Unripe red fruits may be aposematic

The unripe fruits of certain species are red. Some of these species disperse their seeds by wind (Nerium oleander, Anabasis articulata), others by adhering to animals with their spines (Emex spinosa) or prickles (Hedysarum spinosissimum). Certainly neither type uses red coloration as advertisement to attract the seed dispersing agents. Fleshy-fruited species (Rhamnus alaternus, Rubus sanguineus and Pistacia sp.), which disperse their seeds via frugivores, change fruit color from green to red while still unripe and then to black or dark blue upon ripening. The red color does not seem to function primarily in dispersal (unless red fruits form advertisement flags when there are already black ripe fruits on the plant) because the red unripe fruits of these species are poisonous, spiny, or unpalatable. The unripe red fruits of Nerium oleander are very poisonous, those of Rhamnus alaternus and Anabasis articulata are moderately poisonous, those of Rubus sanguineus are very sour, those of Pistacia sp. contain unpalatable resin and those of Emex spinosa and Hedysarum spinosissimum are prickly. We propose that these unripe red fruits are aposematic, protecting them from herbivory before seed maturation.     

Availability peak of caloric fruits coincides with energy-demanding seasons for resident and non-breeding birds in restinga, an ecosystem related to the Atlantic forest,Brazil

We evaluated temporal variation and quality of food resources available to birds especially in two energy-demanding seasons: one when there is a peak of molting residents and another when non-breeding individuals are the bulk of biomass of captured birds. Birds were captured and observed, as well as fruits counted and collected, in two restinga sites for 2 years. Molting resident birds may rely basically on the regularly produced Clusia hilariana and Erythroxylum spp. fruits as lipid-sources, while non-breeders count on Ocotea notata fruits (also rich in lipids) during their passage by the study site. We found that fruits with sugars, lipids or proteins were available throughout the whole period, but a more intense seasonal variation was observed for the before mentioned plant species. The birds studied are known to be potential seed dispersers of these plant species, which are important components of restinga plant community structure.     

Free Methionine Levels in rin and Normal Isogenic Tomato Fruits Ripened in the Field or in Storage

Free methionine levels in rin and normal tomato fruits were determined microbiologically. Similar levels (1750 μg/100 g fresh weight) for mature green fruits of both rin and a normal isogenic line suggest that the lack of ripening of rin fruits is not due to low methionine levels. Methionine levels of mature green rin and normal fruits were 1750 μg/ 100 g fresh weight. Normal fruits ripened either on or off the vine were 2860 and 2500 μg/100 g fresh weight, respectively. The rin fruits which were left on the plant or held in air at 20 C until soft and yellow were significantly lower in methionine than C₂H₄-treated rin fruits or any normal fruits. Harvested rin and normal fruits held at 20 C in continuously applied ethylene (10 μl/l) had higher methionine levels than comparable air controls; levels in treated rin fruits were significantly higher than those in normal fruits.     

Fruits of apple and sweet persimmon are not essential food sources for Riptortus pedestris (Hemiptera: Alydidae) which causes fruit-spotting

Riptortus pedestris (Fabricius) (Hemiptera: Alydidae) has recently become an important fruit-spotting bug of apple and sweet persimmon trees in Korea. Although fruits of cultivated species are unsuitable food for some fruit-spotting bugs, the dietary importance of fruits of apple and sweet persimmon for R. pedestris is unknown. We evaluated harvested fruits of apple and sweet persimmon with or without soybean seeds as a food source for R. pedestris by investigating nymphal development time, immature mortality, preovipositional period, fecundity, and adult size in the laboratory. No first instars of R. pedestris that were fed only apple or sweet persimmon fruits became third instar nymphs. When supplemented with soybean seeds, both fruits supported nymphal development and reproduction of R. pedestris. However, fruits combined with soybean seeds were not a better diet than soybean seeds only. Therefore, apples and sweet persimmons are not essential food sources for the development and the reproduction of R. pedestris. These results suggest that R. pedestris may not reproduce on fruit trees, thus explaining the absence of eggs and nymphs of this bug on fruit trees in orchards. Management of nearby vegetation of fruit orchards would be important for reducing damage by adult R. pedestris.     

Do frugivorous birds concentrate their foraging activities on those alien plants with the most abundant and nutritious fruits in the South African Mediterranean-climate region?

Alien plants with abundant and nutritious fruits may compete more effectively for avian dispersal services than native shrubs. This premise was examined by comparing daily foraging activity (visitation frequency, foraging bird number and foraging period) by four frugivorous bird species of different size on fruits of two native and two alien shrub species co-occurring at four different sites. Also, the quantities of seeds consumed daily by each of the four birds species from fruits of the four shrub species were measured and compared with the numbers of fruits and seeds, and the mass of fruits present in the shrub canopies as well as with their fruit monosaccharide concentrations. The quantities of seed consumed daily by four different size bird species (Columba arquatrix, Colius striatus, Pycnonotus capensis, Zosterops pallidus subsp capensis) were positively correlated with the numbers of seeds per m² of canopy area and with fruit mass and fruit monosaccharide content per m² of canopy area, as well as with the monosaccharide concentration of individual fruits, except in the C. arquatrix (African olive pigeon). All four bird species displayed the highest daily visitation frequencies on fruits of the alien Solanum mauritianum which were more abundant and nutritious than fruits of the other alien Lantana camara and fruits the natives Olea europaea subsp africana and Chrysanthemoides monilifera. They also all consumed greater quantities of seed daily from fruits of the alien S. mauritianum than from fruits of the other shrub species. These results corroborate proposals that frugivorous birds concentrate their foraging activities on those alien plants with the most abundant and nutritious fruits.     

Comparative fruit development in some Euphorbiaceae and Phyllanthaceae

Euphorbiaceae s. str. and Phyllanthaceae were earlier components of Euphorbiaceae. This separation was mainly based on molecular data and also on morphological characteristics. Nevertheless, the structure and development of fruits are poorly investigated in these families and considering this, fruits (pericarp and seed) of Euphorbia hyssopifolia L., Croton glandulosus L. (Euphorbiaceae), Phyllanthus niruri L. and Phyllanthus tenellus Roxb. (Phyllanthaceae) were structurally studied to see in what respects they are similar or different. The Euphorbiaceae schizocarps present two meristems (adaxial and subadaxial) in the ovary wall, but the adaxial meristem is entirely lacking in Phyllanthus fruits. The seeds have an exotegmen with Malpighian palisade cells in Euphorbiaceae species and a short palisade in Phyllanthus. Some special structural features, such as nucellar beak, anatropous ovules and schizocarp fruits were found in all the species and constitute a unique combination. From the present results, it appears that there is no significant difference in fruit and seed development between the studied Euphorbiaceae and Phyllanthaceae.     

Numerical taxonomy of Palaeocarya (Juglandaceae) from the Mangbang Formation of West Yunnan, China

Specimens of Palaeocarya (Juglandaceae) were collected from the upper Pliocene of western Yunnan Province, which is a new geographical and age range record of engelhardioid winged fruits in China. A numerical taxonomic investigation based on 14 morphological characters of fossil and extant specimens of engelhardioid winged fruits in China was conducted using multivariate methods. Phenetic clustering shows that there are four morphotypical groups which we assign to four species. Two groups are assigned to the previously described fossil species, Palaeocarya guangxiensis Li Hao-Min et Chen Yun-Fa, 2003 and Palaeocarya koreanica (Oishi) Manchester, 1987. Two new species are recognized, Palaeocarya yunnanensis and Palaeocarya longialata. These Neogene Engelhardieae fruits provide fossil data for understanding the origin and evolution of the Engelhardia species that now inhabit South China.     

Purple-faced Langurs in Human-Modified Environments Feeding on Cultivated Fruits: A Comment to Dela (2007, 2012)

Recently Dela (International Journal of Primatology, 28 (2007): 607–626; International Journal of Primatology, 33 (2012): 40–72) published her study from the mid-1980s on the diet of purple-faced langurs Trachypithecus (Semnopithecus) vetulus in village gardens and rubber plantations. Unlike studies from the 1970s that reported the species, like other colobines, to be largely folivorous with few ripe fruits eaten, Dela found them to be largely frugivorous. The frequent feeding on ripe fruits challenges the paradigm that colobine digestive adaptations restrict the use of ripe fleshy fruits. No reference was made to any other post-1970s study on the species. Here I provide a concise overview of more than a dozen studies conducted in the 1990s and 2000s that show that 1) other populations live in similar human-modified environments showing feeding adaptations as reported by Dela, 2) these populations rely largely on cultivated crops and feed heavily on fruits, 3) living in these situations introduces them to additional threats. Especially in western Sri Lanka little natural habitat remains and deforestation has led the langurs to exchange the forest jungle for the urban jungle, with power lines, fences, walls, and roofs being used instead of trees. The main fruits that provide a staple for langurs in these areas are jackfruit (Artocarpus heterophyllus), banana (Musa spp.), and mango (Mangifera indica); studies in undisturbed habitats and indeed Dela’s own study suggest the heavy use of human-edible fruits by langurs may not necessarily indicate preferential selection of these food sources. Living in human-modified environments makes the langurs more prone to infection with gastrointestinal parasites, and may lead to death by electrocution or being killed by guard dogs. The large degree of agreement between studies suggest that feeding on ripe fruits from cultivars is not unique to Dela’s two study groups and shows that some langur groups are able to survive for extended periods on uncolobine-like diets when they cannot access their preferred foods.     

Olfactory responses of Grapholita molesta to different developmental stages of immature fruit of peach,plum, and apple

The Oriental fruit moth, Grapholita molesta (Busck) (Lepidoptera: Tortricidae), is known to shift its host use from stone fruits (the primary hosts) to pome fruits (secondary hosts) as the season progresses. Grapholita molesta recognizes potential hosts by semiochemicals from fruits, but few studies have addressed the olfactory responses of G. molesta to host fruits during the seasonal transition of the moth from stone to pome fruits. So, we investigated the olfactory responses of larvae and gravid females of G. molesta to different fruit stages (collected on May 31, June 11, and June 25) of immature peach, plum, and apple fruits, using both multiple and two choice tests. In the multiple choice tests, for fruits collected after June 11, larvae showed a significant preference for peach as their first choice, compared to plum or apple. The final choice rate (when larvae had stayed on the fruit for more than 1 h) of larvae was also highest for peach fruits collected on June 11 and June 25. In two choice tests (Y-tube test), the response rate and overall choice rate of larvae and mated ovipositing adult females were also highest on peaches collected on May 31 (larvae) and June 25 (adults), respectively. In conclusion, we found that both the adults and larvae of G. molesta were highly attracted to immature peach fruits in laboratory choice tests.     

The monoterpene limonene in orange peels attracts pests and microorganisms

Plant volatiles include terpenoids, which are generally involved in plant defense, repelling pests and pathogens and attracting insects for herbivore control, pollination and seed dispersal. Orange fruits accumulate the monoterpene limonene at high levels in the oil glands of their fruit peels. When limonene production was downregulated in orange fruits by the transgenic expression of a limonene synthase (CitMTSE1) in the antisense configuration, these fruits were resistant to the fungus Penicillium digitatum (Pers.) Sacc. and the bacterium Xanthomonas citri subsp. citri and were less attractive to the medfly pest Ceratitis capitata. These responses were reversed when the antisense transgenic orange fruits were treated with limonene. To gain more insight into the role of the limonene concentration in fruit responses to pests and pathogens, we attempted to overexpress CitMTSE1 in the sense configuration in transgenic orange fruits. Only slight increases in the amount of limonene were found in sense transgenic fruits, maybe due to the detrimental effect that excessive limonene accumulation would have on plant development. Collectively, these results suggest that when limonene reaches peak levels as the fruit develops, it becomes a signal for pest and pathogen attraction, which facilitate access to the fruit for pulp consumers and seed dispersers.     

Ethylene: Response of Fruit Dehiscence to CO(2) and Reduced Pressure

These studies were conducted to determine whether ethylene serves as a natural regulator of fruit wall dehiscence, a major visible feature of ripening in some fruits. We employed treatments to inhibit ethylene action or remove ethylene and observed their effect on fruit dehiscence. CO₂ (13%), a competitive inhibitor of ethylene action in many systems, readily delayed dehiscence of detached fruits of cotton (Gossypium hirsutum L.), pecan (Carya illinoensis [Wang.] K. Koch), and okra (Hibiscus esculentus L.). The CO₂ effect was duplicated by placing fruits under reduced pressure (200 millimeters mercury), to promote the escape of ethylene from the tissue. Dehiscence of detached fruits of these species as well as attached cotton fruits was delayed. The delay of dehiscence of cotton and okra by both treatments was achieved with fruit harvested at intervals from shortly after anthesis until shortly before natural dehiscence. Pecan fruits would not dehisce until approximately 1 month before natural dehiscence, and during that time, CO₂ and reduced pressure delayed dehiscence. CO₂ and ethylene were competitive in their effects on cotton fruit dehiscence. All of the results are compatible with a hypothetical role of ethylene as a natural regulator of dehiscence, a dominant aspect of ripening of cotton, pecan, and some other fruits.     

Developmentally Regulated Sesquiterpene Production Confers Resistance to Colletotrichum gloeosporioides in Ripe Pepper Fruits

Sesquiterpenoid capsidiol, exhibiting antifungal activity against pathogenic fungus, is accumulated in infected ripe pepper fruits. In this study, we found a negative relation between the capsidiol level and lesion size in fruits infected with Colletotrichum gloeosporioides, depending on the stage of ripening. To understand the developmental regulation of capsidiol biosynthesis, fungal-induced gene expressions in the isoprenoid biosynthetic pathways were examined in unripe and ripe pepper fruits. The sterol biosynthetic pathway was almost shut down in healthy ripe fruits, showing very low expression of hydroxymethyl glutaryl CoA reductase (HMGR) and squalene synthase (SS) genes. In contrast, genes in the carotenoid pathway were highly expressed in ripe fruits. In the sesquiterpene pathway, 5-epi-aristolochene synthase (EAS), belonging to a sesquiterpene cyclase (STC) family, was significantly induced in the ripe fruits upon fungal infection. Immunoblot and enzyme activity analyses showed that the STCs were induced both in the infected unripe and ripe fruits, while capsidiol was synthesized discriminatively in the ripe fruits, implying diverse enzymatic specificity of multiple STCs. Thereby, to divert sterol biosynthesis into sesquiterpene production, infected fruits were pretreated with an SS inhibitor, zaragozic acid (ZA), resulting in increased levels of capsidiol by more than 2-fold in the ripe fruits, with concurrent reduction of phytosterols. Taken together, the present results suggest that the enhanced expression and activity of EAS in the ripe fruits play an important role in capsidiol production, contributing to the incompatibility between the anthracnose fungus and the ripe pepper fruits.     

Integrative analyses of transcriptome and carotenoids profiling revealed molecular insight into variations in fruits color of Citrus Reticulata Blanco induced by transplantation

Citrus fruits exhibit vivid color and are favored extensively. However, the biochemical and molecular mechanism of Citrus Reticulata Blanco fruits coloring, especially the effect of transplantation on fruits coloring, is unclear. Herein, RNA-Seq and carotenoids profiling were applied to investigate the effect of transplantation on Orah mandarin fruits coloring. Transplantation induces fruit color shallowing, Ca²⁺ and ACC level declining and IAA level increasing. Transplantation induced variation in fruit skin and pulp carotenoids, mainly β-citraurin as one of the important pigments of citrus peel. 2253 up-regulated genes, 1103 down-regulated genes in skin and 815 up-regulated genes, 534 down-regulated genes in pulp of transplanted tree fruits were identified by RNA-Seq. The DEGs involved hormone signal, carotenoids biosynthesis and TFs such as MYB and bHLH family TFs. The carotenoid cleavage dioxygenase gene (Ciclev10028113m.g) is positively correlated with β-citraurin and regulated directly and/or indirectly by MYB1R1, PIF4, ACC and IAA. Integrative analyses revealed potential molecular insights into Orah mandarin peel color variation during transplantation.     

Variations in carambola infestation rates byBactrocera carambolae drew and hancock (Diptera: Tephritidae) with fruit availability in a carambola orchard

The relationship between the infestation rate of carambola fruits byBactrocera carambolae Drew and Hancock was investigated in a carambola orchard. Phenology of the fruits was found to influence percentage infestation of fruits byB. carambolae. The proportion of unbagged or susceptible fruits infested varied with time of year and tended to decrease with the increase of unbagged fruits available on the tree. The number of ovipunctures per fruit varied with fruit size and was also found to be indicative of the number of adult insects (B. carambolae and parasitoids) that will emerge from each fruit. Higher number of susceptible fruits available on each tree also decreased both the number of ovipunctures per fruit and the number of eggs laid per fruit, which could possibly be due to the strategy of spreading the risk adopted by the femaleB. carambolae or a result of random selection with more hosts available. The main parasitoids recorded wereBiosteres vandenboschi (Fullaway) andB. arisanus (Sonan). The mean percentage of parasitism was 38.3% and it followed roughly that of infestation of fruits.     

Frugivorous birds visit fruits of emerging alien shrub species more frequently than those of native shrub species in the South African Mediterranean climate region

We compared daily visitation frequency indices by 4 large (> 150 g), 7 medium-size (50–150 g), 5 small (30–50 g) and 8 and tiny (< 30 g) frugivorous bird species on fleshy fruits of two native shrubs (Olea europaea subsp. africana and Chrysanthemoides monilifera subsp. monilifera), two established alien shrubs (Solanum mauritianum and Lantana camara) and two emerging alien shrubs (Myoporum tenuifolium and Pittosporum undulatum) at nine different sites in the Cape Floristic Region. Large, medium-size and tiny birds as groups displayed significantly higher visitation frequency indices on fruits of both emerging alien shrub species than the other shrub species. Small birds as a group displayed insignificantly different visitation frequency indices on fruits of both emerging and established alien shrub species but significantly higher visitation frequency indices on fruits of both emerging and established alien shrub species than on fruits of the native shrub species. However, there were significant differences in foraging frequency indices of the bird species included within each of these body size groups on fruits of the different shrub species. Among the large birds, Columba guinea and among the medium size birds Sturnus vulgaris, Streptopelia senegalensis, Turdus olivaceus and Onychognathus morio all exhibited significantly higher visitation frequency indices on fruits of both emerging alien shrub species than on fruits of the other shrub species. These findings indicate that alien plant control measures should be focused on eradicating localised populations of emerging aliens to limit preferential consumption of their fruits by birds and consequent dispersal of their seeds that germinate readily into natural areas.     

Potential of patulin production by Penicillium expansum strains on various fruits

In this study, we investigated the pathogenicity and patulin production by ten strains of Penicillium expansum on various fruits (apples, apricots, kiwis, plums and peaches) at two (4°C and 25°C) different temperature regimes. All strains caused the infectious rots on all fruits at 4 and 25°C except one strain (PEX 09) at 4°C. Two strains (PEX 20 and PEX 12) out of ten produced the highest amounts of patulin on all fruits tested. The patulin production by P. expansum is high at 25°C compared to 4°C. All strains of P. expansum accumulated patulin ranging from 100–13,200 μg/kg and nine strains ranging from 100–12,100 μg/kg in all fruits at 25°C and 4°C, respectively. Among ten strains of P. expansum, strain PEX 20 produced the greatest amount of patulin on apricots (13,200 μg/kg of rotten fruit) and on apples (12,500 μg/kg) at 25°C after 9 days of incubation. At 4°C, this strain produced 12,100, 12,000, 2,100 and 1,200 μg/kg of patulin on apricots, apples, plums and peaches, respectively, after 45 days of incubation. Strain PEX 12 produced the highest amount of patulin on kiwis (10,700 μg/kg) at 25°C and 10,300 μg/kg at 4°C. Patulin production by P. expansum on peaches and plums at both temperatures were lower than other fruits. The results of this study showed that careful removal of rotten fruits is essential to produce patulin-free fruit juice, since high patulin levels in apricots, apples and kiwis could result in a level greater than 50 μg/kg of this mycotoxin in finished fruit juices, when one contaminated fruit occurs in 264, 250 and 214 fruits, respectively. So, the fruit processors should take care in not using rotten fruits for juice production to avoid the patulin problem worldwide, since this study proved that most important fruits being used for juice production and direct human consumption are susceptible to P. expansum and subsequent patulin production even at low temperatures. This is the first comprehensive report regarding patulin production by different strains of P. expansum on various fruits from Italy at different temperature regimes.     

A comparison of the retention of pathogenic Escherichia coli?O157 by sprouts,leaves and fruits

The retention (binding to or association with the plant) of Escherichia coli by cut leaves and fruits after vigorous water washing was compared with that by sprouts. Retention by fruits and leaves was similar but differed from retention by sprouts in rate, effect of wounding and requirement for poly-β,1-6-N-acetyl-D-glucosamine. Escherichia coli was retained by cut ends of lettuce leaves within 5 min while more than 1 h was required for retention by the intact epidermis of leaves and fruits, and more than 1 day for sprouts. Retention after 5 min at the cut leaf edge was specific for E. coli and was not shown by the plant-associated bacteria Agrobacterium tumefaciens and Sinorhizobium meliloti. Escherichia coli was retained by lettuce, spinach, alfalfa, bean, tomato, Arabidopsis thaliana, cucumber, and pepper leaves and fruits faster than by sprouts. Wounding of leaves and fruits but not sprouts increased bacterial retention. Mutations in the exopolysaccharide synthesis genes yhjN and wcaD reduced the numbers of bacteria retained. PgaC mutants were retained by cut leaves and fruits but not by sprouts. There was no significant difference in the retention of an O157 and a K12 strain by fruits or leaves. However, retention by sprouts of O157 strains was significantly greater than K12 strains. These findings suggest that there are differences in the mechanisms of E coli retention among sprouts, and leaves and fruits.     

Parasitism of the apple maggot,Rhagoletis pomonella,infesting hawthorns in Washington

Five species of larval parasitoids were reared fromRhagoletis pomonella (Walsh) infested fruit of hawthorn,Crataegus, collected from several locations in southwest Washington over a four year period. A braconid,Biosteres melleus (Gahan), parasitized larvae infesting fruits of a native hawthorn species,Crataegus douglasii Lindl. Another braconid,Opius downesi Gahan, emerged exclusively fromR. pomonella pupae reared from fruits of an introduced species of hawthorn,Crataegus monogyna Jacq. A pteromalid,Pteromalus sp., and two eulophids,Tetrastichus spp., attackedR. pomonella larvae infesting fruits of both hawthorn species. No parasitoids emerged from a total of 4385 pupae reared from apple. Percent parasitism ofR. pomonella was higher inC. monogyna compared toC. douglasii fruits. The highest average levels of parasitism ofR. pomonella inC. monogyna andC. douglasii fruits were 90% and 23% respectively. The kinds of parasitoids, their relative abundances and timing of parasitization on the two hawthorns was related to differences in fruit ripening patterns and its effect on the development ofR. pomonella on these two hosts. Parasitization ofR. pomonella byTetrastichus spp. is a new host record. The detection of these species andPteromalus sp. in southwest Washington are the first records of ectoparasitoids attacking this tephritid.     

Parthenocarpy and seed predation by insects in Bursera morelensis

Background and Aims

While parthenocarpy (meaning the production of fruits without seeds) may limit fecundity in many plants, its function is not clear; it has been proposed, however, that it might be associated with a strategy to avoid seed predation. Bursera morelensis is a dioecious endemic plant that produces fruits with and without seeds, and its fruits are parasitized by insects. Its reproductive system is not well described and no published evidence of parthenocarpy exists for the species. The purpose of this work was to describe the breeding system of B. morelensis and its relationship to seed predation by insects.

Methods

The breeding system was described using pollination experiments, verifying the presence of parthenocarpic fruits and apomictic seeds. Reproductive structures from flower buds to mature fruits were quantified. For fruits, an anatomical and histological characterization was made. The number of fruits in which seeds had been predated by insects was correlated with parthenocarpic fruit production.

Key Results

The major abortion of reproductive structures occurred during fruit set. The results discard the formation of apomictic seeds. Flowers that were not pollinated formed parthenocarpic fruits and these could be distinguished during early developmental stages. In parthenocarpic fruits in the first stages of development, an unusual spread of internal walls of the ovary occurred invading the locule and preventing ovule development. Unlike fruits with seeds, parthenocarpic fruits do not have calcium oxalate crystals in the ovary wall. Both fruit types can be separated in the field at fruit maturity by the presence of dehiscence, complete in seeded and partial in parthenocarpic fruits. Trees with more parthenocarpic fruits had more parasitized fruits.

Conclusions

This is the first time the anatomy of parthenocarpic fruits in Burseraceae has been described. Parthenocarpic fruits in B. morelensis might function as a deceit strategy for insect seed predators as they are unprotected both chemically and mechanically by the absence of calcium oxalate crystals.Key words: Parthenocarpy, Bursera morelensis, predation, seeds, insects, breeding system, calcium oxalate crystals