Insights into the susceptibility of raspberries to Drosophila suzukii oviposition

The spotted wing drosophila (SWD) causes massive losses in red raspberry (Rubus idaeus L.) cultivation by direct oviposition leading to damages of the soft skin fruits. Knowledge of the fly's host preference could help farmers in managing the pest. We used a laboratory-based oviposition assay for screening the germplasm of Rubus to ascertain whether the spotted wing drosophila prefers certain cultivars to others for oviposition and if preference is based on citric acid and Brix content or firmness. Correlation analyses of evaluated characters with no-choice tests results in 3 years obtained no correlation between citric acid, Brix content and oviposition. Primocane raspberries were lower affected by SWD than floricane raspberries. The Rubus hybrid cultivar “Dorman Red” and the primocane cultivar “Pokusa” showed the lowest oviposition rate compared to the other 58 evaluated genotypes. We found that oviposition correlates to firmness of the investigated cultivars, which strongly indicates that host preference is partly connected to that character in raspberries. The results are discussed regarding the use of Rubus genetic resources in breeding and integrated pest management to control spotted wing drosophila in the field.     

Fruit Colour Preferences of Redwings (Turdus iliacus): Experiments with Hand-Raised Juveniles and Wild-Caught Adults

Certain fruit colours and their contrast with the background coloration are suggested to attract frugivorous birds. To test the attractiveness of different colours, we performed three experiments in laboratory with controlled light conditions. In the first two experiments, we studied the fruit colour preferences of naive juvenile redwings. In the third experiment, we continued to investigate whether the contrast of the fruit colour with the background coloration affects the preference of both naive juveniles and experienced adult redwings. In the first experiment, juvenile birds preferred black, UV‐blue and red berries, to white ones. In pairwise trials, a new set of juveniles still preferred red berries to white ones. When testing the effect of contrasts on their choice, juveniles preferred UV‐blue berries to red ones on a UV‐blue background. However, no preference was found, when the background was either red or green. Adult redwings preferred UV‐blue berries to red ones on all backgrounds. According to these results, juveniles seem to have an innate avoidance of white berries. Furthermore, the foraging decisions of fruit‐eating birds are affected more by fruit colour than its contrast with background coloration, at least when contrasting displays are encountered from relatively short distances. Differences in preferences of adult and juvenile birds also indicate that learning seems to play a role in fruit choices.     

Seasonal occurrence of spotted wing drosophila in various small fruits and berries in Pennsylvania and Maryland

Spotted wing drosophila (SWD) (Drosophila suzukii), a major invasive pest of small fruit crops, was first found in Pennsylvania and Maryland during the 2011 crop season, and since then, it has been established throughout the fruit growing regions of both states. A season‐long field study was conducted to find out the seasonal occurrence of SWD in several fruit crops (e.g. blueberry, tart and sweet cherry, floricane‐fruiting summer red raspberry, blackberry, primocane‐fruiting fall raspberries and table grapes) in Pennsylvania and Maryland in 2014. This is the first study determining seasonal occurrence of SWD using a standard commercial lure (Pherocon^® SWD Dual‐Lure^?)‐baited traps in this region. In both states, SWD adults were not captured prior to the month of July, and populations of SWD were found to build up in fruit crops only from mid‐July onwards. This indicates early season fruit crops or varieties are not at risk from SWD fruit injury in these two states. Such early fruit crops, for instance strawberry, sweet and tart cherry, are generally harvested before SWD populations build up in this region. In this context, implications of SWD population in various small fruit crops grown in this region and the utility of SWD Dual‐Lure ^? in season‐long monitoring of SWD population are discussed.     

Effects of fruit‐baited trap height on flower and leaf chafer scarab beetles sampling in Amazon rainforest

There is no standardization of ideal trap installation height for an accurate sampling of flower and leaf chafer scarab beetles in the rainforest canopy. This limits the comparison among different studies on the ecology as well as systematic collecting of this beetle group. Here, we sampled flower and leaf chafer beetles using fruit‐baited traps installed at different heights (1.5, 4.5, 7.5 and 10.5 m) in the Brazilian Amazon rainforest with the following proposals: (i) we tested whether there are effects of trap installation height on the abundance, species richness and biomass of these beetles; and (ii) we tested whether there is a difference in the species composition between each trap height. From January to April 2017, we sampled flower and leaf chafer beetles by using traps baited with a banana and sugarcane juice mixture in Amazon rainforest fragments in Porto Velho, Rondônia, Brazil. The abundance, species richness and biomass of flower chafer beetles (Cetoniinae) were higher in traps installed at 10.5 m. For leaf chafer beetles (Rutelinae), we found the higher species richness and abundance at 4.5, 7.5 and 10.5 m, but the biomass of these insects did not differ among the different heights. Only the community composition of flower chafer beetles differed among the different trap installation heights. Our results showed that flower chafer beetles demonstrate a preference for foraging for resources at greater heights in the Amazon rainforest. Thus, to collect cetoniines from tropical forests, the recommended manner is to install the traps in the forest canopy.     

Susceptibility of cold hardy grapes to Drosophila suzukii (Diptera: Drosophilidae)

Drosophila suzukii (Diptera: Drosophilidae), known commonly as spotted wing drosophila, is a vinegar fly originating from South‐East Asia and a major pest to many soft‐skinned fruits. Due to the species recent arrival in North America in 2008, many fruit varieties are yet untested for susceptibility to infestation. While previous work has focused on Vitis vinifera, this study aimed to determine grape susceptibility of cold hardy varieties based on hybrids of V. labrusca, V. riparia and V. vinifera. Field sampling was conducted in Southern Wisconsin (USA) vineyards to establish adult and larval abundance and determine whether the number of adults caught in traps correlates with fruit infestation. Host susceptibility was further assessed through no‐choice bioassays of both intact and damaged fruits. The field study found D. suzukii adults present in all varieties, low larval abundance and no correlation between adult abundance and larval presence. Peak adult abundance occurred mid‐season between veraison and harvest, while larval infestation rates were highest near harvest. In laboratory no‐choice tests, significantly more eggs, larvae and adults occurred in damaged than undamaged grapes. In damaged grapes, larvae and adult abundance was comparable between varieties and to the highly susceptible control of undamaged raspberry; however, D. suzukii developed significantly faster in raspberry than grapes. Fruit characteristics (°Brix, titratable acidity, pH) in grapes were uncorrelated with D. suzukii performance. Together, these findings suggest that cold hardy grapes are overall resistant to D. suzukii if intact and highly susceptible if damaged.     

Ultraviolet reflection of berries attracts foraging birds. A laboratory study with redwings (Turdus iliacus) and bilberries (Vaccinium myrtillus)

Unlike humans, birds perceive ultraviolet (UV) light (320 to 400 nm), a waveband which is known to play a role in avian mate choice. However, less attention has been paid to the role of UV light in avian foraging. Some blue, violet and black berries reflect UV light. The colour of berries might be an effective advertisement for avian seed dispersers and indicate the stage of fruit ripeness. We conducted an experiment to test how the UV reflection of berries affects birds'' foraging. Redwings were allowed to choose between UV-reflecting bilberries and rubbed bilberries (UV reduced) in the presence and absence of UV light. We used wild-caught adult and hand-raised juvenile birds to assess possible differences between experienced and naive birds. We found that adult redwings preferred UV-reflecting berries when UV illumination was present, but when UV illumination was absent, they did not distinguish between the two berry types. Our study therefore shows, for the first time, that UV wavelengths are used when birds feed on fruit. However, naive birds showed no preferences, suggesting that age and/or learning may affect frugivore preference for UV reflectance.     

The influence of anthropogenic edge effects on primate populations and their habitat in a fragmented rainforest in Costa Rica

When a forest is fragmented, this increases the amount of forest edge relative to the interior. Edge effects can lead to loss of animal and plant species and decreased plant biomass near forest edges. We examined the influence of an anthropogenic forest edge comprising cattle pasture, coconut plantations, and human settlement on the mantled howler (Alouatta palliata), white-faced capuchin (Cebus capucinus), Central American spider monkey (Ateles geoffroyi), and plant populations at La Suerte Biological Research Station (LSBRS), Costa Rica. We predicted that there would be lower monkey encounter rate, mean tree species richness, and diameter at breast height (DBH) in forest edge versus interior, and that monkeys would show species-specific responses to edge based on diet, body size, and canopy height preferences. Specifically, we predicted that howler monkeys would show positive or neutral edge effects due to their flexible folivorous diet, large body size, and preference for high canopy, capuchins would show positive edge effects due to their diverse diet, small body size, and preference for low to middle canopy, and spider monkeys would show negative edge effects due their reliance on ripe fruit, large body size, and preference for high upper canopy. We conducted population and vegetation surveys along edge and interior transects at LSBRS. Contrary to predictions, total monkey encounter rate did not vary between the forest edge and forest interior. Furthermore, all three species showed neutral edge effects with no significant differences in encounter rate between forest edge and interior. Interior transects had significantly higher mean tree species richness than edge transects, and interior trees had greater DBH than edge trees, although this difference was not significant. These results suggest that forest edges negatively impact plant populations at La Suerte but that the monkeys are able to withstand these differences in vegetation.     

Ecomorphology, differentiated habitat use, and nocturnal activities of Rhinolophus and Hipposideros species in East Asian tropical forests

We investigated the wing morphology and foraging distributions of sympatric Rhinolophus and Hipposideros species by acoustic sampling, measuring wing parameters, and observing bats in different settings of tropical East Asian forests, to evaluate their flexibility in habitat use and edge sensitivity. R. formosae and H. terasensis were more abundant at edges/in open habitats and shared the highest overlap, with R. formosae displaying the greatest breadth in habitat use, whereas R. monoceros had a higher abundance and feeding efficiency in forest interiors with a continuous canopy. H. terasensis was significantly larger and had higher wing loading and aspect ratio than R. formosae and R. monoceros, while R. formosae had higher wing loading but a lower aspect ratio than the smaller-sized R. monoceros. Shrubs and herbs were higher at sites where bats were captured than at those without bat captures, and R. monoceros and R. formosae were associated with greater canopy and ground coverage, respectively. R. monoceros always foraged while flying at lower heights close to the herb/shrub layers, while H. terasensis and R. formosae used perching to different extents, with R. formosae preferably using fly-catching techniques and appearing farther from the path in open forests rather than in forest interiors. Our results indicate that differences in wing parameters account for the different degrees of flexibility in habitat use, yet the deviations of call frequency from the expected values in R. formosae and H. terasensis suggest additional adaptations accounting for their flexibility in exploring habitats.     

Can wing morphology inform conservation priorities for Southeast Asian cave bats?

Adaptations for foraging in the complex airspaces of forest interiors may make bat species in the Asian tropics particularly susceptible to forest loss. However, ecomorphological analysis of Vietnamese bat assemblages challenges the hypothesis that, due to their greater vagility, cave‐roosting bats are less vulnerable to habitat fragmentation than foliage‐roosting species. Of the 13 most highly adapted forest‐interior species in our study, eight were cave‐roosting members of the Rhinolophidae and Hipposideridae and had wing morphologies closely resembling five foliage‐roosting members of the Murininae and Kerivoulinae—species typically thought to have low vagility. Overall, both cave‐roosting and foliage‐roosting bats exhibited a wide range of flight indices and species' wing designs corresponded with preferred foraging habitats, suggesting that foraging strategy may outweigh roost preference as a determinant of bat wing morphology and flight performance. Consequently, where such variation occurs, cave‐roosting bat ensembles are likely to include species with low vagility and similar sensitivity to habitat fragmentation. This could have important conservation implications as Asian karst formations support high cave densities and important bat diversity yet increasingly represent forest refugia in anthropogenic landscapes. We, therefore, advocate greater consideration of species vagility in determining conservation priorities for the region's bat fauna.     

Evaluation of organic insecticides for management of spotted‐wing drosophila (Drosophila suzukii) in berry crops

Spotted‐wing drosophila, Drosophila suzukii (Matsumura), is an invasive pest affecting fruit production in many regions of the world. Insecticides are the primary tactic for controlling D. suzukii in organic as well as conventional production systems. Organic growers have a greater challenge because fewer insecticides are approved for use in organic agriculture. The most effective organically approved product is spinosad, but alternatives are needed because of label restrictions limiting the number of applications per year, toxicity to beneficial arthropods and the risk of developing resistance. We evaluated several organically approved insecticides against D. suzukii in laboratory assays and field trials conducted on organic blueberry and raspberry farms. Spinosad was consistently the most effective insecticide, but a few other insecticides such as azadirachtin + pyrethrins, Chromobacterium subtsugae and sabadilla alkaloids showed moderate activity. None of the treatments had long residual activity. Mortality started to decline by 3 days after treatment, and by 5 days after application, the treatments were not different from the controls. These products may be useful in rotation programmes, necessary for reducing reliance on spinosad and mitigating resistance. Cultural and biological control approaches are needed in fruit production for D. suzukii management, but insecticides will likely continue to be the dominant management tactic while these other approaches are being optimized and adopted.     

A seed parasitoid wasp prevents berries from changing their colour,reducing their attractiveness to frugivorous birds

1. Frugivorous and seed‐feeding insects may alter the traits of fruits, such as shape and size, which may influence fruit attractiveness to frugivorous birds. Consequently, trait‐mediated interactions may occur in systems where plants, seed‐dispersing frugivorous vertebrates, and frugivorous or seed‐feeding insects interact. We investigated colour manipulation in Ilex integra Thunb. berries caused by the seed parasitoid wasp Macrodasyceras hirsutum Kamijo and how that manipulation relates to fruit attractiveness for frugivorous birds. 2. In winter, the colour of I. integra berries varied from green to red, but most berries were greenish, indicating that the berries were immature. Berry dissection indicated that the number of live parasitoid larvae present within each berry was closely related to berry colour – the greater the number of live larvae, more intense is the green colour of the berry. However, the wasp larvae did not modify the shape or size of the berries. More than 98% of berries that were protected from the insects by gauze bags ripened and turned red. In the present study, berries with unfertilised seeds alone turned red. Field‐feeding preference tests showed that the brown‐eared bulbul Hypsipetes amaurotis Temminck preferred red berries to green berries. 3. We demonstrated that the seed parasitoid wasp manipulates the berry colour, but not its shape or size, in a density‐dependent manner. Because green berries suffered less from bird foraging, we believe that this colour manipulation helps the wasps to avoid being killed by the birds. The present study indicates that manipulation by wasps may reduce the level of mutualism between the tree and seed‐dispersing birds.     

Plasticity in oviposition and foraging behavior in the invasive pest Drosophila suzukii across natural and agricultural landscapes

The effects and extent of the impacts of agricultural insect pests in and around cropping systems is a rich field of study. However, little research exists on the presence and consequence of pest insects in undisturbed landscapes distant from crop hosts. Research in such areas may yield novel or key insights on pest behavior or ecology that is not evident from agroecosystem-based studies. Using the invasive fruit pest Drosophila suzukii (Matsumura) as a case study, we investigated the presence and resource use patterns of this agricultural pest in wild blackberries growing within the southern Appalachian Mountain range of North Carolina over 2 years. We found D. suzukii throughout the sampled range with higher levels of infestation (D. suzukii eggs/g fruit) in all ripeness stages in natural areas when compared with cultivated blackberry samples, but especially in under-ripe fruit. We also explored a direct comparison of oviposition preference between wild and cultivated fruit and found higher oviposition in wild berries when equal weights of fruit were offered, but oviposition was higher in cultivated berries when fruit number was equal. Forest populations laid more eggs in unripe wild-grown blackberries throughout the year than populations infesting cultivated berries. This suggests D. suzukii may change its oviposition and foraging behavior in relation to fruit type. Additionally, as D. suzukii exploits a common forest fruit prior to ripeness, further research is needed to explore how this affects wild food web dynamics and spillover to regional agroecosystems.     

Pesticide‐mediated disruption of spotted wing Drosophila flight response to raspberries

The disruption of chemical communication between insects and host plants may take place due to an interference with the signal‐emitting host plant, or the signal‐receiving insect, compromising the signal production and emission, or its reception and processing. Anthropogenic compounds, in general, and pesticides, in particular, may impair the chemical communication that mediates host location by insects. Five different pesticides (the insecticides malathion, pyrethrins and spinetoram, and the fungicides fenhexamid and pyrimethanil) were applied at their field rates to raspberry fruits, or Petri dishes enclosing adult spotted wing Drosophila (SWD; Drosophila suzukii), and the attraction to fruit volatiles was evaluated in a series of two‐choice flight bioassays. The application of raspberry fruit with pesticides did not statistically affect attraction of unexposed adults, with exceptions being the spinetoram treatment, which led to mild insect avoidance, and the pyrethrin treatment, which resulted in slightly preferential attraction. In contrast, adults sublethally exposed to the pesticides had their flight take‐off impaired by the insecticides, but not by the fungicides. Furthermore, all pesticides, and particularly the insecticides, compromised the upwind capture of adults. Thus, the treatment with pesticides may indeed interfere with the flight response of SWD to host volatiles, particularly when the insects were previously exposed to pesticides. These findings are suggestive of the potential for sublethal insecticidal exposures to aid pest control and also provide evidence that pesticide use may compromise sampling/trapping strategies for this pest species that are based on attraction to host volatiles.     

Kolmogorov-type competition model with finitely supported allocation profiles and its applications to plant competition for sunlight

A Kolmogorov-type competition model featuring allocation profiles, gain functions, and cost parameters is examined. For plant species that compete for sunlight according to the canopy partitioning model [R.R. Vance and A.L. Nevai, Plant population growth and competition in a light gradient: a mathematical model of canopy partitioning, J. Theor. Biol. 245 (2007), pp. 210–219] the allocation profiles describe vertical leaf placement, the gain functions represent rates of leaf photosynthesis at different heights, and the cost parameters signify the energetic expense of maintaining tall stems necessary for gaining a competitive advantage in the light gradient. The allocation profiles studied here, being supported on three alternating intervals, determine “interior” and “exterior” species. When the allocation profile of the interior species is a delta function (a big leaf) then either competitive exclusion or coexistence at a single globally attracting equilibrium point occurs. However, if the allocation profile of the interior species is piecewise continuous or a weighted sum of delta functions (multiple big leaves) then multiple coexistence states may also occur.     

Vacuuming tarnished plant bug on strawberry: a bench study of operational parameters versus insect behavior

A vacuum apparatus was used in a test bench environment to determine the effects of two operational parameters on vacuuming efficacy for an insect pest. Nymphs and adults of tarnished plant bug, Lygus lineolarisP. de. B. (Hemiptera: Miridae), marked with fluorescent powder, were positioned on strawberry plants according to three height classes. Three speeds of inlet passage (i.e., 2, 4 and 6 km h^–1) and two heights (passage at 2/3 and 3/3 of the canopy) of inlet relative to the top canopy of the plants were investigated. After vacuuming the marked insects remaining on the plants were then found using a UV light and the class height of their position on the plant and the substrate (i.e., soil, leaf, stem or fruit/flower) were noted. The efficacy of the vacuum was optimal when the inlet was passed at 4 km h^–1with the inlet at a height of 2/3 of the strawberry canopy. Nymphs were usually vacuumed more efficiently than adults. Most (64.5%) individuals that were not vacuumed did not change position after inlet passage. Most (85.9%) individuals that changed position after inlet passage experienced vertical, mostly downward, movements.     

Genetics and ecology of Drosophila melanogaster larval foraging and pupation behaviour

In this paper we show that, (1) Drosophila melanogaster larvae utilize a variety of pupal microhabitats in an orchard, (2) variation in larval foraging path length, pupation distance from the food and pupal microhabitat preference (on or off the fruit) is genetically based and, (3) variation in these behaviours can be maintained in a spatially heterogenous environment since there is a reversal in pupation site suitability in wet and dry pupal microhabitats. Differences in path length in both laboratory and natural populations can be attributed to genes on the second pair of chromosomes and is under simple genetic control, whereas differences in pupal height are polygenically inherited (the second pair of chromosomes influences pupal height three times more than the third pair). Pupae collected from on-fruit sites had shorter foraging path lengths and lower pupal heights than off-fruit populations. Populations from the orchard maintained their field pupal microhabitat preferences even after 1 year of rearing them in the laboratory. Larvae with the sitter larval phenotype (short path lengths and low pupal heights tended to pupate more on-fruit than those with the rover phenotype (long path lengths and high pupal heights). To determined if these genetically based differences in microhabitat preference contributed to fitness, larval pupation behaviour was studied in a “field assay” (dish with fruit on soil) with soil water content varied. At low soil water contents, pupal survivorship was significantly better on the fruit whereas, at high soil water contents, survivorship was better in the soil. There was a reversal in which microhabitat (dry or wet) was a better site for pupation. In the field environment where soil water content fluctuates in space and time, such a reversal would explain the maintenance of genetic variation for these larval behaviours. Another selective agent acting on D. melanogaster larvae in our orchard is parasitization by Asobara tabida. This parasitoid parasitizes larvae with high locomotory scores (e.g. rovers) significantly more than those with low scores (sitters). This study relates laboratory phenotypes to field phenotypes thereby linking the ecological, behavioural and genetic components of larval habitat selection in D. melanogaster.     

Accumulating wing damage affects foraging decisions in honeybees (Apis mellifera L.)

Abstract.  1. Nectar-foraging honeybees ( Apis mellifera ) on lavender ( Lavandula stoechas ) appear to forage so as to maximise net energy return from foraging bouts; however, evidence from other studies suggests that foraging has a detrimental effect on survival, due at least in part to physiological deterioration of the flight mechanism. But foragers also acquire wing damage during foraging, which may increase foraging effort and reduce foraging lifespan.
2. The accumulation of damage over time and its effects on foraging flight and flower choice were studied in the field using a system in which the criteria for flower preference by foragers was known from previous work. Wing damage accumulated exponentially over time and resulted in foragers becoming less choosy about the flowers they visited.
3. Damage added experimentally contributed independently to the effect on choosiness. Effects of wing damage (natural and added experimentally) were also independent of those of a relative measure of age, which related in an inconsistent way to changes in foraging preferences.     

The relationship between population density, habitat position and habitat breadth within a neotropical forest bird community

We examined the relationship between local abundance, habitat position and habitat breadth across bird species in a large Atlantic forest reserve in Brazil. This appears to be the first such study for any rainforest taxon. Habitat position for a species was its mean foraging height, along with the mean scores on three principal habitat axes for census stations at which it was recorded. Habitat breadth was the standard deviation of recorded foraging heights and the standard deviations of "positive" station scores on the habitat axes. We also examined differences in habitat position and breadth between endemic and wide-ranging taxa and amongst dietary groups. Amongst 31 species for which density estimation was possible, there were no correlations between local abundance and breadth of habitat use on any of the habitat axes. Breadth of habitat used did not vary with degree of endemism, but herbivores used a greater breadth of habitats on the axis describing canopy closure than did omnivores. Habitat position did not vary with endemic status, but herbivores preferred higher-biomass habitats than faunivores, and higher foraging heights than either faunivores or omnivores. Local abundance was linked weakly to habitat position with commoner species tending to forage in the lower strata of open-canopied areas. The 31 most commonly recorded species tended to occupy "middle-range" habitat positions, while 28 rarer species occupied habitats toward one or other end of the vegetation axes. These results suggest an association between the local abundance of a species and its habitat position, and especially its preference for common or mid-range habitats, rather than with its ability to utilise a wide range of habitats.     

Comparative analysis of quality and nutritional traits from Lonicera caerulea (Honeyberry) cultivars and other berries grown in Scotland

Lonicera caeruleabrix is a perennial shrub native to North America, Europe and Asia. It produces dark blue berries known as honeyberries or haskap berries which are produced commercially in several territories including Canada, Japan, Russia and Poland. Plants are suited to UK environments, but it is yet to be widely commercially developed in the UK. In the present work, quality and nutritional traits of six honeyberry cultivars grown in Scotland were compared with other commonly grown berry fruits (strawberry, raspberry, blueberry, blackberry, blackcurrant) to aid the identification of environmentally stable, high-quality honeyberry cultivars suitable for UK cultivation. Differences were observed in fruit quality variables (soluble solids, titratable acidity and Brix/acid ratios) between honeyberry cultivars. Three of six cultivars examined exhibited notable variation in soluble solids dependent on harvest year with ‘Aurora’ and ‘Strawberry Sensation’ having consistently high ^oBrix values. Titratable acidity exhibited cultivar differences and there was limited variation over harvest years. ‘Aurora’ exhibited consistently high ^oBrix/titratable acidity ratio reflected by high glucose and fructose content. Honeyberry fruit had good nutritional profile relative to other soft fruits with higher polyphenol and anthocyanin content than strawberry, blueberry, blackberry and raspberry, manifested in greater antioxidant capacity. The major anthocyanins in aqueous honeyberry fruit extracts were cyanidin, pelargonidin and peonidin glycosides. These findings indicate that L. caerulea represents a crop suitable for UK cultivation capable of producing high quality fruit with a valuable nutritional profile relative to other soft fruits. Cultivars exhibit significant differences in fruit quality and nutritional profile as well as harvest consistency and growers should consider this when establishing new plantations.     

Within-tree distribution of nest sites and foraging areas of ants on canopy trees in a tropical rainforest in Borneo

It has been argued that canopy trees in tropical rainforests harbor species-rich ant assemblages; however, how ants partition the space on trees has not been adequately elucidated. Therefore, we investigated within-tree distributions of nest sites and foraging areas of individual ant colonies on canopy trees in a tropical lowland rainforest in Southeast Asia. The species diversity and colony abundance of ants were both significantly greater in crowns than on trunks. The concentration of ant species and colonies in the tree crown seemed to be associated with greater variation in nest cavity type in the crown, compared to the trunk. For ants nesting on canopy trees, the numbers of colonies and species were both higher for ants foraging only during the daytime than for those foraging at night. Similarly, for ants foraging on canopy trees, both values were higher for ants foraging only during the daytime than for those foraging at night. For most ant colonies nesting on canopy trees, foraging areas were limited to nearby nests and within the same type of microhabitat (within-tree position). All ants foraging on canopy trees in the daytime nested on canopy trees, whereas some ants foraging on the canopy trees at night nested on the ground. These results suggest that spatial partitioning by ant assemblages on canopy trees in tropical rainforests is affected by microenvironmental heterogeneity generated by three-dimensional structures (e.g., trees, epiphytes, lianas, and aerial soils) in the crowns of canopy trees. Furthermore, ant diversity appears to be enriched by both temporal (diel) and fine-scale spatial partitioning of foraging activity.