Population Dynamics of Anastrepha ludens (Loew) (Diptera: Tephritidae) on Citrus Areas in Southern Tamaulipas, Mexico.

An analysis of adult population fluctuation of Anastrepha ludens (Loew) was performed in southern Tamaulipas, Mexico from 2008 to 2011. The aim was to analyze population dynamics of A. ludens and its relationships with climatic factors in the citrus region of Llera, Tamaulipas, Mexico. Population densities were weekly examined to identify variation through the year and study period. Four periods were identified according to population size, amplitude, host availability and season of the year. The correlation between population density vs. rainfall and temperature (average, minimum and maximum) was determined by linear and multiple regression analyses. Simple linear regression analysis showed that population density with minimum temperature and rainfall was the most consistent correlation, whereas in multiple regression analysis, rainfall and maximum temperature showed more consistency. A seasonal association between the availability of commercial host, climatic variation, and population peaks of A. ludens was determined. This study may have practical implications for the design of specific control strategies, monitoring, and infestation prevention based on different phases of the pest through the year. This strategy, along with the area-wide approach implemented by the Plant Protection Service may lead to an optimization of material, financial and human resources.

Cadmium, lead and zinc concentrations in water, sediment and oyster (Crassostrea virginica) of San Andres Lagoon, Mexico.

The spatial distribution of cadmium, lead and zinc concentrations in water, sediment and oysters from San Andres Lagoon was evaluated. Significantly higher cadmium (0.33 mg L(-1)) and lead (0.70 mg L(-1)) concentrations in water were observed in front of the mouth of Tigre river, whereas, zinc concentration (5.0 mg L(-1)) was significantly higher in the south part of the lagoon. Similarly, lead and zinc values in sediment (1.01 and 9.29 µg g(-1), respectively) and oyster tissue (0.86 and 3.19 µg g(-1), respectively) were significantly higher in the south part of the lagoon. Levels of cadmium and lead in oyster tissue were positively related to those found in sediment. However, concerning zinc no evident relationship was found. Such differences in regression analyses may be explained by differential bioaccumulation of xenobiotic (cadmium, lead) and essential (zinc) metals.