Publications by authors named "Robert Danka"

The negative effects of Varroa and pesticides on colony health and survival are among the most important concerns to beekeepers. To compare the relative contribution of Varroa, pesticides, and interactions between them on honey bee colony performance and survival, a 2-year longitudinal study was performed in corn and soybean growing areas of Iowa. Varroa infestation and pesticide content in stored pollen were measured from 3 apiaries across a gradient of corn and soybean production areas and compared to measurements of colony health and survival.

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The ectoparasite Varroa destructor is the greatest threat to managed honey bee (Apis mellifera) colonies globally. Despite significant efforts, novel treatments to control the mite and its vectored pathogens have shown limited efficacy, as the host remains naïve. A prospective solution lies in the development of Varroa-resistant honey bee stocks, but a paucity of rigorous selection data restricts widespread adoption.

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Honey bees are eusocial animals that exhibit both individual and social immune responses, which influence colony health. This is especially well-studied regarding the mite Varroa destructor Anderson and Trueman (Parasitiformes: Varroidae), a parasite of honey bee brood and disease vector. Varroa was introduced relatively recently to Apis mellifera L.

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Background: The population genetics of U.S. honey bee stocks remain poorly characterized despite the agricultural importance of Apis mellifera as the major crop pollinator.

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A non-activating semen diluent does not cause motility or acrosomal reaction or capacitate the sperm cell. The effects of such a diluent on the viability of honey bee spermatozoa stored in ambient conditions were assessed 60 days pre-cryopreservation and 24 h post-cryopreservation. Seven variations of a Tris-based non-activating diluents (FEM1 - FEM7) were compared to samples treated with conventional activating diluent and untreated semen.

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Field-scale data on the relationship between pollinator activity and fruit set are scarce for rabbiteye blueberries (Vaccinium virgatum Aiton). We measured the densities of Apis mellifera L. (Hymenoptera: Apidae), Habropoda laboriosa F.

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Neonicotinoid insecticides have come under scrutiny for their potential role in honey bee declines. Additionally, reduced access to forage in agricultural areas creates the potential for risk interactions with these pesticides in regions critical for honey production. In this study, we sought to determine whether sufficient access to pollen during larval development could mitigate stress associated with oral clothianidin exposure in honey bee adults.

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Few studies have examined the impact of mosquito adulticides on honey bees under conditions that reflect actual field exposure. Whereas several studies have evaluated the toxicity of mosquito control products on honey bees, most have been laboratory based and have focused solely on acute mortality as a measure of impact. The goal of this study was to determine effects of routine applications of truck-based ultra-low volume (ULV) mosquito adulticides (i.

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Varroa (Varroa destructor Anderson and Trueman) is an external parasite of honey bees (Apis mellifera L.) and a leading cause of colony losses worldwide. Varroa populations can be controlled with miticides, but mite-resistant stocks such as the Russian honey bee (RHB) also are available.

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Since Varroa mites may cause devastating losses of honey bees through direct feeding, transmitting diseases, and increasing pathogen susceptibility, chemical and mechanical practices commonly are used to reduce mite infestation. While miticide applications are typically the most consistent and efficacious Varroa mite management method, miticide-induced insecticide synergism in honey bees, and the evolution of resistance in Varroa mites are reasonable concerns. We treated colonies with the miticide amitraz (Apivar), used IPM practices, or left some colonies untreated, and then measured the effect of different levels of mite infestations on the sensitivity of bees to phenothrin, amitraz, and clothianidin.

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The number of honey bee colonies in the United States has declined to half of its peak level in the 1940s, and colonies lost over the winter have reached levels that are becoming economically unstable. While the causes of these losses are numerous and the interaction between them is very complex, the role of insecticides has garnered much attention. As a result, there is a need to better understand the risk of insecticides to bees, leading to more studies on both toxicity and exposure.

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To combat an increasing abundance of sucking insect pests, >40 pesticides are currently recommended and frequently used as foliar sprays on row crops, especially cotton. Foraging honey bees may be killed when they are directly exposed to foliar sprays, or they may take contaminated pollen back to hives that maybe toxic to other adult bees and larvae. To assess acute toxicity against the honey bee, we used a modified spray tower to simulate field spray conditions to include direct whole-body exposure, inhalation, and continuing tarsal contact and oral licking after a field spray.

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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.

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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.

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Two types of honey bees, Apis mellifera L. (Hymenoptera: Apidae), bred for resistance to Varroa destructor Anderson & Trueman 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.

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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.

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The incidence of nosemosis has increased in recent years due to an emerging infestation of Nosema ceranae in managed honey bee populations in much of the world. A real-time PCR assay was developed to facilitate detection and quantification of both Nosema apis and N. ceranae in both single bee and pooled samples.

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The utility of USDA-developed Russian and varroa sensitive hygiene (VSH) honey bees, Apis mellifera L. (Hymenoptera: Apidae), was compared with that of locally produced, commercial Italian bees during 2004-2006 in beekeeping operations in Alabama, USA. Infestations of varroa mites, Varroa destructor Anderson & Truman (Acari: Varroidae), were measured twice each year, and colonies that reached established economic treatment thresholds (one mite per 100 adult bees in late winter; 5-10 mites per 100 adult bees in late summer) were treated with acaricides.

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Significant additive genetic variance often occurs for male advertisement traits in spite of the directional selection imposed by female choice, a problem generally known in evolutionary biology as the lek paradox. One hypothesis, which has limited support from recent studies, for the resolution of this paradox is the role of genotype x environment interaction in which no one genotype exhibits the superior performance in all environments--a crossover of reaction norms. However, these studies have not characterized the actual variation of reaction norms present in natural populations, and the extent to which crossover maintains genetic variance remains unknown.

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Flight activity was compared in colonies of Russian honey bees, Apis mellifera L. (Hymenoptera: Apidae), and Italian bees during commercial pollination of lowbush blueberries (principally Vaccinium angustifolium Aiton) in Washington Co., ME, in late May and early June in 2003 and 2004.

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Differences in flight activity and in the percentages of pollen foragers between commercially managed honey bees, Apis mellifera L. (Hymenoptera: Apidae), of two stocks (USDA-ARS Russian, n = 41 colonies; and Italian, n = 43 colonies) were evaluated in an almond, Prunus dulcis (Miller) D. A.

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Worker honey bees from genetic strains selected for being resistant (R) or susceptible (S) to tracheal mites typically show large differences in infestation in field colonies and in bioassays that involve controlled exposure to infested bees. We used bioassays exposing newly emerged individuals to infested workers to compare the propensity for tracheal mites to infest queens, drones and workers from R and S colonies. In tests with queens, newly emerged R and S queens were either simultaneously confined in infested colonies (n = 95 and 87 respectively), or individually caged with groups of 5-20 infested workers (n = 119 and 115 respectively).

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We performed 43 open partial nephrectomies with different indications between 1996 and 2004, most of them (29) for renal cancer. We used different types of biocompatible materials for haemostasis. We describe our own recommendations and what is described in literature.

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Honey bees, Apis mellifera L., probe for nectar from robbery slits previously made by male carpenter bees, Xylocopa virginica (L.), at the flowers of rabbiteye blueberry, Vaccinium ashei Reade.

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