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It is increasingly recognized that gut microbiota have a major effect on the physiology, biology, ecology and evolution of their animal hosts. Because in social insects, the gut microbiota is acquired through the diet and by contact with nest provisions, it can be hypothesized that regular supplementation of microorganisms to the diet will have an impact on the fitness of the consumer and on the development of the whole colony. To test this hypothesis, we investigated how supplementation of bacteria, yeasts, and combinations of the two to either pollen or nectar affected colony development in the social bumblebee Bombus terrestris. Three yeasts and three bacterial species that live at the flower-insect interface were used in the experiments and the development of bumblebee colonies was monitored over a period of 10 weeks. The results showed that administration of microbes via pollen had a stronger positive impact on colony development than when provided via sugar water. Supplementation of bacteria led, in general, to a faster egg laying, higher brood size and increased production of workers during the first weeks, whereas yeasts or a combination of yeasts and bacteria had less impact on colony development. However, the results differed between microbial species, with Wickerhamiella bombiphila and Rosenbergiella nectarea showing the strongest increase in colony development. Torulaspora delbrueckii induced early male production, which is likely a fitness cost. We conclude that the tested bacteria-yeast consortia did not result in better colony development than the interacting species alone.

Generalist arthropod predators not only prey on herbivores but also may engage in competitive interactions by attacking and consuming conspecifics (cannibalism) or other predators (intraguild predation [IGP] and hyperpredation). These types of interactions are quite common among predators used in biological control. Although there is evidence that nonprey food relaxes cannibalism and IGP, there is little information regarding the impact of the quality of the nonprey food. Herein, we examined how pollen of different nutritional quality (pine, narrow-leaf cattail, or apple) impacted 1) the cannibalism by females of Euseius stipulatus (Athias-Henriot) (Acari: Phytoseiidae) on conspecific larvae, 2) the reciprocal predation between gravid females of E. stipulatus or Iphiseius degenerans (Berlese) (Acari: Phytoseiidae) and heterospecific larvae, and 3) the predation of E. stipulatus on the eggs of the aphid predator Aphidoletes aphidimyza (Rondani) (Diptera: Cecidomyiidae). E. stipulatus cannibalism was significantly reduced in the cattail pollen treatment, whereas in the pine pollen it did not significantly differ from control (no food). Predation between I. degenerans and E. stipulatus was significantly reduced in the cattail pollen treatment as compared to the control treatment. Finally, predation of E. stipulatus on A. aphidimyza eggs was significantly reduced when cattail or apple pollen was provided compared to the pine pollen or control treatments. These results suggest that cattail or apple pollen is suitable for mitigating negative interactions among generalist predatory mites used in biological control., (© The Author(s) 2017. Published by Oxford University Press on behalf of Entomological Society of America. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.)

Honeybees and bumblebees are the most important pollinators of agricultural crops. For this purpose honeybees and bumblebees are reared and transported. A pathogen-free status of bees in general, is crucial. Indeed anthropogenic transports of hosts carrying parasites could alter the natural host/pathogen association, inducing an extra pathogenic stress. Therefore the creation of a pathogen-free rearing environment is needed. For bumblebees this is possible, as these species are reared in a closed environment. Although, a link remains between reared bumblebees and the outside bee community, as honeybee-collected pollen is essential food for bumblebee mass rearing. Here we evaluated if gamma irradiation can minimize the risk of this potential route of exposure and can inactivate viral particles present in honeybee-collected pollen. We show that 16.9kGy gamma irradiation induced a 100-1000 fold reduction on the ability of IAPV to cause mortality after injections. This result opens avenues toward rearing pathogen-free bumblebees and towards eliminating the risks of pathogen spillover to native wild bee species., (Copyright © 2014 Elsevier Inc. All rights reserved.)

Bee declines are an increasingly recognised problem globally. Nutritional stress due to agricultural intensification is one of the drivers of bee declines. Therefore, understanding the nutritional requirements of bees is crucial to mitigate the effects of food scarcity on bee populations.Laboratory studies evaluating nutritional effects on bumble bees often use microcolonies as a model system for effects on queenright colonies. Microcolonies consist of workers, whereby one worker will lay male‐destined unfertilized eggs. Consequently, microcolonies exclusively produce males, while queenright colonies produce (female) workers and reproductives (males and queens).A comparison between Bombus terrestris (L.) microcolonies and queenright colonies was made by feeding three diets of varying nutritional quality.The experimental diets affected most fitness parameters of microcolonies differently than those of queenright colonies. Low‐protein, largely monofloral, pollen affected queenright colony fitness by reducing colony size and increasing larval mortality, while these fitness parameters were not affected in microcolonies. High‐protein polyfloral pollen reduced larval mortality in queenright colonies but did not affect larval mortality in microcolonies. For both colony types, a similar result was obtained when assessing offspring body mass, which was reduced by the low‐quality diet and increased by the high‐quality diet.In conclusion, our results demonstrate that microcolonies are inaccurate model systems and their use can lead to erroneous conclusions in terms of effects of nutritional stress or pollen quality on bumble bees. Our results further highlight the importance of high‐quality (here high‐protein polyfloral) pollen for sustaining colony development of bumble bees. [ABSTRACT FROM AUTHOR]

Among herbivorous insects with a complete metamorphosis the larval and adult stages usually differ considerably in their nutritional requirements and food ecology. Often, feeding on plant structural tissue is restricted to the larval stage, whereas the adult stage feeds primarily or exclusively on plant-provided food supplements such as nectar and pollen. Research on herbivore nutritional ecology has largely been divided along these lines. Most studies focus on actual herbivory by larval stages, while nectar and pollen feeding by adult herbivores has been addressed mainly in the light of plant-pollinator interactions. Only recently have we started to realize that the two phenomena are closely interlinked and that nectar and pollen feeding by adult herbivores can have a strong impact on plant-herbivore interactions. Here we address this largely ignored aspect of multi-trophic level interactions and discuss its wide-ranging implications. [ABSTRACT FROM AUTHOR]

Highlights: [•] Aphid honeydew enhances adult hoverfly longevity. [•] When pollen and nectar are available, honeydew still generates additional survival. [•] Feeding on floral resources for only one week is sufficient for female reproduction. [•] This implies a reduced need to commute between feeding sites and oviposition sites. [•] Hoverfly larvae are able to suppress aphid colony growth. [ABSTRACT FROM AUTHOR]

[Display omitted] • All hoverfly species tested effectively controlled potato aphids in an experimental strawberry greenhouse. • Strawberry flowers alone did not support preventive hoverfly releases. • Addition of sugars and pollen strongly enhanced the performance of all hoverflies species. • Food supplementation is essential for the hoverflies in a preventative aphid control strategy. Larvae of many hoverfly species (Diptera: Syrphidae) are efficient aphid predators, while the adults feed on pollen and nectar. Strawberry crops can be infested by several aphid species, such as the strawberry aphid Chaetosiphon fragaefolii (Cockerell) and the potato aphid Macrosiphum euphorbiae (Thomas), both of which can cause economic damage. Protected cultivation of strawberry seems to be ideal for introducing biological control agents that depend on flower resources, but the nectar and pollen provided by the crop may not be the most suitable for all flower-dependent insects. In this study, we evaluated the biocontrol potential of hoverflies released preventively or curatively against the potato aphid in strawberry in two separate greenhouse experiments and the effect of adding sugars and pollen on their control efficacy. In the curative experiment, Eupeodes corollae (Fabricius) and Sphaerophoria rueppellii (Wiedemann) were released and supported with flowering plants of Fagopyrum esculentum Moench (buckwheat). Both species reduced the aphid numbers significantly compared to the control treatment. In the preventive experiment, we tested three syrphid species, Episyrphus balteatus (De Geer), S. rueppellii , and E. corollae , in the presence and absence of additional food sources (sugar solution and pollen). All three syrphid species reduced the aphid population to a similar extent, but only in the presence of additional food sources. This study shows that hoverflies perform better in strawberry crops when adults have access to different supplementary food sources. [ABSTRACT FROM AUTHOR]

Phytoseiid mites (Acari: Phytoseiidae) are amongst the most abundant and important predators in citrus. They range from specialist species feeding exclusively on spider mites to generalist species that can feed and reproduce on several prey as well as non-prey foods such as pollen, fungi and honeydew. Feeding on non-prey foods is crucial for the conservation of phytoseiids especially during periods when prey are scarce or absent. In a greenhouse experiment using citrus plantlets we tested the impact of provisioning cattail pollen ( Typha angustifolia L.) and a sucrose solution, alone or in combination, on the population development of the pollen adapted Euseius stipulatus (Athias-Henriot) (Acari: Phytoseiidae). The highest E. stipulatus populations were registered in the treatment where the pollen was supplied in combination with the sucrose solution. The phytoseiid abundance in the sugar and pollen treatment was significantly higher than the sum of the abundances when either the pollen or the sugars were supplied separately. Thus, pollen and sugar acted synergistically on the populations of E. stipulatus . Subsequently, we tested the combination of pollen and sugar in a six month field study in two commercial citrus orchards in eastern Spain. Provisioning of pollen and sugar resulted in significantly higher abundance of the resident phytoseiid mites compared to the control trees that received no food supplements. In both orchards this increase was higher from the end of May until the end of June and from September until the end of October. We conclude that the provisioning of sugar and pollen enhances the conservation of the resident phytoseiid mites in citrus. [ABSTRACT FROM AUTHOR]

• Plant pollen is an alternative food for phytoseiid mites supporting survival. • Pollen with prey in a mixed diet can benefit the numerical response of phytoseiids. • Different pollens affect variably phytoseiid performance in mixed diets with thrips. • The mix of cattail pollen and thrips results in the highest r m of A. limonicus. Plant pollen is an important alternative food for generalist phytoseiid mites ensuring survival and supporting population build-up during periods of prey scarcity. However, in the short term predator efficacy can be negatively affected by pollen provisioning as a consequence of predator satiation or when pollen is preferred over prey. This is counteracted by the fact that, combining pollen with prey in a balanced mixed diet, may benefit the numerical response of the predator and thus, improve the effectiveness of long-term biological control. Here, we assessed the effects of pollen (Typha angustifolia , Zea mays , Pinus brutia) provisioning in a mixed diet with prey (thrips) on the performance and predation efficiency of Amblydromalus limonicus , a predatory mite used against thrips and whiteflies in greenhouse crops. We found that provisioning pollen in mixed diets with high-quality prey resulted in significant decrease in prey consumption. This effect was shown to be stronger for T. angustifolia and weaker for P. brutia when both were combined with thrips larvae. When pollen was provided alongside thrips, this resulted in a significant decrease in juvenile dispersal and oviposition was always higher. The highest value of intrinsic rate of population increase (r m) was recorded for the mix of cattail pollen and thrips, and the strongest increase in r m when thrips were combined with pine pollen followed by corn and cattail pollen. Overall, mixing prey with pollen resulted in higher r m values thus enhancing the medium- to long-term thrips-control potential of A. limonicus. [ABSTRACT FROM AUTHOR]