Age, sex, adult and larval diet shape starvation resistance in the Mediterranean fruit fly: an ecological and gerontological perspective.

The ability of an animal to withstand periods of food deprivation is a key driver of invasion success (biodiversity), adaptation to new conditions, and a crucial determinant of senescence in populations. Starvation resistance (SR) is a highly plastic trait and varies in relation to environmental and genetic variables. However, beyond Drosophila, SR has been studied poorly. Exploiting an interesting model species in invasion and ageing studies-the Mediterranean fruit fly (Ceratitis capitata)- we investigated how age, food and gender, shape SR in this species. We measured SR in adults feeding in rich and poor dietary conditions, which had been reared either on natural hosts or artificial larval diet, for every single day across their lifespan. We defined which factor is the most significant determinant of SR and we explored potential links between SR and ageing. We found that SR declines with age, and that age-specific patterns are shaped in relation to adult and larval diet. Females exhibited higher SR than males. Age and adult diet were the most significant determinants of SR, followed by gender and the larval diet. Starvation resistance proved to be a weak predictor of functional ageing. Possible underlying mechanisms, ecological and gerontological significance and potential applied benefits are discussed

A Framework to Update Hofstede’s Cultural Value Indices: Economic Dynamics and Institutional Stability”,

Abstract This study offers an update of the Hofstede cultural value dimensions. We argue that changes in economic conditions are the source of cultural dynamics, while the endurance of institutional characteristics provides the foundation for cultural stability. It is found that national wealth, measured by GDP per capita, has a curvilinear relationship with individualism, long-term orientation, and power distance scores. Relatively speaking, uncertainty avoidance and masculinity mainly reflect some rather stable institutional traditions, such as language, religion, climate, ethnic homogeneity, and legal origin, and are less likely to change over time

POPULATION ECOLOGY Threshold Temperature for Post-Diapause Development and Degree-Days to Hatching of Winter Eggs of the European Red Mite (Acari: Tetranychidae) in Northern Greece Downloaded from

ABSTRACT The threshold temperature for postdiapause development in overwintering eggs of the European red mite, Panonychus ulmi (Koch), was determined after exposing the eggs to various constant temperatures (5, 10, 15, 20, and 25ЊC) in the laboratory. The mean number of days to 50% hatch in each temperature was Ͼ120, 44.5, 22.0, 14.5, and 8.1 d, respectively. From the regression of postdiapause developmental rate to temperature, it was estimated that 50% of egg hatch coincides with the accumulation of 154.6 degree-days (DD) above the threshold of 7.4ЊC. In the Þeld (1991 and 1993Ð1996), 50% egg hatch occurred from the end of March to 20 April after the accumulation of a mean sum of 129.4 Ϯ 4.5 DD above the threshold of 7.4ЊC from 10 February onward. The starting date of 10 February for heat accumulation was chosen because earlier experiments had shown that diapause is terminated in 50% of the eggs in the Þrst half of February. Using the theoretical sum of 154.6 DD, the predicted dates for 50% egg hatch deviated from Þeld observations by an average of 3.7 Ϯ 0.5 d over the 5 yr of experiments. KEY WORDS Panonychus ulmi, European red mite, degree-days, hatching, winter eggs THE EUROPEAN RED mite, Panonychus ulmi (Koch), is an important foliar pest of apple trees feeding on the palisade and spongy mesophyl cells and causing a reduction in the photosynthetic rates of the plant Application of chemical acaricides early in spring against newly hatched larvae is a widely used method for the control of this mite. The development of a degree-day (DD) model for predicting the time of egg hatch in the Þeld could be a useful tool for the proper timing of acaricide applications. In the current study we determined the threshold temperature for postdiapause development and subsequently using laboratory and Þeld data estimated a sum of degree-days for predicting the time of egg hatch. The accuracy of the degree-day model for predicting egg hatch was validated under Þeld conditions. Materials and Methods Threshold Temperature for PostDiapause Development. Twigs bearing diapause-eggs were cut from an apple orchard in the area of Alexandria (Northern Greece) in the second half of February of 1994, and subsequently transferred to the laboratory. The course of diapause termination in the Þeld was determined in earlier experiments by transferring diapause eggs during winter and early spring for 4 yr (1992Ð 1996) from the same and other apple orchards to short days (a photoperiod of 8:16 [L:D] h) at 20ЊC where percentages of diapause termination were determined Every third day the percentage of eggs hatch at each temperature was determined. The data were then used to estimate the mean number of days required for 50% egg hatch (t 50% ) at each temperature. The reciprocal, 1/t 50% , represented the daily rate of postdiapause embryonic development. The threshold temperature for postdiapause development was estimated by the x-intercept metho

Understanding the seasonal and reproductive biology of olive fruit fly is critical to its management

The olive fruit fly was first detected in Los Angeles in 1998 and in all the olive-growing regions of California soon after. Following its initial detection, UC researchers and Cooperative Extension farm advisors, county agricultural commissioners and the California Department of Food and Agriculture Pest Detection and Emergency Project established a statewide monitoring program to determine the extent of the olive fruit fly’s occurrence, track its seasonal biology and evaluate monitoring tools. Fly populations and infestations can reach high levels throughout California but tend to be lower in the San Joaquin Valley. Trap captures typically exhibit a bimodal distribution with peaks in the spring and fall. Olive infestation is related to fly densities, climate and fruit size. Gravid, mated females vary in density throughout the year but are present at some level year-round. The data is being used to develop models that will better predict when the adults are active and olives are at risk

Cross-talk between high light stress and plant defence to the two-spotted spider mite in Arabidopsis thaliana

Little is known about how plants deal with arthropod herbivores under the fluctuating light intensity and spectra which occur in natural environments. Moreover, the role of simultaneous stress such as excess light (EL) in the regulation of plant responses to herbivores is poorly characterized. In the current study, we focused on a mite-herbivore, specifically, the two-spotted spider mite (TSSM), which is one of the major agricultural pests worldwide. Our results showed that TSSM-induced leaf damage (visualized by trypan blue staining) and oviposition rate (measured as daily female fecundity) decreased after EL pre-treatment in wild-type Arabidopsis plants, but the observed responses were not wavelength specific. Thus, we established that EL pre-treatment reduced Arabidopsis susceptibility to TSSM infestation. Due to the fact that a portion of EL energy is dissipated by plants as heat in the mechanism known as non-photochemical quenching (NPQ) of chlorophyll fluorescence, we tested an Arabidopsis npq4-1 mutant impaired in NPQ. We showed that npq4-1 plants are significantly less susceptible to TSSM feeding activity, and this result was not dependent on light pre-treatment. Therefore, our findings strongly support the role of light in plant defence against TSSM, pointing to a key role for a photo-protective mechanism such as NPQ in this regulation. We hypothesize that plants impaired in NPQ are constantly primed to mite attack, as this seems to be a universal evolutionarily conserved mechanism for herbivores

Financing micro-entrepreneurs for poverty alleviation: a performance analysis of microfinance services offered by BRAC, ASA, and Proshika from Bangladesh

Microfinance services have emerged as an effective tool for financing microentrepreneurs to alleviate poverty. Since the 1970s, development theorists have considered non-governmental microfinance institutions (MFIs) as the leading practitioners of sustainable development through financing micro-entrepreneurial activities. This study evaluates the impact of micro-finance services provided by MFIs on poverty alleviation. In this vein, we examine whether microfinance services contribute to poverty alleviation, and also identify bottlenecks in micro-finance programs and operations. The results indicate that the micro-loans have a statistically significant positive impact on the poverty alleviation index and consequently improve the living standard of borrowers by increasing their level of income

ENTREPRENEURSHIP AND ECONOMIC DEVELOPMENT: THE RELATIONSHIP REVISITED

No abstract received.