Differential effects of weather and natural enemies on coexisting aphid populations.

Study of mechanisms responsible for regulating populations of living organisms is essential for a better comprehension of the structure of biological communities and evolutionary forces in nature. Aphids (Hemiptera: Sternorrhyncha) comprise a large and economically important group of phytophagous insects distributed worldwide. Previous studies determined that density-dependent mechanisms play an important role in regulating their populations.

Reduced viability of Colorado potato beetle, Leptinotarsa decemlineata, eggs exposed to novaluron.

Background: Novaluron is a benzoylphenyl urea chitin synthesis inhibitor that combines good activity against larval stages of the Colorado potato beetle, Leptinotarsa decemlineata (Say) (Coleoptera: Chrysomelidae), with low mammalian toxicity. Previous studies suggest that it has deleterious sublethal effects on adults.

Results: Continuous exposure of adult Colorado potato beetles to novaluron-treated foliage as both ovipositional and feeding substrate did not affect their survivorship or the number of eggs produced, but viable larvae hatched only from the eggs that were laid on the first day of the experiment.