveness of individual visits was greater in the second year. Pollen availability was similar in both seasons, but there were 5 times fewer foragers collecting pollen in the second year compared to the first one. The pool of pollen is limited when producing hybrid seed, especially in confined environments, and our results suggest that in these situations the level of pollen collection may negatively affect the pollination activity of honey bee colonies.
Australian stingless bees contribute to the pollination of some commercially important field crops, but it is unclear whether they can increase crop production reliably in the greenhouse environment. Three 20 week trials were therefore conducted, each using a different hive of Austroplebeia australis Friese and Trigona carbonaria Smith placed in separate glasshouses containing Capsicum annuum L. A third glasshouse contained C. annuum but no bees. In the third week of each trial, the numbers of pollen grains present on stigmatic surfaces and pollen tubes growing along styles were determined. Changes in brood volume were assessed by x-ray computerised tomography at weeks 1, 10 and 20. Additionally, the hives were weighed at these times. At the end of each trial, fruit diameter and length and their fresh and dry weights were measured as were seed fresh and dry weights. Bee behaviour was recorded in the third trial. T. carbonaria foraged less sporadically on C. annuum flowers than did A. australis, and pollination by both bee species showed their potential to increase fruit yield and quality. The effects of pollination by either species were, however, not consistent among the three trials. Hive weights and brood volumes for all colonies increased, so it is considered that both species thrived whilst being able to pollinate the plants. Both species therefore have the potential to improve fruit yield and quality within the greenhouse environment. It was noted that A. australis caused damage to the styles in each trial. This may be attributed to the foraging strategies employed by this species and further work is needed to determine optimum bee to flower stocking rates.
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.
Floral nectaries of annual cultivated Glycine max develop between the bases of the central gynoecium and lateral stamen ring. Each discoid nectary forms immediately before flower opening and degenerates within 24 h. Three stages of nectary development are identified: preactive, active, and postactive. Preactive and active nectaries are composed of a single-layered epidermis that contains many open stomata, with guard cells having thickened walls, starch-engorged plastids, and other organelles. The major portion of each nectary consists of thin-walled special parenchyma cells, each having dense cytoplasm with a nucleus, Golgi bodies and vesicles, mitochondria, plastids, endoplasmic reticulum, many ribosomes, and one or more vacuoles. Fingers of phloem consisting of sieve tubes and companion cells, both with very small wall ingrowths and thought to provide sugars, penetrate the nectary at its base. The fingers originate from 10 vascular bundles with xylem, which innervate the stamen ring peripheral to the nectary. At the beginning of the active stage, special parenchyma around the phloem fingers become highly vacuolated first by each vacuole filling with non-water-soluble material and ribosome-like particles. In many of these cells and in the nonstomata epidermal cells, cytoplasmic bridges are associated with the vacuoles, and straight tubes containing single files of ribosome-like particles occur in the cytoplasm, or traverse plasmodesmata. In addition, bundles of tubules are often seen pressed to the outside of the vacuole tonoplast and in the cytoplasm before and during the time the tonoplast fragments and the vacuole contents mix with the cytoplasmic organelles. These cells then collapse, releasing their contents through the pores of the guard cells and onto the nectary surface. This holocrine secretion is different from that reported for other legume taxa and most other nonlegume taxa and suggests apoptosis. Remaining nectary special parenchyma cells follow the same fate, along with the epidermal cells, so that the entire nectary collapses, leaving only some of the guard cells intact. There are two types of elongate nonglandular trichomes and one type of short five- to seven-celled glandular trichome on the gynoecium adjacent to the nectary. These latter trichomes seem to be developed and functional during the active and postactive stages and following nectary collapse, suggesting that the nectar may consist of a variety of compounds originating from both the nectary and the glandular trichomes.
The percentage of ovules that set seeds per fruit has been used to evaluate the bumblebee activity of a two campaigns greenhouse trial. The experiment was carried out with two commercial cultivars of sweet pepper, ‘bell’ type, called Bardenas and Vergasa. The averages of the percentages of seed set per fruit of the two campaigns were 49.8% (Bardenas) and 40.7% (Vergasa) on the pollination treatment, whereas the averages of the control (self-pollination) treatment were 27.5% and 25.7%, respectively. Percentages of seed set per fruit was strongly related with the number of bee visits, but weakly with duration of visits.The number of pollen grains deposited on stigmas by pollinators or by self-pollination was assessed by staining and microscopy, resulting in a higher number of pollen grains on the bumblebees-pollinated flowers than on the control (self-pollination) ones. As a consequence of this, the number of seeds set on the bumblebees-pollinated fruits, was always higher than in the control.Flowers visited by bumblebees produced larger and heavier fruits than non-visited flowers. Because fruit external maximum diameter, length and weight were highly dependent on seed set, the use of pollinators seems to be required to obtain sweet pepper fruits with improved quality characteristics. Percentage of seed set per fruit was correlated with the number of bumblebee visits to the flowers, seeds per fruit, number of pollen grains on stigma, and the quality fruit traits. The number of pollen grains per stigma was correlated with the number of seeds per fruit.
Pollination of globe artichoke (Cynara scolymus L.) by honey bees (Apis mellifera L.) to produce hybrid seed under enclosure. Globe artichoke is currently multiplied mainly by vegetative means, but the planting of seeds could lead to easier cropping practices and improved yields. This is especially true with hybrid seeds which could be produced using the two genetic male-sterility systems available. For two years, we studied the effectiveness of honey bees as pollinators to produce hybrid seeds of globe artichoke under insect-proof enclosures. We used two adjacent m tunnels covered with 1-mm mesh screen and planted with 2 male-fertile (MF) and 7 male-sterile (MS) lines (tab. I). Each tunnel was provided with a colony of 3,500 bees at the onset of MF flowering. Flowering of MS and MF lines was well synchronized (fig. 1), and the number of flower heads per plant was similar for all lines. Yet, there were over 10-fold differences in both years in the density of foragers that visited the various lines with extremes of 0.04 to 1.18 honey bees per head (fig. 2). Some foragers collected pollen, but these were rarely seen on MS heads. The ranking of MS lines in terms of forager density was similar over both seasons, which suggests that the differences in attractiveness among these lines were of genetic origin and probably resulted from differences in nectar availability or composition. Yield of achenes per plant also varied significantly among lines (fig. 3). The proportion of heads that were empty ranged from 23% to 100% among MS lines, and for each season was negatively correlated with the average forager density on each line (fig. 4). The number of achenes per head in the flower heads which were not empty did not vary significantly among MS lines (tab. II), which suggests that the pollination effectiveness of honey bee visits was similar among these different lines. This achene content was greater in MF heads, which is consistent with a greater pollination effectiveness of honey bees in this inflorescence due to the presence of pollen and some self-fertility in MF lines. The overall forager density was similar between the two seasons as was the proportion of empty MS heads, but the achene content of non-empty MS heads was significantly greater in the second year than in the first one (tab. II). This suggests that the pollination effectiveness of individual visits was greater in the second year. Pollen availability was similar in both seasons, but there were 5 times fewer foragers collecting pollen in the second year compared to the first one. The pool of pollen is limited when producing hybrid seed, especially in confined environments, and our results suggest that in these situations the level of pollen collection may negatively affect the pollination activity of honey bee colonies. On a étudié le butinage des abeilles domestiques (Apis mellifera) et leur efficacité pollinisatrice avec 2 lignées mâle fertiles (MF) et 7 lignées mâle stériles (MS) d'artichaut (Cynara scolymus) sous cages " insectproof "pendant 2 ans. Les floraisons MF et MS étaient synchrones et la floribondité de toutes les lignées était comparable. Néanmoins, les densités de butineuses ont varié selon les lignées avec des extrêmes allant de 0,04 à 1,18 abeilles par capitule et le classement des lignées était similaire lors des 2 années. La proportion de capitules MS sans akène a varié de 23 à 100 % et elle était corrélée négativement avec la densité de butineuses, ce qui souligne l'importance de l'attractivité des lignées MS pour leur pollinisation. Le nombre d'akènes des capitules pourvus d'akènes était plus élevé pour les lignées MF que MS, mais il était uniforme pour toutes les lignées MS à chaque saison, ce qui suggère que l'efficacité pollinisatrice des visites d'abeilles était constante sur ces lignées.
Genetic male sterility was found in the Bell type pepper variety ‘All Big’. Breeding experiments suggest that the character is controlled by a single recessive gene in Bell type pepper varieties. This new source of male sterility appears to be superior to sources formerly reported by being highly stable and already present with a Bell type genetic background, and by the absence of undesirable pleiotropic effects. The usefulness of the character for hybrid seed production is discussed.
l. INTRODUCCIÓN 165 11. MATERIALES y Mt-rODOS 166 111. RESULTADOS 168 IV. DISCUSIÓN 171 V, AGRADECIMIENTOS 174 ~ VI. REFERENCIAS BmLIOGRÁFIcAS 175 VII. RESUMEN; SUMMARY 176 l. INTRODUCCION La distribución geográfica de Nicotiana, excepto por una especie africana, está limitada a Sud y Norte Amélica, Australia y unas pocas islas del Pacífico Sur. Comprende alrededor de 67 especies, 18 de las cuales viven en Argentina (Goodspeed, 1954; Hunziker, 1979). En ge-neral se trata de plantas herbáceas o pequeños arbustos que en muchos casos ocupan sitios con suelo natural o artificialmente perturbado. Ne-cesitan moderada a fuerte iluminación y suelos bien drenados para un normal crecimiento (Goodspeed, 1954). Si bien son numerosos los trabajos realizados sobre la estructura del nectario en Solanáceas (Bemardello, 1986a; Huber, 1980; Moscone, 1986; entre otros) no se conocen antecedentes en cuanto a ese respecto en Nico-tiana; únicamente Goodspeed (1954) hace mención en forma genera 1 a "'-su tamaño y color. Por otra parte, sólo se pud'ieron verificar estudios sobre la composi-ción química del néctar -en algunoJ casos parcial-, en unas 35 espe-cies de Solanaceae Tesis Doctoral a ser pr~sentada en la Facultad de Ciencias Exactas, Físicas y Naturales, Universi-dad Nacional de Córdoba.
Comparative organography (excepting carpels studied previously) and anatomy of the flower are reported for some American members
of the genera of Lyciaeae:Lycium, Grabowskia, andPhrodus. Data obtained are mostly new since no comprehensive floral anatomical work has been carried out in the tribe. These results
include the first report of extrafloral nectaries on the inner epidermis of the calyx inPhrodus andGrabowskia. Results are discussed and compared with previous reports for the family, older than the exclusively AmericanPhrodus andGrabowskia. Lycium shows great morphological diversity while the other two genera are less variable but have more specialized features. A key,
based on floral characters, to the genera, of Lycieae and sections ofLycium is provided.
Honeybee foragers were caught as they returned to their hive. Each was mounted by the dorsum on a wire, and after 45 minutes was offered two sugar solutions alternately. Bees that made a choice (e.g. imbibing one solution after rejecting the other) most often preferred sucrose to either glucose or fructose. A mixture of equal parts of sucrose, glucose and fructose was, like other mixtures tested, less attractive than sucrose or a mixture in which sucrose was dominant.
The anatomy of the nectary, the relative amount of nectar secreted, the composition of the nectar and its sugar concentration, were studied in 9 species of the family, Labiatae (Coridothymus capitatus, Melissa officinalis, Phlomis viscosa, Rosmarinus officinalis, Salvia fruticosa, S. hierosolymitana, S. judaica, Satureja thymbra, Stachys aegyptiaca). The visitng rate of the honeybees to the various species was investigated. The nectar is secreted from the asymmetrically thick, disc-like nectary, through modified stomata. These occur on the thicker side of the nectary only. There is a correlation between the volume of the nectary and the amount of nectar secreted. The larger the nectary, the more nectar it secretes. No correlation was found between the type of vascular tissue (phloem, xylem) and the sugar concentration in the nectar, Rosmarinus officinalis and Coridothymus capitatus were the species most frequently visited by honeybees. The quantitative relationship between sucrose, glucose and fructose differed in the various species examined. Three groups of species were distinguished: 1. Melissa and Rosmarinus, in which the amount of hexoses was equal to that of sucrose; 2. Coridothymus, Salvia judaica and Stachys, in which the hexoses were dominant; 3. Phlomis, Salvia fruticosa and Satureja, in which sucrose was dominant. The concentration of the amino acids in the nectar was, in general, low. No clear correlation between the characteristics of the Sowers or of the nectar and the frequency of honeybee visits could be established.
S ummary
The nectar of 889 species and some fifty varieties of Angiosperms has been analysed by paper partition chromatography.
Ten different types of nectar are distinguished (with two or three very uncommon types in addition) and are broadly classified into:
Nectars with dominant sucrose.
Balanced nectars with about equal amounts of sucrose, fructose and glucose.
Nectars with dominant fructose + glucose.
Three oligosaccharides occurring in nectar are identified and a fourth is named tentatively.
Eight hundred and twenty‐eight species appear to have nectar of constant composition: sixty‐one species have nectar which varies distinctly. The variation does not appear to be linked with locality or date of sampling.
The distribution of nectar types is traced through the Herbaceae.
Sucrose‐dominated nectars appear to be associated with long‐tubed flowers having protected nectar, and fructose +glucose‐dominated nectars with ‘open’flowers having unprotected nectars.
Many humble‐ and honey‐bee, butterfly and moth flowers have nectars with sucrose more or less strongly predominating over fructose and glucose.
The climax groups of the Cruciferae, Umbelliferae, a section of the Compositae, the Euphorbiales and the herbaceous Rosaceae have a completely broken‐down nectar of equal parts of fructose and glucose which is technically honey.
The preference of Apis mellifera for certain sugar mixtures and the types of nectar in some honey‐bee flowers are explored.
1. A cytoplasmic male sterile in peppers has been found, the expression of which is dependent upon a sterile cytoplasm and a nuclear non-restorer gene (ms). 2. Six accessions and six commercial varieties carry the restorer allele, Ms, and two accessions and four commercial varieties carry the nonrestorer, ms. 3. The expression of sterility is affected by modifiers and temperature. Higher temperatures accentuate the sterile expression. 4. Seed set is reduced by approximately one-half in fruit of sterile plants. 5. The significance of temperature influence upon sterility expression is discussed in relation to genic action. 6. The relative infrequency of the ms allele in wild populations and its survival among commercial varieties is discussed.
A study was made of the effect of high temperatures on thermoregulation in a honeybee colony and on the behaviour of the bees. Thermoregulation was limited to the brood-nest. Its temperature did not exceed 37·6°C while the ambient one was 48°C. The activity of forager bees continued in spite of the extremely high temperatures (up to 48°C). During the middle of the day this activity decreased, but it was resumed as a result of transport of liquids when the ambient temperature was still 47·0°C.The activity of ventilating bees at the hive entrance and the velocity of the air current were influenced by the fluctuation of the temperature of the broodnest. The activity of water carriers was not affected directly by the ambient temperature but by that of the brood-nest. On the contrary, the activity of sucrose solution carriers depended upon external temperatures. A similar trend of daily activity was found both in ventilating bees and in water carriers, as opposed to the sucrose solution carriers.
1. In field and in laboratory experiments bees were offered equal volumes of sugar solutions, of different composition but the same total concentration. It was found that sugars which occur in nectar were not equally attractive to bees.
2. Consistent preferences were shown for solutions of single sugars in the following descending order: sucrose, glucose, maltose, fructose.
3. The acceptances of some mixtures differed from those predicted on the basis of an additive effect of the constituent sugars. Anomalous high preferences were shown for sucrose-glucose-fructose solutions.
4. The concentration of the solution appeared to influence the observed preferences, the relative acceptances of solutions at normal threshold level differing from those at higher levels in the series of laboratory experiments.
5. No direct relationship appeared to exist between the chemical constitution of the sugars offered and their acceptance by bees; and no evidence was found to explain the observed differences in preferences for solutions of either single or mixed sugars.
6. Attention is drawn to the possible biological significance of such selective responses by bees--it appears that the sugar composition of nectar may be a contributory factor influencing the visits of bees to flowers.
An artificial-flower feeder was designed to compare the acceptibility of sugar solutions to foraging honey bees, Apis mellifera L. Discrimination against the least preferred solutions was apparently reduced and then eliminated as the number of bees imbibing was increased. Honey bees collected sucrose in preference to fructose and fructose in preference to glucose; 30-50% sucrose in preference to higher or lower concentrations; showed no preference between solutions ranging in pH from 3.2 to 8.8 but rejected those with a pH lower or higher; and showed an aversion to sucrose solutions containing potassium salts.
A summary of 50 years' work on the biology and behavior of honeybees. Liberally illustrated. Harvard Book List (edited) 1971 #215 (PsycINFO Database Record (c) 2012 APA, all rights reserved)
Worker bees (Apis mellifica L. var. ligustica) were exposed to heat for 60 min and the effect of this on the glucose concentration of the haemolymph was noted. An initial rise was found after 15 min exposure followed by a decrease to the initial level after 30 min exposure. The concentration of glucose measured thereafter showed a constant rise. Similar variations were found in the number of bees required to obtain a constant volume of haemolymph by a standard suction power. These are interpreted to show the existence of an osmoregulative mechanism that regulates fluid volume between the tissues and haemolymph.
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