Reaction norm variants for male calling song in populations of Achroia grisella (Lepidoptera: Pyralidae): toward a resolution of the lek paradox

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. Here, we present a study of genotype x environment interaction for the male calling song in populations of Achroia grisella (Lepidoptera: Pyralidae; lesser waxmoth). We report significant variance among reaction norms for male calling song in two North American populations of A. grisella as measured along temperature, food availability, and density gradients, and there is a relatively high incidence of crossover of the temperature reaction norms. This range of reaction norm variants and their crossover may reflect the co-occurrence of plastic and canalized genotypes, and we argue that the different responses of these variants along environmental gradients may contribute toward the maintenance of genetic variance for male song.     

Phosphatase production and activity in copper (II) accumulating Rhizopus delemar

The fungus Rhizopus delemar produced extracellular and cellular acid phosphatase during the growth in starch-supplemented medium in the presence or absence of copper ions. The levels of both AP-ase activities were maximal at the end of exponential growth phase and were dependent on copper concentrations. Copper ions in the medium provoked slight decrease of specific AP-ase activities and significant increase of the values of secreted enzyme per gram dry cells. On the other hand, an increase of copper ions in the reaction mixture leads to considerable increase of the values of cellular enzyme activity. Total uptake of copper (II) was highest at the highest copper (II) concentration, when resting cells were used. Between 27 and 30% copper (II) was not removed by acid washing, suggested that this copper was bound intracellularly by mycelium. Determination of the Michaelis constant for the cellular AP-ase gave value of 0.325 mM. The pH optimum of the enzyme was determined to be in the range of 3.5–4.5 using p-nitrophenyl phosphate (pNPP) as a substrate. The data obtained indicated a possible participation of AP-ases in the processes of heavy metal resistance and heavy metal uptake of this fungus.     

Nectar robbery by bees Xylocopa virginica and Apis mellifera contributes to the pollination of rabbiteye blueberry

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. This relationship between primary nectar robbers (carpenter bees) and secondary nectar thieves (honey bees) is poorly understood but seemingly unfavorable for V. ashei pollination. We designed two studies to measure the impact of nectar robbers on V. ashei pollination. First, counting the amount of pollen on stigmas (stigmatic pollen loading) showed that nectar robbers delivered fewer blueberry tetrads per stigma after single floral visits than did our benchmark pollinator, the southeastern blueberry bee, Habropoda laboriosa (F.), a recognized effective pollinator of blueberries. Increasing numbers of floral visits by carpenter bee and honey bee robbers yielded larger stigmatic loads. As few as three robbery visits were equivalent to one legitimate visit by a pollen-collecting H. laboriosa female. More than three robbery visits per flower slightly depressed stigmatic pollen loads. In our second study, a survey of 10 commercial blueberry farms demonstrated that corolla slitting by carpenter bees (i.e., robbery) has no appreciable affect on overall V. ashei fruit set. Our observations demonstrate male carpenter bees are benign or even potentially beneficial floral visitors of V ashei. Their robbery of blueberry flowers in the southeast may attract more honey bee pollinators to the crop.     

Analysis of the tellurite resistance determinant on the pNT3B derivative of the pTE53 plasmid from uropathogenic Escherichia coli

We have found and sequenced a significant part of the previously described tellurite resistance determinant on mini-Mu derivative pPR46, named pNT3B, originally cloned from a large conjugative plasmid pTE53, found in Escherichia coli. This plasmid contains genes essential for tellurite resistance, together with the protective region bearing genes terX, Y, W, and the conserved spacing region bearing several ORFs of unknown function. Computer analysis of obtained sequence revealed a close similarity to the formerly described ter operons found on the Serratia marcescens plasmid R478 and the chromosome of Escherichia coli O157:H7. This finding confirms the presence of a whole region on the large conjugative plasmid that pTE53 originated from a uropathogenic E. coli strain, and suggests its possible role in horizontal gene transfer, resulting in the development of new pathogenic E. coli strains.     

Assemblage structure and altitudinal distribution of lady beetles (Coleoptera,Coccinellidae) in the mountain spruce forests of Pol’ana Mountains,the West Carpathians

In two successive years we recorded a total of 3,636 individuals and 17 species of adult lady beetles (Coleoptera, Coccinellidae) in the spruce forests of Pol’ana Mts (the West Carpathians) at altitudes ranging from 600 m to 1,300 m a.s.l. Four lady beetle species were documented as predominating (dominance of abundance > 5%) over the study period. They were the following: Aphidecta obliterata (1,828 individuals and 50.3%), Coccinella septempunctata (634 individuals and 17.4%), Adalia conglomerata (594 individuals and 16.3%) and Anatis ocellata (279 individuals and 7.7%). The assemblages of lady beetles differed among the areas and also between the years. The season revealed neglegible effect on distribution of lady beetles, whereas the effect of altitude was more pronounced. A. conglomerata preferred the areas at lower altitude (600–725 m) to those at middle (900–925 m) and/or upper altitude (1,250–1,300 m). In contrast, A. obliterata and C. septempuctata were most abundant in the area at middle altitude. The altitudinal location of area partly explained the variability in abundance of lady beetles. The first ordination axis constructed by means of correspondence analysis (CA) represented an altitudinal gradient and accounted for 19.4% of the total variance of the species data. The great proportion of lady beetle species not typically associated with spruce and/or other coniferous trees than spruce (70.6%, n = 17) may be explained by an ecotonal effect.     

The contribution of tellurite resistance genes to the fitness of Escherichia coli uropathogenic strains

The presence of tellurite resistance gene operons has been reported in several human pathogens despite the fact that tellurium, as well as its soluble salts, are both rare in nature and are no longer in use as antimicrobial agents. We have introduced the cloned terWZA-F genes from an uropathogenic Escherichia coli isolate into another clinical E. coli isolate that was shown to be ter-gene free. The presence of the introduced genes increased the level of potassium tellurite resistance, as well as the level of resistance to oxidative stress mediated by hydrogen peroxide; and prolonged the ability of particular strains to survive in macrophages. We therefore propose that the contribution of tellurite resistance genes to oxidative stress resistance in bacteria is at least one reason for their presence in the genomes of a broad range of pathogenic microorganisms.     

Genetic detection and quantification of Nosema apis and N. ceranae in the honey bee

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. The assay is a multiplexed reaction in which both species are detected and quantified in a single reaction. The assay is highly sensitive and can detect single copies of the target sequence. Real-time PCR results were calibrated to spore counts generated by standard microscopy procedures. The assay was used to assess bees from commercial apiaries sampled in November 2008 and March 2009. Bees from each colony were pooled. A large amount of variation among colonies was evident, signifying the need to examine large numbers of colonies. Due to sampling constraints, a subset of colonies (from five apiaries) was sampled in both seasons. In November, N. apis levels were 1212 ± 148 spores/bee and N. ceranae levels were 51,073 ± 31,155 spores/bee. In March, no N. apis was detected, N. ceranae levels were 11,824 ± 6304 spores/bee. Changes in N. ceranae levels were evident among apiaries, some increasing and other decreasing. This demonstrates the need for thorough sampling of apiaries and the need for a rapid test for both detection and quantification of both Nosema spp. This assay provides the opportunity for detailed study of disease resistance, infection kinetics, and improvement of disease management practices for honey bees.