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Gray mold caused by Botrytis cinerea is a common postharvest disease in strawberries, reducing shelf life considerably. We investigated the potential of the yeast-like biocontrol fungus Aureobasidium pullulans (AP-SLU6) vectored by bumblebees (Bombus terrestris) in the Flying Doctors® system to inhibit the pathogen and increase the shelf life of harvested strawberries (cultivar Sonata). Using bumblebees as vectors of various biocontrol agents is becoming increasingly popular, but any potentially negative effects on bee performance have been understudied. Our results show that, over the 4-week period of the trial, the performance and activity of the bees were not negatively affected by A. pullulans. The bees successfully picked up the powder formulation; then, they carried and deposited it on the flowers. The vectoring of the biocontrol agent significantly reduced gray mold development on the harvested fruits by 45% and increased shelf life by 100% in comparison with control treatments. This suggests that the biocontrol fungus applied during flowering successfully reduced Botrytis infection and thus, effectively protected the fruits from gray mold. In addition, the bee-vectored application of the biocontrol agent was found to be significantly more effective than spray application because the latter may temporarily increase humidity around the flower, thereby creating a suitable environment for the pathogen to thrive. In summary, our study demonstrates that A. pullulans vectored by bumblebees can decrease gray mold infection and improve the shelf life of strawberries without adversely affecting the bees, thus providing a basis for the sustainable and efficient control of gray mold on strawberry. [Formula: see text] Copyright © 2022 The Author(s). This is an open access article distributed under the CC BY 4.0 International license .

The genus Thyreophagus is distributed worldwide, containing species occurring in stored food, house dust, bark, subcortical habitats, scale insect associations, and nests of wasps and bees. As species of this genus prefer concealed habitats, the actual species diversity is currently underappreciated. In addition, some described taxa are poorly known and their species boundaries are not entirely clear. Only a few species are known from both adult and deutonymphal stages. Using high-resolution light microscope and scanning electron microscopy, we describe a new partenogenetic species, Thyreophagus calusorum sp. n. from Florida (USA) based on adult stage (female) and heteromorphic deutonymph. This species was reared in the lab and its morphological variation was also studied. We did not find any substantial variation in the shape of the female spermatheca, but in the heteromorphic deutonymph, we did find extensive variation in the shape of tibial setae hT I (a taxonomically important character). Furthermore, we summarized taxonomic data and compiled an annotated checklist of species of Thyreophagus, with 35 species-level taxa. We clarified the following nomenclatorial questions: type species designation in Monieziella Berlese, 1897 was done by A. Berlese in G. Leonardi 1900 (Tyroglyphus entomophagus Laboulbène) not by A. Jacot (1936) as it was though previously; Monieziella mali Berlese, 1897 is an unjustified emendation and junior objective synonym of the name Acarus malus Shimer, 1868, currently Hemisacoptes malus (Shimer, 1868). Three subspecies of Thyreophagus were elevated to the species status due to their distinct morphology: Thyreophagus italicus Vacante, 1989, stat. nov. (=Thyreophagus entomophagus italicus Vacante, 1989); Thyreophagus mauritianus (Fain, 1982), stat. nov. (=Michaelopus gallegoi mauritianus Fain, 1982), and Thyreophagus ponticus Kadzhaya, 1973, stat. nov. (=Thyreophagus entomophagus ponticus Kadzhaya, 1973).

Background Larvae of many hoverfly species prey upon aphids, whereas the adults, by relying on nectar and pollen, contribute to the pollination of many plant species. Despite their great potential for pest control and pollination, important gaps still exist regarding the efficacy of hoverflies in regulating infestations of major aphid pests in augmentative biological control programs. Here, we tested the potential of the commercially available hoverflies Eupeodes corollae and Sphaerophoria rueppellii to regulate populations of the foxglove aphid Aulacorthum solani in sweet pepper. Results In a semi-field experiment, aphid numbers were 93.2% and 78.4% lower in the E. corollae and S. rueppellii treatments, respectively, compared to the control. Fruit yield was increased by 390% and 361% and seed set by 395% and 399% for E. corollae and S. rueppellii. In a separate laboratory trial, we found that under conditions of limited prey, hoverfly larvae did not complete development, but that larvae of S. rueppellii survived significantly longer than larvae of E. corollae. Conclusion We have shown for the first time that E. corollae and S. rueppellii can reduce infestations of foxglove aphid in sweet pepper. The limited amount of prey, related to the small size of the A. solani colonies, means that hoverfly larvae were often not able to complete development. In practice, repeated releases of hoverflies possibly in combination with other natural enemies might be used to achieve effective suppression of A. solani infestations. This article is protected by copyright. All rights reserved.

To date, some species in the genus Thyreophagus, such as Th. entomophagus and Th. cracentiseta, have been shown to be useful factitious prey for mass-rearing of predacious phytoseiid mites, one of the most common groups of mites used for biological control. Here, we describe a new species, Thyreophagus plocepasseri sp. n. from Kenya that can serve as a factitious prey as well. In addition, the new species is asexual, a trait that can be advantageous for its mass-rearing in industrial settings. In the description, we use high-resolution light microscope imaging and extensive comparison with a similar species, Thyreophagus athiasae, for which the type was studied. We review the literature on asexual acarid mites and point to a lack of data on the presence of sex-manipulating bacteria (Wolbachia, Cardinium) in these asexual mite lineages. Based on the literature, these bacteria are known to induce parthenogenesis in several haplodiploid mites, but they have not been linked so far to parthenogenesis inducement in diplodiploid acarid mites.

Agri-environment schemes are programmes where landholders enter into voluntary agreements (typically with\ud governments) to manage agricultural land for environmental protection and nature conservation objectives.\ud Previous work at local scale has shown that these features can provide additional floral and nesting resources to\ud support wild pollinators, which may indirectly increase floral visitation to nearby crops. However, the effect of\ud entire schemes on this important ecosystem service has never previously been studied at national scale. Focusing\ud on four wild pollinator guilds (ground-nesting bumblebees, tree-nesting bumblebees, ground-nesting solitary\ud bees, and cavity-nesting solitary bees), we used a state-of-the-art, process-based spatial model to examine the\ud relationship between participation in agri-environment schemes across England during 2016 and the predicted\ud abundances of these guilds and their visitation rates to four pollinator dependent crops (oilseed rape, field beans,\ud orchard fruit and strawberries). Our modelling predicts that significant increases in national populations of\ud ground-nesting bumblebees and ground-nesting solitary bees have occurred in response to the schemes. Lack of\ud significant population increases for other guilds likely reflects specialist nesting resource requirements not wellcatered\ud for in schemes. We do not predict statistically significant increases in visitation to pollinator-dependent\ud crops at national level as a result of scheme interventions but do predict some localised areas of significant\ud increase in bumblebee visitation to crops flowering in late spring. Lack of any significant change in visitation to\ud crops which flower outside this season is likely due to a combination of low provision of nesting resource relative\ud to floral resource by scheme interventions and low overall participation in more intensively farmed landscapes.\ud We recommend future schemes place greater importance on nesting resource provision alongside floral resource\ud provision, better cater for the needs of specialised species and promote more contiguous patches of semi-natural\ud habitat to better support solitary bee visitation.

There is increasing evidence that microorganisms emit a wide range of volatile compounds (mVOCs, microbial volatile organic compounds) that act as insect semiochemicals, and therefore play an important role in insect behaviour. Although it is generally believed that phylogenetically closely related microbes tend to have similar phenotypic characteristics and therefore may elicit similar responses in insects, currently little is known about whether the evolutionary history and phylogenetic relationships among microorganisms have an impact on insect‐microbe interactions. In this study, we tested the hypothesis that phylogenetic relationships among 40 Bacillus strains isolated from diverse environmental sources predicted mVOC composition and the olfactory response of the generalist aphid parasitoid Aphidius colemani . Results revealed that phylogenetically closely related Bacillus strains emitted similar blends of mVOCs and elicited a comparable olfactory response of A. colemani in Y‐tube olfactometer bioassays, varying between attraction and repellence. Analysis of the chemical composition of the mVOC blends showed that all Bacillus strains produced a highly similar set of volatiles, but often in different concentrations and ratios. Benzaldehyde was produced in relatively high concentrations by strains that repel A. colemani , while attractive mVOC blends contained relatively higher amounts of acetoin, 2,3‐butanediol, 2,3‐butanedione, eucalyptol and isoamylamine. Overall, these results indicate that bacterial phylogeny had a strong impact on mVOC compositions and as a result on the olfactory responses of insects.

Background Soil-dwelling predatory mites of the family Laelapidae are augmentatively released for the biological control of several pests with an edaphic phase in numerous greenhouse crops. Yet, there is no information about the potential of releasing these predators to control pests in open field crops. We tested, during two consecutive years, the potential of augmentative releases of Gaeolaelaps aculeifer, alone or in combination with coco fiber discs as mulch, to reduce the damage caused on citrus fruits by the invasive thrips Pezothrips kellyanus in Mediterranean citrus. In a separate trial, we also compared different mulch types (coco fiber discs, rice husks or a mixture of sawdust and wheat bran) for their potential to support the establishment and population development of the predatory mites after their release. Results The percentage of unmarketable fruits caused by P. kellyanus was significantly reduced in the plots where G. aculeifer was released. The addition of coco fiber discs did not reduce further the percentage of unmarketable fruits. Sawdust + bran mulch was the most effective in preserving immature and adult predatory mite population after their release. Conclusion Augmentative releases of G. aculeifer have the potential to reduce fruit damage caused by P. kellyanus in citrus. © 2020 Society of Chemical Industry.

To locate mating partners and essential resources such as food, oviposition sites and shelter, insects rely to a large extent on chemical cues. While most research has focused on cues derived from plants and insects, there is mounting evidence that indicates that micro‐organisms emit volatile compounds that may play an important role in insect behaviour. In this study, we assessed how volatile compounds emitted by phylogenetically diverse bacteria affected the olfactory response of the primary parasitoid Aphidius colemani and one of its secondary parasitoids, Dendrocerus aphidum. Olfactory responses were evaluated for volatile blends emitted by bacteria isolated from diverse sources from the parasitoid's habitat, including aphids, aphid mummies and honeydew, and from the parasitoids themselves. Results revealed that A. colemani showed a wide variation in response to bacterial volatiles, ranging from significant attraction over no response to significant repellence. Our results further showed that the olfactory response of A. colemani to bacterial volatile emissions was different from that of D. aphidum. Gas chromatography‐mass spectrometry analysis of the volatile blends revealed that bacterial strains repellent to A. colemani produced significantly higher amounts of esters, organic acids, aromatics and cycloalkanes than attractive strains. Strains repellent to D. aphidum produced significantly higher amounts of alcohols and ketones, whereas the strains attractive to D. aphidum produced higher amounts of the monoterpenes limonene, linalool and geraniol. Overall, our results indicate that bacterial volatiles can have an important impact on insect olfactory responses, and should therefore be considered as an additional, so far often overlooked factor in studying multitrophic interactions between plants and insects. A free Plain Language Summary can be found within the Supporting Information of this article. ispartof: FUNCTIONAL ECOLOGY vol:34 issue:2 pages:507-520 status: published

Simple Summary Biocontrol practitioners have increasingly released generalist predators to control a variety of greenhouse pests. In this study, the effects of alternative food sources on the oviposition rate and the population dynamics of the mite Pronematus ubiquitus were assessed. The alternative food sources were selected among those the mite may encounter or be applied to the tomato crop. Abstract Pronematus ubiquitus (McGregor) is a small iolinid mite that is capable of establishing on tomato plants. Once established, this mite has been shown to control both tomato russet mite, Aculops lycopersici (Tryon) (Acari: Eriophyidae), and tomato powdery mildew (Oidium neolycopersici L. Kiss). In the present study, we explored the effects of a number of alternative food sources on the oviposition rate in the laboratory. First, we assessed the reproduction on food sources that P. ubiquitus can encounter on a tomato crop: tomato pollen and powdery mildew, along with tomato leaf and Typha angustifolia L. In a second laboratory experiment, we evaluated the oviposition rate on two prey mites: the astigmatid Carpoglyphus lactis L. (Acari: Carpoglyphidae) and the tarsonemid Tarsonemus fusarii Cooreman (Acari: Tarsonemidae). Powdery mildew and C. lactis did not support reproduction, whereas tomato pollen and T. fusarii did promote egg laying. However, T. angustifolia pollen resulted in a higher oviposition in both experiments. In a greenhouse trial on individual caged tomato plants, we evaluated the impact of pollen supplementation frequency on the establishment of P. ubiquitus. Here, a pollen addition frequency of every other week was required to allow populations of P. ubiquitus to establish.

Background The tomato russet mite (TRM), Aculops lycopersici, and powdery mildew (PM), Oidium neolycopersici, are two major problems in tomato cultivation for which no effective biocontrol solutions exist to date. In a greenhouse compartment, we investigated the potential of preventatively establishing the iolinid omnivorous mite Pronematus ubiquitus on potted tomato plants to control both pest and pathogen simultaneously. Results Using Typha pollen, P. ubiquitus established well on tomato plants, with numbers reaching up to 250 motiles per tomato leaflet. The built-up population was capable of controlling subsequent infestations with both TRM and PM. This represents the first report of an arthropod protecting a crop against pests as well as disease. Conclusion The implementation of P. ubiquitus in tomato crops could be a real game-changer as it eliminates the need for repeated pesticide use or sulphur applications. The finding that arthropods can effectively control diseases opens up new opportunities for biological crop protection.

1. Pollinators experience large spatio-temporal fluctuations in resource availability when mass-flowering crops are rotated with resource-poor cereal crops. Yet, few studies have considered the effect this has on pollinator population stability, nor how this might be mitigated to maintain consistent crop pollination services.2. We assess the potential of boundary features (standard narrow grassy margins, hedgerows and wide agri-environment margins) to support and stabilise pollinator populations and pollination service in agricultural landscapes under crop rotation. Assuming a six-year rotation, we use a process-based pollinator model to predict yearly pollinator population size and in-crop visitation rates to oil seed rape and feld bean across 117 study landscapes in England, with varying amounts of boundary features. We model both ground-nesting bumblebees and solitary bees and compare the predictions including and excluding boundary features from the landscapes.3. Ground-nesting bumblebee populations, whose longer-lifetime colonies benet from continuity of resources, were larger and more stable (relative to the no-features scenario) in landscapes with more boundary features (up to 20% and 8%, respectively, in some of the most arable landscapes). Ground nesting solitary bee populations were also larger but not significantly more stable, except with the introduction of wide permanent agri-environment margins, due to their shorter lifetimes and shorter foraging/dispersal ranges.4. Crop visitation by ground-nesting bumblebees was greater and more stable in landscapes with more boundary features, partly due to increased colony growth prior to crop flowering. Time averaged crop visitation by ground-nesting solitary bees was slightly lower, due to females dividing their foraging time between boundary features and the crop, however, the more stable delivery (again up to 20% reduction in variability) compensated for this by nonetheless increasing the minimum pollination service delivered in any given year.5. Synthesis and applications. Boundary features have an important role in stabilising pollinator populations and pollination service in rotational systems, although maintenance of larger semi natural habitat patches may be more effective for stabilising less mobile solitary bee populations. We recommend using combinations of boundary features, accounting for pollinator range when spacing features/rotating crops, and synchronising boundary feature management with crop rotation to maximise their stabilising benefits.

Understanding how animals learn is crucial to interpreting animal behaviour. Flower-visiting insects, such as bees and parasitoids, are excellent animal models to study visual and olfactory learning, including memory phenomena. The diversity of resources flower-visiting insects exploit predisposes them to learn and remember the colours, shapes and odours associated with rewarding experiences (e.g. flowers), allowing them to focus on the most rewarding resources. Recent research has shown that nectar-living microbes release volatile organic compounds (VOCs) that contribute to overall flower scent. Nevertheless, little is known about the extent to which nectar microbiota mediate insect learning of floral preferences. In this study, we investigated whether VOCs produced by nectar microbes serve as a learning cue to parasitoids and how long any developed preference is maintained. Experiments were performed using the generalist aphid parasitoid Aphidius ervi and three nectar yeasts, including the nectar specialist Metschnikowia reukaufii and the generalist species Hanseniaspora uvarum and Sporobolomyces roseus. Results showed that naive parasitoids had an innate preference for nectar fermented by the nectar specialist M. reukaufii, but not by the other two yeasts which had either a neutral (H. uvarum) or deterrent (S. roseus) effect. When parasitoids were conditioned with yeast-fermented nectar, they were strongly attracted to their odours 2 and 24 h after conditioning, but not after 48 h. Furthermore, when parasitoids were conditioned to one yeast-fermented nectar, they also showed increased attraction to other yeast-fermented nectars. This generalization suggests that their learning ability may have broader ecological consequences. However, this generalized response to other yeast VOCs lasted for only 2 h. We conclude that parasitoids show conditioned responses to the scent of yeast-fermented nectar, and yeasts, therefore, may play an important but understudied role in shaping their foraging behaviour.

Caffeine is a widely occurring plant defense chemical1,2 that occurs in the nectar of some plants, e.g., Coffea or Citrus spp., where it may influence pollinator behavior to enhance pollination.3,4 Honey bees fed caffeine form longer lasting olfactory memory associations,5 which could give plants with caffeinated nectar an adaptive advantage by inducing more visits to flowers. Caffeinated free-flying bees show enhanced learning performance6 and are more likely to revisit a caffeinated target feeder or artificial flower,7-9 although it is not clear whether improved memory of the target cues or the perception of caffeine as a reward is the cause. Here, we show that inexperienced bumble bees (Bombus terrestris) locate new food sources emitting a learned floral odor more consistently if they have been fed caffeine. In laboratory arena tests, we fed bees a caffeinated food alongside a floral odor blend (priming) and then used robotic experimental flowers10 to disentangle the effects of caffeine improving memory for learned food-associated cues versus caffeine as a reward. Inexperienced bees primed with caffeine made more initial visits to target robotic flowers emitting the target odor compared to control bees or those primed with odor alone. Caffeine-primed bees tended to improve their floral handling time faster. Although the effects of caffeine were short lived, we show that food-locating behaviors in free-flying bumble bees can be enhanced by caffeine provided in the nest. Consequently, there is potential to redesign commercial colonies to enhance bees' forage focus or even bias bees to forage on a specific crop.

The spider mitesTetranychus evansiBaker & Pritchard andTetranychus urticaeKoch (Acari: Tetranychidae) are key tomato pests worldwide. Biological control of spider mites using phytoseiid predatory mites remains challenging. The glandular trichomes on the tomato leaves and stem severely hamper the movement and establishment of the predatory mites. As a result, smaller predatory mites, able to thrive under the sticky heads of the glandular trichomes, have gained much interest. As some iolinid predatory mites were reported to feed on spider mites, we investigated the potential ofPronematus ubiquitusMcGregor to control bothT. urticaeandT. evansion tomato plants. On whole tomato plants,P. ubiquituswas able to suppress populations ofT. urticae, but not ofT. evansi. Based on the marginal number of spider mites killed in laboratory trials, the observed biocontrol effect on full tomato plants might not be due to direct predation but to a plant-mediated indirect impact. The oviposition ofT. urticaewas found to be significantly lower on tomato leaflets pre-exposed toP. ubiquitusas compared to non-exposed leaflets. The oviposition rate ofT. evansiwas not affected by previous exposure of the tomato host plant toP. ubiquitus. We demonstrated thatP. ubiquitusreduces the population growth ofT. urticaeon tomato plants. Further large-scale field trials need to confirm the findings of the present study.

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. ispartof: OECOLOGIA vol:195 issue:3 pages:689-703 ispartof: location:Germany status: published

Insecticides are contributing to global insect declines, thereby creating demand to understand the mechanisms underlying reduced fitness. In the eusocial Hymenoptera, inclusive fitness depends on successful mating of male sexuals (drones) and efficient collaborative brood care by female workers. Therefore, sublethal insecticide effects on sperm and glands used in larval feeding (hypopharyngeal glands (HPG)) would provide key mechanisms for population declines in eusocial insects. However, while negative impacts for bumblebee colony fitness have been documented, the effects of insecticide exposure on individual physiology are less well understood. Here, we show that field-realistic concentrations (4.5-40 ng ml-1) of the neonicotinoid insecticide thiamethoxam significantly impair Bombus terrestris sperm and HPGs, thereby providing plausible mechanisms underlying bumblebee population decline. In the laboratory, drones and workers were exposed to five thiamethoxam concentrations (4.5 to 1000 ng ml-1). Then, survival, food consumption, body mass, HPG development, sperm quantity and viability were assessed. At all concentrations, drones were more exposed than workers due to higher food consumption. Increased body mass was observed in drones starting at 20 ng ml-1 and in workers at 100 ng ml-1. Furthermore, environmentally realistic concentrations (4.5-40 ng ml-1) did not significantly affect survival or consumption for either sex. However, thiamethoxam exposure significantly negatively affected both sperm viability and HPG development at all tested concentrations. Therefore, the results indicate a trade-off between survival and fitness components, possibly due to costly detoxification. Since sperm and HPG are corner stones of colony fitness, the data offer plausible mechanisms for bumblebee population declines. To adequately mitigate ongoing biodiversity declines for the eusocial insects, this study suggests it is essential to evaluate the impact of insecticides on fitness parameters of both sexuals and workers. ispartof: SCIENCE OF THE TOTAL ENVIRONMENT vol:785 ispartof: location:Netherlands status: published

Background Although around 1% of cytosines in bees’ genomes are known to be methylated, less is known about methylation’s effect on bee behavior and fitness. Chemically altered DNA methylation levels have shown clear changes in the dominance and reproductive behavior of workers in queen-less colonies, but the global effect of DNA methylation on caste determination and colony development remains unclear, mainly because of difficulties in controlling for genetic differences among experimental subjects in the parental line. Here, we investigated the effect of the methylation altering agent decitabine on the developmental rate of full bumblebee colonies. Whole genome bisulfite sequencing was used to assess differences in methylation status. Results Our results showed fewer methylated loci in the control group. A total of 22 CpG loci were identified as significantly differentially methylated between treated and control workers with a change in methylation levels of 10% or more. Loci that were methylated differentially between groups participated in pathways including neuron function, oocyte regulation and metabolic processes. Treated colonies tended to develop faster, and therefore more workers were found at a given developmental stage. However, male production followed the opposite trend and it tended to be higher in control colonies. Conclusion Overall, our results indicate that altered methylation patterns resulted in an improved cooperation between workers, while there were no signs of abnormal worker dominance or caste determination.

In many agroecosystems, the implementation of an integrated pest management (IPM) program against mealybugs (Hemiptera: Pseudococcidae) is undermined by the presence of ants (Hymenoptera: Formicidae). In a mutualistic association, ants obtain carbohydrates from the mealybugs in the form of honeydew and, in exchange, protect the mealybugs against their natural enemies. Ants however also need protein in their diet. Thus, they can also prey on the mealybugs especially when their carbohydrates requirements are met. This study aims to assess whether providing ants with sugar-feeders (representing ad libitum sources of carbohydrates) I) alters their mutualistic relationships with the mealybugs (ant-tending), II) increases the parasitism of mealybugs, III) increases ant predation rate and IV) alters the protein and carbohydrate profile in ant workers. For this study, we selected a citrus orchard with high infestation levels of the mealybug Planoccocus citri tended by the ant Lasius grandis. Our results showed that sugar provisioning reduced ant activity and ant tending, resulting in an increase of mealybug parasitism rates. Ants showed a tendency to prey more sentinel preys in trees with sugar-feeders, even though the differences were not significant. The gut content in terms of carbohydrates and proteins of ant workers did not differ among trees with and without sugar-feeders. Overall, our results show that sugar provisioning can be used for improving pest management strategies against mealybugs; while further research is necessary to corroborate that predation by ants of honeydew producers increases when sugar-feeders are provided.

There is increasing evidence that microorganisms, particularly fungi and bacteria, emit volatile compounds that mediate the foraging behaviour of insects and therefore have the potential to affect key ecological relationships. However, to what extent microbial volatiles affect the olfactory response of insects across different trophic levels remains unclear. Adult parasitoids use a variety of chemical stimuli to locate potential hosts, including those emitted by the host’s habitat, the host itself, and microorganisms associated with the host. Given the great capacity of parasitoids to utilize and learn odours to increase foraging success, parasitoids of eggs, larvae, or pupae may respond to the same volatiles the adult stage of their hosts use when locating their resources, but compelling evidence is still scarce. In this study, using Saccharomyces cerevisiae we show that Trichopria drosophilae, a pupal parasitoid of Drosophila species, is attracted to the same yeast volatiles as their hosts in the adult stage, i.e. acetate esters. Parasitoids significantly preferred the odour of S. cerevisiae over the blank medium in a Y-tube olfactometer. Deletion of the yeast ATF1 gene, encoding a key acetate ester synthase, decreased attraction of T. drosophilae, while the addition of synthetic acetate esters to the fermentation medium restored parasitoid attraction. Bioassays with individual compounds revealed that the esters alone were not as attractive as the volatile blend of S. cerevisiae, suggesting that other volatile compounds also contribute to the attraction of T. drosophilae. Altogether, our results indicate that pupal parasitoids respond to the same volatiles as the adult stage of their hosts, which may aid them in locating oviposition sites. info:eu-repo/semantics/acceptedVersion

Repeated mass introductions of natural enemies have been widely used as a biological control strategy in greenhouse systems when the resident population of natural enemies is insufficient to suppress the pests. As an alternative strategy, supporting the establishment and population development of beneficials can be more effective and economical. The preventative establishment of predators and parasitoids, before the arrival of pests, has become a key element to the success of biological control programs. This “Predators and parasitoids-in-first” strategy is used both in Inoculative Biological Control (IBC), and in Conservation Biological Control (CBC). Here, we provide an overview of tools used to boost resident populations of biocontrol agents.

1. Pollination is a key ecosystem service for global agriculture but evidence of pollinator populationdeclines is growing. Reliable spatial modelling of pollinator abundance is essential if we are toidentify areas at risk of pollination service deficit and effectively target resources to support pollinatorpopulations. Many models exist which predict pollinator abundance but few have been calibratedagainst observational data from multiple habitats to ensure their predictions are accurate. 2. We selected the most advanced process-based pollinator abundance model available and calibrated it for bumblebees and solitary bees using survey data collected at 239 sites across GreatBritain. We compared three versions of the model: one parameterised using estimates based on expert opinion, one where the parameters are calibrated using a purely data-driven approach and onewhere we allow the expert opinion estimates to inform the calibration process. 3. All three model versions showed significant agreement with the survey data, demonstrating thismodel’s potential to reliably map pollinator abundance. However, there were significant differencesbetween the nesting/floral attractiveness scores obtained by the two calibration methods and fromthe original expert opinion scores. 4. Our results highlight a key universal challenge of calibrating spatially-explicit, process-basedecological models. Notably, the desire to reliably represent complex ecological processes in finelymapped landscapes necessarily generates a large number of parameters, which are challenging to calibrate with ecological and geographical data that is often noisy, biased, asynchronous and sometimesinaccurate. Purely data-driven calibration can therefore result in unrealistic parameter values, despite appearing to improve model-data agreement over initial expert opinion estimates. We thereforeadvocate a combined approach where data-driven calibration and expert opinion are integrated intoan iterative Delphi-like process, which simultaneously combines model calibration and credibility assessment. This may provide the best opportunity to obtain realistic parameter estimates and reliablemodel predictions for ecological systems with expert knowledge gaps and patchy ecological data.

Simple Summary The spotted wing drosophila (SWD) is an invasive fruit fly that causes serious economic damage to many fruit crops. Monitoring is the first step for any management program to determine the characteristics of a pest. For this purpose, there are no efficient baits registered to date. Certain bacteria release chemical compounds that attract SWD. We studied the bacterial impact on the enhanced attractiveness of a commercial bait (Droskidrink®) under field and laboratory conditions. At first, Oenococcus oeni belonging to lactic acid bacteria (LAB) was found to release chemical compounds that were highly attractive for SWD. The attractiveness of Droskidrink® bait was increased by O. oeni culture, resulting in a higher capture rate of SWD in traps. Therefore, our findings suggest the use of the bacterial culture inside the commercial SWD baits. The use of these kinds of baits can minimize the risk of pest outbreaks in fruit orchards in both domestic and wild environments. Our pest management approach is farmer-friendly in all aspects, as well as the food sector. Abstract (1) Monitoring of Drosophila suzukii is based on the use of effective traps and baits. The current baits are insufficient to provide efficient monitoring. The use of bacteria as bio-catalyzers to produce bioactive volatiles may improve flies’ attraction. Thus, we conducted this work to improve Droskidrink® bait’s attractiveness using lactic acid bacteria. (2) Different baits that were based on the use of Droskidrink® were assessed for flies’ attraction in a Droso-Trap® in a vineyard. Oenococcus oeni, Pediococcus spp., and Lactobacillus spp. were used. The performance of the most attractive species, O. oeni, inoculated into Droskidrink® was assessed in laboratory tests. The responses of female flies to volatiles produced by Droskidrink® with O. oeni strains were recorded by electroantennography. (3) Preliminary field assessment of baits recorded O. oeni as the most attractive species. Three strain groups showed adaptation to test conditions. Volatiles extracted by the headspace of baits inoculated with O. oeni, elicited electroantennographic responses from fly antennae. (4) Droskidrink® inoculated with O. oeni is a highly attractive bait for monitoring. These findings will be useful for improving the attractiveness of D. suzukii commercial baits based on the utilization of LAB volatiles in a strain-dependent manner.

Phytoseiid predatory mites are the most important group of biocontrol agents currently used in protected cultivations worldwide. The possibility to produce these predators at high densities on factitious prey mites is a crucial factor for their success. Commonly used factitious prey mites comprise mainly species belonging to the cohort of Astigmatina. In the present study, we investigated the potential of tarsonemid prey mites as a food source for the spider mite predator Neoseiulus californicus (McGregor) (Acari: Phytoseiidae). The oviposition of N. californicus on mixed stages of Tarsonemus fusarii Cooreman (Acari: Tarsonemidae) was similar to that on its natural prey, the two-spotted spider mite Tetranychus urticae Koch (Acari: Tetranychidae). As most tarsonemids are specialized fungus-feeders, we tested the effect of different fungal species on the growth of T. fusarii. Subsequently, we analysed the impact on the fungal growing medium on the oviposition of N. californicus. The fungal growing medium of T. fusarii had a significant negative effect on the reproductive output of the predatory mite. When T. fusarii was separated from the rearing medium, these detrimental effects were not observed. The present study shows the potential of using tarsonemid prey mites in the production of phytoseiid predatory mites.

Genomic imprinting is the differential expression of alleles in diploid individuals, with the expression being dependent upon the sex of the parent from which it was inherited. Haig’s kinship theory hypothesizes that genomic imprinting is due to an evolutionary conflict of interest between alleles from the mother and father. In social insects, it has been suggested that genomic imprinting should be widespread. One recent study identified parent-of-origin expression in honeybees and found evidence supporting the kinship theory. However, little is known about genomic imprinting in insects and multiple theoretical predictions must be tested to avoid single-study confirmation bias. We, therefore, tested for parent-of-origin expression in a primitively eusocial bee. We found equal numbers of maternally and paternally biased expressed alleles. The most highly biased alleles were maternally expressed, offering support for the kinship theory. We also found low conservation of potentially imprinted genes with the honeybee, suggesting rapid evolution of genomic imprinting in Hymenoptera.Impact summaryGenomic imprinting is the differential expression of alleles in diploid individuals, with the expression being dependent upon the sex of the parent from which it was inherited. Genomic imprinting is an evolutionary paradox. Natural selection is expected to favour expression of both alleles in order to protect against recessive mutations that render a gene ineffective. What then is the benefit of silencing one copy of a gene, making the organism functionally haploid at that locus? Several explanations for the evolution of genomic imprinting have been proposed. Haig’s kinship theory is the most developed and best supported.Haig’s theory is based on the fact that maternally (matrigene) and paternally (patrigene) inherited genes in the same organism can have different interests. For example, in a species with multiple paternity, a patrigene has a lower probability of being present in siblings that are progeny of the same mother than does a matrigene. As a result, a patrigene will be selected to value the survival of the organism it is in more highly, compared to the survival of siblings. This is not the case for a matrigene.Kinship theory is central to our evolutionary understanding of imprinting effects in human health and plant breeding. Despite this, it still lacks a robust, independent test. Colonies of social bees consist of diploid females (queens and workers) and haploid males created from unfertilised eggs. This along with their social structures allows for novel predictions of Haig’s theory.In this paper, we find parent of origin allele specific expression in the important pollinator, the buff-tailed bumblebee. We also find, as predicted by Haig’s theory, a balanced number of genes showing matrigenic or patrigenic bias with the most extreme bias been found in matrigenically biased genes.

Plants play a pivotal role in interactions involving herbivores and their natural enemies. Variation in plant primary and secondary metabolites not only affects herbivores but, directly and indirectly, also their natural enemies. Here, we used a commercial NPK fertilizer to test the impact of three fertilizer, namely 50, 100, and 200 ppm nitrogen, and one control (i.e., water) treatments, on the weight of the nymphs of the whitefly Bemisia tabaci (Gennadius) (Hemiptera: Aleyrodidae). Subsequently, the whitefly parasitoid Eretmocerus mundus Mercet (Hymenoptera: Aphelinidae) was reared on the different groups of whitefly nymphs and upon parasitoid emergence, the number of oocytes was determined as a measure of reproductive capacity. Trials were done on tomato and tobacco plants. The level of nitrogen concentration in tobacco leaves was directly correlated with the fertilizer applications, thus confirming the effect of our fertilizer treatments. Both in tomato and tobacco plants, healthy as well as parasitized whitefly nymphs, were heaviest in the 200 ppm nitrogen treatment. The highest number of oocytes per female parasitoid was recorded in the 200 ppm nitrogen treatment in tomato (31% more oocytes as compared with the control) and in the 100 and 200 ppm nitrogen treatments in tobacco (200% more oocytes). We suggest that the increase in oocytes was the result of the enhanced size (food quantity) and/or nutritional quality of the whitefly host. The practical implications of these results for the mass rearing of whitefly parasitoids and for biological pest control are discussed.

BACKGROUND\ud Recent studies have shown that microorganisms emit volatile compounds that affect insect behaviour. However, it remains largely unclear whether microbes can be exploited as a source of attractants to improve biological control of insect pests. In this study, we used a combination of coupled gas chromatography‐electroantennography (GC–EAG) and Y‐tube olfactometer bioassays to identify attractive compounds in the volatile extracts of three bacterial strains that are associated with the habitat of the generalist aphid parasitoid Aphidius colemani, and to create mixtures of synthetic compounds to find attractive blends for A. colemani. Subsequently, the most attractive blend was evaluated in two‐choice cage experiments under greenhouse conditions.\ud \ud RESULTS\ud GC–EAG analysis revealed 20 compounds that were linked to behaviourally attractive bacterial strains. A mixture of two EAG‐active compounds, styrene and benzaldehyde applied at a respective dose of 1 μg and 10 ng, was more attractive than the single compounds or the culture medium of the bacteria in Y‐tube olfactometer bioassays. Application of this synthetic mixture under greenhouse conditions resulted in significant attraction of the parasitoids, and outperformed application of the bacterial culture medium.\ud \ud CONCLUSION\ud Compounds isolated from bacterial blends were capable of attracting parasitoids both in laboratory and greenhouse assays, indicating that microbial cultures are an effective source of insect attractants. This opens new opportunities to attract and retain natural enemies of pest species and to enhance biological pest control.

The presence of yeasts in pollen and floral nectar is rather the norm than the exception. Due to the metabolic activities of yeasts, sugar and amino acid composition of nectar often drastically change and may negatively impact the nutritional value of nectar for pollinators and hence insect fitness. On the other hand, the presence of yeasts in floral nectar may also increase its nutritional value due to yeast's probiotic effect and the release of yeast's metabolites. In this study, we investigated whether the presence of defined flower‐ and insect‐associated yeasts affected individual and colony fitness of the bumble bee pollinator Bombus terrestris. Specifically, we tested whether the presence of yeasts in nectar affected bumble bee foraging behavior and nectar consumption, individual growth and colony development, larval and queen mortality, and mating success. Quantitative analyses of sugar and amino acid profiles showed that nectar yeasts significantly affected the chemical composition of nectar. However, dual‐choice experiments indicated that yeast inoculation did not significantly affect foraging behavior or consumption rates. Nest development, on the other hand, was significantly affected by the presence of yeasts, but effects largely depended on species identity, with Candida bombiphila, Metschnikowia gruessii, and Rhodotorula mucilaginosa having the largest positive impact on colony growth. Interestingly, the effects at the colony level were more pronounced than at the individual level. In vitro growth tests further showed that yeasts have the potential to suppress the growth of the bumble bee gut pathogen Crithidia bombi. Overall, these results demonstrate that nectar‐inhabiting yeasts can have diverse effects on bumble bee fitness and therefore may mediate plant–pollinator mutualisms.

With the global decline of wild pollinators, supplemental pollination is implemented frequently in agricultural practices. Honeybees, however, show little attraction towards low-rewarding crops such as pear or kiwi. As a result, many growers trust on mechanical application of pollen, which require a big amount of product and does not ensure a continuous vectoring of pollen that would match the receptive phase of the flowers. The entomovector technology utilizes insects as vectors of either biological control agents for targeted precision biocontrol towards plant pests and diseases or pollen for outcrossed pollination. In this chapter, we will describe two practical cases of the use of commercial bumblebee hives equipped with the patented dispenser “Flying doctor” for outdoor crops. The first involves open field studies conducted in France with kiwi vines where male pollen was dispensed, and the second focuses in pear orchard in Belgium where the Flying Doctor technology is compared to the use of regular bumblebee hives and default pollination practices such as the use of phytohormones and wild pollinators. Our results unambiguously show the advantages of entomovector technology compared to current pollination practices at both crops. The use of the Flying Doctors technology gave the best results in terms of fruit weight and size and number of fruits of high market value, while reducing overall pollen use compared to mechanical blowing of the pollen.

Myzus persicae (Sulzer) (Hemiptera: Aphididae) is one of the most common and harmful pest species attacking sweet pepper. Here, we compared the predation rate and performance of Adalia bipunctata (L.), Hippodamia variegata (Goeze), and Scymnus interruptus Goeze (Coleoptera: Coccinellidae) fed on M. persicae infesting sweet pepper. In the laboratory, when offered 150 aphids daily, A. bipunctata was the most voracious species (predation per adult female of 122.7 aphids per 24 h) followed by H. variegata (87.7) and S. interruptus (27.3). When offered 50 aphids, 92% of the S. interruptus larvae developed to adults, 48% of H. variegata, and only 7% of A. bipunctata. In greenhouse experiments, A. bipunctata completely eradicated the aphid population within 2 days following release, whereas H. variegata and S. interruptus initially reduced the aphid population; however, in the long‐term, the infestation was not controlled. Adults of A. bipunctata remained on the plants even in the absence of prey but they laid almost no eggs. Very few adults of H. variegata and S. interruptus were recorded on the plants despite the presence of prey, yet egg laying was observed. Overall, A. bipunctata had an immediate impact on the aphids and is more suitable for curative releases. However, it showed limited potential to establish in the crop. Due to their capacity to complete development with low prey availability, the potential of H. variegata and S. interruptus for preventative releases against aphids in greenhouse crops should be studied further.

[EN] 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., This research was supported by the European grant FP7-IAPP #324475 'Colbies'. We would like to thank Nancy Lenaerts for help with the greenhouse trial preparation and sampling.

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.

Beneficial insects and mites, including generalist predators of the family Miridae, are widely used in biocontrol programs against many crop pests, such as whiteflies, aphids, lepidopterans and mites. Mirid predators frequently complement their carnivore diet by feeding plant sap with their piercing–sucking mouthparts. This implies that mirids may act as vectors of phytopathogenic and beneficial microorganisms, such as plant growth-promoting bacterial endophytes. This work aimed at understanding the role of two beneficial mirids (Macrolophus pygmaeusandNesidiocoris tenuis) in the acquisition and transmission of two plant growth-promoting bacteria,Paraburkholderia phytofirmansstrain PsJN (PsJN) andEnterobactersp. strain 32A (32A). Both bacterial strains were detected on the epicuticle and internal body of both mirids at the end of the mirid-mediated transmission. Moreover, both mirids were able to transmit PsJN and 32A between tomato plants and these bacterial strains could be re-isolated from tomato shoots after mirid-mediated transmission. In particular, PsJN and 32A endophytically colonised tomato plants and moved from the shoots to roots after mirid-mediated transmission. In conclusion, this study provided novel evidence for the acquisition and transmission of plant growth-promoting bacterial endophytes by beneficial mirids.&nbsp

BACKGROUND The vine mealybug, Planococcus ficus (Signoret) (Hemiptera: Pseudococcidae) is a key pest of grapevine in the Mediterranean Basin. Some honeydew collecting ant species are known to increase mealybug populations in other grape-growing regions. However, there is scarce information on either the ant species present in Mediterranean vineyards or their impact on mealybugs. We conducted a study in four commercial vineyards in Eastern Spain in order to i) identify the ant species foraging on the vine canopies, ii) study the association among ant activity, vine mealybug abundance and fruit damage, and iii) test a novel method for ant management, distracting ants from guarding vine mealybugs by providing artificial sugars. RESULTS We recorded three ant species native to the Mediterranean foraging on the vine canopies: Lasius grandis (Forel), Pheidole pallidula (Nylander) and Plagiolepis schmitzii (Forel). The mean percentage of damaged fruits per vine was positively correlated with the number of vine mealybugs captured in traps placed at the trunk. We detected a positive but weak relationship between ant activity, vine mealybug abundance and fruit damage. The provisioning of artificial sugars reduced the number of ants foraging on the vines by 23.4% although this reduction was not statistically significant. Vine mealybug abundance was significantly reduced (72%) after sugar provisioning. CONCLUSION Our results suggest that the ant species native to vineyards in eastern Spain induce population increases of the vine mealybug. Moreover, the provisioning of artificial sugars can be a valuable tool for ant management.

[EN] Ants can act simultaneously as predators and as protectors of honeydew producing pests. As a result, their impact on plants can be both positive and negative. By guarding honeydew producers against their natural enemies, ants can severely disrupt biological control programs and are often seen as important indirect pests. Chemical control, as well as physical ant-exclusion is employed to disrupt the mutualistic relationship between ants and honeydew producers. However, the exclusion or killing of ants also eliminates their services as biocontrol agents. Herein, we tested whether it is possible to use artificial sugar supplements to shift the balance in ant-pest interaction from pest guarding to pest control. Sugar feeders were supplied either on the ground near the tree trunk, or on the tree branches of citrus trees. Subsequently we assessed whether the provisioning of artificial sugar sources i) alters ant activity ii) disrupts the association between the ant Lasius grandis and the aphid Aphis spiraecola and iii) reduces the aphid populations over time. Compared to control trees (no sugars), ant activity within the tree was significantly reduced when the sugar feeders were placed on the ground and significantly increased when the feeders were placed on the tree branches. Ant tending of aphid colonies was reduced in all trees featuring sugar feeders. Similarly, aphid colony size was significantly reduced relative to control trees, both for trees with sugars on the ground or on the branches. However, the reduction was more pronounced when the sugars were offered on the tree branches. Finally, the abundance of natural enemies being associated with the aphid colony was significantly increased on trees with sugars on the branches. This shows that the provisioning of artificial sugar sources has practical potential as a sustainable strategy for ant management in programs aiming at the biological control of honeydew producing pests.

Summary 1.Nectar is a crucial energy resource that strongly mediates the interactions between plants and animal pollinators or plant defenders. Previous research has shown that nectar is commonly colonized by microorganisms, most commonly bacteria and yeasts, which can have a strong impact on nectar chemistry. However, at present little is known about the effects of microorganisms on the fitness of animals feeding on nectar. 2.We used three nectar bacteria representing different metabolic groups (Asaia sp., Lactococcus sp. and Rosenbergiella sp.) and the common generalist aphid parasitoid Aphidius ervi (Haliday) (Hymenoptera: Braconidae) to test the hypothesis that different nectar-dwelling bacteria affect nectar consumption and insect longevity differently by altering the chemistry of nectar. 3.Bacteria significantly affected nectar chemistry by altering its acidity, sugar and amino acids composition/concentration and by adding compounds synthesized by the microbes. Although inoculation with bacteria did not affect nectar consumption, a significant difference in insect longevity was observed. The impact on longevity was species specific, with Lactococcus being beneficial and Asaia having a detrimental effect.​ 4.Bacteria have a strong impact on nectar chemistry and changes in nectar chemistry may not only influence the foraging behavior of flower-visiting animals and impact on plant fitness, but also influence the fitness of nectar-consuming organisms. As effects were species dependent, changes in nectar chemistry induced by different bacteria may have contrasting effects on the interactions between plants and insects. It is therefore essential to know how different microbes alter nectar chemistry to understand the relationships between plants, nectar-inhabiting microbes and nectar-consuming animals. This article is protected by copyright. All rights reserved.

Ecological studies are increasingly moving towards trait-based approaches, as the evidence mounts that functions, as opposed to taxonomy, drive ecosystem service delivery. Among ecosystem services, biological control has been somewhat overlooked in functional ecological studies. This is surprising given that, over recent decades, much of biological control research has been focused on identifying the multiple characteristics (traits) of species that influence trophic interactions. These traits are especially well developed for interactions between arthropods and flowers – important for biological control, as floral resources can provide natural enemies with nutritional supplements, which can dramatically increase biological control efficiency. Traits that underpin the biological control potential of a community and that drive the response of arthropods to environmental filters, from local to landscape-level conditions, are also emerging from recent empirical studies. We present an overview of the traits that have been identified to (i) drive trophic interactions, especially between plants and biological control agents through determining access to floral resources and enhancing longevity and fecundity of natural enemies, (ii) affect the biological control services provided by arthropods, and (iii) limit the response of arthropods to environmental filters, ranging from local management practices to landscape-level simplification. We use this review as a platform to outline opportunities and guidelines for future trait-based studies focused on the enhancement of biological control services.

Many plants offer food rewards such as extrafloral nectar and food bodies, which have been shown to attract and retain entomophagous arthropods. In addition to food rewards, plants may possess structures that serve as shelter and/or oviposition sites for beneficial arthropods, so-called domatia. Acarodomatia are commonly used by beneficial mites for oviposition and protection from intraguild predators and adverse climatic conditions (drought). While in nature these food and shelter traits often occur in combination, they have been largely studied in isolation and we know little about how these traits interact, i.e., whether they act independently, antagonistically or synergistically. In the present study, we used citrus seedlings to test the impact of provisioning fibers (as a proxy for acarodomatia), as well as two different categories of food rewards (pollen and sugars) on oviposition and population development of phytoseiid mites. The highest oviposition and abundance of predatory mites was obtained in the treatment where the three resources were offered in combination. The combined impact of the three resources when provided jointly was up to five times higher than the summed impacts of each resource provided individually, thus providing evidence for a three-way synergy between the fibers, pollen and sugars. From an ecological point of view, our results demonstrate that combining multiple indirect defensive traits can strongly enhance the impact on the mutualistic arthropods. Differences in resource provisioning strategies in plant-phytoseiid and plant-ant mutualisms are being discussed. The presented results are of particular importance for our understanding of the functioning of defensive plant-arthropod mutualisms, as well as for the use of predatory mites in conservation- or inundative biological control.

Flower strips are widely recommended as a tool to boost insect pollinators and yield in pollinator-dependent crops. Using UK cider apple orchards (Malus domestica Borkhausen) as a model system, we assessed whether flower strips increased pollination services in orchards. Pollinator communities (visual observation) and pollination services (fruit set) were assessed at increasing distance from surrounding semi-natural habitats (0 – 200 m) in eight orchards. In four orchards, perennial flower strips had been established and bloomed in the year before the main experiment. In a separate experiment, insect visits to apple flowers were observed to investigate possible functional mechanisms underpinning pollinator efficacy. The visit rate of wild insects to apple flowers (non-Apis bees and flies), but not that of honeybees (Apis mellifera L.), increased by 40% in flower strip orchards compared to control orchards, particularly in areas close to semi-natural habitat (

BACKGROUND The temperature-size rule is a well-known example of phenotypic plasticity in ectothermic organisms. When exposed to colder temperatures, ectotherms develop more slowly, but mature at larger body sizes and vice versa at higher temperatures. We investigated whether a phytoseiid predatory mite can obtain a larger body size by rearing it at a low temperature and how the increased body size affected predatory performance on its natural prey. Therefore, we allowed the predatory mite Amblydromalus limonicus (Garman & McGregor) (Acari: Phytoseiidae) to develop at either 15 or 25 degrees C. RESULTS A. limonicus reared at 15 degrees C had a 6% larger body size than those reared at 25 degrees C. Larger predators showed higher predation rates on first instars of the western flower thrips, Frankliniella occidentalis Pergande (Thysanoptera: Thripidae), with 9.6 instars/female/day and 8.5 instars/female/day, for larger and standard-sized females, respectively. After three generations reared at 15 degrees C, body size did not increase any further. When reared for five generations at 15 degrees C, larger A. limonicus females demonstrated a better ability to subdue second-instar F. occidentalis. CONCLUSION Low juvenile rearing temperatures may result in phytoseiid predators with a predator/prey size benefit that could improve their biological control function. (c) 2019 Society of Chemical Industry

Pilophorus gallicus can establish resident populations in orchards by entering diapause in winter. We studied diapause induction and termination to predict seasonal activity and improve its management in IPM programs.Pilophorus gallicus Remane (Hemiptera: Miridae) is an important predator of the pear psyllid Cacopsylla pyri L. (Hemiptera: Psyllidae) in pear orchards (Pyrus communis L. -Rosaceae-). In the Mediterranean area, it has a multivoltine lifecycle, and can establish resident populations by entering into a facultative embryonic diapause to survive the winter season. Facultative diapause is regulated by environmental factors, and its role in population dynamics is essential because it determines the presence of active individuals in the field. The objective of this work was to investigate the effect of (i) photoperiod and temperature on diapause induction in P. gallicus and (ii) photoperiod, temperature, and exposure time on diapause termination.Diapause induction was triggered by a short photoperiod (9L:15D), whereas temperature did not influence it significantly. In contrast, diapause termination required a prolonged exposure to low temperature while photoperiod did not have a significant effect. At 6 °C, diapause termination increased significantly between 50 and 70 days of exposure, but not among 70, 90 and 150 days. The longer the exposure of diapausing eggs to 6 °C the shorter their hatching times. Additionally, three different reproductive classes were observed among the female population: diapause inducing, non-diapause inducing, and mixed.This work contributes to the knowledge of the reproductive and overwintering strategy of P. gallicus. Embryonic diapause may greatly determine the structure of populations according to environmental conditions and the response of the predator as biological pest control agent. In addition, knowledge of the factors regulating egg diapause may be a useful tool for the mass rearing industry.

Many reptiles, amphibians, mammals, and insects practice some form of hibernation during which their metabolic rate is drastically reduced. This allows them to conserve energy and survive the harsh winter conditions with little or no food. While it can be expected that a reduction in host metabolism has a substantial influence on the gut microbial community, little is known about the effects of hibernation on the composition of the microbial gut community, especially for insects. In this study, we assessed and compared the bacterial gut community composition within the midgut and ileum of indoor-reared queens of Bombus terrestris before and after an artificial hibernation period of 16 weeks. Deep sequencing of 16S ribosomal RNA gene amplicons and clustering of sequence reads into operational taxonomic units (OTUs) at a similarity threshold of 97% revealed several bacterial taxa that are known to be strongly associated with corbiculate bees. Bacterial community composition after hibernation compared to before hibernation was characterized by higher OTU richness and evenness, with decreased levels of the core bacteria Gilliamella (Proteobacteria, Orbaceae) and Snodgrassella (Proteobacteria, Neisseriaceae), and increased relative abundance of non-core bacteria, including several psychrophilic and psychrotrophic taxa. ispartof: Insects vol:9 issue:4 ispartof: location:Switzerland status: published

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 (rm) was recorded for the mix of cattail pollen and thrips, and the strongest increase in rm when thrips were combined with pine pollen followed by corn and cattail pollen. Overall, mixing prey with pollen resulted in higher rm values thus enhancing the medium- to long-term thrips-control potential of A. limonicus.

Naturally occurring predators and parasitoids are known to reduce the abundance of pest invertebrates in arable crops, yet current treatment thresholds do not account for such a contribution to pest management. In the present study, we provide evidence for the presence of natural enemies correlating with a subsequent reduction in pest population growth. The abundance of cereal aphid pests and two key aphidophagous natural enemies, parasitoid wasps (Aphidiinae) and hoverfly larvae (Syrphinae), was assessed at field boundaries and interiors in southeast England. The highest rate of aphid population growth was associated with locations where no natural enemies were found. The presence of either Aphidiinae wasps or predatory Syrphinae larvae was associated with a reduction in the rate of aphid population growth, irrespective of location within the field, and overall aphid population growth was negatively correlated with increasing natural enemy abundance. The results of the present study indicate that natural enemies contribute significantly to pest control, and provide further evidence supporting the use of management strategies for promoting natural enemies in agro-ecosystems. Aphid predators and parasitoids make an important contribution to aphid pest control within cereal fields, and thresholds for insecticide application should account for this to avoid unnecessary treatments.