Japanese beetles facilitate feeding by green june beetles (Coleoptera: Scarabaeidae) on ripening grapes

Adult activity of native green June beetles, Cotinis nitida L., and invasive Japanese beetles, Popillia japonica Newman, peaked in late July in Kentucky coincident with later stages of veraison in early- and midseason ripening grape (Vitis spp.) cultivars. Most C. nitida feeding aggregations sampled on clusters of early-ripening grapes in the research vineyard also contained Japanese beetles. Assays showed C. nitida generally are unable to bite into intact ripe grape berries, whereas Japanese beetles readily do so. The beetles' disparate biting ability is likely because of differences in their mandibles, which are sharply pointed and opposable in P. japonica compared with C. nitida mandibles that are bluntly spatulate, do not meet at their tips, and seemingly are only suited for feeding on fruit pulp or other soft food. Japanese beetles were shown to facilitate C. nitida feeding by biting through the skin and providing access to the soft berry pulp. Juice from early- and midseason ripening grape cultivars with relatively high sugar content elicited the greatest feeding by P. japonica. A scenario is suggested wherein Japanese beetles open wound sites and contaminate fruits with yeasts that induce fermentation volatiles that attract C. nitida. Japanese beetles had difficulty biting berries of Sunbelt, a late-ripening cultivar. Phenological resistance, i.e., planting cultivars that ripen after peak flight, could be an effective management strategy. Establishment of P. japonica in grape-growing regions of the southeastern United States will likely elevate the pest status of C. nitida in vineyards.     

Environmentally sustainable pest control options for Drosophila suzukii

The spotted‐wing drosophila or cherry vinegar fly (Drosophila suzukii) is native to Asia but has invaded other continents since 2008 and has spread throughout Europe. The females have a serrated ovipositor allowing them to penetrate the skins of intact ripening fruits to deposit their eggs, and the developing larvae rapidly destroy the fruits close to harvest. Drosophila suzukii has a rapid life cycle and the larvae develop well beneath the fruit surface. This means that the use of pesticides is problematic and often not effective, first due to their restricted use close to harvest to protect consumers, and second because the larvae are deep enough inside the fruit to avoid contact. There are currently no effective and environmentally sustainable pest control methods for this species, resulting in extensive damage to fruit crops. Here, we review the current status of D. suzukii as a fruit crop pest and discuss the feasibility of current pesticide‐free control methods. We also consider the potential of new technologies as a basis for the urgently needed specific and long‐term control of this species.     

Regulation of the expression of lipoxygenase genes in <Emphasis Type="Italic">Prunus persica</Emphasis> fruit ripening

Three genes of the lipoxygenase (LOX) family in peach (Prunus persica var. compressa cv. Ruipan 4) were cloned, and their expression patterns during fruit ripening were analyzed using real-time quantitative PCR. All of the three peach LOX genes had been expressed during fruit ripening; however, their expression patterns were significantly different. During the normal ripening of peach fruits, the expression levels of PpLox1, PpLox2 and PpLox3 increased in varying degrees accompanying upsurge of ethylene evolution. After treated by methyl jasmonic acid (MeJA), the peak of ethylene releasing occurred in advance, and the declining rate of fruit hardness was accelerated, the expression level of the three peach LOX genes in fruits markedly enhanced at the early stage of storage, but significantly decreased at the late storage stage. So, it could be suggested that all three LOXs relate to fruit ripening; however, their functions might be different. PpLox1 expression increase along with the upsurge of ethylene evolution in both control and MeJA-treated peach fruits suggested that PpLox1 probably played a major role in the peach fruit ripening. Expression peak of PpLox2 appeared at the 1 DAH (days after harvest) in both control and MeJA-treated peach fruits, while obvious changes in ethylene evolution and fruit hardness was not observed, which suggested that the rise of PpLox2 expression can be induced by certain stimulation related to ripening, such as harvesting stress and MeJA treatment. The expression of PpLox3 kept a lower level in the natural ripening fruits, whereas raced up at the early stage of storage in the fruits treated with MeJA, which indicated that PpLox3 was expressed inductively and had minor roles during the normal ripening of peach fruits, but when encountered with external stimulation, its expression level would rapidly enhance and accelerate the ripening of peach fruit.     

Xyloglucan endotransglycosylase activity during fruit development and ripening of apple and kiwifruit

Xyloglucan endotransglycosylase (XET) activity was measured in apple (Malus domestica Borkh. cv. Braeburn) pericarp and kiwifruit (Actinidia deliciosa [A. Chev.] C. F. Liang et A. R. Ferguson var. deliciosa cv. Hayward) outer pericarp and core tissues in order to establish whether a correlation exists between the activity of the enzyme and different stages of fruit development Whereas the growth rate of kiwifruit paralleled changes in XET activity throughout fruit growth, that of apple did not. Both fruits showed the highest XET activity, on a fresh weight basis, in the first two weeks after anthesis when cell division was at its highest. XET activity then decreased sharply, but as the fruit increased in size (4–8 weeks after anthesis) there was a concomitant increase in XET activity in both fruits. In the latter stage of fruit development (16–26 weeks after anthesis) XET activity increased to peak at harvest in apple fruit. During this time there was relatively little increase in fruit size and presumably therefore minimal cell expansion. XET activity then declined as fruit softened after harvest. In core tissue from kiwifruit, XET activity increased throughout the later stages of fruit growth to harvest maturity in a similar manner to apple, but continued to increase after harvest until fruit were ripe. In contrast, XET activity in the outer pericarp of kiwifruit did not increase until ripening after harvest. In apple tissue up to 30% of the XET activity was cell wall bound and could not be solubilised, even in buffer containing 2 M NaCl. The results implicate XET in cell wall assembly during cell division and expansion early in apple and kiwifruit growth. However, the disparity between apple and kiwifruit with respect to XET activity late in fruit development and ripening and the different affinities of the enzyme for the cell wall in each fruit, suggest that XET has several roles in plant development, not all of which are related to cell wall loosening during periods of accelerated growth.     

Damage evaluation of Rhynchites cribripennis (Col., Attelabidae) in olive fruits

Rhynchites cribripennis is a pest of olives widely distributed in the Mediterranean region. The adults drill holes in the flesh of olives, resulting in fruit drop. Although earlier studies reported high damage levels, its damage potential has not been specifically investigated. In the current study, the damage potential of this weevil was evaluated with regard to its density. Olive shoots were enclosed in muslin cages, along with two or four adult weevils, during the initial phase of the olive fruit development. In each cage, the shoots bore 357 fruits, on average. The percentage of fruits dropped and the damage level on the fruits were recorded at about 1‐month intervals. At harvest, the fruits that remained on the shoots were individually weighed to evaluate the damage as regards fruit weight. The results showed that R. cribripennis can cause a significant damage because of fruit drop (54 ± 6%, 38 ± 4% and 16 ± 2% in the cages with 4, 2 and 0 adults, respectively). The damage was more severe in fruits within the first month after their formation. A single feeding hole was shown to cause the drop of small fruits. The high percentage of dropped fruits caused a significant decrease in the weight of the olives at harvest among treatments. These results show that R. cribripennis can cause serious damage to olive production and offer useful information for quantifying its damage potential and developing a more rationale control strategy for this pest.     

Antioxidant Systems in Ripening Tomato Fruits

Two cultivars of tomato (Lycopersicon esculentum Mill.), Selection-7 (shelf life 7–8 d) and ARTH-3 (shelf life 14–15 d) were analyzed for oxidative stress and the antioxidant enzyme system at different stages of fruit ripening. The results presented here suggest that during the early stages of fruit ripening, efficient antioxidant system protects the tomato fruits against the damaging effect of progressive oxidative stress. At later stages, however, oxidative damage occurs due to decreased activities of the ROS scavenging enzymes.     

Superoxide dismutase and catalase activities in apple fruit during ripening and post‐harvest and with special reference to ethylene

Oxidative stress is involved in many biological systems, among which are fruit ripening and senescence. Free radicals play an important role in senescence and ageing processes. Plants have evolved antioxidative strategies in which superoxide dismutase (SOD, EC 1.15.1.1) and catalase (CAT, EC 1.11.1.6) are the most efficient antioxidant enzymes, influencing patterns of fruit ripening. Variations in total SOD and CAT activities were determined at regular intervals during ripening and senescence in on‐tree and cold‐stored apple fruits of the cultivars Fuji and Golden Delicious. In all fruits, internal ethylene concentration was also measured. The results suggest that the onset of ripening, signalled by ethylene burst, is closely related to SOD and CAT activities. In on‐tree fruits the climacteric peak in ethylene was associated with the peaks of SOD and CAT activity in both cultivars. Quite different results were obtained in cold‐stored fruits: Ethylene concentration increased in both cultivars during the storage. CAT activity doubled in both cultivars. SOD activity decreased in Golden Delicious and peaked in Fuji.     

Western Purple-faced Langurs (Semnopithecus vetulus nestor) Feed on Ripe and Ripening Fruits in Human-modified Environments in Sri Lanka

Although most colobines feed mainly on leaves and a few feed heavily on seeds, colobine digestive adaptations for folivory are thought to preclude the high use of ripe fleshy fruits. In this long-term study of Semnopithecus vetulus nestor, the endemic western purple-faced langur of Sri Lanka, I investigated the feeding ecology and dietary flexibility for fruit feeding in 2 free-ranging groups (PT1 and R1) living in human-modified environments with abundant cultivated fruit, at Panadura and Piliyandala, for 19 mo and 13 mo respectively, using scan-sampling, vegetation enumeration, and phenological studies. In contrast to folivorous forest-living colobines, including other subspecies of Semnopithecus vetulus, my focal groups used more fruit (>50%) than foliage (PT1: 36%; R1: 34%). Both groups used many plant species (PT1 115; R1 59), but selected their food species, fruits over leaves, and young leaves over mature leaves. Fruit use was independent of young leaf availability. Notably, 78.4% and 83.4% of fruits consumed by PT1 and R1 were fleshy and human-edible, most of which were ripening or ripe (PT1: 72.4%; R1: 94.8%). The main fruit for both groups was Artocarpus heterophyllus (Moraceae; jakfruit), a cultivar with fleshy fruit. These findings differ from previous understanding of colobine diets. I suggest that environmental factors, such as the abundance and nature of available fruits, and the absence of arboreal-primate fruit competitors, could influence the use of ripe fleshy fruits by colobines strongly, highlighting the need to review the dietary and digestive flexibility of this group in changed and changing natural environments to formulate effective conservation action.     

Lack of Involvement of Nutrients in the Latency of Alternaria alternata in Unripe Mango Fruits

The possible relation between changes in mango fruit composition during ripening and the latency of Alternaria alternata infections was investigated. The main increase in total soluble solids and the decrease in acid content in ripening mangofruits occurred during the initial 13 days after harvest, while symptoms of A. alternata appeared only 5 days later. Susceptibility of resistant peeled mango fruits flesh could not be increased by infiltration with sucrose, at a concentration that sustains maximal growth in vitro.     

Physiological and molecular analyses of early and late Coffea arabica cultivars at different stages of fruit ripening

Coffee quality is strongly influenced by a great number of factors, among which the fruit ripening stage at harvest time has a major influence on this feature. Studies comprising ethylene production and the regulation of ethylene biosynthesis genes during the ripening process indicate that ethylene plays an important role on coffee fruit ripening. Coffee early cultivars usually show a more uniform ripening process although little is known about the genetic factors that promote the earliness of ripening. Thus, in order to better understand the physiological and genetic factors involved in the regulation of ripening time, and consequently ripening uniformity, this study aimed to analyze ethylene and respiration patterns during coffee ripening, as well as to analyze ACC oxidase, an ethylene biosynthesis enzyme, gene expression, in fruits of early (Catucaí 785-15) and late (Acauã) coffee cultivars. Coffee fruits were harvested monthly from 124 days after flowering (end of February), until complete maturation (end of June). Dry matter, moisture content, color, respiratory rate and ethylene production analysis were performed. In silico analysis identified a coffee ACC oxidase gene (CaACO-like) and its expression was analyzed by real-time PCR. Dry matter and relative water content constantly increased and gradually decreased, respectively, during fruit ripening, and the color analysis enabled the observation of the earliness in the ripening process displayed by Catucaí 785-15 and its higher fruit ripening uniformity. The results obtained from the CaACO-like expression analysis and respiration and ethylene analysis suggest that the differences in ripening behavior between the two coffee cultivars analyzed in this study may be related to the differences in their capacity to produce ethylene, with fruits of Catucaí 785-15 and Acauã showing a typical and an attenuated climacteric phase, respectively, which may have lead to differences in their ripening time and uniformity.     

Foliar application of aminoethoxyvinylglycine (AVG) delays fruit ripening and reduces pre-harvest fruit drop and ethylene production of bagged “Kogetsu” apples

Covering apple fruits with double layer waterproof bags to enhance fruit quality and evenness of blush colour is typical on many cultivars in Korea and Japan. Aminoethoxyvinylglycine (AVG) applied to unbagged apple fruits at 3–4 weeks before commercial harvest reduces ethylene production in the fruit, delays fruit ripening and reduces pre-harvest fruit drop. Spray application of AVG to trees of bagged apples should have no effect on apple ripening as there is␣no direct contact with the fruit and the translocation of AVG in apple trees is regarded as negligible. However, preliminary experiments suggested that AVG applied to trees of bagged apples reduced pre-harvest fruit drop in “Kotgetsu” apples. This study investigated the effect of spray treatments of 125 ppm of AVG on fruit drop, fruit ripening (firmness, starch conversion and soluble solids) and ethylene production to whole trees with bagged or unbagged “Kogetsu” fruit, as well as sprays of only the bagged or unbagged fruit on trees on two orchards. AVG applied to whole trees with unbagged apples reduced fruit drop from an average of 58.9% to 10.4%, delayed starch conversion and decreased ethylene production. AVG applied to whole trees with bagged fruit was equally effective in reducing pre-harvest drop, delaying fruit ripening and reducing ethylene production. Application of AVG to unbagged fruit only was nearly as effective as application to whole trees with unbagged fruit but application to bagged fruit only had no effect on fruit ripening or ethylene production. Application of AVG to bagged fruit only did reduce fruit drop to an average of 42.5% but this was not as effective as spraying unbagged fruit only or whole trees with bagged fruit. Possible mechanisms for this effect are discussed.     

Phenological variation in fruit characteristics in vertebrate-dispersed plants

Summary We investigated inter-specific variation in fruit characteristics — fruit size, seed number per fruit, seed weight, nutritional content, fruit persistence, and fruit synchronization — in relation to flowering and fruiting phenology in 34 species of fleshy fruited plants. Except for aspects of fruit synchrony and persistence, the results in general were inconsistent with previous suggestions about adaptive variation in phenologically related fruit traits. The main results were as follows: (1) Late flowering, late fruiting, lengthy development time from flower to fruit, and highly persistent fruits constitute a complex of correlated characteristics among the species. (2) Synchronization of fruiting within individuals increased from early ripening fruits to late ripening fruits. Fruiting synchrony was more pronounced in species with a small crop size than in species with a large fruit crop, whereas synchrony was not significantly related to flowering synchronization, nor to life form. (3) Nitrogen and carbohydrate content of fruit pulp did not vary in relation to phenology, whereas lipid content decreased from early to late ripening fruits. (4) No seasonal trends were found for variation in seed size or seed number per fruit. (5) Interactions with flowering phenology and developmental constraints are important in phenological fruiting patterns. Temporal variation in start of fruiting was partly (36%) explained by variation in flowering time. Seed weight variation explained 17% of variation in development time from flower to fruit. (6) Despite constraints from flowering and seed development, some adaptive adjustment in fruiting phenology is likely to be allowed for among the investigated species. Such an adaptive variation in fruiting phenology was suggested by intra-generic comparisons of Prunus and Vaccinium species.     

Mango - Postharvest Biology and Biotechnology

Mango is one of the choicest fruits in the world and popular due to its delicate taste, pleasant aroma and nutritional value. Mango is indigenous to north-east India and north Burma, but now grown in over 90 countries. In the past two decades, mango production has increased appreciably with international trade jumping approximately four-fold valued close to US$ 950 million. Mango belongs to the category of climacteric fruits and its ripening is initiated and proceeded by a burst in ethylene production and a dramatic rise in the rate of respiration. Although there are a few hundred mango cultivars grown in the Indian subcontinent and other parts of the world, the most popular cultivars are generally highly perishable and ripen within 7 to 9 days of harvest at ambient temperature. Currently, the export potential and international trade of mango is limited due to several factors such as its perishable nature, disease and pest infestation, and susceptibility of certain premium cultivars to chilling injury when stored at low temperatures. Efforts are ongoing to develop technologies for improved storage and packaging, and overcome limitations encountered during storage and transit. Controlled atmosphere (CA) and hypobaric storage of mango are powerful means to overcome its perishable nature. The composition of CA varies among cultivars to ensure its original taste, flavor and aroma. Edible coating on the fruit skin may further cut down the rate of deterioration. Recently, significant advances have been made in understanding ripening characteristics of mango at the molecular level. Candidate genes related to ethylene biosynthesis and signalling, cell wall modification, aroma production and stress response have been cloned and characterized for future use in mango improvement. Efforts are also being made to establish a suitable transformation and plant regeneration system so that transgenic mango with added value and increased shelf life for long distance transportation could be developed.     

Role of the Polygalacturonidase Inhibitor Protein in the Ripening of Apples and Their Resistance to Monilia fructigena, a Causative Agent of Fruit Rot

We investigated the dynamics of the activity of the polygalacturonidase inhibitor protein (PGIP) in apple fruits of six cultivars differing in ripening time and correlated it with the degree of damage by the causative agent of fruit rot, Monilia fructigena. The apple cultivars studied differed significantly in PGIP activity and degree of damage by Monilia fructigena. The rate of dissemination of the fungus over fruit tissues was inversely related to PGIP activity. The resistance of apples to M. fructigena increased with ripening. The simultaneous increase in PGIP activity suggests its important role in the reduction of apple damage by fruit rot.     

A Process-Based Model of TCA Cycle Functioning to Analyze Citrate Accumulation in Pre- and Post-Harvest Fruits

Citrate is one of the most important organic acids in many fruits and its concentration plays a critical role in organoleptic properties. The regulation of citrate accumulation throughout fruit development, and the origins of the phenotypic variability of the citrate concentration within fruit species remain to be clarified. In the present study, we developed a process-based model of citrate accumulation based on a simplified representation of the TCA cycle to predict citrate concentration in fruit pulp during the pre- and post-harvest stages. Banana fruit was taken as a reference because it has the particularity of having post-harvest ripening, during which citrate concentration undergoes substantial changes. The model was calibrated and validated on the two stages, using data sets from three contrasting cultivars in terms of citrate accumulation, and incorporated different fruit load, potassium supply, and harvest dates. The model predicted the pre and post-harvest dynamics of citrate concentration with fairly good accuracy for the three cultivars. The model suggested major differences in TCA cycle functioning among cultivars during post-harvest ripening of banana, and pointed to a potential role for NAD-malic enzyme and mitochondrial malate carriers in the genotypic variability of citrate concentration. The sensitivity of citrate accumulation to growth parameters and temperature differed among cultivars during post-harvest ripening. Finally, the model can be used as a conceptual basis to study citrate accumulation in fleshy fruits and may be a powerful tool to improve our understanding of fruit acidity.     

Spatio-temporal dynamics of willow beetle (Phratora vulgatissima) in short-rotation coppice willows grown as monocultures or a genetically diverse mixture

1 Phratora vulgatissima (Chrysomelidae) is the major pest of short-rotation coppice willows in the U.K., capable of causing severe defoliation in monoculture plantations. As this beetle shows feeding preferences between willow clones, knowledge of the spatio-temporal dynamics of P. vulgatissima is needed in order to assess the effects of mixed clonal plantings on the management of this pest. 2 Distribution patterns of adult P. vulgatissima were monitored over a season at a spatial scale of every tree or every other tree in single clone plantings (monocultures) of three willow clones and in a regular row mixture of these clones. 3 Distribution indices (deviation from Complete Spatial Randomness) demonstrated that P. vulgatissima adults were spatially aggregated on favourable clones in the monocultures and the mixture. The degree of aggregation (measured by the k-parameter of the negative binomial) differed between willow clones. Beetles were highly aggregated at the start of the season, but less so later. 4 Dispersal studies of P. vulgatissima adults over time showed a pattern of beetle infestation along rows of the preferred clones in a regularly structured mixture. In the monocultures, movement was less directional. 5 Plantation design offers some potential for more effective non-chemical pest management for P. vulgatissima. Monitoring of the pest must take account of our findings that adults occur in mobile aggregations.     

Endophytic fungal community succession in reproductive organs of two olive tree cultivars with contrasting anthracnose susceptibilities

The factors shaping endophytic fungal assemblages in reproductive organs have been less evaluated than in vegetative organs. Here, the temporal dynamics of fungal endophytes in inflorescences and fruits of olive tree cultivars with contrasting anthracnose susceptibilities was assessed, starting before flowers open until fruit ripening. Fungal diversity assessed by rRNA sequencing of cultivable isolates revealed a higher richness and abundance of endophytes in inflorescences than in fruits. Endophytes from Sordariomycetes were dominant in inflorescences, while in fruits they were from Dothideomycetes. The overall assemblages of inflorescences and fruits were shaped mainly by the plant organ, followed by the phenological stage and lastly, by the plant cultivar. The importance of cultivar as a shaping factor varied according to the plant organ, being only significant in inflorescence-associated endophytes. A set of fungal taxa were positively associated with a particular cultivar and phenological stage, likely contributing to the plant anthracnose resistance.     

Water-deficit Stress, Ethylene Production, and Ripening in Avocado Fruits

Differential rates of water loss were achieved in picked avocado (Persea americana Mill.) fruits, either by controlling the evaporation rate or by supplying water through the fruit stalk. A negative linear correlation was found between the daily rate of water loss from fruits and their ripening, as determined by the time from harvest to peak of ethylene production. Ripening rate was hastened by 40% in fruits which had lost water at rate of 2.9% fresh weight per day, compared with those which lost only 0.5% per day.     

Phytophagous preferences of the multicolored Asian lady beetle (Coleoptera: Coccinellidae) for autumn-ripening fruit

The objective of this study was to assess the potential pest status of Harmonia axyridis (Pallas) on autumn-ripening fruit. In autumn, H. axyridis has been observed feeding on pumpkins, apples, grapes, and raspberries in Minnesota. To determine whether H. axyridis can inflict primary feeding damage to fruit (i.e., breaking the skin of the fruit), we conducted laboratory feeding experiments with undamaged pumpkins, apples, grapes, and raspberries. The only fruit that H. axyridis was able to damage directly was raspberry. Laboratory choice tests were conducted to determine whether H. axyridis exhibits a preference between damaged and undamaged fruit, between cultivars of fruit, and between sugar water and water alone. For all fruits tested, H. axyridis showed a preference for damaged fruits over undamaged fruits. H. axyridis also exhibited a strong preference for sugar water over water alone. However, few differences were exhibited in preference between cultivars of fruit. In autumn, it seems that H. axyridis is an opportunist, taking advantage of previously damaged fruit, caused by other agents.