The effects of temperature on the life history traits of Rhopalosiphum maidis (Fitch) were determined at 6, 10, 15, 20, 25, 30, and 35 +/- 1 degrees C on corn leaves, Zea mays (L.). At 35 degrees C, only a few nymphs survived and completed development, but all failed to reproduce. Total immature stages from birth to adult decreased as temperature increased from 51.7 d at 6 degrees C to 5.2 d at 30 degrees C, but became 8.0 d at 35 degrees C. Overall immature development required 119.05 degree-days above 4.44 degrees C. Adult longevity was as high as 26.7 d at 15 degrees C, but significantly declined at 30 and 35 degrees C. The average adult fecundity was as high as 45 offspring at 15 and 20 degrees C, but dropped to 1.8 at 6 degrees C and 8.6 at 30 degrees C. In general, as temperatures increased, age-specific survivorship (I-x) declined more quickly, but age-specific fecundity (m(x)) peaked earlier. At 25 degrees C, the age-specific net maternity was the highest in the early reproductive period, resulting in the highest intrinsic rates of increase (r(m)=0.329). At 20-30 degrees C, the values of r(m) were significantly higher than those at lower temperatures. The results indicate that corn leaf aphids probably are better adapted in population growth to a wider range of high temperatures in warm regions

The presence of microplastics (MPs) in the environment has generated global concerns. However, the explicit assessment of the effect of multiple anthropogenic activities on the existence of MPs in the freshwater system is scarcely reported. This study quantified anthropogenic activities and analyzed their relationship with MPs on a freshwater organism: the midge larvae (Diptera: Chironomidae). The study took place in an urban river and consisted of comparing the abundance and types of MPs. Our results highlight that, while industrial area was the most important variable contributing to the total MP concentration in midge larvae, residential area also influenced the concentration of microfibers in midge larvae. The impact of a residential area on the relative abundance of microfibers in each sample site was diluted by the proximity to an industrial area. In conclusion, we suggest that industrial areas are a potential source of MP pollution in river sediment, and midge larvae can be a good indicator of the MP concentrations in urban river systems. Quantifying anthropogenic activities can help discern their effects on MP concentration in a river system and promote management strategies.