Measuring pollinator performance has become increasingly important with emerging needs for risk assessment in conservation and sustainable agriculture that require multi-year and multi-site comparisons across studies. However, comparing pollinator performance across studies is difficult because of the diversity of concepts and disparate methods in use. Our review of the literature shows many unresolved ambiguities. Two different assessment concepts predominate: the first estimates stigmatic pollen deposition and the underlying pollinator behaviour parameters, while the second estimates the pollinator's contribution to plant reproductive success, for example in terms of seed set. Both concepts include a number of parameters combined in diverse ways and named under a diversity of synonyms and homonyms. However, these concepts are overlapping because pollen deposition success is the most frequently used proxy for assessing the pollinator's contribution to plant reproductive success. We analyse the diverse concepts and methods in the context of a new proposed conceptual framework with a modular approach based on pollen deposition, visit frequency, and contribution to seed set relative to the plant's maximum female reproductive potential. A system of equations is proposed to optimize the balance between idealised theoretical concepts and practical operational methods. Our framework permits comparisons over a range of floral phenotypes, and spatial and temporal scales, because scaling up is based on the same fundamental unit of analysis, the single visit.
Summary 1.The honeybee Apis mellifera is currently in decline worldwide because of the combined impacts of Colony Collapse Disorder and the Varroa destructor mite. In order to gain a balanced perspective of the importance of both wild and managed pollination services, it is essential to compare these services directly, a priori, within a cropping landscape. This process will determine the capacity of other flower visitors to act as honeybee replacements. 2. In a highly modified New Zealand agricultural landscape, we compared the pollination services provided by managed honeybees to unmanaged pollinator taxa (including flies) within a Brassica rapa var. chinensis mass flowering crop. 3. We evaluate overall pollinator effectiveness by separating the pollination service into two components: efficiency (i.e. per visit pollen deposition) and visit rate (i.e. pollinator abundance per available flower and the number of flower visits per minute). 4. We observed 31 species attending flowers of B. rapa. In addition to A. mellifera, seven insect species visited flowers frequently. These were three other bees (Lasioglossum sordidum, Bombus terrestris and Leioproctus sp.) and four flies (Dilophus nigrostigma, Melanostoma fasciatum, Melangyna novae-zelandiae and Eristalis tenax). 5. Two bee species, Bombus terrestris and Leioproctus sp. and one fly, Eristalis tenax were as efficient as the honeybee and as effective (in terms of rate of flower visitation). A higher honeybee abundance, however, resulted in it being the more effective pollinator overall. 6. Synthesis and applications. Alternative land management practices that increase the population sizes of unmanaged pollinator taxa to levels resulting in visitation frequencies as high as A. mellifera, have the potential to replace services provided by the honeybee. This will require a thorough investigation of each taxon's intrinsic biology and a change in land management practices to ensure year round refuge, feeding, nesting and other resource requirements of pollinator taxa are met.
Determining the potential for hybridisation between transgenic crops and their relatives is a major component of risk assessment. Recent assessments of the extent of reproductive compatibility between crops and their relatives draw heavily on existing data from experimental crosses to infer the likelihood of hybridisation and introgression. Since the literature in this area continues to grow at a rapid pace, it is essential that such analyses can be easily updated. We used a database approach to assemble data on reproductive compatibility for eight crop species in Brassica, Raphanus and Sinapis, using data from hand pollination, spontaneous (unassisted) pollination and trials using in vitro techniques (e.g. embryo rescue), incorporating 326 studies and 216 species combinations. We found many reports for major crop species (B. juncea, B. napus, B. oleracea and B. rapa), but fewer for minor crops (B. carinata, B. nigra, Raphanus sativus and Sinapis alba). Many species combinations remain untested, and we highlight these information gaps. While reproductively incompatible species can be discounted as targets for transgene escape, compatible species must be evaluated further in the particular context where transgenic crops are grown. Because the data is retained in a database in a relatively unmodified form, multiple views of the data can be generated; this review represents one possible view of this data. Our approach also allows new data to be easily incorporated into future reanalyses and can be extended to other crop groups, and as such is a useful method of assembling, analysing and sharing data for risk assessment.
Understanding the role of unmanaged arthropod flower visitors as crop pollinators is critical if robust and reliable long‐term alternatives are to be found for honey bee pollination. However, data on pollinator assemblages can be scant. Field observation of crop flower visitors is a common data collection technique but it can be inadequate for species identification and is labour‐intensive if used across many sites. Trapping may reduce this problem, but trap performance and sampling consistency over long distances (sites separated by >100 km) are rarely examined. Window traps were designed to collect flower‐visiting arthropods from peak‐flowering onion (Allium cepa) and pak choi (Brassica rapa var. chinensis) fields across several regions throughout New Zealand. Trap efficacy was evaluated by comparing trapped samples with observations of flower visiting arthropods during the same trapping period, from dawn (6:00 to 7:00 hours) through to dusk (20:00–21:00 hours) at the same locations. Similar types of larger arthropods (length ≥3 mm) were observed and trapped within both crops, with the hymenopteran genera Apidae, Colletidae and Halictidae and the dipteran families Syrphidae, Calliphoridae, Anthomyiidae, Stratiomyidae, Sarcophagidae, Bibionidae, Tachinidae and Muscidae the most commonly recorded. The total counts of these taxa across fields were strongly correlated between the two methods; however, the ratio of trapped to observed individuals could vary greatly between taxa. Trapping allowed more arthropods to be identified to the species level and also helped record more small arthropods (body length <3 mm) when compared with observation. Window traps can be effective for assessing the relative diversity of flower visitor assemblages and the abundance of specific taxa in specific cropping systems at the regional scale, but variation in trap efficiency between arthropod taxa must be assessed for a true measure of assemblage composition.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.