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Mexico is one of the world’s foremost producers and exportersof bees’ honey (Apis melliferaL.), and the state of Jalisco is one of the top threehoney producers in Mexico. However, the Mexican beekeeping industry is affectedby the high defensive behavior and lower honey production of Africanized honeybees compared to European bees. The objective of this study was to determinethe African or European ancestry of honey bee colonies in six regions of temperateand subtropical climates in the state of Jalisco, Mexico, using morphometric andmitochondrial DNA analyses. More than 50% of the colonies in Jalisco had Africanmitotype and morphotype (59.0% and 62.5%, respectively).The frequency ofafricanization of the studied colonies was significantly higher (p < 0.05) in regionsof low altitude and in subtropical climates, such as the Southeast and Southwestregions, than in regions of higher elevation and in temperate climates, such as LosAltos. There was a significant correlation between the forewing length of the beesand the altitude at which their colonies were located (r = 0.51, p< 0.01), indicatingthat the lower the altitude, the higher the degree of africanization of the bees. Futurestudies are warranted to determine if the degree of africanization of honey beecolonies increases or remains in equilibrium. These studies will make it possibleto design mitigation strategies against the negative effects of the africanization ofhoney bees., México es de los principales productores y exportadores de miel deabejas (Apis melliferaL.) a nivel mundial y el estado de Jalisco se encuentraentre los tres primeros productores a nivel nacional. Sin embargo, la apiculturamexicana es afectada por el alto comportamiento defensivo y menor productividadde las abejas africanizadas en comparación con abejas europeas. El objetivo deeste estudio fue determinar la ancestría africana o europea de colonias de abejasmelíferas en seis regiones de clima templado y subtropical en el estado de Jalisco,México, mediante análisis morfométricos y de ADN mitocondrial. Más del 50%de las colonias de abejas de Jalisco tuvieron mitotipo y morfotipo africano (59.0 y62.5%, respectivamente). La frecuencia de africanización de las colonias fue sig-nificativamente mayor (p < 0.05) en regiones de baja altitud y climas subtropicales(regiones Sureste y Suroeste), que en regiones de mayor elevación y en climastemplados (región de los Altos). Hubo correlación significativa entre la longitud delala de las abejas y la altitud a la que se encontraban las colonias (r = 0.51, p < 0.01);esto indica que a menor altitud hay un mayor grado de africanización de las abejas.Se recomiendan realizar estudios para determinar si el grado de africanización delas colonias de abejas aumenta o se mantiene en equilibrio, lo que permitirá diseñarestrategias de amortiguamiento de los efectos negativos de la africanización de lasabejas melíferas.

The invasive aquatic plant Egeria densa (Brazilian waterweed) is a submersed aquatic plant that has expanded its distribution in both its native and introduced range. Because the plant grows so densely, it can become a problem for management of waterways and habitat restoration projects. It is difficult to remove once established and mechanical and chemical controls have shown limited effectiveness. Here we analyze the distribution of E. densa in the Sacramento–San Joaquin Delta (the Delta) of California, USA, using environmental variables that include mean water velocity, mean water turbidity, and water column depth. We found that increasing water column depth strongly limited E. densa occurrence, especially when depth at mean lower low water (MLLW) exceeds 2 m. The highest probability of occurrence occurred at locations with a water column depth of −1 to 2 m at MLLW. Turbidity had a reliably negative effect on E. densa occurrence; as water clarity has increased in the Delta, it has likely favored the spread of the plant. Neither mean water velocity nor maximum water velocity had a reliable effect on E. densa probability, in spite of scientific and observational evidence that it is sensitive to flows. These results suggest potentially serious problems with restoration projects that emphasize shallow water habitat in the range favored by E. densa. Without some way to manage spread of the plant—through spraying, sediment loading, or gating—channels in such projects are at risk of being taken over by E. densa. However, these results should be interpreted in light of the fact that water outflow in water year 2008 was very low, and that E. densa abundance may be partially controlled by higher water flows than those considered here.

The invasive aquatic plant Egeria densa (Brazilian waterweed) is a submersed aquatic plant that has expanded its distribution in both its native and introduced range. Because the plant grows so densely, it can become a problem for management of waterways and habitat restoration projects. It is difficult to remove once established and mechanical and chemical controls have shown limited effectiveness. Here we analyze the distribution of E. densa in the Sacramento–San Joaquin Delta (the Delta) of California, USA, using environmental variables that include mean water velocity, mean water turbidity, and water column depth. We found that increasing water column depth strongly limited E. densa occurrence, especially when depth at mean lower low water (MLLW) exceeds 2 m. The highest probability of occurrence occurred at locations with a water column depth of −1 to 2 m at MLLW. Turbidity had a reliably negative effect on E. densa occurrence; as water clarity has increased in the Delta, it has likely favored the spread of the plant. Neither mean water velocity nor maximum water velocity had a reliable effect on E. densa probability, in spite of scientific and observational evidence that it is sensitive to flows. These results suggest potentially serious problems with restoration projects that emphasize shallow water habitat in the range favored by E. densa. Without some way to manage spread of the plant—through spraying, sediment loading, or gating—channels in such projects are at risk of being taken over by E. densa. However, these results should be interpreted in light of the fact that water outflow in water year 2008 was very low, and that E. densa abundance may be partially controlled by higher water flows than those considered here.