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Characterizing compositional heterogeneity in Earth’s lower mantle is critical to understanding its dynamics. Three low-nitrogen diamonds from Koffiefontein (South Africa), containing inclusion assemblages of ferropericlase ± orthopyroxene ± magnesite, constrain diamond formation in an Mg-rich lower-mantle environment. Ferropericlase inclusions have Mg# 82.7–88.5 and orthopyroxene inclusions (retrogressed bridgmanite) have Mg# 95.0–95.1 and mantle-like δ18O of +5.6‰ ± 0.2‰. Magnesite included in one diamond implicates carbonated fluids in diamond formation. High Mg# and low Ca, Al, and Na of the assemblage indicate a melt-depleted meta-harzburgitic environment, in contrast to more fertile compositions expected for primitive lower mantle. Extremely low Ca in orthopyroxene inclusions may reflect a combination of melt depletion and low equilibration temperatures at the time of trapping. Inclusion compositions implicate subducted oceanic slab meta-harzburgite as the host for diamond growth. Mantle-like δ18O of the orthopyroxene inclusions indicates unaltered oceanic lithosphere. Similar melt-depleted characteristics in lower-mantle inclusion assemblages worldwide support that meta-harzburgite is the dominant host of lower-mantle diamonds.

The introduction of volatile-rich subducting slabs to the mantle may locally generate large redox gradients, affecting phase stability, element partitioning and volatile speciation

Thanks to the physical strength of diamonds and their relatively unreactive chemical nature, their mineral inclusions may remain exceptionally preserved from alteration processes and chemical exchanges with surrounding minerals, fluids and/or melts following diamond formation. Cr-bearing spinels are relatively common inclusions found in peridotitic diamonds and important oxybarometers providing information about the oxygen fugacity (fO2) of their source mantle rocks. Here, we investigated a magnesiochromite–olivine touching pair in a diamond from the Udachnaya kimberlite (Siberia) by in situ single-crystal X-ray diffraction and energy-domain synchrotron Mössbauer spectroscopy, aiming to constrain the physical–chemical conditions of diamond formation and to explore the redox state of this portion of the Siberian craton when the diamond was formed. The P–T–fO2 entrapment conditions of the inclusion pair, determined by thermo- and oxybarometric analyses, are ∼ 5.7(0.4) GPa and ∼ 1015(50) ∘C (although entrapment at higher T and re-equilibration during subsequent mantle storage are also possible) and fO2 near the enstatite–magnesite–olivine–diamond (EMOD) buffer. The determined fO2 is similar to, or slightly more oxidized than, those of xenoliths from Udachnaya, but whilst the xenoliths last equilibrated with the surrounding mantle just prior to their entrainment in the kimberlite at ∼ 360 Ma, the last equilibration of the inclusion pair is much older, occurring at 3.5–3.1, ∼ 2 or ∼ 1.8 Ga before final encapsulation in its host diamond. Hence, the similarity between xenoliths and inclusion fO2 values indicates that the modern redox state of this portion of the Siberian lithosphere was likely attained relatively early after its formation and may have persisted for billions of years after diamond formation, at least at the local scale. Moreover, the oxygen fugacity determination for the inclusion pair provides direct evidence of diamond formation near the EMOD buffer and is consistent with recent models suggesting relatively oxidized, water-rich CHO fluids as the most likely parents for lithospheric diamonds.

Varroa Sensitive Hygiene (VSH) is a useful resistance trait that honey bee (Apis mellifera) breeders could increase in different populations with cost-effective and reliable tests. We investigated ...

Neonicotinoids have been implicated as a contributing factor to the observed decreases in honey bee populations. It has been suggested that honey bees can be exposed to seed-treated neonicotinoids through pollen and nectar from treated plants. To investigate the uptake and persistence of neonicotinoids in plant tissue and soil, we conducted seed treatment trials with corn, cotton, and soybean planted in Mississippi, Arkansas, and Tennessee during the 2013 and 2014 growing seasons. Leaf tissue was collected and analyzed beginning shortly after emergence until plants began to flower to better understand how neonicotinoid concentrations change in plant tissues over time. The youngest leaf in the terminal of the plant was sampled as an indicator of the neonicotinoid concentrations within the plant. Soil samples were also collected and analyzed for neonicotinoid concentrations at the first and last sampling dates. The mean clothianidin concentrations in corn treated with Poncho® 250, 500, and 1250 seed treatments declined by 99.3, 99.3, and 97.8 percent, respectively, as the plants developed from seedlings to reproductive plants. The mean concentration of imidacloprid detected in Aeris®-treated cotton decreased by 99.6 percent during the sampling period. For cotton seed treated with Avicta® Duo, the mean concentrations of thiamethoxam and clothianidin in leaf tissue declined by 99.9 and 100 percent, respectively, by the time flowering occurred. There was a 99.9 percent reduction in the mean concentration of thiamethoxam by the time of flowering in leaf tissue from soybean treated with a CruiserMaxx® seed treatment. Mean clothianidin concentrations completely diminished (&lt, 1 ng/g) in CruiserMaxx®- and Poncho®/VOTiVO®-treated soybean plants by the time plants reached reproductive growth. The data for neonicotinoid concentrations in the soil were more variable than leaf tissue samples, and the reduction in neonicotinoid concentrations in leaf tissues did not closely correlate with concentrations in the soil. Our results suggest that neonicotinoid insecticides, when used as seed treatments in these crops, decline rapidly throughout vegetative growth stages. However, the biological impact on target or non-target arthropods was not examined.

Two types of honey bees, Apis mellifera L., bred for resistance to Varroa destructor Anderson & Trueman, were evaluated for performance when used for honey production in Montana, and for almond pollination the following winter. Colonies of Russian honey bees and outcrossed honey bees with Varroa-sensitive hygiene (VSH) were compared with control colonies of Italian honey bees. All colonies were managed without miticide treatments. In total, 185 and 175 colonies were established for trials in 2010–2011 and 2011–2012, respectively. Survival of colonies with original queens or with supersedure queens was similar among stocks for both years. Colony sizes of the Varroa-resistant stocks were as large as or larger than the control colonies during periods critical to honey production and almond pollination. Honey production varied among stocks. In the first year, all stocks produced similar amounts of honey. In the second year, Russian honey bees colonies produced less honey than the control colonies. V. destructor infestations also varied among stocks. In the first year, control colonies had more infesting mites than either of the Varroa-resistant stocks, especially later in the year. In the second year, the control and outcrossed Varroa-sensitive hygiene colonies had high and damaging levels of infestation while the Russian honey bees colonies maintained lower levels of infestation. Infestations of Acarapis woodi (Rennie) were generally infrequent and low. All the stocks had similarly high Nosema ceranae infections in the spring and following winter of both years. Overall, the two Varroa-resistant stocks functioned adequately in this model beekeeping system.

International audience; Honeybees, Apis mellifera, selected for the hygienic removal of freeze-killed brood (FKB), resist several microbial diseases and have some resistance to Varroa destructor. Bees with Varroa-sensitive hygiene (VSH) have good resistance to V. destructor. We determined whether the response to FKB could be used to select for VSH by measuring the responses of different bees (VSH, FKB-selected, F1 VSH, and unselected control) to combs with FKB and combs with mite-infested brood. All bee types completely removed much FKB (77–88 %) within 24 h. The removal of mite-infested brood after 1 week was much more variable among bee types (VSH, 66 %; F1 VSH, 51 %; FKB hygienic, 14 %; control, 3 %). There was some relationship between 24-h manipulation of FKB cells (i.e., cell contents at least partially removed) and the removal of mite-infested brood, but this appears to have little practical relevance because of a large inherent variation.

International audience; AbstractWe investigated an effect of Apis mellifera worker brood on the reproduction of Varroa destructor as a resistance trait by conducting seven generations of bidirectional selection. Initial tests showed twofold differences in mite fecundity (progeny per foundress mites) between colonies of different origins. In the first two generations of selection, low and high lines differed significantly in mite fecundity (2.6 vs. 2.9 and 2.3 vs. 2.8), but in five subsequent generations the average values of the low fecundity lines (ranges of 2.7 to 3.3) became indistinguishable from high lines (2.9 to 3.1). Similarly, the relationship between mite fecundity in 117 offspring colonies and in their 26 queen and 22 drone parent colonies was partly significant in the first three generations but not in subsequent generations. These findings suggest that adaptation of mites to host cues, loss of resistance alleles in a small breeding population, or environmental effects present challenges to breeding for this trait.

Honey bees (Apis mellifera L.) bred for Varroa sensitive hygiene (VSH) selectively remove pupae infested with Varroa destructor Anderson & Trueman (Mesostigmata: Varroidae) from capped brood that is inserted into the nest. After 1 wk, remaining brood cells tend to have been uncapped and recapped, and remaining mites are mostly infertile. A primary goal of this experiment was to compare the reproductive status of mites that remained in recapped and normally capped cells after a 1-wk exposure to VSH and control colonies. Differences in distribution of fertile mites in normally capped brood cells between VSH bees and control bees may suggest that the stimulus for hygiene is related to reproduction by mites. Identification of stimuli triggering VSH behavior could be used to develop new bioassays for selective breeding of this important resistance mechanism. Combs of capped brood that were exposed to control bees had 10 times more pupae with fertile mites in normally capped brood as did VSH bees (6.7 and 0.7%, respectively). They also had 3 times more pupae with infertile mites in normally capped brood than did VSH bees (1.4 and 0.5%, respectively). Thus, VSH bees targeted fertile mites by a 3:1 ratio by either removing or uncapping and recapping their host pupae. Biased removal of mite-infested pupae with fertile mites suggested that stimuli triggering VSH behavior were enhanced by the presence of mite offspring within the brood cell. This bias for fertile mites is not seen during experiments of short 3-h duration. The differing results are discussed relative to a behavioral threshold model for hygienic behavior in honey bees in which different experimental protocols may reflect activities of honey bees having different sensitivities to pupae infested by fertile mites. In addition, mortality of mite offspring was significantly higher in recapped cells than in normally capped cells and contributed to decreased reproduction by the mites.

Two types of honey bees, Apis mellifera L. (Hymenoptera: Apidae), bred for resistance to Varroa destructor AndersonTrueman were evaluated for performance when used in migratory crop pollination. Colonies of Russian honey bees (RHB) and outcrossed bees with Varroa-sensitive hygiene (VSH) were managed without miticide treatments and compared with colonies of Italian honey bees that served as controls. Control colonies were managed as groups which either were treated twice each year against V. destructor (CT) or kept untreated (CU). Totals of 240 and 247 colonies were established initially for trials in 2008 and 2009, respectively. RHB and VSH colonies generally had adult and brood populations similar to those of the standard CT group regarding pollination requirements. For pollination of almonds [Prunus dulcis (Mill.) D.A.Webb] in February, percentages of colonies meeting the required six or more frames of adult bees were 57% (VSH), 56% (CT), 39% (RHB), and 34% (CU). RHB are known to have small colonies in early spring, but this can be overcome with appropriate feeding. For later pollination requirements in May to July, 94-100% of colonies in the four groups met pollination size requirements for apples (Malus domestica Borkh.), cranberries (Vaccinium macrocarpon Aiton), and lowbush blueberries (Vaccinium angustifolium Aiton). Infestations with V. destructor usually were lowest in CT colonies and tended to be lower in VSH colonies than in RHB and CU colonies. This study demonstrates that bees with the VSH trait and pure RHB offer alternatives for beekeepers to use for commercial crop pollination while reducing reliance on miticides. The high frequency of queen loss (only approximately one fourth of original queens survived each year) suggests that frequent requeening is necessary to maintain desired genetics.

Honeybees have evolved a social immunity consisting of the cooperation of individuals to decrease disease in the hive. We identified a set of genes involved in this social immunity by analysing the brain transcriptome of highly varroa-hygienic bees, who efficiently detect and remove brood infected with the Varroa destructor mite. The function of these candidate genes does not seem to support a higher olfactory sensitivity in hygienic bees, as previously hypothesized. However, comparing their genomic profile with those from other behaviours suggests a link with brood care and the highly varroa-hygienic Africanized honeybees. These results represent a first step toward the identification of genes involved in social immunity and thus provide first insights into the evolution of social immunity.

Breeding for resistance to Varroa destructor in North America provides the long-term solution to the economic troubles the mite brings. This review reports the development of two breeding successes that have produced honey bees of commercial quality that do not require pesticide treatment to control Varroa, highlights other traits that could be combined to increase resistance and examines the potential uses of marker-assisted selection (MAS) for breeding for Varroa resistance. Breeding work continues with these stocks to enhance their commercial utility. This work requires knowledge of the mechanisms of resistance that can be further developed or improved in selected stocks and studied with molecular techniques as a prelude to MAS. Varroa resistance / breeding program / Russian honey bees / Varroa-sensitive hygiene / marker-assisted selection

Varroa sensitive hygiene (VSH) is a trait of honey bees, Apis mellifera L. (Hymenoptera: Apidae), which supports resistance to Varroa destructor Anderson & Trueman. VSH is the hygienic removal of mite-infested pupa. Bees selectively bred for VSH produce colonies in which the fertility of mites decreases over time. In addition, mite fertility decreases after infested brood is exposed to VSH bees for 1 wk. The purpose of this study was to decide whether the reduction in mite fertility is caused by selective removal of mites that produce offspring. Initially, we monitored changes in a small patch of capped brood during exposure to VSH bees at 2-h intervals through 60 h, which provided a reference for the subsequent experiment. The first test showed that VSH bees uncapped, recapped, and began to remove many pupae in ≈2 h. The approach in the second experiment was to compare the percentage of fertile mites from brood exposed to VSH bees for a 3-h period to the percentage of fertile mites in brood that was protected from hygiene by a screen. There were no significant differences in fertility between mites on pupae that were being removed by the bees and mites on protected pupae. These results suggest that neither egg-laying by foundress mites nor mite offspring are the stimuli that trigger hygienic removal of mite-infested pupae by VSH bees. It may be that hygienic activities such as the uncapping of brood cells inhibits or disrupts reproduction by varroa mites.

SummaryVarroa Sensitive Hygiene (VSH) is a trait of honey bees, Apis mellifera, that supports resistance to Varroa destructor mites. Components of VSH were evaluated to identify simple methods for selection of the trait. Mite population growth was measured in colonies with variable levels of VSH in two field trials using 24 and 16 colonies. Mite population growth was significantly lower in VSH and hybrid colonies than in control (i.e., unselected) colonies. In resident brood with mite infestations below 5%, the percentage of uncapped pupal cells did not differ significantly among VSH, hybrid and control colonies, but the percentage of recapped cells was highest in VSH colonies (P = 0.03). When brood from more highly infested colonies (9–49% of pupae infested) was introduced for forty hours, VSH colonies reduced infestation more than control colonies (P< 0.01) but final mite fertility was similar (P= 0.12). When infested brood was exposed in colonies for one week, VSH colonies reduced both mite fertility (...

Summary Mite resistance that we had earlier called suppression of mite reproduction (SMR) is a form of hygienic behaviour that we have named Varroa Sensitive Hygiene (VSH). With VSH, adult worker bees (Apis mellifera) disrupt the reproduction of parasitic mites (Varroa destructor) by removing mite infested bee pupae from their cells. This study determines which brood cells are targeted by bees with VSH and which are not, and describes the relationship between brood removal and the sudden prevalence of sterile mites. We produced 26 colonies with different levels of VSH by backcrossing 14 queens from a high line, H (100% expression of VSH), and 12 queens from a low line, L (no VSH), to drones produced by an HL (high × low) queen. Because each of the 26 queens was mated to one drone, the resulting colonies were expected to represent the complete range of variability (0 to 100% of the alleles for VSH). To estimate brood removal, we measured mite populations in capped worker brood that was 0 - 3 days postcapping and again 7 days later when the cohort was aged 7 - 10 days postcapping. We correlated removal of mite-infested brood with the relative presence (at 7 – 10 days postcapping) of three classes of foundress mites: (1) viable: those with at least one daughter that could mature before emergence of the host bee; (2) nonviable: those with progeny but with no daughters that could reach maturity; and (3) no eggs: those with dead or nonovipositing foundress mites. As the rate of removal increased, both classes 1 and 2 showed significant declines, whereas class 3 was unchanged. Therefore, oviposition of the mite or something associated with mite oviposition provides the stimulus for bees with the VSH trait to remove mite infested pupae.

Honey bees (Apis mellifera L.) (Hymenoptera: Apidae) have been selectively bred for varroa-sensitive hygiene (VSH), which is the removal of pupae that are infested by Varroa destructor Anderson & Trueman from capped brood cells. This hygienic behavior is a complex interaction of bees and brood in which brood cells are inspected, and then brood is either removed or recapped. Previous work has shown that VSH bees uncap and remove significantly more varroa-infested worker pupae than nonhygienic bees do, but nothing is known about the reactions of VSH bees to mite-infested drone brood. This study compared the reactions of VSH bees with mite-infested worker and drone brood in a laboratory test and a field test. VSH bees inspected brood cells containing mite-infested pupae of both types of brood, but they removed significantly fewer mite-infested drone pupae than mite-infested worker pupae after 1 wk. This result suggests that mite populations in VSH colonies could increase more rapidly when drone brood is available. Additionally, the percentages of uncapped pupae and uncapped mite-infested pupae were positively correlated to the natural infestation rate of brood after a 24-h exposure, but not after an exposure of 1 wk. This result suggests that the rate of uncapping brood by hygienic bees may depend on the infestation rate, which gradually decreases with longer exposures to bees that remove mite-infested pupae from capped brood.

*Summary Suppressed Mite Reproduction (SMR) is a trait of honey bees that provides resistance to Varroa destructor. The mechanism of resistance in SMR bees is the removal of infested pupae from capped brood, so a better name is VSH bees (acronym for Varroa Sensitive Hygiene). This study compared the removal of infested brood by VSH and control bees to determine whether VSH bees removed infested pupae of different ages at similar rates. A pair of infested combs containing all stages of pupae were transferred into each host colony (six VSH and six control colonies) for 40 hours. VSH bees removed significantly more (55%) infested cells (singly and multiply infested), than controls (13%). They removed significantly more (66%) singly infested pupae aged from one to five days post capping (cohort A) than did controls (16%). The two types did not differ in the removal of singly infested pupae aged five to 10 days post capping (cohort B) (5‐22%). Many pupae were found in uncapped cells at the end of the test, and most of the uncapped pupae were infested with mites. None of the uncapped cells contained prepupae, the development stage occurring during the first three days post capping. Thus, removal of infested pupae may be triggered by stimuli in cells with pupae aged 3‐5 days post capping.

SUMMARYThis study compared brood production, honey consumption (in winter only), population growth of honey bees (Apis mellifera), and population growth of parasitic mites (Varroa destructor) in hives with open screen or wood as floor material. Two experiments were conducted in Baton Rouge, Louisiana, USA, one in winter (19 colonies) and one in summer (22 colonies). In both experiments, we established uniform colonies of honey bees by subdividing 30 kg of mite-infested bees. Each colony began with about 11 000 bees, no brood, and uniform populations of mites (127 and 480 mites per colony in winter and summer, respectively). The summer test included a third treatment (8 colonies) where a wooden tray (5 cm deep) closed the space beneath a screen floor. After the first 20 days of the experiments, when no adult bees or mites had yet been produced in any of the colonies, the treatments showed no differences in brood production, honey consumption, or survival of adult bees. At nine weeks, colonies with screen f...

We measured significant variation in the instantaneous growth rates for varroa mites, Varroa destructor (Anderson & Trueman) from 1993 to 2002 in Baton Rouge, LA. Mite population growth was monitored in colonies of honey bees, Apis mellifera L., with queens from miscellaneous U.S. sources that had not been selectively bred for varroa resistance. Mite populations were measured at the beginning and end of short field tests that started in the late spring of each year. Analyses of multiple regression showed that only the first two of the following regressors were linear predictors of r, the instantaneous growth rate: 1) percentage of reproducing female mites, 2) proportion of total mites in capped brood, 3) mortality of mites in brood cells, 4) growth of the bee population, 5) capped brood area at the end of a test, and 6) duration of the test. Analysis of commonality indicated that the percentage of reproducing female mites explained ≈26% of the total variation in r, and the proportion of total mit...

This study demonstrated (1) that honey bees, Apis mellifera L, can express a high level of resistance to Varroa destructor Anderson & Trueman when bees were selected for only one resistant trait (suppression of mite reproduction); and (2) that a significant level of mite-resistance was retained when these queens were free-mated with unselected drones. The test compared the growth of mite populations in colonies of bees that each received one of the following queens: (1) resistant--queens selected for suppression of mite reproduction and artificially inseminated in Baton Rouge with drones from similarly selected stocks; (2) resistant x control--resistant queens, as above, produced and free-mated to unselected drones by one of four commercial queen producers; and (3) control--commercial queens chosen by the same four queen producers and free-mated as above. All colonies started the test with approximately 0.9 kg of bees that were naturally infested with approximately 650 mites. Colonies with resistant x control queens ended the 115-d test period with significantly fewer mites than did colonies with control queens. This suggests that beekeepers can derive immediate benefit from mite-resistant queens that have been free-mated to unselected drones. Moreover, the production and distribution of these free-mated queens from many commercial sources may be an effective way to insert beneficial genes into our commercial population of honey bees without losing the genetic diversity and the useful beekeeping characteristics of this population.

Varroa destructoris a parasitic mite of the Asian honey bee, Apis cerana. Owing to host range expansion, it now plagues Apis mellifera, the world's principal crop pollinator and honey pro- ducer. Evidence from A. mellifera in far-eastern Russia, Primorsky (P) originating from honey bees imported in the mid 1800's, suggested that many colonies were resistant toV. destructor. A con- trolled field study of the development of populations of V. destructor shows that P colonies have a strong, genetically based resistance to the parasite. As control colonies (D) were dying with infesta- tions of ca. 10 000 mites, P colonies were surviving with infestations of ca. 4 000 mites. Several characteristics of the P bees contributed to suppressing the number of mites parasitizing their colonies. Apis mellifera / mite resistance / Varrao destructor / Russia / disease resistance / natural selection

Summary The sound or ‘buzzing response’ from groups of fifteen worker honey bees, Apis mellifera L., to the presentation of isopentyl acetate, an alarm pheromone component, was recorded through a microphone connected via a digital–analogue converter into a computer. The effects of ingested biogenic amine precursors 5-hydroxytryptophan, L-DOPA and tryptophan were tested on three variables measurable from the sound traces: onset of the buzzing response after presentation of the pheromone stimulus, the duration of the buzzing event, and the maximal sound frequency produced during the buzzing event. Bees fed high doses of 5-hydroxytrytophan were found to react significantly more slowly and with a significantly lower maximum frequency than bees that were only fed sucrose controls. Bees fed DOPA were no different from controls for any of the variables measured, and bees fed tryptophan were so hyperactive that reliable responses to the presentation of alarm pheromone could not be made. Finally, the brains of worker bees fed these different precursors were examined for content of various neurochemicals. Bees fed 5-hydroxytryptophan were found to have dose-dependent elevations of both 5-hydroxytryptophan and serotonin within their brains. Bees fed tryptophan were found to have dose-dependent elevations of tryptophan and kynurenine in the brain but no change in brain serotonin. Bees fed DOPA had dose-dependent increases in DOPA and dopamine levels within their brains. These results suggest that the hyperactive condition results from kynurenine metabolism, and the reduced response to alarm pheromone is related to serotonin metabolism.

This study uses sibling analysis to measure the heritability in honey bees, Apis mellifera L., of characteristics that have been associated with resistance to the mite, Varroa jacobsoni Oudemans. Twenty-eight uniform colonies of bees were established on 13 May in Baton Rouge, LA, each with 1 kg of mite-infested bees and a queen. The 28 unrelated queens in these colonies were divided into 7 groups of 4 based on the insemination of 4 queens with the same mixture of semen from 1 of 7 sire colonies. After worker progeny from these queens had replaced the initial bee populations, a colony was related as a full sister to the other 3 colonies in its sire group and unrelated to the other 24 colonies. Heritability ( h 2) was 1.24 for proportion of mites in brood, 0.65 for hygienic behavior, 0.89 for the duration of the capped period, 0.46 for suppression of mite reproduction, and 0.00 for physical damage to mites (measured by the presence of physically broken or dented mites on the bottom board). These results suggest that it should be possible to enhance the expression of 4 of these 5 characteristics with selective breeding of bees, thus reinforcing confidence in our ability to breed honey bees for resistance to V. jacobsoni.

A breeding program for honey bees, Apis mellifera L., resistant to varroa mites, Varroa jacobsoni Oudemans, selected for bees that maintain low populations of mites with decreased reproduction. This study examines the causes for this suppressed mite reproduction. Nonreproductive mites were classified into 3 groups as follows: (1) mites that were alive but did not lay eggs, (2) mites that began laying eggs later than normal, and (3) mites that died before laying eggs (usually

Cet article examine les methodes de selection d'abeilles melliferes resistantes a l'acarien V. jacobsoni. Un plar. de selection est decrit ci-apres, qui devrait etre mis en œuvre dans tout programme de selection prenant en compte les caracteres des abeilles mesures au niveau de la colonie. 1) Developper des methodes pour mesurer les populations d'abeilles et d'acariens et pour mesurer les caracteres associes a la resistance. 2) Identifier les caracteres specifiques en relation avec la croissance des populations d'acariens. 3) Determiner si ces caracteres sont hereditaires. 4) Renforcer ces caracteres par un elevage selectif. 5) Regrouper les composantes de la resistance dans des abeilles productives et resistantes aux acariens. Dans cet article on entend par resistance a V. jacobsoni la selection chez les abeilles de caracteres qui vont retarder la croissance de la population d'acariens etablie dans la colonie. Lors du criblage initial des caracteres, nous avons utilise des reines fecondees par un seul mâle. Nous pensons que cela a permis de detecter aussi des caracteres peu frequents. Les caracteres au niveau de la colonie auraient pu etre caches si les reines avaient ete fecondees par plusieurs mâles. Notre approche decrit la croissance de la population d'acariens au sein d'une colonie d'abeilles par l'equation: P (ab)II = P 2 , ou P 1 et P 2 sont les populations initiale et finale d'acariens, a la variation de la population tant que les acariens sont dans les cellules de couvain, b la variation quand ils sont hors des cellules de couvain et n le nombre de cycles reproducteurs de l'acarien. L'equation est valable pour une colonie qui a un apport regulier en couvain d'ouvrieres de facon a permettre la reproduction de l'acarien. Seules les femelles adultes d'acariens sont comptees et toutes les mesures sont des moyennes pour la colonie. En comparant les taux de croisssance des populations d'acariens de chaque colonie (P 2 / P 1 ), on peut determiner la croissance reelle dans chaque colonie. Les valeurs a, b et n peuvent alors expliquer comment la population d'acariens est passee de P 1 , a P 2 en termes de composantes mesurables du cycle reproducteur de l'acarien. Les variations de la population d'acariens doivent se refleter dans une ou plusieurs de ces composantes. Les caracteres specifiques des abeilles (qui sont la base de la selection) peuvent alors etre associes a l'une de ces trois composantes. Quand plusieurs caracteres specifiques agissent sur une meme composante (par exemple, la suppresssion de la reproduction de l'acarien et le comportement hygienique), leur effet combine n'est pas necessairement additif ni benefique. Si en revanche un meme caractere specifique agit en meme temps sur differentes composantes, ceux-ci se combineraient probablement pour donner une colonie ayant une resistance accrue a V. jacobsoni. Jusqu'ici notre selection s'est concentree sur un caractere, la suppression de la reproduction de l'acarien, qui provoque la non reproduction des acariens qui penetrent dans les cellules de couvain. Sur la base de ce seul caractere hereditaire, nous avons produit des colonies dans lesquelles la population d'acariens decline durant une periode test de 70 j. Deux autres caracteres hereditaires, le comportement hygienique et la proportion d'acariens sur le couvain, peuvent avoir aussi une importance pour la selection d'abeilles resistantes.

SUMMARYSuppressed mite reproduction (SMR) is a heritable trait of the honey bee (Apis mellifera) that can control the parasitic mite, Varroa destructor. The purpose of this study was to determine whether adult bees with the SMR trait affect mites in brood after cells are capped. Colonies with or without the SMR trait were each given a comb of newly-capped worker brood that was naturally infested with varroa. Each of 7 source colonies provided a comb of brood to at least one SMR (n = 9) and one control colony (n = 8). These combs were removed from their host colonies 8 days later and mite populations evaluated in cells with bee pupae that were >8 days post-capping. Colonies with SMR bees averaged 2.2% of their cells infested with mites; controls averaged 9.0%. Therefore, bees with the SMR trait apparently removed mites from capped cells. Of the mites that remained, the SMR colonies had a much lower rate of reproductive mites, 20% vs. 71%. This suggests that bees with the SMR trait removed reproductive mite...

SUMMARYSeveral experiments were conducted to examine the effects of exposure to CO2 or CO2 containing 20% O2 on the amounts of biogenic amines in the brain, and on development of ovaries in worker and queen honey bees. When workers were fed pollen and exposed to CO2, their ovaries were less developed and brain dopamine (DA), tryptophan (TRP) and tyrosine (TYR) levels were significantly reduced versus untreated controls that were also fed pollen. If workers were not fed pollen and exposed to CO2, the differences in brain amine content between untreated controls and CO2-treated workers were not significant; however, a significant reduction in brain TRP and TYR levels through time was found for both groups of workers. Treatment with CO2 stimulated free-running queens to lay eggs sooner than untreated free-running queens, but CO2 narcosis had no significant affect on queen brain chemistry. However, the brain chemistry of caged queens (many queens caged within a single colony) responded differently from free-r...

Brain levels of octopamine (OA), dopamine (DA) and serotonin (5HT) were compared between worker honey bees ( Apis mellifera L.) kept with or without queens in various experiments. Levels of DA were significantly higher in queenless bees than in their sisters that had been kept with queens either (1) in small field colonies for 30 days or (2) in incubator cages through 18 days. This difference was not observed in a separate incubator experiment after 6 and 12 days. A correlation between ovariole width and brain DA levels was found in groups of caged queenless workers after 18 days. In pairs of caged workers kept in an incubator through 10 days, the worker having the largest ovariole width was significantly more likely to have higher brain DA levels. The increased DA levels in queenless bees probably reflect changes in behavioral states that occur after onset of oogenesis.

Varroa mites (V. destructor) are a major threat to honey bees (Apis melilfera) and beekeeping worldwide and likely lead to colony decline if colonies are not treated. Most treatments involve chemical control of the mites; however, Varroa has evolved resistance to many of these miticides, leaving beekeepers with a limited number of alternatives. A non-chemical control method is highly desirable for numerous reasons including lack of chemical residues and decreased likelihood of resistance. Varroa sensitive hygiene behavior is one of two behaviors identified that are most important for controlling the growth of Varroa populations in bee hives. To identify genes influencing this trait, a study was conducted to map quantitative trait loci (QTL). Individual workers of a backcross family were observed and evaluated for their VSH behavior in a mite-infested observation hive. Bees that uncapped or removed pupae were identified. The genotypes for 1,340 informative single nucleotide polymorphisms were used to construct a high-resolution genetic map and interval mapping was used to analyze the association of the genotypes with the performance of Varroa sensitive hygiene. We identified one major QTL on chromosome 9 (LOD score = 3.21) and a suggestive QTL on chromosome 1 (LOD = 1.95). The QTL confidence interval on chromosome 9 contains the gene 'no receptor potential A' and a dopamine receptor. 'No receptor potential A' is involved in vision and olfaction in Drosophila, and dopamine signaling has been previously shown to be required for aversive olfactory learning in honey bees, which is probably necessary for identifying mites within brood cells. Further studies on these candidate genes may allow for breeding bees with this trait using marker-assisted selection.

We tested six commercial sources of honey bees, Apis mellifera L. (Hymenoptera: Apidae), whose breeding incorporated the trait of Varroa sensitive hygiene (VSH). VSH confers resistance to the parasitic mite Varroa destructor Anderson & Trueman by enhancing the ability of the bees to hygienically remove mite-infested brood. VSH production queens (i.e., queens commercially available for use in beekeepers' production colonies) from the six sources were established in colonies which later were measured for VSH. Their responses were compared with those of colonies with three other types of queens, as follows: VSH queens from the selected closed population maintained by USDA-ARS for research and as a source of breeding germplasm, queens from the cooperating commercial distributor of this germplasm, and queens of a commercial, mite-susceptible source. The reduction of mite infestation in brood combs exposed to test colonies for 1 wk differed significantly between groups. On average, colonies with VSH production queens reduced infestation by 44%. This group average was intermediate between the greater removal by pure ARS VSH (76%) and the cooperators' breeding colonies (64%), and the lesser removal by susceptible colonies (7%). VSH production colonies from the different sources had variable expression of hygiene against mites, with average reduced infestations ranging from 22 to 74%. In addition, infertility was high among mites that remained in infested cells in VSH breeder colonies from ARS and the commercial distributor but was lower and more variable in VSH production colonies and susceptible colonies. Commercial VSH production colonies supply mite resistance that generally seems to be useful for beekeeping. Resistance probably could be improved if more VSH drones sources were supplied when VSH production queens are being mated.

The effects of environmental and genetic factors on levels of octopamine, dopamine and serotonin in brains from worker honey bees (Apis mellifera L.) were measured using high-performance liquid chromatography with electrochemical detection. Exiting foragers were stressed by clamping their legs, which resulted in peak elevation of octopamine and serotonin after 10 min. Significant seasonal differences in levels of all three biogenic amines were found for bees sampled from an observation colony during the spring, summer and autumn of 1990. Levels of the amines were highest during June–September, corresponding to high levels of colony foraging activity. These differences may reflect seasonal changes in colony nutrition, population size, or brood-rearing activity. The levels of all three amines were significantly lower in the brains of newly emerged bees than in brains from randomly aged worker bees from the same colony. Since the total protein content in bee brains was not different for bees from these two groups, age-related differences were not related to brain growth. Significantly different levels of octopamine, dopamine and serotonin were detected among workers in colonies that contained unrelated queens.

Because a solitary worker honey bee ( Apis mellifera L.) will not lay eggs, eggs were produced from small populations of caged workers. First, worker bees from four colonies were evaluated for their rate of worker ovary development. Groups of 25 workers were kept in incubator cages at 34 ± 1°C, and each cage was given an empty section of drone comb and unlimited supplies of honey, water, and pollen. Workers from colonies A and B began laying eggs rapidly (about 9 d), workers from colony D were intermediate (about 12 d), and workers from colony C required about 25 d. Five workers from colony A were mixed with 25 workers from the same colony, from colony B, or from colony C and maintained for 10 d. The five workers developed their ovaries most rapidly with their own sisters or with workers from colony C and slowest with unrelated, fast-developing workers from colony B ( P < 0.05). When a single worker from colony A was caged with 25 workers from colony C, all eggs were laid by the worker from colony A. Overall, 50% (19/38) of the workers from colony A became egg layers when they were caged alone with workers from colony C. Although workers from colony A developed their ovaries sooner than workers from colony C, the two groups had the same number of ovarioles. Yet, among sisters, ovaries with more ovarioles were significantly more developed than ovaries with fewer ovarioles.

SummaryNewly emerged worker honeybees (Apis mellifera L.) aged less than 24 h were placed into queen less cages and given a section of empty drone comb and unlimited supplies of honey, water and pollen. Cages were kept in an incubator at 34 ± 1°C. Workers treated with a 15-min exposure to CO2, at 0–3 days of age produced significantly fewer eggs than controls that received no CO2;. Workers in queenless cages for 4–6 days before CO2 narcosis had egg production equal LO that of controls. Thus CO2, had no apparent effect after the workers had been queenless for 4 days. In a second study, 5 untreated workers shared cages with 25 sisters that had been treated with three 15-min doses of CO2. Association with the treated workers retarded ovary development of the untreated cagemates when compared to sister bees in identical cages that contained no bees given CO2, Cages with treated workers consumed only 17% as much pollen as controls. So low pollen consumption may have reduced the total amount of protein that was...

This study examines changes in reproduction and mortality of Varroa destructorwhen queens from stocks of honey bees (Apis mellifera L.) that differ in susceptibility to the mites were exchanged between colonies. Queens were selected for suppression of mite reproduction (SMRD). In two experiments uniform colonies of bees were established; half the colonies were given queens selected for SMRD, and half were given unselected queens. Queens were exchanged after 7 (exper- iment 1) and 13 weeks (experiment 2). The percentage of mites that had no progeny was determined for each colony at 5 times (2 before and 3 after exchanging queens). Mites that had no progeny included live and dead mites. Results showed (1) that reproduction of mites is suppressed by adding a queen selected for SMRD, and (2) that a mite population recovers its reproduction when a SMRD queen is replaced by an unselected queen. Selection of the SMRD trait can be reduced to counting only live mites that laid no eggs and dead mites. Apis mellifera / Varroa destructor / resistance to pests / suppression of mite reproduction (SMRD)