Egg Hatching of Periphyllus Californiensis (hemiptera: Aphididae) in Two Microhabitats with Different Budburst Phenologies

Egg hatching of the maple aphid, Periphyllus californiensis Shinji, was observed on saplings of Acer amoenum Carriere in two microhabitats, i.e., the understory of a maple stand (a shaded site) and an open area in a nursery (a sunny site), over a 2-year period. Buds of A. amoenum opened earlier at the shaded site than at the sunny site and eggs of P. californiensis also hatched a little earlier at the shaded site. To test whether oviposition timing or microhabitat characteristics affected the timing of egg hatching, eggs were collected during four periods in December to observe egg hatching in the laboratory. Hatching occurred earlier at the shaded site than at the sunny site only for eggs laid in early December. The duration of egg hatching was shorter for eggs laid earlier compared with those laid later. The duration of the egg stage (estimated as the median oviposition date to the median egg hatching date) was negatively correlated with the time when the eggs were laid. These results suggest that differences in timing of egg hatching between habitats may be affected by the microhabitat and date of oviposition.