From pantrapping of bee specimens in the region , we know that total bee abundance is highest in the spring in natural areas. However, towards the end of the summer when yellow starthistle is in flower, there is little difference in collected bee abundance between human-altered landscapes and natural areas, and human-altered areas may even exhibit overall higher bee abundance. Our results of bee visitation to yellow starthistle support this pattern. Agricultural areas have large populations of managed honey bee colonies, so one would predict visitation to yellow starthistle by honey bees to be positively associated with surrounding agricultural land use. By contrast for native bees , the highest rates of visitation to yellow starthistle were in sites with more surrounding urban land use. Urban gardens have many exotic plants, often selected for aesthetic purposes, many of which are in flower later in the season than most California native plants. In addition, many of the plants in urban areas both directly and indirectly receive supplementary resources, particularly water, that further extend their flowering time. Even though agricultural areas also have supplementary resources, the main crop in flower in East Contra Costa County later in the season is maize, garden grow bags which is wind pollinated. There may be multiple impacts of exotic plants in urban areas. By filling the phenological flowering gap noted above, they may help attract even larger populations of bees into the urban landscape.

In addition, bees in urban sites may be behaviorally more likely to visit non-native plants due to the increased encounters they have with novel plants. In agricultural and natural landscapes, a positive correlation between pollinator visitation and seed set is typical . Surprisingly in our system, in human-altered landscapes, higher total observed bee visitation did not result in higher proportions of seed set, as would be expected. In fact, urban areas, despite receiving the highest rates of native bee visitation, exhibited the lowest rates of seed set. Conversely, natural areas, which received the lowest amount of total bee visitation, had the highest rates of seed set. We suggest 2 possible explanations for this discrepancy between pollinator visitation and rates of seed set: 1) pollinator efficiency; and/or 2) the composition of the local flowering community. Depending on the plant, certain pollinator species are much more effective than others. For example, Osmia, Habropoda, and Apis, have been found to produce varying amounts of seed set as a result of a single visit to blueberry, but these results vary slightly depending on the blueberry variety [52]. In the case of yellow starthistle, it is likely that the most frequent visitors are perhaps not the most efficient. When we directly compared average seed set at each site against visitation rates, we found a significant positive association with the medium hairy leg bees. The medium hairy leg bee morphotype includes those species which fall in both the Tribes Emphorini and Eucerini.

Emphorini are known to largely be oligolectic , meaning they specialize on certain plant groups, which theory suggests would make them more efficient pollinators than generalists. The medium hairy leg bee morphotype was not significantly associated with any of the land use typesIt was also the only group that was observed most frequently during morning sampling, perhaps reflecting a difference in when yellow starthistle is most receptive to pollination. Despite the overwhelming abundance of honey bees in agriculture areas, we did not observe higher seed set in those regions, consistent with the observation that honey bees can be poorer pollinators than other species.It is also important to note that this study used a morphotype classification, and there may be multiple species that fit within the same morphotype that provide varying degrees of pollination services. It is possible there are rare, but highly efficient, pollinators that were rarely observed during the sampling period, or were lumped together with a more frequently observed morphotype. An alternative explanation for the lack of an association between floral visitation and seed set is that higher plant diversity in urban and agricultural areas may decrease pollinator efficiency. Previous research has shown that invasive alien plants can have a negative effect on native plant communities by acting as attractors for pollinators, or decreasing pollinator efficiency by providing a wider range of resources for pollinators to visit, with the consequence that visitors transfer pollen from non con-specifics, potentially clogging stigmas and reducing pollination success.

In this case, our target plant, yellow starthistle is indeed considered an invasive alien plant, but the hypothesis of it being in a novel diverse community could lead to a similar effect on the frequency and quality of pollination services that it receives. In sites where there are many other potential plants to visit and accompanying decreased floral fidelity leading to diverse pollen loads, one predicts decreased pollinator efficiency. Abundant sources of exotic plant pollen could occur in areas where there is a greater diversity of nearby plants for pollinators to visit. This explanation might account for the observation that shield-tipped small dark bees were negatively correlated with seed set. We selected yellow starthistle as the target plant for this study because of its ubiquitous distribution, reliance on pollination, and its attraction for a wide set of visitors; it is also a highly invasive and undesirable plant. Previous research on yellow starthistle has found that its invasion can be facilitated other non-native pollinator species such as the honey bee, Apis mellifera, and the starthistle bee, Megachile apicalis, which is included in the medium striped hairy belly bee morphotype. However, the abundance of bees in both of these 2 morphotypes were most closely associated with agricultural areas, which did not have the highest rates of seed set as would be predicted by visitation alone. Our results indicate clearly that bee visitation in human-altered landscapes can be higher than that in comparable natural areas, especially towards the end of the flowering season when there are few resources available in natural landscapes. Because the response of bee visitors to land use change depends on species specific requirements and these pollinators also have variable effects on plants, understanding the effect of land use change on pollination services requires knowledge not only of which pollinator groups shift to the human-altered landscapes, but also the rate of pollination that those groups have on the plant species in those landscapes. Future research will benefit from looking at a wider range of plants with a different range of target pollinators and that flower earlier in the year to better tease out these hypotheses. If the patterns of bee visitation and seed set that we observed are indeed consistent across other plant species, the novel plant communities created in these human-altered landscapes and the generalist bee species that are favored in such landscapes will lead to a reduction in overall pollination services.Strawberries are among the world’s favorite fruits, cherished for their distinct flavor, nutritional value, health benefits, low calorie content, vibrant color, and versatility. They can be consumed fresh, frozen, or processed. However, their soft texture makes them highly vulnerable to tissue damage, moisture loss, microbial contamination, tomato grow bags and physiological deterioration during postharvest handling. Once harvested, they are quickly contaminated by microorganisms, leading to reduced firmness, discoloration, and a much shorter shelf life. This makes strawberries one of the most delicate and perishable horticultural products. Fresh strawberries have a very short shelf life of just 1–2 days at room temperature, and low-temperature storage is the most commonly used method for extending their shelf life. However, strawberries can only be stored for approximately 7 days at around 5 ◦C due to their delicate skin and soft flesh.

Globally, postharvest losses of strawberries can reach up to 50%, severely affecting the economic returns for growers and the availability of this nutritious fruit to consumers. The berry industry has acknowledged the urgent need to extend the initial quality of strawberries beyond the current constraints. There is a growing need for alternative, non-damaging, innovative, and environmentally friendly methods to preserve strawberries. Consequently, extensive research has been conducted worldwide to develop advanced storage and distribution technologies for strawberries. Some typical technologies include freezing, modified atmosphere packaging, gamma irradiation, and synthetic fungicides. Although these methods are effective, they have certain limitations and environmental concerns. The use of synthetic fungicides raises significant safety and health concerns due to chemical residues on the fruit. Gamma irradiation, though successful in controlling microbes, faces challenges related to environmental impact and consumer acceptance. Additionally, freezing is energy-intensive, leading to questions about its sustainability and cost-effectiveness for long-term storage. Modified atmosphere packaging is less harmful to the environment but can be expensive and complicated to implement. Given these challenges, there is an increasing need for innovative and sustainable postharvest preservation techniques that reduce economic losses and environmental impact while ensuring the quality and microbial safety of strawberries. Isochoric cold storage is one of the latest techniques developed to extend the shelf life of fresh fruits and vegetables. It uses subfreezing isochoric storage temperatures associated with pressures higher than atmospheric levels to decrease microbial loads. In isochoric cold storage, food is preserved at subfreezing temperatures within a fixed-volume chamber filled with a liquid solution. The freezing process follows the liquidus line on the phase diagram of the solution, with concurrent changes in pressure and temperature. At thermodynamic equilibrium, a significant volume of unfrozen liquid remains at any given temperature in the chamber. This allows food products to be preserved without harmful ice formation if they are kept in the unfrozen portion of the system. Unlike traditional freezing, which requires energy-intensive cooling to lower temperatures below the freezing point, isochoric systems maintain food at a constant pressure, using minimal energy to achieve preservation. This results in lower energy consumption, reduced operational costs, and a more environmentally sustainable alternative for food preservation. Isochoric cold storage is more energy-efficient than conventional freezing due to less ice formation and reduced temperature fluctuations experienced by the food. Also, recent studies have shown that the pressure generated during isochoric freezing can facilitate the infusion of liquid solutions into the pores of food products. As a result, isochoric impregnation is an effective method for rapidly introducing external liquids, including those containing active compounds, into the porous structures of food products at subfreezing temperatures. The objective of this study was to evaluate isochoric impregnation during isochoric cold storage at −2 ◦C/48 MPa as a postharvest treatment to extend the shelf life of strawberries during the subsequent refrigerated storage at 4 ◦C. Several nutritional and physicochemical quality attributes such as color, pH, titratable acidity, total soluble solids, weight change, fungal decay, texture, ascorbic acid, and total anthocyanin content were measured during the storage period.Fresh organic strawberries , sucrose, and food-grade calcium chloride were purchased from a local supermarket. Only strawberries with similar size and maturity stage were selected. Strawberries were stored for a maximum of one day at 4 ◦C before the subsequent sample processing. While all the strawberries were sourced and stored under identical conditions to ensure consistency at the start of the trials , it is important to note that immediate postharvest processing was not feasible due to the supply chain involved in acquiring the fruit. Strawberries were carefully sorted aseptically to discard over-ripe, damaged, deformed, or poor-quality fruits, ensuring a uniform sample in terms of size and color. Each sterile polyethylene bag was filled with 80 ± 10 g of strawberries in the following two different impregnation solutions: sucrose solution containing 11% sucrose and solution containing 1% CaCl2, 1% ascorbic acid, and 7.5% sucrose. CaCl2 was used to reduce softening, and the 1% concentration was selected as the maximum salt concentration that did not result in a salty flavor, based on sensory testing conducted with a panel of evaluators. In these preliminary tests, participants were asked to rate the intensity of the salty flavor in different concentrations of CaCl2, and the 1% concentration was determined to be the highest level that was still acceptable based on taste preferences. Ascorbic acid was used to prevent enzymatic browning, and the 1% concentration was chosen to ensure no alteration of the strawberry flavor, based on sensory testing where participants evaluated the flavor of the strawberries treated with varying concentrations of ascorbic acid. The simultaneous application of calcium salts and ascorbic acid improved fruit color and enhanced vibrancy and stability.