[Improvement of crop pollination service through planting field-side companion plants: Current understan-ding and prospect]

Insect pollinators play a vital role in global crop pollination. Due to climate change, agricultural intensification, and urbanization in recent decades, insect pollinator abundance and species richness have declined rapidly at global and regional scales. Insufficient pollination on croplands is becoming a significant challenge worldwide. In recent years, planting of field-side companion plants that flower concurrently in the vacant space on croplands has been proposed as an effective measure in developed countries to improve pollinator abundance and diversity. These companion plants can provide stable food sources (such as nectar and pollen) and nesting sites for pollinators. Related studies in China are still limited. We reviewed the global research status on the effects of field-side companion plants on crop pollination services, focused on the factors influencing the impacts of co-flowering plants on crop pollination, optimal selection principles for companion plants, and put forward perspectives for application in Chinese agriculture.

Apis mellifera Solinvivirus-1, a Novel Honey Bee Virus That Remained Undetected for over a Decade, Is Widespread in the USA

A metagenomic analysis of the virome of honey bees (Apis mellifera) from an apiary with high rates of unexplained colony losses identified a novel RNA virus. The virus, which was named Apis mellifera solinvivirus 1 (AmSV1), contains a 10.6 kb positive-strand genomic RNA with a single ORF coding for a polyprotein with the protease, helicase, and RNA-dependent RNA polymerase domains, as well as a single jelly-roll structural protein domain, showing highest similarity with viruses in the family Solinviviridae. The injection of honey bee pupae with AmSV1 preparation showed an increase in virus titer and the accumulation of the negative-strand of AmSV1 RNA 3 days after injection, indicating the replication of AmSV1. In the infected worker bees, AmSV1 was present in heads, thoraxes, and abdomens, indicating that this virus causes systemic infection. An analysis of the geographic and historic distribution of AmSV1, using over 900 apiary samples collected across the United States, showed AmSV1 presence since at least 2010. In the year 2021, AmSV1 was detected in 10.45% of apiaries (95%CI: 8.41-12.79%), mostly sampled in June and July in Northwestern and Northeastern United States. The diagnostic methods and information on the AmSV1 distribution will be used to investigate the connection of AmSV1 to honey bee colony losses.

Bee pollination services and the burden of biogeography

Native bees augment pollination services in the Northern Hemisphere, especially cultivated apple crops, yet Southern Hemisphere contexts are poorly known. We observed the foraging behaviour of 69 354 invertebrate flower visitors in Australian orchards (two regions, 3 years) to assess the efficacy of pollination service (P_eff). Native stingless bees and introduced honey bees were the most abundant visitors and most efficacious pollinators (Tetragonula P_eff = 6.16; Apis P_eff = 13.02), with Tetragonula becoming important service providers above 22°C. However, visits by tree-nesting stingless bees decreased with distance from native forest (less than 200 m) and their tropical/subtropical distribution precludes pollination service in other major Australian apple-producing regions. More broadly distributed native allodapine and halictine bees transferred the most pollen per-visit, but their low abundances reduce efficacies (Exoneura P_eff = 0.03; Lasioglossum P_eff = 0.06), resulting in a general dependence on honey bees. This reliance is a burden of biogeography, since key Northern Hemisphere pollinators of apple (Andrena, Apis, Bombus, Osmia) do not naturally occur in Australasia-where there is only 15% generic overlap with Central Asian bees sympatric with wild apple distributions (cf. Palaearctic 66% and Nearctic 46% generic overlaps). The historical biogeography of bees therefore drives an extreme dependence on one introduced species for apple pollination in Australia.

Effects of Managed and Unmanaged Floral Margins on Pollination Services and Production in Melon Crops

Melon is among the most consumed fruits in the world, being a crop that depends almost entirely on insects for its reproduction, which is why it is especially sensitive to declining pollination services. Restoration and maintenance of hedgerows and agricultural borders around crops are generally carried out by sowing flowering herbaceous plants or establishing shrubby species; however, a cost-effective and lower-maintenance alternative for farmers could be as simple as allowing vegetation to regenerate naturally without any management actions. This work aimed to test the effects of three different types of margins (managed herbaceous, managed shrubby, and unmanaged herbaceous) on the overall abundance and richness of wild pollinators in melon crops. The work was performed in three localities in southern Spain over two years. Pollinators were monitored visually using 1 × 1 m sampling squares and pan traps within melon fields. Moreover, crop yield was estimated by measuring fruit weight and the number of seeds. In general, higher abundances of pollinators were observed in melon fields during the second year. In addition, the abundances of Syrphidae, Andrenidae, Apidae (excl. Apis mellifera), and pollinators other than bees, belonging to the orders Diptera, Coleoptera, Hymenoptera, and Lepidoptera, showed higher values in melon fields with shrubby margins than in fields with herbaceous margins (managed or unmanaged). However, no effect of floral margins on the yield of melon crops was found.

Use of a Managed Solitary Bee to Pollinate Almonds: Population Sustainability and Increased Fruit Set

Simple Summary

Methods to rear Osmia bees to pollinate fruit trees have been developed in various parts of the world. These bees are excellent pollinators but evidence that their populations can be sustained in orchards and their use results in increased fruit production is scarce. We released an Osmia cornuta population at one end of an almond orchard. Then, we surveyed the pollinators visiting the almond flowers and measured fruit set in trees located at increasing distances from the nesting stations. We found that fruit production was higher in the trees that received more Osmia visits. Importantly, this result was obtained against a strong background of honeybees, which were 10 times more abundant than Osmia. The Osmia population obtained at the end of the flowering period was 1.28 larger than the population initially released. Our study demonstrates that Osmia populations can be sustained in orchard environments and that even a small population of a highly effective pollinator may have a significant impact on fruit set. Our results are encouraging for the use of Osmia populations and for the implementation of measures to promote wild pollinators in agricultural environments.

Abstract

Osmia spp. are excellent orchard pollinators but evidence that their populations can be sustained in orchard environments and their use results in increased fruit production is scarce. We released an Osmia cornuta population in an almond orchard and measured its population dynamics, as well as visitation rates and fruit set at increasing distances from the nesting stations. Honeybees were 10 times more abundant than O. cornuta. However, the best models relating fruit set and bee visitation included only O. cornuta visitation, which explained 41% and 40% of the initial and final fruit set. Distance from the nesting stations explained 27.7% and 22.1% of the variability in initial and final fruit set. Of the 198 females released, 99 (54.4%) established and produced an average of 9.15 cells. Female population growth was 1.28. By comparing our results with those of previous O. cornuta studies we identify two important populational bottlenecks (female establishment and male-biased progeny sex ratios). Our study demonstrates that even a small population of a highly effective pollinator may have a significant impact on fruit set. Our results are encouraging for the use of Osmia managed populations and for the implementation of measures to promote wild pollinators in agricultural environments.

Why the views of Latin American Scientists on Citizen Science as a Tool for Pollinator Monitoring and Conservation Matter?

Pollinators are threatened all over the planet; scientific data about the status of them is essential for planning conservation and impact mitigation. Appropriate methods and costs for monitoring are being discussed and non-scientist participation in data collection in citizen science (CS) projects is a very promising option. However, there is criticism regarding the quality of data gathered by non-scientists and their real contribution to scientific research, which makes the engagement of scientists in these projects crucial for data verification and validation and training volunteers. CS is still poorly spread in Latin America, so in order to propose strategies to engage scientists, it is necessary to understand the attitude of these professionals towards CS and their interests in engaging in it. To this end, we conducted a survey with 96 biodiversity scientists based in five Latin American countries. In general, the respondents have a very favorable attitude towards CS, although only a small percentage of them are engaged in CS projects. Obtaining data for scientific research is the scientists' main interest in CS, although some of them have also expressed more altruistic reasons for engaging in CS related to ethical and social values. Our paper also suggests five interrelated strategies that can be taken to engage scientists in CS, covering the following: (a) create funding lines to support projects, (b) include extension and outreach activities in the system of scientists' evaluation, (c) promote an inter and transdisciplinary infrastructure, (d) promote scientists' building capacities in CS, and (e) encourage scientists to do science communication.

Scale-Dependent Waylaying Effect of Pollinators and Pollination of Mass-Flowering Plants

Pollinators foraging for food resources can be waylaid by mass-flowering plants located in their foraging pathway in landscapes. The waylaying effect of pollinators is often studied at a single spatial scale; to date, little is known about the best spatial extent at which waylaying effect of pollinators can be measured. In this study, we selected a landscape with mass-flowering tufted vetches to determine the spatial scale of waylaying effect of honey bees as well as the consequence of waylaying effect on vetch pollination service. The spatial scale of waylaying effect was determined by the strongest association between honey bee density and distance, selected from a gradient of nested circular buffers centering on apiaries in three different locations. Linear models were used to predict the influence of flower visitor densities on pollination service. For our landscape, honey bee densities were best associated with distances at spatial scales of 500 m, 1150 m, and 1400 m respectively for the three locations of apiaries. Honey bee was the only pollinator whose density displayed a positive relationship with pollination service. At the scales of effect, honey bee density and pollination service declined along the distance. Our findings suggest that the waylaying effect of pollinators needs to be examined at a specific spatial scale and farmers who use honey bees to pollinate their mass-flowering crops need to consider the spatial scale of waylaying effect of pollinators in order to maximize pollination service within agricultural ecosystems.

Abundance and Diversity of Wild Bees (Hymenoptera: Apoidea) Found in Lowbush Blueberry Growing Regions of Downeast Maine

Insect-mediated pollination is critical for lowbush blueberry (Ericaceae: Vaccinium angustifolium Aiton) fruit development. Past research shows a persistent presence of wild bees (Hymenoptera: Apoidea) providing pollination services even when commercial pollinators are present. We undertook the study to 1) provide a description of bee communities found in lowbush blueberry-growing regions, 2) identify field characteristics or farm management practices that influence those communities, 3) identify key wild bee pollinators that provide pollination services for the blueberry crop, and 4) identify non-crop plants found within the cropping system that provide forage for wild bees. During a 4-year period, we collected solitary and eusocial bees in over 40 fields during and after blueberry bloom, determining a management description for each field. We collected 4,474 solitary bees representing 124 species and 1,315 summer bumble bees representing nine species. No bumble bee species were previously unknown in Maine, yet we document seven solitary bee species new for the state. These include species of the genera Nomada, Lasioglossum, Calliopsis, and Augochloropsis. No field characteristic or farm management practice related to bee community structure, except bumble bee species richness was higher in certified organic fields. Pollen analysis determined scopal loads of 67-99% ericaceous pollen carried by five species of Andrena. Our data suggest two native ericaceous plants, Kalmia angustifolia L. and Gaylussacia baccata (Wangenheim), provide important alternative floral resources. We conclude that Maine blueberry croplands are populated with a species-rich bee community that fluctuates in time and space. We suggest growers develop and maintain wild bee forage and nest sites.