Effects of propylparaben on fecundity and lifespan in Drosophila melanogaster

Parabensare are widely used as preservatives in cosmetics, foods and pharmaceutical products. Although parabens have generally been considered safe, several studies have cautioned that parabens have estrogenic or endocrine-disrupting properties. With the present study, the effects of four concentrations of propylparabens (200, 500, 1000, and 2000 mg L^?1) on fecundity, development and the lifespan of Drosophila melanogaster have been investigated. Decreased daily mean egg production was found in all exposure groups. In addition, the 100 mg L^?1 treatment significantly shortened egg-to-prepupa time and extended flies lifespan, consistent with a significant reduction in malonyldialdehyde (MDA) level and an increase in superoxide dismutase (SOD) activities. The 200 mg L^?1 treatment prolonged egg-to-prepupa time and decreased flies lifespan significantly, being consistent with a significant increase in MDA level and reduction in SOD activities.     

Effects of alternating temperatures on development and reproduction of the armyworm,Mythimna separata (Walker)

Effects of cycling and constant temperature on development and reproduction of the armyworm, Mythimna separata (Walker) were investigated by rearing the insects on the artificial diet under temperatures covering low(16-24℃ vs. 20 ℃ ), medial(20-28℃ vs. 24℃ ) and high(24-32 ℃ vs. 28 ℃) regions. In the low region, all the immature stages of the insect developed significantly faster under alternating temperatures than at corresponding constant temperatures. For the medial region, their development was little affected by variable temperatures. For the high region, developmental durations tended to be longer under cycling temperatures except egg stage.Mean fecundities of the adult moths markedly increased under cycling temperatures as compared with those at respective constant temperature in all regions.Possible reasons for effect of alternating temperatures on insect development are discussed in some details.     

Floater mortality within settlement areas can explain the Allee effect in breeding populations

The Allee effect (the positive relationship between population growth rate and population size) is a constraint of some animal populations at low numbers, which increases their likelihood of extinction because of a decrease in reproduction and/or survival. We were able to demonstrate that the Allee effect can be the result of a mortality increase affecting floaters (i.e. dispersing individuals able to enter as breeders in the reproductive population when a breeding territory or a potential mate – owner of a suitable breeding territory – becomes available). Previously, potential mechanisms underlying Allee effects were always related to the breeding portion of a population only. In contrast, our understanding of or solutions to population declines due to the Allee effects can reside elsewhere, away from breeding territories.     

Repellency and oviposition deterrence of wild tomato leaf extracts to spider mites,Tetranychus urticae Koch

Glandular trichomes on the leaves of wild tomato, Lycopersicon hirsutum f. hirsutum Mull, also known as Solanum habrochaites (Solanaceae) synthesize and accumulate high levels of methyl ketones (MKs). The potential of using MKs as alternatives to synthetic acaricides for controlling the twospotted spider mite, Tetranychus urticae Koch, is explored in this study. Plants of L. hirsutum accession LA 407 having high concentrations of MKs were grown from seeds under greenhouse conditions. The main objective of this investigation was to conduct bioassays that are quick and easy to implement, consistent over time (repeatable) with the ability to utilize small amounts of test material for testing repellency and fecundity (number of eggs laid by a female mite) of MKs in pure forms and in LA 407 crude extracts. Four MKs (2-tridecanone, 2-undecanone, 2-dodecanone, 2-pentadecanone) and their mixture were screened for their repellency and ability to alter fecundity of spider mites. All MKs repelled spider mites at the two periods tested. Following spraying of tomato leaf extracts prepared in ethanol (ethanol extracts), average number of eggs laid per female mite on bean leaf discs dropped from 0.8 to 0.3 and from 0.9 to 0.3 at 4 and 24 h after exposure representing 65 and 68% reduction, respectively. However, spraying of tomato leaf extracts prepared in water (water extracts) reduced number of eggs laid per female mite from 1.7 to 0.7 and from 2.6 to 0.9 at 4 and 24 h after exposure representing 60 and 67% reduction, respectively. We concluded that all MKs have repellent and egg laying deterrence activities against spider mites. This investigation suggests that ethanol and water extracts of LA 407 have a potential for repelling female spider mites and reducing their laid eggs which might be explored under field conditions for managing populations of spider mites, which could reduce reliance on synthetic acaricides.     

Demographic Parameters of the Tartarian Roe Deer Population in the Transural Region and the Main Factors Determining Them

The demographic parameters (sex and age structure, fecundity, and population growth) and the main environmental factors (legal hunting and poaching, predators, weather, and food supply) affecting the structure and dynamics of the large Tartarian roe deer (Capreolus pygargus Pall.) population of Kurgan oblast were studied. The question of the conformity between the population size and the carrying capacity of its range is considered.     

Response of successive three generations of cotton,bollworm,Helicoverpa armigera (Hübner),fed on cotton bolls under elevated CO_2

The growth,development and consumption of successive three generations of cotton bollworm,Helicoverpa armigera(Hübner),fed on cotton bolls grown under elevated CO_2(double-ambient vs.ambient)in open-top chambers were examined.Significant decreases in protein,total amino acid,water and nitrogen content and increases in free fatty acid were observed in cotton bolls.Changes in quality of cotton bolls affected the growth,development and food utilization of H.armigera.Significantly longer larval development duration in three successive generations and lower pupal weight of the second and third generations were observed in cotton bollworm fed on cotton bolls grown under elevated CO_2.Significantly lower fecundity was also found in successive three generations of H.armigera fed on cotton bolls grown under elevated CO_2.The consumption per larva occurred significant increase in successive three generations and frass per larva were also significantly increased during the second and third generations under elevated CO_2.Significantly lower relative growth rate,efficiency of conversion of ingested food and significant higher relative consumption rate in successive three generations were observed in cotton bollworm fed on cotton bolls grown under elevated CO_2.Significantly lower potential female fecundity,larval numbers and population consumption were found in the second and third generations of cotton bollworm fed on cotton bolls grown under elevated CO_2.The integrative effect of higher larval mortality rate and lower adult fecundity resulted in significant decreases in potential population consumption in the latter two generations.The results show that elevated CO_2 adversely affects cotton bolls quality,which indicates the potential population dynamics and potential population consumption of cotton bollworm will alleviate the harm to the plants in the future rising CO_2 atmosphere.     

Comparative Analysis of Coat Color Morphs in a Polymorphic Population of the Northern Mole Vole

Long-term stationary observations (1985–2000) on a polymorphic population of the northern mole vole (Ellobius talpinus Pall.) in Kurgan oblast were performed using the mark-recapture method. Original data were obtained on the abundance and structure of this population, which comprised individuals of three color morphs: black, brown, and intermediate (bicolor). Each morph proved to have its specific features with respect to abundance, age and sex composition, migration, birthrate, mortality, and life span. In general, this polymorphism contributes to population heterogeneity and the maintenance of population homeostasis.     

Response of successive three generations of cotton bollworm, Helicoverpa armigera (Hübner), fed on cotton bolls under elevated CO2

The growth, development and consumption of successive three generations of cotton bollworm, Helicoverpa armigera （Htibner）, fed on cotton bolls grown under elevated CO2 （double-ambient vs. ambient） in open-top chambers were examined. Significant decreases in protein, total amino acid, water and nitrogen content and increases in free fatty acid were observed in cotton bolls. Changes in quality of cotton bolls affected the growth, development and food utilization of H. armigera. Significantly longer larval development duration in three successive generations and lower pupal weight of the second and third generations were observed in cotton bollworm fed on cotton bolls grown under elevated CO2. Significantly lower fecundity was also found in successive three generations of H. armigera fed on cotton bolls grown under elevated CO2. The consumption per larva occurred significant increase in successive three generations and frass per larva were also significantly increased during the second and third generations under elevated CO2. Significantly lower relative growth rate, efficiency of conversion of ingested food and significant higher relative consumption rate in successive three generations were observed in cotton bollworm fed on cotton bolls grown under elevated CO2. Significantly lower potential female fecundity, larval numbers and population consumption were found in the second and third generations of cotton bollworm fed on cotton bolls grown under elevated CO2. The integrative effect of higher larval mortality rate and lower adult fecundity resulted in significant decreases in potential population consumption in the latter two generations. The results show that elevated CO2 adversely affects cotton bolls quality, which indicates the potential population dynamics and potential population consumption of cotton bollworm will alleviate the harm to the plants in the future rising CO2 atmosphere.