K r y s t y n a P

`Kent' strawberries were harvested at red, pink, and white stages of development, and stored at 15C in the light. Fruit were sampled over a 10-day period and evaluated for volatile production and surface color. Volatile production by red and pink fruit peaked after 4 days of storage. Maximum volatile production by red fruit was 8- and 25-fold greater than maximum production by pink and white fruit, respectively. Aroma volatiles were not detected in the headspace over white berries until 4 days following harvest after which volatile production increased through the tenth day of storage. Changes in the surface color of white berries during postharvest ripening coincided with the production of volatiles. In another experiment, red, pink, and white `Kent' strawberries were stored for 3 days at 10 or 20C in the dark or light. Fruit were then evaluated for volatile production, weight loss, anthocyanin content, and surface color changes. White berries produced volatile esters after 3 days of storage at 20C in the light. Both light and temperature influenced the relative production of the volatiles produced by pink fruit. Fresh weight loss, color change, and anthocyanin content were temperature and light dependent.

Effects of methyl jasmonate (JA-Me) on anthocyanin accumulation, ethylene production, and CO 2 evolution in uncooled and cooled tulips (Tulipa gesneriana L. cvs. Apeldoorn and Gudoshnik) were studied. JA-Me stimulated anthocyanin accumulation in stems and leaves from uncooled and cooled bulbs of both cultivars. The highest level of anthocyanin accumulation was observed in leaves from cooled bulbs treated with 200 L/liter JA-Me. In sprouting bulbs treated with 100 L/liter and higher concentrations of JA-Me, the ethylene production began to increase at 3 days after treatment, being extremely greater in uncooled bulbs than in cooled ones. JA-Me also stimulated CO 2 evolution in both cultivars, depending on its concentrations. CO 2 evolution in sprouting bulbs was not affected by cooling treatment. These results suggest that anthocyanin accumulation by JA-Me in tulip leaves is not related to ethylene production stimulated by JA-Me.

We investigated how different antioxidant defenses (ADSs) were shaped by evolution in young/old Apis mellifera workers and queens to broaden the limited knowledge on whether ADSs are effective in contemporary pesticide environments and to complete bee oxidative-aging theory. We acquired 1-day-old, 20-day-old, and 2-year-old queens and 1-day-old and 20-day-old workers (foragers) fed 0, 5, or 200 ppb imidacloprid, a pesticide oxidative stressor. The activities of catalase, glutathione peroxidase, glutathione S-transferase, and superoxide dismutase and the level of total antioxidant potential were determined in hemolymph. The ADS was upregulated in workers with age but downregulated in queens. Imidacloprid suppressed the ADS in all workers, particularly in foragers with an upregulated ADS, but it did not affect the ADS in 1-day-old queens. In contrast to foragers, the downregulated ADS of 2-year-old queens was unexpectedly highly upregulated by imidacloprid, which has not been previously shown in such old queens. The principal component analysis confirmed that queen and worker ADSs responded to imidacloprid in opposite ways, and ADS of 2-year-queens was markedly different from those of others. Thus, evolutionary shaped ADSs of older queens and workers may be of the limited use for foragers dwelling in pesticide ecosystems, but not for old queens.

DDT (dichlorodiphenyltrichloroethane) was used worldwide as an organochlorine insecticide to control agricultural pests and vectors of several insect-borne human diseases. It was banned in most industrialized countries; however, due to its persistence in the environment, DDT residues remain in environmental compartments, becoming long-term sources of exposure. To identify and select fungal species suitable for bioremediation of DDT-contaminated sites, soil samples were collected from DDT-contaminated agricultural soils in Poland, and 38 fungal taxa among 18 genera were isolated. Two of them, Trichoderma hamatum FBL 587 and Rhizopus arrhizus FBL 578, were tested for tolerance in the presence of 1-mg liter−1 DDT concentration by using two indices based on fungal growth rate and biomass production (the tolerance indices Rt:Rc and TI), showing a clear tolerance to DDT. The two selected strains were studied to evaluate catabolic versatility on 95 carbon sources with or without DDT by using the Phenotype MicroArray system and to investigate the induced oxidative stress responses. The two strains were able to use most of the substrates provided, resulting in both high metabolic versatility and ecological functionality in the use of carbon sources, despite the presence of DDT. The activation of specific metabolic responses with species-dependent antioxidant enzymes to cope with the induced chemical stress has been hypothesized, since the presence of DDT promoted a higher formation of reactive oxygen species in fungal cells than the controls. The tested fungi represent attractive potential candidates for bioremediation of DDT-contaminated soil and are worthy of further investigations. IMPORTANCE The spread and environmental accumulation of DDT over the years represent not only a threat to human health and ecological security but also a major challenge because of the complex chemical processes and technologies required for remediation. Saprotrophic fungi, isolated from contaminated sites, hold promise for their bioremediation potential toward toxic organic compounds, since they might provide an environment-friendly solution to contamination. Once we verified the high tolerance of autochthonous fungal strains to high concentrations of DDT, we showed how fungi from different phyla demonstrate a high metabolic versatility in the presence of DDT. The isolates showed the singular ability to keep their functionality, despite the DDT-induced production of reactive oxygen species.

The present studies are the second part of the research project dedicated to finding the causes for increased winter mortality of honey bee colonies. The aim of this task was to investigate incidents of overwintered colonies′ death with regard to the potential interrelation to the exposure to pesticides. The samples of winter stores of bee bread and sugar food (honey or syrup processed by bees), beeswax and bees collected from apiaries with low and high rates of winter colony mortality were searched for acaricides used to control V. destructor and plant protection pesticides. The presence of acaricides used in apiculture has been detected in the 51% beeswax samples. The most abundant acaricide was tau-fluvalinate. The stores of bee bread and sugar food had a similar frequency of plant protection pesticide occurrence, ranging between 50-60%, but the number of active substances and their concentrations were substantially lower in sugar food samples. The most prevalent pesticides in pollen were fungicides (carbendazim and boscalid) and insecticides (acetamiprid and thiacloprid). Only a few pesticides were found in the several dead honey bees. The level of pesticide contamination (frequency, concentration, toxicity) of hive products and bees originating from apiaries with both a high and low winter colony survival rates, was similar, which created a similar extent of risk. Although the multiple varroacides and pesticides were present in the hive environment we not found unequivocal links between their residues and high winter colony mortality.

A b s t r a c t The effects to honeybee colonies (Apis mellifera L.) during and after exposure to flowering maize (Zea mays L.), grown from seeds coated with clothianidin and imidacloprid was assessed in field-realistic conditions. The experimental maize crops were adjacent to the other flowering agriculture plants. Honey bee colonies were placed in three differently protected maize fields throughout the blooming period, and thereafter they were transferred to a stationary apiary. Samples of pollen loads, bee bread, and adult bees were collected and analyzed for neonicotinoid residues. To ensure high specificity and sensitivity of detection of the analyzed pesticides, a modified QuEChERS extraction method and liquid chromatography coupled with tandem mass spectrometry were used. Clothianidin was detected only in the samples of pollen loads. Their residue levels ranged from 10.0 to 41.0 ng/g (average 27.0 ng/g). Imidacloprid was found in no investigated sample. No negative effects of neonicotinoid seed-treated maize on the development and long-term survival of honey bee colonies were observed. The low proportion of Zea mays pollen in total bee-collected pollen during the maize flowering period was noted. The findings suggest that maize plants are less attractive forage for honey bees than phacelia (Phacelia tanacetifolia Benth.), buckwheat (Fagopyrum Mill.), white clover (Trifolium repens L.), goldenrod (Solidago L.), and vegetation from Brassicaceae family. The results indicate a possibility of reducing the risk of bees being exposed to the toxic effect of insecticidal dusts dispersed during maize sowing by seeding, in the areas surrounding maize crops, plants that bloom later in the year.

The effect of sublethal doses of imidacloprid on protein content and activity of proteases on honey bees was analyzed. The study was conducted in three experimental groups: colonies from groups BE-5 and BE-200 were contaminated with 5 and 200 ppb of imidacloprid, respectively, via their food supply (syrup and pollen), while group BE was used as control (untreated). Bee samples were collected 3 and 10 weeks after feeding started. Protein concentration in bee tissue extracts was analyzed with reference: (a) to the dose of imidacloprid; and (b) duration of exposure to the chemical. The average quantity of protein content was significantly higher at the 3-week interval than in the 10-week interval and the bees from control colonies (BE) had significantly higher protein contents than contaminated bees (BE-5 and BE-200), even 3 weeks after feeding with imidacloprid started. Similarly, the activity of proteolytic enzymes (proteases) was found to be dependent on the dose of imidacloprid used, compared to bees from control colonies showing significantly higher activity.Influencia de las dosis subletales de Imidacloprid en el contenido de proteína y la actividad proteolítica en las abejas melíferas (Apis mellifera L.)Se ha analizado el efecto de las dosis subletales de imidacloprid en el contenido de proteínas y la actividad de las proteasas en las abejas melíferas. El estudio se realizó en tres grupos experimentales: las colonias de los grupos de BE-5 y BE-200 se contaminaron con 5 y 200 ppb de imidacloprid, respectivamente, a través del alimento suministrado (jarabe y polen), mientras que el grupo SER se utilizó como control (sin tratar). Se recogieron muestras de abejas en las semanas 3 y 10 después del comienzo de la alimentació n. La concentració n de proteína en extractos de tejido de abejas se analizó en relació n con: a) la dosis de imidacloprid; y b) la duració n de la exposició n a la sustancia química. La cantidad promedio del contenido de proteína fue significativamente mayor en el intervalo de 3 semanas que en el intervalo de 10 semanas y las abejas de las colonias control (BE) tuvieron un contenido de proteína significativamente más alto que las abejas contaminadas (BE-5 y BE-200), incluso 3 semanas después de que comenzara la alimentació n con imidacloprid. Del mismo modo se encontró que la actividad de las enzimas proteolíticas (proteasas) depende de la dosis de imidacloprid usada, en comparació n con las abejas de colonias de control que muestran una actividad significativamente más alta.