Avocado Pollen Research Articles

Honey bee protein and lipid nutrition in avocado and blueberry agroecosystems with conventional and organic management

Honey bees play a crucial role in agricultural production. Farmers rely on commercial bee pollination to obtain optimal yields, and beekeepers on the income from pollination fees. However, commercial pollination confronts honey bees with pests and pathogens, pesticides, and low-quality food, which in many cases do not fulfill the minimal nutritional requirements of honey bees. In this work, we evaluated honey bee nutrition in avocado and blueberry plantations under organic and conventional management, by assessing the nutritional quality of pollen and bee bread based on their protein, fatty acid, and microbial content, and by analyzing honey bee health through the examination of abdominal fatty acid profiles and head protein content. Low protein content in honey bee hemolymph was evident under conventional management. Regardless of management, avocado pollen showed higher protein levels, which were translated into higher honey bee head protein levels being 60% higher in avocado under conventional management when compared to blueberry under the same management. However, higher protein levels in avocado pollen were also translated into lower amounts of fatty acids in bee bread and in honey bee fat. In particular, the total amount of fatty acids in bee bread from conventional management was 50% lower than that from organic management. Additionally, the saturated fatty acids in conventional blueberries were lower compared to that of organic blueberries. Crop system and bee bread microbial composition altered the plant-honey bee nutrition cascades transforming pollen to bee bread with increased amount of saturated, unsaturated, and total fatty acids. In conclusion, both crop species and crop systems determine honey bee nutrition through alterations in the pollen transformation, affecting protein and fatty acid assimilation.

Survival, Body Condition, and Immune System of Apis mellifera liguistica Fed Avocado, Maize, and Polyfloral Pollen Diet.

Nutritional stress is the major factor contributing to decline in the honey bee (Apis mellifera L.) populations given the high degree of dependence on floral resources, and due to the habitat loss. In this sense, monocultures of maize and avocado have great extensions in Mexico, but their impact on the physiology and morphology of A. mellifera is unknown. This research evaluated the effect of total protein content in monofloral (maize or avocado pollen diets) and polyfloral (using five types of pollen: Persea americana Mill., Zea mays L., Melampodium perfoliatum Cav., Drymaria villosa Cham Schltdl., and Lopezia racemosa Cav.) on their survival, body condition (controlled density, head mass, and development of hypopharyngeal glands; protein content in hemolymph), and immune response [lytic activity and activity of prophenoloxidase in the hemolymph (proPO)]. Corbicular pollen of P. americana had the highest protein content, followed by the corbicular pollen of Z. mays, M. perfoliatum, D. villosa, and L. racemosa. Polyfloral diet seems to be better for A. mellifera than the monofloral maize and avocado. Bees fed polyfloral pollen diet showed a high content of protein in the hemolymph in comparison with that fed maize or avocado pollen diets. Bees fed polyfloral and avocado pollen diet had the highest lytic activity but showed a decrease in proPO activity. In conclusion, polyfloral diets seem to be better for A. mellifera than the monofloral maize and avocado.

Moths as potential pollinators in avocado (Persea americana) orchards in temperate regions

ABSTRACT Avocado (Persea americana) flowers are primarily diurnal, however low minimum overnight temperatures can delay in the opening of female-phase flowers such that the flowers open late in the day and remain open overnight. To determine whether moths are important visitors to avocado flowers at night, we trapped moths in the Bay of Plenty, New Zealand, and examined the pollen moths carried. 11.5% of moths carried avocado pollen grains, and 50.4% of all moths were found to carry pollen grains from other plant species. Moth species diversity was highly variable between orchards, but Ichneutica mutans, Ichneutica ustistriga, Epyaxa rosearia, Rhapsa scotosialis, Phrissogonus laticostatus were observed at all sites and Ichneutica steropastis at three sites, with avocado pollen grains found on 10%–33% of these individual species. We suggest that these species may be the most important pollinating moth species because of their abundance, proportion of individuals carrying avocado pollen, and the number of pollen grains per individual. This exploratory study has shown that moths are capable of carrying avocado pollen grains and may be providing a background pollination service to complement that of honey bees (Apis mellifera). To better understand moth contribution to pollination, fruit set needs to be assessed.

Native bees as putative pollinators of the avocado Persea americana Mill. cv. Hass in Colombia

Hymenoptera, especially bees, play a fundamental role in increasing the fruitiness and quality of the avocado through proper pollination. This study proposed to determine hymenopteran floral visitor fauna and potential pollinators of the Hass avocado cultivar in Colombia. The research was carried out on a single plot of land on a farm during two consecutive flowering periods (Aug-Sep. 2013/ Feb-Mar. 2014), randomly selecting four trees for the sampling and changing them every week. Hymenoptera richness did not differ significantly between flowering periods. Besides Apis mellifera, a wide diversity of floral visitors was found in the cultivar studied. Thirteen families of Hymenoptera were recorded, among them, three bee species of the Meliponini tribe: Scaptotrigona barrocoloradensis (Schwarz) (37%), Partamona cf. aequatoriana Camargo (32%) and Tetragonisca angustula (Latreille) (17.65%). Bees carried pollen from 18 botanical families, the most frequent were: Asteraceae (30.08%), Lauraceae (28.02%) and Urticaceae (19.49%). Although A. mellifera has the highest diversity and abundance in its pollen load, the stingless bees together transported about half of the available avocado pollen (47.53%). These bees stood out for having greater specificity in their pollen load, on surveying the insect body areas where they transport pollen. In A. mellifera, P. cf. aequatoriana and S. barrocoloradensis, avocado pollen adheres mainly to the legs while in T. angustula the greater pollen adherence was in the head and thorax. Although A. mellifera was the main pollinator, as a result of greater visit frequency and pollen load, the potential importance of the native bee species for pollination services is discussed.

Cargas polínicas en entomofauna visitante floral de <i>Persea americana</i> (Lauraceae) cv. Hass

El análisis de las cargas de polen de los insectos visitantes florales del aguacate Hass es un método que permite determinar la importancia de estas especies en planes de manejo de la polinización del cultivo y elucidar el uso de hábitat e importancia de la flora en el sostenimiento de estas especies. El objetivo de este estudio fue identificar mediante un análisis polínico en los insectos visitantes florales las especies vegetales que visitan con mayor frecuencia. El estudio se realizó en dos huertos de Morales (Cauca, Colombia), durante dos periodos de floración. Se recolectaron manualmente los insectos visitantes florales y se obtuvieron muestras del polen en sus cuerpos. Se extrajo la carga polínica de las cinco especies más frecuentes durante el muestreo. El análisis palinológico mostró que los visitantes florales no limitan su visita a un recurso específico como el polen de aguacate Hass, sino que utilizan diferentes especies en el agroecosistema y sus alrededores. Los insectos transportan polen de 18 familias botánicas, siendo las plantas Bidens pilosa, Tridax procumbens, Emilia fosbergii, Brachiaria sp., y Mikania sp. importantes como flora polinífera. El estudio revela la importancia de preservar la diversidad de especies que, con su carga polínica, garanticen la óptima polinización de las flores.

Characterization of avocado honey (Persea americana Mill.) produced in Southern Spain

Plant origin, physicochemical parameters and composition were analysed to characterize the avocado honey (Persea americana Mill.) from Andalusia (Southern, Spain). Ashes content, total polyphenol, and electrical conductivity corresponded to these of a typical dark honey (>80 mm scale Pfund). Regarding mineral elements, K was predominant, followed by P and Mg. Antioxidant and invertase activities presented some desirable values. In the 20 analysed samples, 48 pollen types corresponding to 33 families were identified. Avocado pollen was found in high variability (13–58%). At least a 20% was suggested to guarantee the authentic avocado honey. Perseitol, sugar-alcohol identified only in avocado honey, fundamentally contributes to distinguish this kind of honey. The content varied between 0.31 and 1.56 g/100 g. The correlation between perseitol and avocado pollen was found to be significant. A minimum concentration of 0.30 g/100 g of perseitol is suggested to characterize the proposed monofloral avocado honey.

Low overnight temperatures delay ‘Hass’ avocado (<i>Persea americana</i>) female flower opening, leading to nocturnal flowering

Avocado (Persea americana) has synchronously protogynous flowers: flowers open first in female phase before closing and opening the next day in male phase. Cultivars are grouped based on whether the flowers typically first open in female phase in the morning (type A), or in the afternoon (type B). However, it is known that environmental factors can alter the timing of flower opening, with cold temperatures being shown to affect the timing of flowering. The aim of this study was to investigate how low spring temperatures in New Zealand affect the flowering cycle of commercial avocado cultivars, focusing primarily on the receptive female phase of ‘Hass’, a type A cultivar. Time-lapse photography was used to assess flower opening times of ‘Hass’ over three years. Decreasing minimum overnight temperatures were associated with a delay in the timing of ‘Hass’ female flower phases and resulted in nocturnal flowering of both male and female phase flowers. We recorded insects visiting female flowers at night, and some nocturnal flower visitors collected were carrying avocado pollen. Our study suggests that nocturnal pollination needs to be considered for avocados grown in temperate regions. Furthermore, as the timing of the female phase of ‘Hass’ varied significantly with overnight temperature, the activity patterns of potential pollinators need to be considered to ensure adequate pollinator activity across the range of times in which ‘Hass’ flowers are receptive.

The contribution of honey bees, flies and wasps to avocado (<i>Persea americana</i>) pollination in southern Mexico

Although avocado is native to Mexico, there are no comparative measures in this country on the performance of its flower visitors as pollinators. The contribution of honey bees, flies and wasps to the pollination of avocado from tropical Mexico was assessed by comparing abundance, speed of flower visitation, quantity of pollen carried per individual and pollen deposited on virgin flowers after single visits. The values of abundance and frequency of flower visitation with pollen deposition were combined to obtain a measure of pollinator performance (PP). The most abundant insects on avocado were flies (mean ± SE: 15. 2 ± 6.2), followed by honey bees (9.4 ± 6.3) and wasps (4.2 ± 3.1) (ANOVA F = 91.71, d.f. = 2,78; P < 0.001). Honey bees and wasps visited similar number of flowers (8.2 ± 3.1 and 7.5 ± 2.6 respectively), and more than flies (4.1 ± 1.2) in the same time period (F = 17.63; d.f. = 2,33; P < 0.01). Although flies carried far more avocado pollen on their bodies (44.9 ± 16.8 grains) compared with honey bees and wasps, (21.3 ± 6.2 and 23.8 ± 8.11 grains, respectively; H = 26.522, df = 2, P = 0.001), the number of pollen grains deposited on a stigma after a single visit was similar for the three taxa (2-5). There was evidence for a significant and similarly positive PP of both honey bees and flies as avocado pollinators over wasps, given their abundance, potential for pollen transport and deposition of pollen on stigmas.

Re-evaluation of the roles of honeybees and wind on pollination in avocado

SummaryAvocado (Persea americana Mill.) flowers, with their synchronously dichogamous behaviour, are considered to be pollinated by honeybees, despite the lack of any direct evidence. Results in southern Florida showed that avocado pollen was transferable by wind, and was dispersed over a brief period of time (15 – 60 min) each day. Ten ‘Hass’ avocado orchards in the Santa Clara River Valley, CA, USA, planted far from any known ‘Zutano’ polliniser trees, were selected to investigate the impact of honeybees on pollen transfer. ‘Zutano’ pollen (5 g per insert) was placed at the entry to beehives (approx. eight beehives per orchard) and refreshed four-to-five times during the flowering season. Successful pollinations were determined by parental analysis of harvested ‘Hass’ fruit from trees located at various distances from the beehives, and at three different stages of fruit development, using microsatellite DNA markers. The results showed no significant difference in the proportions of ‘Zutano’-pollinated fruit with respect to distance and/or development stage between orchards provided with beehives containing ‘Zutano’ pollen and those without supplemented pollen. This strongly suggests that honeybees are not the major pollinators of avocado, and that most avocado flowers are self-pollinated by wind.

Physical, chemical and palynological characterization of avocado (Persea americana Mill.) honey in Israel

SummaryVarious methods were used to characterize avocado honey in Israel. Perseitol, a unique sugar present only in avocado honey, served as an indicator for the degree of purity of avocado honey. Low avocado pollen counts made the common melissopalynology method ineffective at predicting the contribution of avocado nectar to honey. It was also found that the levels of fructose, sucrose and glucose do not uniquely characterize avocado honey. Potassium content and eight other minerals were linearly highly correlated to perseitol content. Moreover, pH level, absorbance and degree of darkness were significantly correlated to perseitol content, and can therefore be used to characterize avocado honey.

Evaluation of factors influencing augmentative releases of Chrysoperla carnea for control of Scirtothrips perseae in California avocado orchards

Weekly releases of Chrysoperla carnea for control of Scirtothrips perseae were evaluated in replicated field plots in two commercial avocado orchards in southern California, USA. Two release techniques and rates commonly employed by commercial pest control advisors who routinely use this generalist predator for S. perseae control were assessed. Release technique one utilized C. carnea eggs glued to paper squares that were stapled to leaves of experimental trees at a rate of 41,000 eggs per ha. Release technique two used a motorized backpack sprayer to apply a dry mixture of lacewing eggs and larvae to trees at a rate of 514,501 per ha. Pest populations were monitored by making bi-weekly population counts of S. perseae larvae and adults on leaves, and adult densities were simultaneously monitored in each experimental plot with yellow sticky cards. In the laboratory, degree-day accumulation until death of immature C. carnea was determined at temperatures representative of field conditions when predators were provisioned with varying amounts of food or different food types. Preference for S. perseae instars by first, second, and third instar C. carnea was assessed in the laboratory, and intraguild predation towards larvae and adult females of a co-occurring generalist predatory thrips, Franklinothrips orizabensis , was investigated along with intraspecific predation rates. Both release strategies failed to significantly reduce S. perseae populations in comparison to non-treated control plots. Approximately 35–96% of C. carnea eggs and larvae applied with the motorized sprayer landed on the ground. C. carnea larvae lived for approximately 1–2 days when provisioned with either no food, an avocado leaf or avocado pollen. Longevity was extended to 14–15 days when prey was provided. C. carnea larvae showed no preference for first or second instar S. perseae , all predator instars attacked first instar F. orizabensis , but only second and third instar C. carnea managed attacks on second instar F. orizabensis larvae. No adult female F. orizabensis were attacked and no attacks by F. orizabensis on C. carnea were recorded. Second instar C. carnea engaged in the highest levels of intraspecific predation.

INSECTOS POLINIZADORES DEL AGUACATERO EN LOS ESTADOS DE MÉXICO Y MICHOACÁN, MEXICO

Avocado (Persea americana Mill.), pollinators were colleted in orchards in Coatepec Harinas. (State of Mexico) and Ziracuaretiro (MichoacÅn), Mexico. from January to March of 1998 and 1999. The insects were studied with incident light microscopy in order to identify and count the avoacado pollen grains attached to each body region. A higher diversity of pollinators were detected in the State of Mexico orchards and a lower in MichoacÅn. There were 45 species of Diptera, belonging to 5 families, 20 species (6 families) of Hymenoptera, and 5 species of five families of Coleoptera. Apis mellifera L. (Apidae), Eristalis tenax L. (Syrphidae), Phaenicia mexicana Macquart (Calliporidae) and Palpada mexicana Macquart (Syrphidae) were the most abundant species in both localities. Geotrigona acapulconis Strand (Apidae), Brachygastra mellifica Say (Vespidae), Chrysomya megacephala (Calliphoridae) A. mellifera and had the greater amount of avocado pollen attached to the vertex, ventral thorax and legs, surpassing the species efectiveness. Nevertheless, G. acapulconis appeared in very low number, which implies that the honey bee is the main pollinator in the avocado tree complemented by the other species. These results will be integrated into to a greater projet on the avocado pollinators efectiveness. related with their behavior and with the avocado flowering nature.

AVOCADO (Persea Americana MilI.) POLLINATORS IN ITS REGION OF ORIGIN

Insects visiting avocado flowers were collected over the course of five research trips to Mexico, in the states of Midnoacan, Mexico, Puebla, Veracruz and Chiapas. Most of the specimens were identified at the species level, and the amount and distribution of pollen on their bodies were determined. Both the density and behavior of species found to carry a large amount of avocado pollen were observed on the avocado bloom. In commercial orchards sprayed with potent insecticides, only a small number of visitors of a few species were observed, most of them honeybees (Apis mellifera). In contrast, on unsprayed trees (in small plots, backyards, etc) large numbers of visitors of numerous species were usually observed. More than 1 ,OOO individual insects, of about 100 species, were collected on avocado bloom, most of them of the orders Hymenoptera, Diptera, Coleoptera and Heteroptera. Apparently, some of the visitor species did not pollinate the avocado flowers, but most Of them did contribute to its pollination. The following species were found to be effective pollinators of avocado: the honeybee, 8 to 10 species of stingless bees (Apidae, Meliponinae) and the " Mexican honey was$' (Brachygastra mellifica). These species were the main pollinators of the three avocado races: Mexican. Guatemalan and West Indian. Honeybees were active on the avocado bloom at most sites; however, in some cases they abandoned the avocado bloom to collect nectar and pollen from nearby competing flowers. The stingless bee species and the Mexican honey wasp showed a greater preference for the avocado bloom. We assume that the original pollinators of the avocado, before the introduction of the honeybee to the American continent, were stingless bee and wasp species, which are better adapted for its pollination.

AVOCADO (Persea Americana MilI.) POLLINATORS IN ITS REGION OF ORIGIN

Insects visiting avocado flowers were collected over the course of five research trips to Mexico, in the states of Michoacan, Mexico, Puebla, Veracruz and Chiapas. Most of the specimens were identified at the species level, and the amount and distribution of pollen on their bodies were determined. 80th the density and behavior of species found to carry a large amount of avocado pollen were observed on the avocado bloom. In commercial orchards sprayed with potent insecticides, only a small number of visitors of a few species were observed, most of them honeybees (Apis mellifera). In contrast, on unsprayed traes (in small plots, backyards, etc) large numbers of visitors of numerous species were usually observed. More than 1,000 individual insects, of about 100 species, were coIlected on avocado bloom, most of them of the orders Hymenoptera, Diptera, CoIeoptera and Heteroptera. Apparently, some of the visitor species did not pollinate the avocado flowers, but most of them did contribute to its pollination. The following species were found to be effective pollinators of avocado: the honeybee, 8 to 10 species of stingless bees (Apidae, Meliponinae) and the. Mexican honey wasp" (Brachygastra mellifica). These species were the main pollinators of the three avocado races: Mexican, Guatemalan and West Indian. Honeybees were active on the avocado bloom at most sites; however, in some cases they abandoned the avocado bloom lo collect nectar and pollen from nearby competing flowers. The stingless bee species and the Mexican honey wasp showed a greater preference for the avocado bloom. We assume that the original pollinators of the avocado, before the introduction of the honeybee to the American continent, were stingless bee and wasp species, which are better adapted for its pollination.

The importance of Persea americana as a source of nectar in some honeys from La Palma (Canary Islands)

The melissopalynological analysis of eight honey samples from five different apiaries on La Palma (Canary Islands) where avocado (Persea americana) pollen was found is presented. Avocado pollen was always found in low proportions except in one honey that proved to be unifloral. This avocado honey has a medium to low pollen content (7333 grains/g of honey: Class II of Maurizio). It has medium pollen richness with a total of 26 pollen types. There is no secondary pollen and the important minor pollen are: Castanea sativa (14.4%) and Prunus‐type (probably P. dulcis), Rumex sp., Chamaecytisus proliferus‐type, Echium plantagineum, Erica arborea, Brassica‐type, Euphorbia obtusifolia and Cistus sp. which range from 8.8% for Primus‐type to 3.0% for Cistus sp. and Euphorbia obtusifolia.

Effect of pre-incubation humidity and temperature treatment on the in vitro germination of avocado pollen grains

Optimum in vitro germination of pollen grain of the avocado cultivars Fuerte, Nabal, Ettinger, Bacon and Zutano occurred at 25 °C. However, there were significant differences between cultivars in percentage germination and relative humidity (RH) requirements for optimum pollen grain growth. The most sensitive cultivar to relative humidity was Fuerte, in which the germination of pollen grain rose from 11.4%, at 40% RH, to about 50%, after one hour at 100% RH. The germination% of Nabal pollen grain was already high at 40% RH and was not increased by higher relative humidity. Increased relative humidity also helped to sustain the viability of avocado pollen. At 30 °C and 5% RH the pollen grains of Fuerte quickly lost its ability to germinate, at 40% RH for 1 hour, germination was reduced spectacularly compared to pollen kept in saturated with moisture environment where it was not affected the first 24 hours. The effects of temperature and relative humidity on fruit-set and yield of avocado are discussed.

The behaviour of honey bees (Apis mellifera) visiting avocado (Persea americana) flowers and their contribution to its pollination

SUMMARYObservations of honey bee (Apis mellifera) foraging behaviour on five cultivars of avocado (Persea americana) were carried out in 1982–1984 and 1990–1992 in Galilee, Israel. Examination of the morphology of avocado flowers showed that the pistillate and staminate flower stages have similar structures. Bees collecting nectar, or nectar and pollen, visited both pistillate and staminate flowers, and due to the flower structure they were forced to touch both pistil and anthers. Only limited sites on a bee's body contacted the anthers, and these ‘collection sites’ also contacted the stigma, which occupied the same position as the anthers of the inner stamens. Most avocado pollen grains on bees visiting staminate flowers were clumped at the ‘collection sites’ and constituted the main pollen available for pollination. Some pollen grains randomly distributed over the entire bodies of bees visiting either pistillate or staminate flowers could have been acquired inside the hive, and did not play an important role in pollination. The observations suggest that pollination within a cultivar is accomplished during the overlapping phase of its pistillate and staminate flowering, during which bees collecting nectar and pollen move freely among neighbouring staminate and pistillate flowers. Pollination between cultivars of opposite flowering type is carried out by bees moving between them throughout the overlapping period of pistillate flowering of one cultivar and staminate flowering of the other. Bees which collect only pollen usually do not visit pistillate flowers and do not contribute to pollination.

Storage of avocado pollen

Avocado pollen was stored at a range of temperatures and relative humidities (RH) for up to one year and the pollen was tested for viability in vivo.

Some Factors Influencing the Abundance of the Predaceous Mite Amblyseius hibisci in Southern California (Acarina: Phytoseiidae)1

Mite population surveys carried out in 3 avocado orchards from 1961 through 1963 showed that the predaceous mite Amblyseius hibisci (Chant) often attained its highest population density of the season in the spring or early summer, when mite prey densities were very low. The crawler stage of the latania scale, Hemiberlesea lataniae (Signoret), was a suspected source of food but no correlation was found between the abundance of A. hibisci and that of scale crawlers or crawler-producing females. Another suspected food was pollen. Rapid increases of A. hibisci followed the the beginning of blossoming and egg production peaks showed a close correlation with peaks in flowering intensity. In another orchard the predaceous mite population reached unusually high levels, apparently as a result of large quantities of pollen drifting from adjacent plants of Ricinus communis L. Marked population increases of A. hibisci were induced artificially by dusting caged branches with pollen at weekly intervals. Laboratory tests showed that mites confined on excised avocado leaves fed and reproduced on avocado pollen applied at an average density of only 6.6 pollen grains per square inch of leaf surface. The characteristic of pollen feeding in relation to the potential effectiveness of A. hibisci as a predator is discussed.