Hygiene-Eliciting Brood Semiochemicals as a Tool for Assaying Honey Bee (Hymenoptera: Apidae) Colony Resistance to Varroa (Mesostigmata: Varroidae)

Despite numerous interventions, the ectoparasitic mite Varroa (Varroa destructor Anderson and Trueman [Mesostigmata: Varroidae]) and the pathogens it vectors remain a primary threat to honey bee (Apis mellifera Linnaeus [Hymenoptera: Apidae]) health. Hygienic behavior, the ability to detect, uncap, and remove unhealthy brood from the colony, has been bred for selectively for over two decades and continues to be a promising avenue for improved Varroa management. Although hygienic behavior is expressed more in Varroa-resistant colonies, hygiene does not always confer resistance to Varroa. Additionally, existing Varroa resistance selection methods trade efficacy for efficiency, because those achieving the highest levels of Varroa resistance can be time-consuming, and thus expensive and impractical for apicultural use. Here, we tested the hypothesis that hygienic response to a mixture of semiochemicals associated with Varroa-infested honey bee brood can serve as an improved tool for predicting colony-level Varroa resistance. In support of our hypothesis, we demonstrated that a mixture of the compounds (Z)-10-tritriacontene, (Z)-8-hentriacontene, (Z)-8-heptadecene, and (Z)-6-pentadecene triggers hygienic behavior in a two-hour assay, and that high-performing colonies (hygienic response to ≥60% of treated cells) have significantly lower Varroa infestations, remove significantly more introduced Varroa, and are significantly more likely to survive the winter compared to low-performing colonies (hygienic response to <60% of treated cells). We discuss the relative efficacy and efficiency of this assay for facilitating apiary management decisions and selection of Varroa-resistant honey bees, as well as the relevance of these findings to honey bee health, pollination services, and social insect communication.

Stock-specific chemical brood signals are induced by Varroa and Deformed Wing Virus, and elicit hygienic response in the honey bee

The health of the honey bee Apis mellifera is challenged by the ectoparasitic mite Varroa destructor, and the numerous harmful pathogens it vectors. Existing pesticide-based Varroa controls are not sustainable. In contrast, one promising approach for improved honey bee health is the breeding of hygienic bees, capable of detecting and removing brood that is parasitized or diseased. In three experiments we find evidence to support the hypothesis that stock-specific chemical brood signals are induced by Varroa and Deformed Wing Virus, and elicit hygienic response in the honey bee. By collecting, analyzing, and running bioassays involving mite-infested and control brood extracts from three honey bee breeding stocks we: 1) found evidence that a transferrable chemical signal for hygienic behavior is present in Varroa-infested brood extracts, 2) identified ten stock-specific hydrocarbons as candidates of hygienic signaling, and 3) found that two of these hydrocarbons linked to Varroa and DWV were also elevated in brood targeted for hygienic behavior. These findings expand our understanding of honey bee chemical communication, and facilitate the development of improved hygienic selection tools to breed honey bees with greater resistance to Varroa and associated pathogens.

Risk factors for Nipah virus encephalitis in Bangladesh

Patients in Goalando were likely infected by direct contact with fruit bats or their secretions, rather than through contact with an intermediate host.

Nipah virus (NiV) is a paramyxovirus that causes severe encephalitis in humans. During January 2004, twelve patients with NiV encephalitis (NiVE) were identified in west-central Bangladesh. A case–control study was conducted to identify factors associated with NiV infection. NiVE patients from the outbreak were enrolled in a matched case-control study. Exact odds ratios (ORs) and 95% confidence intervals (CIs) were calculated by using a matched analysis. Climbing trees (83% of cases vs. 51% of controls, OR 8.2, 95% CI 1.25–∞) and contact with another NiVE patient (67% of cases vs. 9% of controls, OR 21.4, 95% CI 2.78–966.1) were associated with infection. We did not identify an increased risk for NiV infection among persons who had contact with a potential intermediate host. Although we cannot rule out person-to-person transmission, case-patients were likely infected from contact with fruit bats or their secretions.

Design and performance of a sub-nanoradian resolution autocollimating optical lever

Precision goniometry using optics has the advantage that it does not impose much stress on the object of investigation and, as such, is adopted extensively in gravitational wave detection, in torsion balances investigating fundamental forces, in specialized studies of biological samples, and it has potential applications in condensed matter physics. In this article we present the considerations that go into designing optical levers and discuss the performance of the instrument we have constructed. We motivate the design by considering an idealized setup and the limitations to the angular resolution induced by statistical fluctuations of the photon count rate and diffraction at the apertures. The effects of digitization of the count rate and of the spatial location of the photons on the image plane motivating the actual design are discussed next. Based on these considerations, we have developed an autocollimating optical lever which has a very high resolution and dynamic range. An array of 110 slits, of 90 microm width and a pitch of 182 microm, is located in the focal plane of a field lens, of focal length 1000 mm, and is illuminated by a CCFL tube. This array is imaged back onto the focal plane after retroreflection from a mirror placed just beyond the lens. The image is recorded on a linear charge-coupled device array at the rate of 1000 images/s and is processed through a special algorithm to obtain the centroid. The instrument has a centroid stability of approximately 3 x 10(-10) rad Hz(-1/2) and a dynamic range of approximately 10(7).

Different expression and activity of the alpha1 and alpha4 isoforms of the Na,K-ATPase during rat male germ cell ontogeny

Two catalytic isoforms of the Na,K-ATPase, alpha1 and alpha4, are present in testis. While alpha1 is ubiquitously expressed in tissues, alpha4 predominates in male germ cells. Each isoform has distinct enzymatic properties and appears to play specific roles. To gain insight into the relevance of the Na,K-ATPase alpha isoforms in male germ cell biology, we have studied the expression and activity of alpha1 and alpha4 during spermatogenesis and epididymal maturation. This was explored in rat testes at different ages, in isolated spermatogenic cells and in spermatozoa from the caput and caudal regions of the epididymis. Our results show that alpha1 and alpha4 undergo differential regulation during development. Whereas alpha1 exhibits only modest changes, alpha4 increases with gamete differentiation. The most drastic changes for alpha4 take place in spermatocytes at the mRNA level, and with the transition of round spermatids into spermatozoa for expression and activity of the protein. No further changes are detected during transit of spermatozoa through the epididymis. In addition, the cellular distribution of alpha4 is modified with development, being diffusely expressed at the plasma membrane and intracellular compartments of immature cells, finally to localize to the midregion of the spermatozoon flagellum. In contrast, the alpha1 isoform is evenly present along the plasma membrane of the developing and mature gametes. In conclusion, the Na,K-ATPase alpha1 and alpha4 isoforms are functional in diploid, meiotic and haploid male germ cells, alpha4 being significantly upregulated during spermatogenesis. These results support the importance of alpha4 in male gamete differentiation and function.

Field evaluation of a method for estimating gaseous fluxes from area sources using open-path Fourier transform infrared

This paper describes results from the first field experiment designed to evaluate a new approach for quantifying gaseous fugitive emissions of area air pollution sources. The approach combines path-integrated concentration data acquired with any path-integrated optical remote sensing (PI-ORS) technique and computed tomography (CT) technique. In this study, an open-path Fourier transform infrared (OP-FTIR) instrument sampled path-integrated concentrations along five radial beam paths in a vertical plane downwind from the source. A meteorological station collected measurements of wind direction and wind speed. Nitrous oxide (N2O) was released from a controlled area source simulator. The innovative CT technique, which applies the smooth basis function minimization method to the beam data in conjunction with measured wind data, was used to estimate the total flux from the simulated area source. The new approach estimates consistently underestimated the true emission rates in unstable atmospheric conditions and agreed with the true emission rate in neutral atmospheric conditions. This approach is applicable to many types of industrial areas or volume sources, given the use of an adequate PI-ORS system.