The extent of our reliance on animal pollination for world crop production for human food has not previously been evaluated and the previous estimates for countries or continents have seldom used primary data. In this review, we expand the previous estimates using novel primary data from 200 countries and found that fruit, vegetable or seed production from 87 of the leading global food crops is dependent upon animal pollination, while 28 crops do not rely upon animal pollination. However, global production volumes give a contrasting perspective, since 60% of global production comes from crops that do not depend on animal pollination, 35% from crops that depend on pollinators, and 5% are unevaluated. Using all crops traded on the world market and setting aside crops that are solely passively self-pollinated, wind-pollinated or parthenocarpic, we then evaluated the level of dependence on animal-mediated pollination for crops that are directly consumed by humans. We found that pollinators are essential for 13 crops, production is highly pollinator dependent for 30, moderately for 27, slightly for 21, unimportant for 7, and is of unknown significance for the remaining 9. We further evaluated whether local and landscape-wide management for natural pollination services could help to sustain crop diversity and production. Case studies for nine crops on four continents revealed that agricultural intensification jeopardizes wild bee communities and their stabilizing effect on pollination services at the landscape scale.

/pdf/importance-of-pollinators-in-changing-landscapes-for-world-2j8o9ygr29.pdf

Importance of pollinators in changing landscapes for world crops

Pollinators are a key component of global biodiversity, providing vital ecosystem services to crops and wild plants. There is clear evidence of recent declines in both wild and domesticated pollinators, and parallel declines in the plants that rely upon them. Here we describe the nature and extent of reported declines, and review the potential drivers of pollinator loss, including habitat loss and fragmentation, agrochemicals, pathogens, alien species, climate change and the interactions between them. Pollinator declines can result in loss of pollination services which have important negative ecological and economic impacts that could significantly affect the maintenance of wild plant diversity, wider ecosystem stability, crop production, food security and human welfare.

/pdf/global-pollinator-declines-trends-impacts-and-drivers-5gfi4zur4k.pdf

Global pollinator declines: trends, impacts and drivers.

Bees are subject to numerous pressures in the modern world. The abundance and diversity of flowers has declined, bees are chronically exposed to cocktails of agrochemicals, and they are simultaneously exposed to novel parasites accidentally spread by humans. Climate change is likely to exacerbate these problems in the future. Stressors do not act in isolation; for example pesticide exposure can impair both detoxification mechanisms and immune responses, rendering bees more susceptible to parasites. It seems certain that chronic exposure to multiple, interacting stressors is driving honey bee colony losses and declines of wild pollinators, but such interactions are not addressed by current regulatory procedures and studying these interactions experimentally poses a major challenge. In the meantime, taking steps to reduce stress on bees would seem prudent; incorporating flower-rich habitat into farmland, reducing pesticide use through adopting more sustainable farming methods, and enforcing effective quarantine measures on bee movements are all practical measures that should be adopted. Effective monitoring of wild pollinator populations is urgently needed to inform management strategies into the future.

https://science.sciencemag.org/content/sci/early/2015/02/25/science.1255957.full.pdf

Bee declines driven by combined stress from parasites, pesticides, and lack of flowers

https://www1.montpellier.inra.fr/lameta/articles/5.4.2_POLLINATION.pdf

Economic valuation of the vulnerability of world agriculture confronted with pollinator decline

Plant essential oils for pest and disease management

Experiments were conducted in commercial tomato, Lycopersicon esculentum Miller (Solanaceae), greenhouses to compare the relative foraging effort of two bumble bee species, Bombus occidentalis Greene and Bombus impatiens Cresson, to examine interspecific competition between B. occidentalis and B. impatiens, and to determine whether bumble bee colonies grew to their full population potential in commercial tomato greenhouses. B. impatiens colonies had more brood and workers and made more foraging trips per hour than B. occidentalis colonies. However, B. impatiens returned to the colony without pollen loads and left their colonies without dropping off their pollen loads more frequently than B. occidentalis greenhouse colonies. Our data also suggest that the presence of B. impatiens had a detrimental effect on B. occidentalis populations. Furthermore, B. occidentalis colonies did not grow to their full population potential in tomato greenhouses, with fewer workers in greenhouse colonies than in colonies placed outside in a natural environment, or in colonies that were physically enclosed and protected from external mortality. Together, this study suggests that B. impatiens is a better pollinator than B. occidentalis. It also shows that unknown factors are limiting the size of B. occidentalis colonies in tomato greenhouses.

https://bioone.org/journals/journal-of-economic-entomology/volume-97/issue-4/0022-0493-97.4.1384/Comparison-and-Examination-of-Bombus-occidentalis-and-Bombus-impatiens-Hymenoptera/10.1603/0022-0493-97.4.1384.pdf

Comparison and examination of Bombus occidentalis and Bombus impatiens (Hymenoptera: Apidae) in tomato greenhouses.

Workers of social insects are members of colonies that survive and reproduce together. Therefore, the behavioral activities of individual workers should be integrated with colony state. We here summarize and discuss the relationship between colony state and foraging behavior of individual workers under the provisional assumption that the colony is a unit. We argue that colony state can be described by a number of variables that should relate to fitness components in order to be meaningful. Among the possible candidates, colony population size seems to have an overriding importance in many respects, as shown by its relation to fitness components such as survival probability and reproductive performance. Other important variables include colony demography, i.e. caste or size distributions, nutritional status, or queen number. Each of these variables has been shown to affect fitness components; however, the evidence is rather scanty. We also discuss the evidence that variation in colony state variables relates to variation in individual worker behavior. Nutritional status (i.e. low or high levels of food stores) and colony size have been shown repeatedly to affect individual behavior. However, most of the evidence comes from the honey bee. Some studies suggest that behavioral responses are hierarchically structured. More work needs to be done to investigate the actual mechanisms of integration of individual behavior with colony state. Some knowledge has accumulated about the processes that govern recruitment to food sources. We conclude this review by discussing some concepts and problems for further research. These include the concept of a preferred colony state to which the colony should return after disturbance through the behavioral activities of the workers. Further theoretical elaboration and empirical investigations may help to elucidate whether this concept is useful and necessary. A largely neglected issue concerns the number versus effort problem, i.e. whether individuals should work harder or more workers should be allocated to a task that is in demand. We propose a simple scenario that suggests testable predictions. Finally, we discuss how colony state, individual work load, and the dependence of worker mortality rate on activity level may interact to generate different short-term foraging strategies that workers should adopt.

/pdf/invitation-paper-c-p-alexander-fund-foraging-of-individual-dz711sarwf.pdf

Invitation paper (c.p. alexander fund): foraging of individual workers in relation to colony state in the social hymenoptera

The influence of colony pollen storage and pupal infestation by the parasitic mite Varroa jacobsoni on worker longevity, foraging age, and behavior were investigated in the honey bee, Apis mellifera L. Workers reared in colonies with low pollen stores began foraging at younger ages and may have had shorter lifespans than workers reared in colonies with high pollen availability. Similarly, workers began foraging at younger ages and had shorter lifespans when they had been infested by V. jacobsoni as pupae. The decrease in foraging age and possibly lifespan caused by the pupal infestation was offset by the colony's pollen environment during brood rearing. Therefore, temporal task schedules are affected by both colony investment and parasitism by V. jacobsoni during brood rearing.

The influence of pollen storage area and Varroa jacobsoni Oudemans parasitism on temporal caste structure in honey bees (Apis mellifera L.)

Dominance and effects of strange conspecifics on aggressive interactions in the hermit crab Pagurus longicarpus (say).

The seasonal variation of pollen collected from different plant species by greenhouse bumblebees was investigated to determine how frequently bumblebees forage outside of commercial tomato greenhouses. Pollen was collected from bumblebees at three greenhouses between February and September 2001 and the plant species identity of pollen collected was determined with light microscopy. A significant amount of non-tomato pollen was collected by bumblebees during one or more months from outside each of the three greenhouses studied. The bees brought back as little as an average of 5% non-tomato pollen between February and September at one greenhouse and as much as 73% during July at another. Therefore, greenhouse tomato growers are probably not obtaining maximum pollination benefit from bumblebee colonies and should address methods to reduce their foraging outside the greenhouse. Key words: Bumblebee, Bombus occidentalis, Bombus impatiens, pollen, greenhouse, tomato

Mark L. Winston

Papers

Comparison and examination of Bombus occidentalis and Bombus impatiens (Hymenoptera: Apidae) in tomato greenhouses.

Invitation paper (c.p. alexander fund): foraging of individual workers in relation to colony state in the social hymenoptera

The influence of pollen storage area and Varroa jacobsoni Oudemans parasitism on temporal caste structure in honey bees (Apis mellifera L.)

Dominance and effects of strange conspecifics on aggressive interactions in the hermit crab Pagurus longicarpus (say).

Plant-species identity of pollen collected by bumblebees placed in greenhouses for tomato pollination