ABSTRACT
The diamondback moth, Plutella xylostella (L.), is the most important pest of brassicaceous crops worldwide. Since temperature is the major abiotic factor influencing insect development and thermal requirements may vary among insect populations, it is important to know the effect of temperature on development and survival of a subtropical strain of P. xylostella. Development and survival of the diamondback moth was evaluated under seven constant temperatures ranging from 10°C to 35°C. Development was completed between 10°C and 32.5°C, but at 35°C all individuals died in the larval stage. Data were fitted to one linear and five nonlinear models. Considering as criteria the goodness of fit and the ability to estimate parameters of biological significance, the models Briere-1 and Briere-2 were the most adequate to describe the relationship between temperature and development of P. xylostella. The linear model demonstrated that P. xylostella required 312.5 degree-days above a lower threshold of 6.3°C to complete development. The degree-day model showed that the number of diamondback moth generations in the tropical region of Brazil is nearly twice the number in the subtropical region of the country. This result explains, at least in part, the higher population levels of this species in the tropical region of Brazil, and also demonstrates that P. xylostella is tolerant to a wide range of temperatures (6.1-32.5°C). Therefore, temperature cannot be considered a limiting factor for the occurrence of diamondback moth throughout the year in most regions of Brazil.
Subject(s)
Animals , Moths/growth & development , Brazil , Temperature , Tropical ClimateABSTRACT
The effects of sex and behavioral flexibility on leader perceptions were examined in small groups performing under two task conditions. We predicted, based on theory and previous empirical research, that leadership perceptions would be higher for: (1) persons higher in three indicators of behavioral flexibility (self-monitoring, self-reported behavioral capabilities, and androgyny), (2) males in general, and (3) tasks that were sex-congruent. Results showed significant, strong support for behavioral flexibility and sex effects and weak support for the effects of sex-congruent tasks. Exploratory analyses showed that perceived target capabilities mediated the effects of sex and behavioral flexibility. The discussion is organized around a theoretical model which suggests that target behavior and sex-based cues leading to leader categorization are in part mediated by inferred target capabilities. These capabilities show parallels to leadership-relevant traits such as masculinity, dominance, extroversion, and adjustment, identified in early leadership research. Copyright 1998 Academic Press.
