Distribution and population trends of two New Zealand endemic aphids (Hemiptera, Aphididae, Aphidinae)

Visual observations for colonies of Aphis healyi Cottier on Carmichaelia odorata Benth. bushes and Schizaphis sp. indet. on Aciphylla aurea W.R.B. Oliv. shrubs were made over several seasons at usually 4- to 8-week intervals (but seldom over winter) at two South Island, New Zealand sites (420 and 880 m above sea level, respectively). The presence of aphid parasitoid mummies was also noted. On several occasions, aphid samples were taken to verify species and identify morphs. Both aphid species appear to be monoecious (i.e. not alternating between woody and herbaceous plant hosts), with A. healyi exhibiting cyclical parthenogenesis and overwintering as eggs (i.e. holocyclic) and Schizaphis sp. indet. exhibiting year round parthenogenesis and overwintering as active morphs (i.e. anholocyclic). Aphis healyi colonies were found from December to May with the greatest numbers of colonies being found from December to February. Schizaphis sp. indet. colonies were found throughout the year, including mid-winter, with the greatest numbers of colonies usually being found from October to December. Updated distribution data indicate that both species are more widespread than previously reported, with A. healyi found from the Poor Knights Islands in the north to Southland in the south, and the Schizaphis sp. indet. on Aciphylla spp. found throughout the South Island but not the North Island. This short communication adds population, ecological and biological knowledge on these relatively poorly understood endemic aphid species from New Zealand that informs their conservation status.